Report on Pool Boiling Experiment Prototype Model Flown on STS-47 (PBE-IA) Herman Merte, Jr. Ho Sung Lee Robert B. Keller NASA Contract NAS 3 - 25812 Report No. UM-MEAM-94-09 June 1994 Conducted under:, National Aeronautics and Space Administration Lewis Research Center Cleveland, Ohio

ii7iusSe

Table of Contents Page # List of Figures...............................................iii List of Tables.......................................... xii List of Appendices............................................. xiii 1. INTRODUCTION......................................... 1 1.1 General Background.................................... 1 1.2 Objectives of Study..................................... 3 1.3 Basic Mechanisms of Pool Boiling........................... 5 1.3.1 Nucleate Boiling................................. 5 1.3.2 Dryout (Film Boiling in Earth Gravity).................. 9 2. EXPERIMENTAL CONCEPTS AND PARAMETERS................. 10 2.1 Geometry and Configuration........................ 11 2.2 Fluid....................................... 12 2.3 Controlled Variables.............................. 12 2.4 Measured Parameters............................. 13 3. HARDWARE DESCRIPTION................................. 16 3.1 Heater Surface........................................ 16 3.2 Test Vessel.......................................... 17 3.3 Accelerometer System.................................. 18 3.4 Optical System....................................... 18 4. TEST MATRIX........................................... 29 5. EXPERIMENTAL RESULTS......................... 31 5.1 Measured Parameters 5.1.1 Internal to Test Vessel............................. 31 5.1.2 Accelerometer.................................. 34 5.2 Thermal Results....................................... 36 5.2.1 Canister Ambient................................ 36 5.2.2 Test Matrix Runs................................ 36 5.3 Test Matrix Representative Photographic Views................. 37 6. DISCUSSION......................... 102 6.1 Conduction Eftfects.................................... 102 6.1.1 Conduction in Substrate....................... 102 6.1.2 Conduction in Fluid....................... 103 6.2 Nucleation......................... 105 6.3 Bubble Dynamics.106 6.4 Heat Transfer to Fluid................................... 110 7. CONCLUSIONS...,......................... i152 References.............................................. 154 Appendix 155 ii

List of Figures Figure 2. 1. R- 113 Degassing Unit Schematic. Figure 3.1. Transparent gold film heater/resistance thermometer on quartz substrate. PBE-IA. STS-47. Figure 3.2. Schematic of Test Vessel with concepts to provide constant pressure and initially uniform fluid temperature. Figure 3.3. Locations of Sensors for Scientific Analysis. Figure 3.4. Locations of R- 113 fluid thermistor in test vessel. Figure 3.5. Test vessel. Relative locations of internal components, lights and viewing windows. Figure 3.6. PBE Components in GAS canister. Side view. Figure 3.7. PBE Components in GAS canister. Front view. Figure 3.8. Correlation between PBE-IA accelerometer and SAMS and STS-47 units. Figure 3.9. Correlation between PBE-IA accelerometer and Photographic view on STS-47. Primary heater is in use on left side. Figure 3.10. Scheme for LED timing lights in camera field of view. Figure 5.1. PBE-IA structure temperature in GAS canister. Figure 5.2a. Run No. 1 PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.2b. Run No. 1. PBE-IA. STS-47. Heat flux input. Figure 5.2c. Run No. 1. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.2d. Run No. 1. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.2e. Run No. 1. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.3a. Run No. 2. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.3b. Run No. 2. PBE-IA. STS-47. Heat flux input. Figure 5.3c. Run No. 2. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.3d. Run No. 2. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.3e. Run No. 2. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures.

Figure 5.4a. Run No. 3. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.4b. Run No. 3. PBE-IA. STS-47. Heat flux input. Figure 5.4c. Run No. 3. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.4d. Run No. 3. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.4e. Run No. 3. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.5a. Run No. 4. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.5b. Run No. 4. PBE-IA. STS-47. Heat flux input. Figure 5.5c. Run No. 4. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.5d. Run No. 4. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.5e. Run No. 4. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.6a. Run No. 5. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.6b. Run No. 5. PBE-IA. STS-47. Heat flux input. Figure 5.6c. Run No. 5. PBE-IA. STS-47. STS-47. System pressure and fluid side heat flux. Figure 5.6d. Run No. 5. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.6e. Run No. 5. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.7a. Run No. 6. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.7b. Run No. 6. PBE-IA. STS-47. Heat flux input. Figure 5.7c. Run No. 6. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.7d. Run No. 6. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.7e. Run No. 6. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.8a. Run No. Run No. 7. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.8b. Run No. 7. PBE-IA. STS-47. Heat flux input. iv

Figure 5.8c. Run No. 7. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.8d. Run No. 7. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.8e. Run No. 7. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.9a. Run No. 8. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.9b. Run No. 8. PBE-IA. STS-47. Heat flux input. Figure 5.9c. Run No. 8. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.9d. Run No. 8. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.9e. Run No. 8. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.10a. Run No. 9. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient. Figure 5.10b. Run No. 9. PBE-IA. STS-47. Heat flux input. Figure 5.10c. Run No. 9. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.10d. Run No. 9. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. Figure 5.10e. Run No. 9. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. Figure 5.11 Run No. 1. PBE-IA. STS-47. Selected Photographic Images. Figure 5.12. Run No. 2. PBE-IA. STS-47. Selected Photographic Images. Figure 5.13. Run No. 3. PBE-IA. STS-47. Selected Photographic Images. Figure 5.14. Run No. 4. PBE-IA. STS-47. Selected Photographic Images. Figure 5.15. Run No. 5. PBE-IA. STS-47. Selected Photographic Images. Figure 5.16. Run No. 6. PBE-IA. STS-47. Selected Photographic Images. Figure 5.17. Run No. 7. PBE-IA. STS-47. Selected Photographic Images. Figure 5.18. Run No. 8. PBE-IA. STS-47. Selected Photographic Images. Figure 5.19. Run No. 9. PBE-IA. STS-47. Selected Photographic Images. Figure 6.1. Comparisons of 1-D and 3-D predicted temperatures with measurements. PBE-IA on STS-47. Run No. 3. qT = 1.8 w/cm2, ATsub = 10.9~C. Figure 6.2. PBE-IA on STS-47. Run No. 3. Isometric plot of 3-D temperature distribution in quartz substrate at 40 seconds. Figure 6.3. PBE-IA on STS-47. Run No. 3. Isometric plot of 3-D temperature distribution in quartz substrate at 90 seconds. v

Figure 6.4. PBE-IA on STS-47. Run No. 3. Comparison of fluid heat transfer coefficients computed from measured mean heater surface temperatures using 1-D finite difference and 3 - D finite element models. Figure 6.5. PBE-IA on STS-47. Measured heater surface temperature filtered by averaging three (3) consecutive measurement points sequentially. Figure 6.6. PBE-IA on STS-47. Run No. 3. Measured heater surface temperature filtered by averaging five (5) consecutive measurement points sequentially. Figure 6.7. PBE-IA on STS-47. Run No. 3. Comparison of the fluid heat transfer coefficients obtained by taking the input heat flux as constant or variable. Figure 6.8. Nucleation delay correlation developed during ground based and 5.1 second drop tower testing. Figure 6.9. Comparison between nucleation delay times of PBE-IA prior to, during, and following STS-47 Flight with ground based and 5.1 second drop tower correlation. Figure 6.10. T.eater surface nucleation superheat during ground based r.nd 5.1 second drop tower testing. Figure 6.11. Heater surface nucleation superheat of PBE-IA prior to, during, and following STS-47 Flight. Figure 6.12. Prediction of spherical vapor bubble growth in saturated R-113, corresponding to PBE-IA Run Nos. 7-9. Figure 6.13. Schematic representation of boiling observed on heater surface in microgravity, from PBE-IA on STS 47. Figure 6.14. Heater surface representation from underside with defined terms. Figure 6.15a. PBE-IA on STS-47. Run No. 9. Transient measured mean heater surface temperature and fractional dry area. Time interval: 61.5-67.5 seconds. Figure 6.15b. PBE-IA on STS-47. Run No. 9. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 61.567.5 seconds. Figure 6.15c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 61.567.5 seconds. Figure 6.15d. PBE-IA on STS-47. Run No. 9. Sample images showing rewetting. Time interval: 61.5-67.5 seconds. vi

Figure 6.16a. PBE-IA on STS-47. Run No. 9. Transient measured mean heater surface temperature and fractional dry area. Time interval: 80.5-85.5 seconds. Figure 6.16b. PBE-IA on STS-47. Run No. 9. Relation between measured heat transfer coefficient and heater fractional wet area. Time interval: 80.5-85.5 seconds. Figure 6.16c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 80.585.5 seconds. Figure 6.16d. PBE-IA on STS-47. Run No. 9. Sample images showing dryout. Time interval: 80.5-85.5 seconds. Figure 6.17a. PBE-IA on STS-47. Run No. 9. Transient measured heater surface temperature and fractional dry area. Time interval: 42-50 seconds. Figure 6.17b. PBE-IA on STS-47. Run No. 9. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 42-50 seconds. Figure 6.17c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 42-50 seconds. Figure 6.17d. PBE-IA on STS-47. Run No. 3. Sample images showing dryout. Time interval: 61.5-67.5 seconds. Figure 6.18a. PBE-IA on STS-47. Run No. 9. Transient measured heater surface temperature and fractional dry area. Time interval: 83.5-90 seconds. Figure 6.18b. PBE-IA on STS-47. Run No. 9. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 83.590 seconds. Figure 6.18c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured hater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 83.5-90 seconds. Figure 6.18d. PBE-IA on STS-47. Run No. 3. Sample images showing gradual dryout. Time interval: 83.5-90 seconds. Figure 6.19a. PBE-IA on STS-47. Run No. 9. Transient measured heater surface temperature and fractional dry area. Time interval: 50-58 seconds. vii

Figure 6.19b. PBE-IA on STS-47. Run No. 9. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 50-58 seconds. Figure 6.19c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 50-58 seconds. Figure 6.19d. PBE-IA on STS-47. Run No. 6. Sample images of increase in wetting. Time interval: 50 - 58 seconds seconds. Figure C1. PBE-IA accelerometer measurement. Run No. 1. Figure C2. PBE-IA accelerometer measurement. Run No. 2. Figure C3. PBE-IA accelerometer measurement. Run No. 3. Figure C4. PBE-IA accelerometer measurement. Run No. 4. Figure C5. PBE-IA accelerometer measurement. Run No. 5. Figure C6. PBE-IA accelerometer measurement. Run No. 6. Figure C7. PBE-IA accelerometer measurement. Run No. 7. Figure C8. PBE-IA accelerometer measurement. Run No. 8. Figure C9. PBE-IA accelerometer measurement. Run No. 9. Figure D la. Mean heater surface temperature and derived heat transfer coefficient. Run No. 1 Figure Dib. Heat flux input. Run No. 1. Figure Dlc. System pressure and heat flux into fluid. Run No. 1. Figure D2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2. Figure D2b. Heat flux input. Run No. 2. Figure D2c. System pressure and heat flux into fluid. Run No. 2. Figure D3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3. Figure D3b. Heat flux input. Run No. 3. Figure D3c. System pressure and heat flux into fluid. Run No. 3. Figure D4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4. Figure D4b. Heat flux input. Run No. 4. Figure D4c. System pressure and heat flux into fluid. Run No. 4. Figure D5a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 5. viii

Figure D5b Heat flux input. Run No. 5. Figure D5c. System pressure and heat flux into fluid. Run No. 5. Figure D6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6. Figure D6b. Heat flux input. Run No. 6. Figure D6c. System pressure and heat flux into fluid. Run No. 6. Figure D7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7. Figure D7b. Heat flux input. Run No. 7. Figure D7c. System pressure and heat flux into fluid. Run No. 7. Figure D8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8. Figure D8b. Heat flux input. Run No. 8. Figure D8c. System pressure and heat flux into fluid. Run No. 8. Figure D9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9. Figure D9b. Heat flux input. Run No. 9. Figure D9c. System pressure and heat flux into fluid. Run No. 9. Figure Ela. Mean heater surface temperature and derived heat transfer coefficient. Run No. 1. Figure Elb. Heat flux input. Run No. 1. Figure Elc. System pressure and heat flux into fluid. Run No. 1. Figure E2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2. Figure E2b. Heat flux input. Run No. 2. Figure E2c. System pressure and heat flux into fluid. Run No. 2. Figure E3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3. Figure E3b. Heat flux input. Run No. 3. Figure E3c. System pressure and heat flux into fluid. Run No. 3. Figure E4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4. Figure E4b. Heat flux input. Run No. 4. Figure E4c. System pressure and heat flux into fluid. Run No. 4. Figure E5a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 5. ix

Figure E5b. Heat flux input. Run No. 5. Figure E5c. System pressure and heat flux into fluid. Run No. 5. Figure E6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6. Figure E6b. Heat flux input. Run No. 6 Figure E6c. System pressure and heat flux into fluid. Run No. 6. Figure E7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7. Figure E7b. Heat flux input. Run No. 7. Figure E7c. System pressure and heat flux into fluid. Run No. 7. Figure E8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8. Figure E8b. Heat flux input. Run No. 8. Figure E8c. System pressure and heat flux into fluid. Run No. 8. Figure E9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9. Figure E9b. Heat flux input. Run No. 9. Figure E9c. System pressure and heat flux into fluid. Run No. 9. Figure Fla. Mean heater surface temperature and derived heat transfer coefficient. Run No. 1. Figure Flb. Heat flux input. Run No. 1. Figure Flc. System pressure and heat flux into fluid. Run No. 1. Figure F2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2. Figure F2b. Heat flux input. Run No. 2. Figure F2c. System pressure and heat flux into fluid. Run No. 2. Figure F3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3. Figure F3b. Heat flux input. Run No. 3. Figure F3c. System pressure and heat flux into fluid. Run No. 3. Figure F4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4. Figure F4b. Heat flux input. Run No. 4. Figure F4c. System pressure and heat flux into fluid. Run No. 4. Figure FSa. Mean heater surface temperature and derived heat transfer coefficient. Run No. 5. x

Figure F5b. Heat flux input. Run No. 5. Figure F5c. System pressure and heat flux into fluid. Run No. 5. Figure F6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6. Figure F6b. Heat flux input. Run No. 6. Figure F6c. System pressure and heat flux into fluid. Run No. 6. Figure F7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7. Figure F7b. Heat flux input. Run No. 7. Figure F7c. System pressure and heat flux into fluid. Run No. 7. Figure F8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8. Figure F8b. Heat flux input. Run No. 8. Figure F8c. System pressure and heat flux into fluid. Run No. 8. Figure F9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9. figure F9b. Heat flux input. Run No. 9. Figure F9c. System pressure and heat flux into fluid. Run No. 9. xi

List of Tables Page # I. Original Prior Flight Calibration Coefficients for PBE-IA on STS-47. Measurements made 2/13/92................. 16 II. Test matrix for PBE-IA on STS-47. (Prototype Hardware).... 30 III. PBE-IA. Parameters measured at ag = -1 and a/g = +1 in Pre flight and Post flight tests, and during STS-47 Space Flight........ 32 IV. Summary of relatively larger acceleration excursions during PBE-IA in STS-47 Flight............................. 35 V. PBE-IA. Comparison of measured mean heat transfer coefficients between a/g = +1 and STS-47 Space Flight................ 109 VI. PBE-IA on STS-47. Candidates for heater surfacy dry spot area measurements and computation of microgravity nucleate pool boiling heat transfer coefficient....................... 115 xii

List of Appendices Page # A. Specific Technical Requirements............................. 155 B. Coefficients for the Vapor-Pressure Curve for R- 113............... 156 C. Plots of the X, Y, Z, accelerometer measurements for each Run of PBE-IA in the STS-47..1.................................. 157 D. Plots of results of Pre-Flight test conducted for PBE-IA at a/g = -1 on 4/28/92........................................... 167 E. Plots of results of Post-Flight test conducted for PBE-LA at a/g = +1 on 11/4/92...................................... 195 F. Plots of results of Post-Flight test conducted for PBE-IA at a/g = - 1 on 12/22/92............................................ 223 xiii

1. INTRODUCTION 1.1 General Background Nucleate boiling is an important mode of heat transfer in that relatively small temperature differences can provide large rates of heat transfer, which can result in significant economic and other benefits associated with the smaller heat transfer areas necessary to accomplish a given function. A limitation in the development of more compact power sources using nuclear energy lies in the ability to remove the large heat generation rates possible from the reactor core in a manner that is consistent, reliable and predictable. Nucleate boiling would be a candidate for such an application were the fundamental mechanisms that govern the process sufficiently well understood. Additional important applications of nucleate boiling exist, such as steam generation in conventional power plants, distillation processes in petroleum and other chemical plants, and the boiling of refrigerants in cooling coils, in which the motion of the bulk liquid is generally imposed externally. This is termed forced convection boiling, and the liquid motion moves the vapor formed away from the heated surface so that the vapor may be utilized and/or further processed and the nucleate boiling process can continue. Other applications exist in which externally forced flow is absent, where buoyancy provides the major mechanism for vapor removal from the vicinity of the heating surface, and is generally designated pool boiling. Even in circumstances where forced convection exists to some extent, the forces associated with flow acting on the vapor bubbles may be sufficiently small that buoyancy or body forces will continue to be responsible for the vapor removal process. It should then be possible to describe the behavior, in terms of the basic governing mechanisms, by the pool boiling process. Devices in which pool boiling occurs are two-phase closed thermosyphons, reboilers, and heat pipes, whether gravity assisted or not. Potentially significant applications exist in the cooling of microelectronic circuitry and the internal cooling of gas turbine blades. The latter would involve pool boiling under high gravity fields, and its successful application would permit higher operating temperatures with attendant higher efficiencies, and would also eliminate the need for the development of exotic ceramic materials with the difficulties of thermal stresses and reliability. Another important and as yet poorly understood area incorporated in the mechanism of pool boiling is the breakdown of film boiling into the transition boiling regime. This is of concern in the loss-of-coolant accident in nuclear power plants, and is encompassed in the reflooding and fuel element rewetting processes. A good 1

understanding of this rewetting process in microgravity or in the absence of buoyancy would improve its application with buoyancy. The effective and enhanced applications of both nucleate pool and forced convection boiling requires a sound understanding of the mechanisms governing the processes. The vapor removal from the vicinity of the heater surface, as understood to this point, occ.Trs primarily by buoyancy in the case of pool boiling and bulk liquid inertia in the case with forced convection. Although the variation of both gravity and forced flow are known to influence the overall heat transfer processes, other forces or potentials are acting as well, and the relative significances of these are as yet poorly understood. Requirements for the proper functioning of equipment and personnel in the space environment of reduced gravity and vacuum, as will be necessary in space station modules and space power generation, energy dissipation, the storage, transfer, control and conditioning of fluids (including cryogenic liquids), and liquid-vapor separation. The temperature control in certain locations where internal heat generation takes place as a result of dissipation, as from friction or joulian heating, electronic equipment, or as a consequence of a nuclear or chemical heat source, may require that this energy be transported to other locations of the facility or stored locally for later transport and elimination. The use of the phase changes of vaporization and condensation to transport energy have the advantage of accommodating large variations in heat loads with relatively small temperature gradients and changes in temperature levels, along with the economical use of pumping power. Energy storage might be advantageous for intermittent processes or for processes where momentary surges could not be accommodated by a steady transfer of mass to a remote location, and also could take advantage of the latent heat associated with phase changes. A distinction must be made between pool boiling and flow boiling when considering applications in the space environment of microgravity, since these two processes may arise in quite different specific technical applications. Pool boiling, for example, would be important for the short term cooling of high power electronic and other devices, and for the long term space storage of cryogens. Flow boiling, on the other hand, occurs in applications where liquid flow is imposed externally, such as in Rankine:vcle vapor generation or in thermal energy management using pumped latent heat transport. Certain effects which can be neglected at normal earth gravity, such as sun tension and vapor momentum, can become quite significant at microgravity co.nditions. Momentum imparted to the liquid by the vapor bubble during growth tends to draw the vapor bubble away from the surface, depending on the rate of growth, which in turn is governed by the temperature distribution of the liquid. Thermophoretic forces, arising 2

from the variation of the liquid-vapor surface tension with temperature, on the other hand, tend to move the vapor bubble toward the region of higher temperature. The bubble motion will be governed by which of these two effects prevail. In addition, thermophoretic forces acting at the liquid-vapor interface of vapor bubbles in contact with a heated surface could act to bring cooler liquid to the heater surface, delaying or inhibiting the onset of dryout, or promoting and enhancing the rewetting of the heater surface. 1.2 Objectives of Study The research as originally proposed was intended to seek to improve the understanding of the fundamental mechanisms that constitute nucleate pool boiling. The vehicle for accomplishing this is an investigation, including experiments conducted in microgravity and coupled with appropriate analyses, of the heat transfer and vapor bubble dynamics associated with nucleation, bubble growth/collapse and subsequent motion, considering the interrelations between buoyancy, momentum and surface tension which will govern the motion of the vapor and surrounding liquid, as a function of the heating rate at the heat transfer surface and the temperature level and distribution in the bulk liquid. As will become clear when the results obtained to date are examined below, a more accurate representation would have been a proposal for a general study of pool boiling in microgravity. The circumstances under which nucleate boiling and what is generally termed, to this point, film boiling takes place with pool boiling in microgravity is as yet unclear. Both of these processes were observed, sometimes simultaneously, in the work to be presented here. An adequate understanding of the mechanisms in any process implies that its behavior can be predicted in terms of the governing parameters. The behavior here would include the conditions for the onset of boiling, the dynamics of the vapor bubbles, including both the number density of active nucleating sites and the frequency of formation, and the associated heat transfer. Although a considerable amount of research has been conducted on nucleate boiling over the years, and has been useful with respect to application to various technologies on earth, the ability to predict its behavior is as yet very limited, owing to the involvement and interactions of the many parameters. To this now should be added also the limitations in predicting the onset of dryout or rewetting, whether in earth gravity or microgravity. For the basic study proposed and conducted, with results presented here, it was deemed essential to establish a well-defined "bench mark" which could withstand future interrogations. The availability of a long period of quiescence prior to the onset of each test, as a result of the microgravity environment, means that the initial state at the onset of 3

heating and at the onset of boiling (nucleation) will be well-defined. This is not possible in a gravity field. The availability of relatively long test periods permit the combination of low heat flux and subcooling that require more time for the inception of boiling than is available in a drop tower, and also permit the observing of long-term vapor dynamic behavior following the transient bubble growth. The components which constitute the nucleate boiling process-nucleation. growth, motion, collapse (if subcooled) of the vapor bubbles - are common to both pool and flow boiling. The study here focuses on the fundamental mechanisms of pool boiling only, under microgravity conditions. This eliminates the complications associated with having an external flow field superimposed on that generated by growing/collapsing vapor bubbles. In addition, this eliminates the possibility of having other effects masked by an external flow field similar to that produced by buoyancy. In the experiments as conducted, a pool of liquid, initially at a precisely defined pressure and temperature, is subjected to a step imposed heat flux from a semi-transparent thin-film heater forming part of one wall of the container such that boiling is initiated and maintained for a defined period of time at a constant pressure level. Transient measurements of the heater surface and fluid temperatures near the surface are made, noting in particular the conditions at the onset of boiling, along with motion photography of the boiling process in two simultaneous views, from beneath the heating surface and from the side. The conduct of the experiment and the data acquisitions are completely automated and self-contained. A total of nine tests were conducted at three levels of heat flux and three levels of subcooling. The results presented here were obtained with what is termed the Prototype Version of the experimental facility. Following the successful development work conducted during the ground-based activity under NASA Grant NAG3-663, which included reduced gravity testing in the evacuated 5 second drop tower at the NASA Lewis Research Center, the results of which were reported in Ervin and Merte (1991), Ervin et al (1992), and Lee and Merte (1993), approval was given for a space experiment. An Engineering Model was developed by the NASA Lewis Research Center for testing the feasibility of incorporating the experimental concepts described in the Science Requirements Document by Merte (1989) into the space available in a Get-Away-Special (GAS). Following the successful demonstration of the operation of the Engineering Model, the construction of a Prototype Version was undertaken. This proved to operate so successfully with full testing in earth gravity that when an opportunity for an unexpected early GAS flight came to light a request was made to fly the Prototype Version. This was justified primarily as an opportunity to further test the heretofore untried engineering concepts in the facility, and to confirm the 4

camera timings which could not be determined in the drop tower testing. The successful acquisition of any experimental measurements was thus viewed to be a bonus. The results obtained later with the Flight Version of the experimental apparatus will be the subject of a future report, and will include comparisons with the results presented here. 1.3 Basic Mechanisms of Pool Boiling As stated above, consideration of any externally imposed flow field on the boiling process, termed as forced convection boiling, is explicitly excluded here in order to: (a) Eliminate an additional complicating variable from an already complex process at the outset. Pool boiling is the limiting case of forced convection boiling as the imposed velocity is reduced to zero. (b) Minimize the possibility that certain weak effects would be overshadowed by the kinetic energy associated with the imposed bulk liquid flow. The supposedly weak effects were considered to consist primarily of thermophoretic and molecular momentum forces. 1.3.1 Nucleate Boiling Nucleate boiling may be characterized as: (i) A liquid-vapor phase change occurs with the formation of discrete bubbles at individual sites. (ii) The energy transfer rates are large with small temperature difference driving potentials. (iii) The process is inherently transient, although quasi cyclic repetitions are possible with vapor removal mechanisms such as buoyancy acting. Before a nucleate pool boiling system can attain the steady periodic behavior normally observed in a gravity field, where buoyancy is the predominant vapor removal mechanism, the process must pass through a transient phase referred to as the nucleation, initiation or onset of nucleate boiling. Before understanding the cyclic nature of nucleate boiling, one must first understand the elements of the initial transient process. To provide a perspective of the relationship between the study conducted here and the overall processes which constitute pool boiling, a qualitative physical description of the sequence of events which occur is presented, beginning with the transient heating of a liquid at a solid-liquid interface 5

a. Conduction With an initially static liquid the heat transfer process can be described by conduction alone until buoyancy, thermophorysis or other forces set the liquid in motion. The rate of temperature rise and the temperature distributions in this early interval depend G;u the nature of the heat source and the dynamic interactions with the system. The common Riealizations taken as limits in analyses are step changes in either temperature or heat flux at the solidliquid heater interface. The degree and extent to which the liquid becomes superheated above its saturation temperature in a given time depends on whether and by how much the bulk liquid is subcooled. This temperature distribution will be modified by the onset of natural convection or by other disturbances. b. Onset of Natural convection Natural convection is driven by buoyancy, and its onset is described in terms of a stability in which the enervating disturbances are always present. Reducing the buoyancy by reducing the body forces such as to microgravity delays the onset of the convection and reduces the resulting convection velocities. Both of these serve to increase the temperature levels in the liquid adjacent to the heating surface for a given heating time, regardless of whether the bulk liquid is initially saturated or subcooled. The liquid temperature levels and distributions adjacent to the heater surface are thus influenced by buoyancy, and in turn can influence the next two elements of nucleate boiling: the nucleation and bubble growth rates. c. Nucleation Vaporization can take place only at an existing liquid-vapor interface, which then constitutes the growth phase of nucleate boiling. If an interface does not exist it must be formed. The formation of a vapor nucleus is called nucleation, and is classified either homogeneous or heterogeneous, depending on the presence of other components or species in the vicinity of the nucleation. The circumstances under which nucleation takes place on a heated solid surface depends on: (i) The Heater Surface Microgeometry. This can provide the crevices and intergranular defects which serve as pre-existing interfaces. The temperature levels required to activate these pre-existing nuclei have been modeled in terms of thermodynamic equilibrium at curved liquid-vapor interfaces. Assuming that the pre-existing interface has the form of a hemisphere of the size of the surface defect, the liquid superheat required for subsequent bubble growth can be related to cavity size. The smaller is the cavity, the larger is the 6

heater surface superheat required for the onset of nucleate boiling, and the larger will be the bulk liquid temperatures at the onset of the next element of the boiling process. (ii) The Solid-Fluid properties. This governs not only the temperature distributions in both the heater and fluids, related by their respective thermal properties, but also the surface energy relationships between the solid-liquid-vapor, often expressed in terms of a contact angle or wettability. (iii) The Liquid Temperature Distribution. This includes the solid-liquid interface temperature, since this is one spatial limit of the liquid temperature. As discussed under "b" above, the onset of natural convection governs the subsequent temperature distributions, as does also the initial imposed heat flux. Once nucleation has occurred, the following bubble growth rates will be governed by the bulk liquid temperature distribution at this time. d. Vapor Bubble Growth/Collapse Vapor bubble growth requires that the liquid at the liquid-vapor interface be superheated with respect to the saturation temperature corresponding to the interfacial liquid pressure. The rate of vapor formation, and hence bubble growth, depends on this superheat and on the liquid temperature gradient at the interface, and thus on the liquid temperature distribution at the onset of bubble growth. The interfacial liquid superheat governs the internal vapor bubble pressure, which acts to move the bulk liquid away from the vicinity of the heater surface. In the dynamics of the growth process this pressure is balanced in a complex manner by the liquid inertia, liquid viscosity, buoyancy, and surface tensions. If the bulk liquid is subcooled, the pressure difference can reverse with the subsequent collapse of the vapor bubble. The various forces acting in the bubble growth/collapse can be summarized: (i) Internal Bubble Pressure. This is governed by the liquid temperature distribution, which in turn is influence by buoyancy. (ii) Liquid Momentum. This is sometimes referred to as bulk liquid inertia. (iii) Buoyancy. The pressure differences associated with the liquid-vapor density differences in a body force field act in addition to those natural convection effects which influence the liquid temperature distribution. (iv) Surface Tension. This includes both that occurring at the liquid-vapor interface and at the liquid-solid-vapor interline. 7

(v) Viscosity. This refers primarily to the liquid viscosity acting in the vicinity of the solid surface, but could include the viscous normal shear at the liquidvapor interface away from the solid surface in circumstances where the radial growth rate is very large. Vapor viscosity could also be a factor during the very early periods when surface rates of vapor formation are large. Since the liquid-vapor interface is deformable, the interfacial shape during growth will be governed by the net balance of the dynamic forces acting at each point on the interface, and the interface will not necessarily be spherical or hemispherical, as has been assumed in the absence of capabilities for dealing with flexible interfaces. e. Departure The subsequent motion of the vapor bubble depends on the net effect of the forces listed in "d" above, plus a phenomena associated with simultaneous evaporation and condensation across a vapor bubble, referred to as a molecular momentum effect. This is related to the molecular kinetic energy necessary for vapor molecules to escape or to be retained at a liquid-vapor interface. With thermodynamic equilibrium the net rate of evaporation and condensation is zero, but the normal nucleate boiling process is highly non-equilibrium. The net resulting molecular momentum forces are generally unobservable in the presence of the overwhelming body and other forces which usually exist. The bulk liquid momentum induced by the rapid bubble growth can act to assist in the removal of the bubble from the heater surface. In microgravity, of course, buoyancy effects are reduced significantly. f. Motion Following Departure If the circumstances of the forces acting on the vapor bubble are such that departure takes place, the subsequent motion depends on the following: (i) Buoyancy (ii) Initial velocity upon departure. This velocity induces momentum in the bulk liquid, which must be considered, and can tend to accelerate the vapor bubble if collapse takes place, or will decelerate the bubble if it grows. (iii) Degree and distribution of liquid superheat and/or subcooling. The bulk liquid temperature distribution can act via the liquid-vapor surface tension or Marangoni-induced effects, via the bulk liquid momentum effects associated with growth or collapse, together with liquid viscosity, and via the molecular momentum effects. In microgravity conditions, only buoyancy will be 8

changed, except for its more indirect influence on the bulk liquid temperature distribution. 1.3.2 Dryout (Film Boiling in Earth Gravity) Nucleate boiling can take place only in circumstances where the liquid substantially wets the heater surface. This entails two implications. First, the liquid itself must be inherently wetting on the heater surface. As observed and discussed by Merte (1967), it is well known, for example, that mercury is generally non-wetting except for materials with which it forms amalgams. For the operation of mercury power generation plants it was necessary to add traces of Magnesium and Titanium to the mercury to promote wetting and nucleate boiling in the boiler tubes. The second implication is that the vapor generation rate and hence the heat flux level is not sufficiently high to reach the critical heat flux, sometimes referred to as the first boiling crisis, the nucleate boiling maximum heat flux, or the burnout heat flux. A specific heater surface temperature is generally related to this heat flux, and if the heater surface temperature exceeds this level a decrease in the heat transfer rate takes place, hence the term maximum heat flux. This decrease takes place because of a progressive increase in the dryout of the surface until the liquid is no longer in contact with the heater surface. This condition is then referred to as film boiling, since in the buoyancy of earth gravity it takes on the form of a thin vapor film in contact with the heater, and departure of the vapor from the vicinity occurs in various ways depending on the heater surface configuration and orientation relative to gravity. The minimum heater surface temperature at which film boiling can be sustained at its corresponding heat flux is referred to as the minimum film boiling heat flux, the Leidenfrost point, or the second boiling crisis. The so-called transition boiling region between the first and second boiling crises can be considered as a spatially averaged combination of nucleate boiling and film boiling, in which the fractional proportion of film boiling or dryout changes from O to 1 over this domain. This perspective neglects the contributions of dry areas under individual bubbles at the individual nucleation sites. In the present work, the use of the transparent heater surface permits the direct viewing and assessment of the relative proportions of the dry areas on the heater surface. The processes of the first and second boiling crises, including the transition boiling regime between, can be generically designated by a single term as dryout or wetting, depending on the direction in which this inherently transient or dynamic process is taking place. It appears that the circumstances of operation in the transition region taking place during pool boiling in microgravity are considerably less well-defined than in earth gravity, and could be the subject of further studies. 9

2. EXPERIMENTAL CONCEPTS AND PARAMETERS The basic study conducted here is intended to assist in extending the understanding of the mechanisms of nucleate pool boiling. Because of the complexity associated with the conduct of research in a microgravity environment it is essential to establish a well defined "bench mark" which will not require repeating. The availability of a reasonably long period of quiescence prior to the onset of each test means that the initial state at the onset of heating and at the onset of boiling (nucleation) will be well-defined. The availability of relatively long test periods for each run, with a maximum value of 2 minutes selected as representing a compromise, permits the combinations of low heat flux and subcooling that require more than the 5 seconds previously available in a drop tower for the inception of boiling, and also permits the observing of long-term vapor dynamic behavior following the transient bubble growth. Although the experiment as conducted is quite specific and well defined, it is also exploratory in nature, and has the potential for relatively fast turn-around with follow-on experiments. The elements of nucleate boiling for which research conducted under microgravity would advance the basic understanding are stated in brief here: (i) Nucleation or onset of boiling. Indications are that both heater surface temperature and temperature distribution in the liquid are necessary to describe nucleation, in addition to the character of the heater surface itself. (ii) The dynamic growth of a vapor bubble in the vicinity of the heater surface. This includes the shape as well as motion of the liquid-vapor interface as growth is taking place. These are influenced by the liquid temperature distribution at the initiation of growth. (iii) The subsequent behavior of the vapor bubble. This includes the motion, whether departure takes place or not, and the associated heat transfer. Each of the specific features of the experiment were selected so as to provide data which will be consistent with and maximize the objectives of improving the basic understanding embodied in these elements. The features include: 10

2.1 Geometry and Configuration (a) Pool boiling. This eliminates the complications associated with having an external flow field superimposed on that generated by a growing/collapsing vapor bubble. (b) Large flat heater surface. A flat surface avoids poorly defined local surface tension effects associated with curved interfaces, and with a transparent substrate can permit viewing from beneath the heater surface. A size as large as possible consistent with other constraints is desirable in order to minimize edge effects, and to permit a reasonable degree of axial symmetry of the vapor bubble as it grows to a quasi-steady condition. Additional considerations associated with large flat heater surfaces are: (i) With heating from curved surfaces, different liquid flow patterns will occur during bubble growth depending on whether the liquid is on the convex or concave side. (ii) With flat surfaces, which may also be approximations of curved surfaces, the orientation with respect to the body force vector will affect the flow behavior, down to some (as yet) unknown body force level. (iii) The fluid motion with large surfaces will differ depending on whether the surface is heated uniformly or locally. One further facet of vapor bubble nucleation and growth as influenced by surface tension and related to geometry can be mentioned here. The superheat that the liquid acquires in the boundary layer adjacent to the heater surface can be considerable, prior to nucleation. It is thus possible for the vapor formed initially to completely envelope the heater surface. With certain configurations such as small wires or cylinders it is possible that subsequent surface tension effects will maintain a stable "pseudo" film boiling process only because of the particular geometry used. It is expected that even if film boiling becomes suppressed to nucleate boiling on a small wire or cylinder, thermophoretic and surface tension effects and the resulting heat transfer will be quite different than with flat surfaces. Observations made by Weinzierl and Straub (1982) that pool nucleate boiling is uninfluenced by changes from earth gravity to microgravity are believed 11

to be a result of the large surface tension effects associated with the fine wire used, so that buoyancy is relatively unimportant. (c) Transparent heater surface. This permits the observation of the det.-lled behavior of the boiling process from beneath the heating surface, including -. vetting of the heater surface and possibly the microlayer behavior, without di: ortions due to intervening liquid-vapor interfaces. This also permits viewing of the behavior of the liquid-vapor interfaces simultaneously from the side and from under the heater surface, providing details of behavior otherwise not observable. (d) Thin-film heater. Using the technique of a thin gold film as a simultaneous heater and resistance thermometer provides a well-defined heat flux and temperature at a precise location, as well as a transparent heater surface. 2.2 Fluid The fluid to be boiled must be non-conducting. The fluid is in direct contact with the electrical resistance heat source, and a conducting fluid such as water would quickly destroy the thin film surface. For energy conservation in the conduct of the experiment and convenience in comparing results with ground tests it is desirable that the fluid have a boiling point in the vicinity of earth ambient temperatures at near atmospheric pressures. It is further desirable that the fluid used initially have wetting characteristics with the heater surface such that the contact angle is relatively small, in order to evaluate fluids expected to be early candidates for space use, such as cryogenic liquids. The fluorocarbon R-1 13 meets these requirements, and its properties are well established. 2.3 Controlled Variables: (a) Pressure. This defines the liquid saturation temperature, and maintaining it constant keeps the temperature at the liquid-vapor interface constant at the saturation level during the transient process. The pressure level also defines the initial liquid subcooling. (b) Initial uniform temperature in the bulk liquid. This permits the precise calculation of the temperature distribution in the liquid at the onset of boiling, in the absence of buoyancy. 12

(c) Step change in a uniform heat flux. This permits the ready computation of the temperature distribution in the liquid at the point of nucleation. A constant imposed heat flux provides a well-defined temperature gradient in the liquid at the heat transfer surface. Additionally, it is possible to construct all other desired functional behaviors in heat flux from combinations of step changes. (d) Length of test. Each individual test should be as long as possible consistent with compromises arising between the size of the test vessel, heater surface size and heat flux, so that a reasonably quasi-static condition can be attained when the early dynamic growth transients are completed. Additionally, certain liquid temperature distributions at the time of nucleation will only be possible with low levels of heat flux, which will require relatively long test periods to achieve nucleation. Independent control of the initial liquid subcooling and imposed heat flux permit the independent variation of the transient temperature distribution in the liquid. 2.4 Measured Parameters: (a) Bulk liquid temperature distribution. This is necessary to assure the uniformity of the initial temperatures. (b) Transient temperature of the thin film heater surface. During the nonboiling phase, this serves as an indication of the presence/absence of natural convection effects. During the boiling phase this provides a means for computing the net mean heat flux to the boiling fluid. It also provides a measure of the effectiveness of the boiling heat transfer process. (c) Local system acceleration. This is necessary to assess the presence/absence of uncontrolled acceleration forces acting on the experimental vessel. (d) Precision current/voltage drops across the thin film electrical heater. This permits computation of the heater resistance and hence temperature, as well as the heat flux. 13

(e) Photography. This enables the determination of the time interval between the onset of heating and boiling, along with the transient growth of the vapor bubble and its subsequent motion, as a function of the initial liquid temperature distribution, governed by the heat flux and initial liquid subcooling. The specific technical requirements for the experiment, taken from the Science Requirements Document, are listed in Appendix A. The vapor-pressure equation and coefficients used for the R-113 are given in Appendix B. The commercial R-1 13 was purified and degassed by distillation, filtering, and freezing under a vacuum on stainless steel fins cooled to liquid nitrogen temperatures. The apparatus used is shown schematically in Figure 2.1. The distillation was repeated, and followed by measurement of the vapor-pressure under equilibrium conditions. The R113 was deemed to be adequately degassed when the measured vapor-pressure corresponded to that given by the equation in Appendix B to within + 0.025 psia for temperatures measured to within a calibrated accuracy of + 0. 10F in the laboratory. The Resistance- Temperature relationship for the heater surface was determined by calibration over the anticipated temperature operating range prior to installation in the experiment test vessel. Prior experience had demonstrated that a linear relationship was entirely adequate. Although maximum laboratory absolute measurement uncertainties of ~ 10F (~ 0.6~C) in the mean heater surface temperatures were attained, these were increased to ~ 30F (~ 1.70C) for the space experiments. However, instrumentation equipment sensitivities were requested to detect changes in heater surface temperatures of + 1~F (~ 0.60C), if not the absolute uncertainty. To reduce the uncertainties, a single point calibration was conducted prior to each test run of the test matrix, using the prevailing equilibrium system temperature as an anchor point of the linear calibration curve. 14

P2 V2 ttN2 FmmFaing then~~~~~t Water warm Flm Heater. a.f H ww" Vapor H 0~t Non-Condensable Absor Ga Removal (Molecular V3 Vs Sieve) P3 f, V3 V5 Sight V4 V6 Window - TC 42 V1 P1 i Trap Heiaa TAN Source VaPuM TANK I Vessl eG I 7~~~~~~~~~~~~~~~~~~~~~~~~~~~ A _ I He aOegesed fR113 V7 outlet Hot 7 Plate P4 ~V!98 V10 RECEIVER NASA TANK TANK RECEIVER U.M. TANK TANK 11 PS Figure 2.1 R-113 Degassing Unit Schematic. 15

3. HARDWARE DESCRIPTION 3.1 Heater Surface A sketch of the transparent gold film heater is shown in Figure 3.1. Two separate heaters are mounted on each surface, identified as the primary and back up heaters, and configured so that should the primary heater fail the backup heater is automatically activated for the next test run of the matrix. A nominal film thickness of 400 Angstroms in the central heater section of size 0.75" x 1.50" (19.1 mm x 38.1 mm) corresponds to a nominal resistance of 3.8 ohms, and provides the desired transparency for viewing the boiling process from beneath. Power to the heater is provided by Silver-Zinc batteries, and the voltage is controlled, with the voltage drops across the potential taps and the calibrated shunt resistor (for the current measurement) stored in the data acquisition system. The instantaneous heat flux input and the mean heater surface temperature are computed from the voltage drop across the potential tap and the current. Calibration of both the primary and backup heaters took place prior to installation in the test vessel over temperature ranges of 660F to 152~F. The electrical resistance temperature follows a linear relationship within + 10F, well within the precision tolerances specified. A slope - intercept equation of the form T=A+BxR (1) is used to compute the mean heater surface temperature T from the mean resistance R measured. The original values of A and B are given in Table I below. Table I. Original Prior Flight Calibration Coefficients for PBE-1A on STS-47. Measurements made 2/13/92. Primary Backup A (OF) -1306.46 -1375.72 B (~F/ohm) 402.065 404.876 16

The coefficient B is the slope, while A is the intercept at R = O. A single-point calibration is conducted just prior to each Run of the test matrix, using the bulk liquid temperature measured with a calibrated thermister in the immediate vicinity of the heater surface, 1 mm away. This is used to modify the coefficient A for each Run, using the original prior value of B, which was found to change relatively little with a suitably aged heater surface. The surface will be calibrated again over the temperature range, and a new value of B obtained. However, the single-point calibration significantly reduces the effects of unlikely large changes in B taking place over a period of time. 3.2 Test Vessel A schematic of the test vessel is shown in Figure 3.2, together with the hardware concepts necessary to provide a constant pressure during each Run and an initially uniform fluid temperature. Although the stirrer was intended to be activated only between the various runs of the matrix in order to promote the uniformity of temperature of the fluid, it was also activated toward the end of several runs so as to observe its influence on the vapor bubbles and, in some cases, on the heat transfer. Figure 3.3 shows the locations of the various sensors used to determine the behavior of the boiling process. PRIHV and PRHI are the primary heater voltage taps and current readings, while BRHV and BRHI are the respective values for the back up heater, when used. TM01-TM03 and TM07-TM09 are thermistors above the primary and back up heaters to measure the respective fluid temperatures, at locations 1 mm, 5 mm, and 10 mm above the center of each heater. The thermister beads have a maximum diameter of 0.6 mm, and are stated by the manufacturer as having a time constant of 23 msec when plunged into water. The respective locations of TM04-TMO05-TM06 are given in Figure 3.4 as A, B and C, and are provided to check the uniformity of fluid temperatures prior to the beginning of each Run. Thermistors TM12 and TM11 are cemented to the quartz substrate on the side opposite the gold film, at the center of the primary and back up heaters, respectively, while TM13 is in the canister air space very near the quartz substrate backside. Figure 3.5 gives the relative locations of the internal components of the test vessel, including the viewing and lighting windows. The lighting is diffused internally for maximum clarity. The maximum internal dimensions of the R-1 13 chamber are also given, as 14.48 cm diameter by 11.5 cm long, which implies that the maximum diameter of a vapor bubble that can be accommodated without pressing on the heater surface is about 12 cm. 17

Figures 3.6 and 3.7 present the side and front views of the entire system components within the GAS canister, with the optical path followed to the 16 mm camera, which has a 400 ft. film capacity. This gives a total of approximately 18,000 frames, which must be budgeted among the various Runs. 3.3 Accelerometer System A space Acceleration Measurement System (SAMS) type traxial accelerometer head is included in the payload, shown in Fig. 3.7. This provides acceleration data in the direct vicinity of the test chamber. The use of an internal accelerometer also eliminates the need to correlate experiment data with a remote acceleration measurement system. Three Sunstrand QA2000-030 accelerometers are used. The manufacturer resolution specification for this model is 1 micro-g, and the accuracy is given as +100 micro-g, found by using the root sum of squares of the various stabilities (thermal, shock and time). The correlation between the accelerometer outputs and the local and vehicle coordinates are given in Figs. 3.8 and 3.9. The upper right view in Fig. 3.9 is taken through the heater surface, viewed from left to right in the right side of Fig. 3.5, while the upper left view is taken from the side, viewed from the bottom side of Fig. 3.5. 3.4 Optical Svstem The views in the upper part of Fig. 3.9 are obtained by combining the images, as illustrated in Fig. 3.6. Also within the camera field of view are LED timing lights for synchronization with the Data Acquisition Unit, seen in Fig. 3.9. The binary code for time is given in Fig. 3.10.

1.50 2.75 DIA 3.25 DIA.75.03.12 12000 - 15000 -- 400 A GOLD GOLD EACH END HEATER AREA BOTH HEATERS.375 1.~~~~~~~~~~~750.006 THICK X.06 WIDE.006 THICK X.06 WIDE-/ X.28 IG COPPER STRIP X.50 LG COPPER STRIP VOLTAGE TAP - 4 REQUIRED POWER LEAD - 4 REQUIRED 20 GA (.032) COPPER WIRE WR GA (.051) COPPER WIRE ATTACHMENT IS SIMILAR TO SILVER BRAZED TO COPPER POWER LEADS STRIPS - GOLD PLATE ASSEMBLY - INDIUM SOLDER ASSEMBLY TO GOLD COVER ENTIRE ATTACHMENT WITH EPOXY Figure 3.1. Transparent gold film heater/resistance thermometer on quartz substrate. PBE-IA. STS-47.

INLET RELIEF VALVE REMOTE 75N STOA TAN ONIOFF RELIEF VALVE VENT REMOTE ONIOFF 35 PStD N, STORAGE TANK7 S 800 PSIA VENT TO CANISTE PRESSURE REGULATO 800 TO 30 PSIA HEATER OFF BELLOWS PN, CHAMBER LI~MIT SWITCH |, CHAMBERPRESSURE TRANSDUCE. 0 50 PSIA BELLOWS STOP BELLOWS ~I I ~3-'12" START PRESSURE TRANSDUCER SOD HEIGHT;)- 50 PSIA PT -,/ - 2" CHAMBER VACUUM FILL/DRAIN - VACUUM FILL(DRAIN THERMAL HEATERS OVER SURFACE OF R-113 CHAMBER FLAT BOIUNG HEATER SURFACE STIRRER MOTOR Figure 3.2. Schematic of Test Vessel with concepts to provide constant pressure and initially unifonnrm fluid temperature. 20

N2 Chamber ACCZ.. ACCY ACOX -_-. Ji-j: __ Triaxial Sensor TM04 * TM05 ~ TM06 TM03 ~ ~ TM09 R1 13 Chamber T M02 ** TM08 TM01 ~ TM07 PRHV TM12 TM11 BRHV PRHI TM13 BRHI Figure 3.3. Location of Sensors for Scientific Analysis.

I!'x J ~~~~~~~~~~~~~~~/ ~' —--- -1 — ~'" I: t Figre 3.4. Locations of R-1 13 fluid thermistors in test vessel. 22

NASA SPACE EXPERIMENTS DIVISION SFSD Lewis Research Center Space Flight Systems Directorate TEST SECTION ASSEMBLY't~LIGHT N I L-t-~~~~~~~~~~~~-l I, ~~~~~~~16.80 NITROGEN R113 CHAMBER CHAMEBER IMPELLER 13.50 THERMAL BARRIER INTERFACE: - - T- BELLO~WS ASSEMBLY Figure 3.5. Test vessel. Relative locations of internal components, lights and viewing windows.

\JSA I SPACEEXPERIMENTS DIVISION SFSD Lewis Research Center Space Flight Systems Directorate:]_. _.::._1 20- DIMUTMR LI-. t I ~ I ~~ r' e~rrtFtI W ze8I/4 vC X LATERAL SLWPORT. _i, iji LIII _Ur CAMIEAA )' bAyA INTEFAC'E I ElQUIlPtfENt VOLE I Figure 3.6. PBE components in GAS canister. Side view.

NiASA SPACE EXPERIMENTS DIVISION SFSD Lewis Research Center Space Flight Systems Drctorae IRIAXIAL ACCLMcRc -7ER II.. —.- - _ -- BOliLIG. l HEAITI cnRe.e P014O SUPPLY PRESSURE SHIARING OT0R TISDUCE CAMERA #2 fRESS~RE POUER CONT'ROL Figure3.7. PBEcompoentsinGScaniste.FrontLIIIT Figure 3.7. PBE components in GAS canister. Front view.

rBE/STS AXIS iTANSLATIEN SED-PBE-DOC-028 PBE STS SAMS +Y +X +Y +Z +Y -X +X +Z. +Z TAIL /-.-\ |PPRE GAS ERIDGE / PROTOTYPE ASSEMBLY I TMOI TRIAXIAL SENSOR / E +Z +X SAMS (SMIDEX Rack 9) +Z signal indicates that acceleration +x +Z is in direction indicated above. e.g., - this decreases buoyancy moving STS-47 vapor bubble away from heater, or would move the vapor bubble towaNd heater. < < *Z NOSE Figure 3.8. Correlation between PBE-IA accelerometer and SAMS and STS-47 units. 26

Acceleration coordinate for the space experiment Example.'...... ~"' —-::....." —!.'........ 7"i17......'% l....:~ ~:.:' *.:.'-...'.... 7777" =77..:t i\;..... -.. f. iP::-. —.. _ t - ->. 2~.. 7' ~~~~~, _ V:.'t,'Z 7''-,5: +:-T: The above figure shows both side view in left hand side and bottom view in right hand side. J PBE Triaxial Senr TMO1 TM07 ^ ___ _\s, 5 e- * -.'~ Priar heater in uL.:se on left ie'. { u;zt = Y2 ~~1- ]rX~i.~~p —:_~~'s'~i~r ~i _~-~X,"; L ~~~ _t~`; Sb - c~r.I * h boefguesos ohsieve ginlfhadseadbotmvwinrgthd side.c (l TMO I ) \i,n M Figure ~;*O 3.9 Co ~b~rrc*Arel HCPt~~ation: between PB-I aceeo e and~ phtgapi ie nST-7 Priaryheaer n ue o let sde''~~~~":~ Y~~2

PBE LED ORDER 0.02 0.08 0.32 1.28 5.J 2 20.48 LSB 0.01 t II N9~ ~ ~ ~ ~ |I~ ~ ~ ~ ~ ~ |I~ ~ ~~ I~, I lTEST NO. LED'S co MSB 0.04 0.16 0.64 2.56 10.24 40.96 L-F in Binary 81.92 THE LED's COUNT IN BINARY FROM LEFT 10 RIGHT, EXCEPT THAT THE LEAST AND MOST SIGNIFICANT BITS HAVE BEEN SWAPPED. NIUMBERS INDICATED WITIH EACH LED ARE IN SECONDS. JUST ADD UP THE LIT LED'S TO GET THE TOTAL TIME. Figure 3. 10. Scheme for LED timing lights in camera field of view.

4. TEST MATRIX The test matrix followed for the PBE-IA on the STS-47 is given as Table II below. The nominal levels of heat flux input (in w/cm2) and the initial bulk liquid subcooling (in ~F) are given for each Test Run, followed by the timing sequences used. The test is initiated with the heater power at 10 seconds. The camera is operated at the maximum speed of 100 pps in the time domain when nucleation is expected to occur in microgravity, based on the prior drop tower testing and extrapolations. Only for Run No. 5 was the nucleation process not captured with the camera speed of 100 pps. Nucleation occurred at 26.15 seconds, and the camera returned to 10 pps at 25 seconds. Both pre flight and post flight ground tests were conducted conforming to the test matrix with the heater surface in the inverted position, at a/g = -1, in order to confirm that the system operated reproducibly following the space flight. A post flight ground test was also conducted at a/g = + 1 in order to provide normal gravity boiling data, if possible, with which to compare the microgravity boiling behavior. Results of these tests at a/g = -1 and a/g = +1 are included in this report.

1 8 20 + 2 10-70 1 5-80 1 0-1 5 65- - 80 10-15 2 4 20+ 2 10-100 25-130 15-25 - - 130 20-30 3 2 20 + 2 10-120 50-1 30 30-50 1 10- - 130,...... 4 8 5 + 1 10-55 15-65 10-15 50- - 65 0 < l | l 1 10-15 5 4 5 +1 1 10-100 25-105 15-25 - - 105 20-30 6 2 5 + 1 10-105 50-115 30-50 - - 11 5.......... ~.. _. 7 8 0.5 + 0.4 1 0-40 1 5-55 10-1 5 - 45- 55 10-15 8 4 0.5 + 0.4 10-70 25-80 15-25 65- - 80 _itiii~i~i~.Sii~i~~li~i~i~S _:~f:~:~:~:~:~i~iP~S:~:~I:~Sf -:~:~~:~:~;5:;:::::::~::..............:.~: ~............. 10-30 9 2 0.5 + 0+.4 10-11 5 50-125 30- 50 105- - 125 Table II. Test matrix for PBE-IA on STS-47. (Prototype Hardware).:~~~~~~ii~~i~j i~~~5lji~~i)S:~i~~E~ii~if~i~ii~iii~i~~~I ~ If~ ~ ~f~F:jI 0-1 5ii:::: Table lI. Test matrix for PBE-lA on STS-47. (Prototype Hardware).

5. EXPERIMENTAL RESULTS 5.1 Measured Parameters 5.1.1 Internal to Test Vessel Table Il gives the parameters as measured for each of the Runs during the pre- and post- flight tests at a/g = -1 and a/g = +1, and during the STS-47 Space Flight. These are identified in each Run No. by the date conducted and the orientation. Following this are the nominal and actual levels of input heat flux, followed by the nominal and actual initial bulk liquid subcooling. The initial bulk liquid temperature is virtually constant, and the subcooling is changed by varying the system pressure, which changes the saturation temperature, as indicated in the succeeding columns of Table III. Tw, TsUp and t* are the mean heater surface temperature, the mean heater surface superheat, and the time from the onset of heating that nucleation or the onset of boiling takes place, respectively.

I...... ——.............. a/g 1 expe iimen't based on date 4/28/92 | -......-..........a/g 0 experiment based on date 9/11/92 STS-47......_a/g _-experiment based on date _1/22/92....... a/g+l experiment based on data 11/4/92 -II-I. _~_1:-, —- 1 -1-=- I__~T —-...-.. -...-....-l-. —. — i'- l.-...... Run# Date of Fl Iihjt........ Gravl Heat Flux, W/cm^ Subccrol,oF Tbulk Sys.Pres! Tsat T'wall T'sup t fme OOpp Remark Experinent system a/gNNom. Actual Nom.oiActual coC psi oC oC oC sec On-Otl 1 4/2 /92 IPrtot~typr -11 8.00 6.70 20 21.00 49.44 22.26 61'11 93 31.89. 1..01 —5 9/11/92(Prototype 0 8.00- 7.00 20 18.50- 494'4 21.61 59.721 951 35.28 i 5810 —5 12/22/921Prototype -1 8.00 6.22 20 19.94 49.42 22.191 60.50 771 16.50 0.5410 —5.. - 11/4/921Prototype 1 8.00 7.02 20 20.02 4831 21.451 59.431 931 33.57 2. 010 —5 4/2 8/92'PrototYpE -1 4.00 3.65 20 19.80 49-00 21.981 60.... 81 21.00 2.6815 — 15...9/!!/92 _PrototYp_6 4.00 3.601_ 20 21.50 49.171 22.40 61.11 1101 48.89 12.3815 —15 12/22/92 PrototypE -1 4.00 3.37 20 19.92 49.28 22.09 60.35 100 39.65 8.5015 —15 W I..I~ 11/4/92IPro.otpE 1 4I.00 13.56120 20.00 48.14 21.33 59.25 101 41.75 51.2015 —15 3-4/28/921Protyp_ E -1l _-~2.0.... 1.78 j 20 21.00 49.44 -2.40 61.11. 891 27.89 23.40120 —40 9/11/921Prototype 0 2.00 1.801 20 19.70 49.06 21.93 60.00 95 35.00 31.39120 —40.2/22/92 IPrototyp -1 2.00 1.80 20 20.28 49.56 22.38 60.83 102 4!.17 90. 0120 —40...!/4/92 Prototyp6..1 2.00. 1.81 20!9.95 48.49 21.54 59.571. 1 120 —40 No Nucleation 4 1 ~ 4/2 /92jProtot-yPfl _!| -~l_ _6.5_1 _ 5 5.3-0 49.00 16.95 51.94. 91 39.06 1.:100 -- 5 9/1_/92 PrototypE 0 8.00_ 7.00. 5 4.80 49.00_ 16.80 51.67 91 39.33 1.3410 —5 12/22/92 Prototype -1 8.00 6.30 5 4.22 49.08 16.71 51.43 75 23.57 0~1~5 — 5 11!4/92Prototype_ --- 8.0 —0....7:05,5....,F).05 47.81 -6.25 50.62 94 43.38. 1.-900:, 5 5 4/28/92 __lr otoh/_p...... -i 4.00 3.40...5 l 5.401 49122'-!7100- 5._O1 1021 49.78 8.70 15 —15... 9/11/921 Protntvir:.~ 0j 4.00 3.60 5 5.00 48.89 16.80 51.67 120 68.33 16.155 —15 12/22/92_PrototypE -1 4.00 3.381 5 4.93 49.04 16.90 51.78 109 57.22 12.7015 —15 11/4/921Prototype 1 4.00! 3.541 5 4.98 47.92 16.29 50.691 I 1 15 —15 No Nucleation I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' — 1 —. —---—. —-I.I I.I I.I I.I I. I I. [.... Table III. PBE-IA. Parameters measured at a/g = -1 and a/g = +1 in Pre flight and Post flight tests, and during STS-47 Space Flight.

Page 2 of2 71 Run# Date of Fli t Gravi Heat Flux, W/cm Subcool,oF Tbulk Sys.Prev Tsat Flwall T'sup to timeO1pps __ ~Experiment system ag_ HNomr. Actual Nomro Actual oC psi oC 0oC oC sec _ On-Off 6 4/28l92 Prototyp -1 2.00 1.76 5 4.70 49.06 16-80 51.67 87 35-33 34-30 20 —40 9/11/92 Protolyp 0 2.00 1i82 5 5 00 49.17 16.90 51.94 98 46-06 37.47 20 — 40 12/22/92 Prototyp -1 2.00 1.77 5 4.95 49.25 17 02 52.00 - 20 — 40 No Nucleation 11/4/92 Prototyp 1 2.00 1.81 5 5 01 48.04 16-37 50.82 20 — 40 No Nucleation 7 4/28/92 PrototYPE -1 8.00 6.70 0.50 1.20 48.78 15-50 4.9.44 93 43-56 1.180 —S 9/11/92 Prototyp 0 8.00 7.00 0.50 1.00 48.89 15.50 49.44 94 44 56 1.36 0 — 5 12/22/92 Prototyp -1 8.00 6.42 0.50 4 92 48.79 16.76 51.52 86 34 48 1.00 0 — 5 11/4/92 PrototypE 1 8.00 7.06 0.50 4.74 47.51 16-00 50.14 91 40.86 1.900 — s 8 4/28/92 Prototyp -1 4.00 3.50 0.50 1.40 48.67 15.50 49.44 101 51.56 9.30 5 —15 9/11/92 Prototyp 0 4.00 3.50 0.50 0.70 49.06 15.50 49.44 106 56.56 10.63 5 —15 12/22/92 Prototyp -1 4.00 3.42 0.50 0.45 49.09 15.61 49.34 111 61.66 14.50 5 —15 11/4/92 Prototyp 1 4.00 3.55 0.50 0.56 47.42 14.78 47.73 5 — 15 No Nucleation 9 4/28/92 Prototyp -1 2.00 1.80 0.50 1.00 48.72 15-40 49.28 99 49.72 65.90 20 — 40 9/11/92 Prototyp 0 2.00 1.80 0.50 0 40 49.22 15.50 49.44 100 50.56 41.48 20 —40 12/22/92 Prototyp __-1 2.00 1.76 0.50 0.41 49.05 15.58 49.28 89 39.72 27.00 20 —40 11/4/92 Prototyp 1 2.00 1.81 0.50 1.23 47.49 15.00 A48.17 1 1 120 — 40 No Nucleation Table IH. Continued.

5.1.2 Accelerometer Table IV lists a summary of the relatively larger acceleration excursions measured during each of the Runs in the PBE-IA of the STS-47 Flight. The accelerometer units here are given as micro-g's, and the heating for each Run begins at 10 seconds. The larger excursions are indicated in bold type in Table IV, and no consistent observable effects were noted at these times either in the vapor bubble boiling behavior from the motion picture films, or in the heat transfer behavior as might be reflected in the heater surface temperature measurements. The interface motions during boiling are reasonable intense, and the relatively large surface tensions are believed to mask influences of these residual acceleration levels. The accelerometer measurements from which the data in Table IV were extracted are plotted as functions of time for each Run, and are given in Appendix C. The units are given here as milli-g's, and each major ordinate division corresponds to 50 micro-g's. 34

RUN # Time, sec Plots _ Max Value Uncertainty (Noise) Comments........x Y z 2.40E+01 1 no 50 52 50 2.40E+01 2 no 76 77 50 2.40E+01 3 no 51 77 50 2.40E+01 4 no 101 77 75 2.40E+01 5 98.3 yes 179 52 348 2.40E+01 5 98.9 yes 51 103 50 2.40E+01 6 89.9 yes 51 52 273 2.40E+01 6 90.3 yes 51 258 50 2.40E+01 6 90.2 yes 254 52 50 2.40E+01 7 no 76 77 75 2.40E+01 8 4.9 yes 306 52 75 2.40E+01 8 5.2 yes 51 103 75 2.40E+01 9 48.2 yes 51 103 50 2.40E+01 9 60.4 yes 281 52 75 2.40E+01 Notes: (1) Accelerometer units are given as micro-g's. (2) Heating in each run begins at t = 10 sec. Table IV. Summary of relatively larger acceleration excursions during PBE-IA in STS-47 Flight.

5.2 Thermal Results 5.2.1 Canister Ambient Fig. 5.1 presents the output of a thermistor mounted on one of the structural members of the PBE-IA, following liftoff of the STS-47. The disturbances initiated by the onset of each of the nine (9) Runs in the test matrix is clearly discernible. The general increase in temperature during and following the tests is a consequence of heating the R-1 13 to its nominal 120~F (48.90C) operating temperature level. 5.2.2 Test Matrix Runs The experimental thermal data for each of the nine (9) Runs of PBE-IA conducted in the microgravity of space on the STS-47 are plotted in Figs. 5.2 - 5.10. Each Run includes five (5) Figures subdivided as a-e, to be described below, with the same format followed for each Run. Figures 5.2 (a-e) are for Run No. 1, and follow the sequences given in Table II with the experimental parameters listed in Table III. Figure 5.2a includes the measured mean heater surface temperature and the heat transfer coefficient computed from a one-dimensional finite difference procedure in the quartz substrate, using the measured surface temperature as a boundary condition. Cubic splines are fitted through successive data points to provide interpolation between the measured points. The procedure is described by Merte (1992). During the conduction phase of heating the heat transfer coefficient is defined in terms of the difference between the heater surface temperature and the initial temperature. This permits a comparison with the well-known analytical solution of conduction in two semi-infinite solids with a step input in heat flux at the plane between the two solids. This is shown by the labeled dotted curves in Fig. 5.2a. Once motion takes place in the fluid, comparison with the analytic conduction solution is no longer appropriate. However, it is included in all such plots in order to provide a reference. It becomes obvious that deviations from the one-dimensional behavior takes place because of the finite lateral heater dimensions. This issue will be addressed below. Once nucleation takes place the heat transfer coefficient is appropriately defined in terms of the difference between the measured heater surface temperature and the liquid saturation temperature. Figure 5.2b shows the temporal variation of the input heat flux to the thin gold film. The change noted is a consequence of the increase in resistance of the gold film as it is heated, with the imposed voltage being controlled to remain essentially constant. This variation is relatively small, and it was not deemed worthwhile to control the power input to remain constant. 36

The measured system pressure is plotted in Fig. 5.2c, along with the heat flux to the fluid as computed from the measured power input and the heat flux to the substrate, computed in turn from the measured heater surface temperature. This parameter makes it possible to determine when steady-state conditions are reached, since the heat flux to the fluid becomes equal to the heat flux input to the film heater. This condition is almost attained in Run Nos. 2, 3, 6 and 9. The measured mean heater surface temperature is included in both Figs. 5.2d and 5.2e in order to provide temporal reference marks for the various temperatures measured. The center plot in Fig. 5.2d gives the fluid temperatures above the active primary heater at distances of 1 mm, 5 mm and 10 mm above the heater surface. The lower plot in Fig. 5.2d gives the bulk liquid temperatures at the various distances indicated above the heater surfaces, around the perimeter as given in Fig. 3.4. The center plot in Fig. 5.2e shows the changes in liquid temperature at 1 mm, 5 mm, and 10 mm above the center of the backup heater, and thus gives an indication of the effects of lateral motions of the vapor bubble. In the lower part of Fig. 5.2e, TM1 1 measures the quartz surface temperature centered under the backup heater, while TM 12 measures the quartz surface temperature under the center of the primary heater. TM13 measures the air space temperature slightly removed from the center of the underside of the quartz substrate. If necessary, it permits estimating the heat loss from the back side of the quartz substrate. The figures corresponding to Run Nos. 2 - 9 follow the same pattern described above. 5.3 Test Matrix Representative Photographic Views Twelve (12) selected representative frames from the 400 ft. 16 mm motion film are presented for each Run in Figs. 5.11 - 5.19, along with the frame number, counted from frame 100 at the onset of heating, and with the time from the onset of heating, at 10 seconds. Filming took place at either 10 or 100 pps, as indicated in the matrix given in Table II. The images were obtained by projecting the film on a large screen, picking it up with a video camera, and using a frame grabber and digitizer for storage on laser discs. The times shown may differ slightly from the frame number because the camera speed may vary, as when changing framing speed. The LED's seen in the bottom of each image provide synchronization with the thermal data, following the time format given in Fig. 3.10. 37

120 100 - 80 11i F Uo s, 0 00 E 60 - 40 - 20 - 0 I t -.-... -. —--— I -. —---—. - -- - --- -1 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 Time (seconds) Figure 5.1. PBE-IA structure temperature in GAS canister.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #1, q"total=7.O Wfcr2 4000 -- _ _ _ _ ______ - 160 1 -D Analyti I surf. temp. 3500 -- 3000 --- --- --- --- -- _-_ - 120 3 2500 1 __________ Measured 5urface temp. _ __ 2500 _ 0/ 2 2000 -1 —- -_ _ _ _ _ _ _ __ -__ ___ _ - 80 0 1500 -t —---- — t f'g_-t___. -- _.._ -___~ __t --— _. _ -___. _ —__-. — _ —------- __ - 60 i "h" comput from measurements 1000' 10 500 1-______ t —— ____ - -DIAnalfiaFTfjl~" —t — ~ - -- -f --- 20 0 -I —--- ~~- ~ —-1 -- - ----- - -~ —- -~ -- i ---- - -n -I- --- 0a 0 10 20 30 40 50 60 70 Time, sec Figure 5.2a. Run No. 1 PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #1 8 7.5 E o u L 7 o 6.5 6.5 7..... 0 10 20 30 40 50 60 70 Time, sec Figure 5.2b. Run No. 1. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and Sy tern Pressure vs. Time for Space Exp.#1 Run#1 152, 16 151 - 14 - 14 12 E ~150................. 14 9_-_ __IV_ _ _ _ _ _ _ _ _T VWI_ _V I__ ___ _ _ _ _I _ _ _ _ _ _ I 0 148 - 147 Time, sec Figure 5.2c. Run No. 1. PBE-IA. STS-47. System pressure and fluid side heat flux. Figure 5.2c. Run No. 1. PBE-1A. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 165 T,i 135 _ E 105 t f o 75+ 45 0 10 20 30 40 50 60 70 80 Time. sec B. Local Fluid Temperatures 5 TMO1, 1mm - - TM02. 5mm TM03, 10mm 65 i ~ 55 _ 45 0 10 20 30 40 50 60 70 80 Time, sec C. Far Field Bulk Temperatures 55 T- M04, 23.4 mm - - TM05, 48.9mm TMO6. 74.4mm 2 50 _ _ _ _ __ 0. E D 45.., 0 1 0 20 30 40 50 60 70 80 Time, sec STS 47 - RUN#1 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 8 20 ~ 2 10-70 sec. 10-15 sec. 65 sec. ---. 80 sec. Figure 5.2d. Run No. 1. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 42

A. Mean Heater Surface Temperature 165 U i 135 _ 0 1 E 105 U75 45 0 10 20 30 40 50 60 70 80 Time, sec D. ~~~~~53 2 ~TM07 ------- TM08 ---- TM09 52 Il 0 10 20 30 40 50 60 70 80 Time, sec E. 60 TM TM12 TM13 o 45.. —- a.. 30 0 10 20 30 40 50 60 70 80 Time, sec STS 47 - RUN #1 30~~~~~~43 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPREss TOTAL FLUX (F) ON/OFI ON/OFF START START TEST TIME 8 20 ~ 2 10-70 sec. 10-15 sec. 65 sec. -........80 sec. 43

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #2, q"total=3.6 W/cm2 4000 -.- 160 3500 - - - - - - -.-. —- - -- ----- t - --—. —- ---- 140 1-D \nalytlcal s Irf. temp. 3000 - - ---- t I h- - - 20 2500Mea ure surface t rnp. 12000 80 9 "h" co puted fro measure ents 500 -- --- 20 0 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure 5.3a. Run No. 2. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #2 3.8 E 3.6 3.4 3.2 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure 5.3b. Run No. 2. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp.#1 Run#2 8 I I_ I I - 158 7 156,c 6 -~ -~: V~l~FigureS.3c Y,. P'iun.'"'to.}2.~~~ PBE-IA."f"~'- Si-I 154 Pq~~~~~~~~~~~~~~~~~~~~~~~~ 152:3 0 -142 0 20 40 60 80 100 120 140 Time, sec Figure 5.3c. Run No. 2. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 120 U 0 1 o 80t E 60 t _ I 40 20t —. 4 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Time. sec B. Local Fluid Temperatures TMO1, lmm- TM02. 5mm - - - - TM03. 10 U 255 E V -7 45,, -0 10 20 30 40 50 60 70 80 90 100 110 120 130 Time. sc C. Far Field Bulk Temperatures ~55.*,,,1TM04. 23.4'. TMO6 48.v - - TMO6. 74.4'Y o E 50. F- ----—.. —0 10 20 30 40 50 60 70 80 90 100 110 120 130 Tme. sec STS 47 - RUN#2 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 4 20 t 2 10-100 sec. 15-25 sec. ----- ------ 130 sec. Figure 5.3d. Run No. 2. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 47

A. Mean Heater Surface Temperature 120 U 100 ~ 40 t 20 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Tme. sc D. 55 -- - TM07 - TM08 - - - - TM09 250 _. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 nme, sec E. f - TMIl I TM12 TM13 60 3 0 1 -------------------- - --, -. - -- -,,-,, E40 30 0 10 20 30 40 50 60 70 80 90 100 110 120 130 lime. sec STS 47 - RUN #2 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 4 20 t 2 10-100 sec. 15-25 sec. ----- 130 sec. Figure 5.3e. Run No. 2. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 48

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #3, q"total=1.8 W/cm2 1 -4 Analytical surf. te np. 3500 -- --- - -- -- - -- 100 2500...- -. _ —.. —------ ----- -L-.. — t-. —. 60 Measured sur ace temp. 2 E 2000 40 "h" com uted from measurements 1500 - _ ___ _ —— t- - 1 _ — t —-------------- -- - -- 1 - - ItfW 20 u 1000 ---- -- 0 0._.......... —... - ---- - -40 0 20 40 60 80 100 120 Time, sec Figure 5.4a. Run No. 3. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #3 2 1.8 0 E 1E.61.4 1.2 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure 5.4b. Run No. 3. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp.#1 Run#3 0.- - 154 0. 20. 40.. 8. 1 152 cu 6...... 1 t ------------ t ------------ t ~ t- 150 E 1 3 148 10 140 0 -I............ 138 0 20 40 60 80 100 120 140 Time, sec Figure 5.4c. Run No. 3. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature U 120 l loot 100 t 80t 0 E bQ t - 40 1 20 0 L O. - - -.,,.. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Time, sec B. Local Fluid Temperatures - - TM01. l mm - - - - TM02. Smm TM03. 1 Omm 65 I Ui -ZD -A i 45 I - 45 - 0 10 20 "30 40 50 60 70 80 90 100 110 120 130 Time, sec C. Far Field Bulk Temperatures 55 j TM04. 23.4mm TM05 48.9mm - - TMO6. 74.4mm E.. 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Tme. sec STS 47 - RUN#3 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 2 20: 2 10-120 sec. 30-50 sec. 1 10 sec. -----.. —- 130 sec. Figure 5.4d. Run No. 3. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 52

A. Mean Heater Surface Temperature o 120 100 t 2 80 J E 60t / - 40 t 0 20t: o.I.......,...i 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Time, sec D. I TM07 TM09 I 60 j. 0 1 O 1O 20 30 40 50 60 70 80 90 100 110 120 130 Time, sec 0..... I 35 0 10 20 30 40 50 60 70 80 90 100 110 120 130 Time, sec STS 47 - RUN #3 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 2 20 ~ 2 10-120 sec. 30-50 sec. 110 sec. --- --- 130 sec. Figure 5.4e. Run No. 3. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 53

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #4, q"total=7.0 W/cm2 3300 220 Il-D An lytical surf temp. 200 3000 2700 - " 180 Mea ured surface tem). / 01'1800 - -- 10- 6 a. 1500 i-I.......__. ___/_ - --- ----- -:- ---- 100 1200 --- --- --- 80 1 D) Alr(ilylec~l "I 1 "1I" (:()[1 ) fll0 m I r oi i st'iJ otrils 600 40 0 10 20 30 40 50 60 Time, sec Figure 5.5a. Run No. 4. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #4 7.5 6.5 6.5 6 -,_ 0 10 20 30 40 50 6( Time, sec Figure 5.5b. Run No. 4. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp.#1 Run#4 12, 118 1 1 8 i.. 0 117 c4 E 8 116 g6 115 -U6~~~~~~~~~~~~~~~~~~~~ 4~~~~114 2 113 Time, sec Figure 5.5c. Run No. 4. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 250 U T 200+ o E 150 + 50 0 100 + 0 10 20 30 40 50 60 70 Time, sec B. Local Fluid Temperatures 75 -i TMO1. lmm TMO2. 5mm - TMO3. 0mm 75 0U1 1 45 0 10 20 30 40 50 60 70 Time, sec C. Far Field Bulk Temperatures 2505 E 45TM04, 23.4mm TM05 48.mm.. 0 10 20 30 40 50 60 70 Time, sec STS 47 - RUN#4 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 8 05: 1 10-55 sec. 10-15 sec. 50 sec. - --- 65 sec. Figure 5.5d. Run No. 4. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 57

A. Mean Heater Surface Temperature 250 1, 200 E 150 t O 100 t H' 0 10 20 30 40 50 60 70 Time, sec D. - - - TM07 TMO8 TM09 60 __ 5 5 0 o 1\ E 50 45 0 10 20 30 40 50 60 70 Time, sec E. TM11 TM12 TM13 60 U. 50 E 40 30 0 10 20 30 40 50 60 70 Time. sec STS 47 - RUN #4 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 8 5 ~ 1 10-55 sec. 10-15 sec. 50 sec. - 65 sec. Figure 5.5e. Run No. 4. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 58

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #5, q"total=3.6 W/cm2 4000 -- -I l__ _ E_ I_ _ - 160 1-D Anal tical suFf. tOmp. 3500 - -. —- -- 140 3000 /; _ -- - - 20 Figure 5.6a. Run No. 5. PBE-IA. STS-47. Meahsured surfacce temp. an 2500- 1ea. / 2E 200 0.........67 80 9 1500 - -- ____ ___ - _ - -- - ------ 60 ~ 1000 1-D Nnalytlcal /,h, 500 - - $ y 20 0 -------- _- _____- -- ------ - --- 0 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure 5.6a. Run No. 5. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #5 4 3.8 E 3.6 3.4 3.2 0 10 20 30 40 50 60 70 80 90 1()() Time, sec Figure 5.6b. Run No. 5. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp. #1 Run #5 8 117 7 _ lw; tagwn MI l 116 -.: 5 114 00 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ C I I 2112 -' 2 1 l l l I I -1 t F 10 0 109 0 20 40 60 80 100 120 Time, sec Figure 5.6c. Run No. 5. PBE-IA. STS-47. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 150 130 E 70 ~ 701 / 50 0 10 20 30 40 50 60 70 80 90 100 110 nTime, sec B. Local Fluid Temperatures 75 - TMO1. lmm.TM. 5mm TM02. 1cnm 65+ E 55 I y/ s' 45 0 10 20 30 40 50 60 70 80 90 100 110 Time, sec C. Far Field Bulk Temperatures TM04, 23.4mm - - - TM05, 48.9rnm MO6. 74.4mm 55 ~~a~~~~~~ 50..._............ -............ - -. —..-.. — -. —--,,. ---- E 45 0 10 20 30 40 50 60 70 80 90 100 110 time, sec STS 47 - RUN#5 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 4 5 - I 10-100 sec. 15-25 sec. -------- - 105 sec. Figure 5.6d. Run No. 5. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 62

A. Mean Heater Surface Temperature 150 130 110 E 90, 70 50 0 10 20 30 40 50 60 70 80 90 100 110 Tmne, sc D. 55 1 - - TM07 TM08 - - TM09 U _ ID 45 0 10 20 30 40 50 60 70 80 90 100 110 Time, sec TM111 TM12 - TM13 65. 55 E 45 i " I O 10 20 30 40 S0 60 70 80 90 100 110 Time, sec STS 47 - RUN #5 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 4 5 I 0-lOO sec. 15-25 sec. -------- ---------- 105 sec. Figure 5.6e. Run No. 5. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 63

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #6, q"total=1.82 W/cm2 I1-D Analytical surf. temp. 2500 - 100 Mea ured surface ter p. 2000 E 1500 60 1000~~~~~~~~~~~~~~~~~~~~~~~~~~ 1000 t —--- ____ ___ —- --— ___ —- -- -- _ A 0o "h" cornTi uted froM mneasuri rnits 500 - --- _ ---- --- __ - - 20 1 -D Analytical "h" 0 20 40 60 80 100 120 Time, sec Figure 5.7a. Run No. 6. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

J~~ m o H~T i i " C~ C.-)~~ E C-, aS~~~~~~~~~:: iE~~~~~~~~i "E I~~~~~ _ 1 I I I c z ~~~I I I I I I. I.H 65cI: S I [~ v Q,,!,, i...., Ir or ~ t _ Lrr ~ _ ~~~~~~~~~~t z/j Ixt l v a Q) I I I I I 65

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp. #1 Run #6 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __... *...... 118 5-. 117 c_ 6................. -i 1 1 6 2l4 112 3- 113 0- I r —--— t-I 110 0 20 40 60 80 100 120 Time, sec Figure 5.7c. Run No. 6. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 100 E 9 0 90 6 B O i T 0 8 0 20 40 60 80 100 120 Time, sc B. Local Fluid Temperatures TMO 1, 2mm TM02. 5mm - - - - TM03, 10mm 65 0 55 E 45 0 20 40 60 80 100 120 Time, sec C. Far Field Bulk Temperatures 5 TM04 23.4mm TM05,48.9mm - - TM06. 74.4mm 55 o 50 45 0 20 40 60 80 100 120 Time, sec STS 47 - RUN#6 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLux (F) ON/OFF ON/OFF START START TEST TIME 2 5 ~ I 10-105 sec. 30-50 sec. ------ ------- 115 sec. Figure 5.7d. Run No. 6. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 67

A. Mean Heater Surface Temperature 100 - - U ~90 t 80 E * 70 0 50 0 20 40 60 80 100 120 Time, ec D. - - - -TM07 TM0 - TM09 50, 45 0 20 40 60 80 100 120 Time, sec E. TM11.- - TM12 TM13 55..50................. —---------------- o 45 0 40 35 0 20 40 60 80 100 120 Time, sec STS 47 - RUN #6 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FlUX (F) ON/OFF ON/OFF START START TEST TIME 2 5 ~ I 1]0-105 sec. 30-50 sec. --------------- 1 15 sec. Figure 5.7e. Run No. 6. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #7, q"total=7.O W/cm2 4000 7- - - - —. — r —------- ___-___ --- - -- T -- _ —--- -__ —~,~1 __ - - -. —-___ - - ---- - - - - - -- - --- -. I 240 3-D An Itcal surf. f tmr — 3500 __ 1 ~~, 3000 ----- ---- - - -~ - - - -- 180 U 2500 - - _____ - -~ - Meas red surfac temp. 10 2500 -1 ------ 150 2 2000~~~~~~~~~~~~~~~~~~~~~~~ 1000 60 1 -D Nnalyilcal "h "h" ornputed fr In mieasure rients 500 -- - - - _ _ - - - --- — 3 0 -_ -- --------- -- ---.- --- __ -- - - - 0 ----- ------ -1- - -—.- - 1 ---- --— f —— ~ ~ - -- 0 5 10 15 20 25 30 35 40 45 Time, sec Figure 5.8a. Run No. 7. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #7 7.5 - _ 6.5 6 0 5 10 15 20 25 30 35 4( Time, sec Figure 5.8b. Run No. 7. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp. #1 Run #7 87- = 170 7- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~150 6 E6It I —-A- ~~~~~~~~~~~~~~~~~~~~~~~~~~130 E u:5 3..... —- CXr _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 110 0' - - _x.. 3 3 U50 J:2h 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 30 10 0 10 20 30 40 50 60 Time, sec Figure 5.8c. Run No. 7. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 250 -, 150 E, 0 50 0 10 20 30 40 50 60 Time, sec B. Local Fluid Temperatures CI a! E 5I 45 0 "10 20 30 40 50 60 Time, sec C. Far Field Bulk Temperatures - TMO4. 23.mm TM05. 48.9mm - - TM0. 74.4mm U 55 0 10 20 30 40 50 60 Time, sec STS 47 - RUN#7 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 8.5 ~.4 10-40 sec. 10-15 sec. - 45 sec. 55 sec. Figure 5.8d. Run No. 7. PBE-IA. STS-47. Fluid temperatures nearprimary heaterand far field bulk. 72

A. Mean Heater Surface Temperature 250 U 1 200 150 i o 100 l 50 0 10 20 30 40 50 60 Time, sec D. _ TM07 - - - - TM08 TM09 55.. s, 2 50 45 0 10 20 30 40 50 60 Time. sec E. - - - - TM11 TM12 - TM13 55 o 45 E 35 0 10 20 30 40 50 60 Time, sec STS 47 - RUN #7 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 8.5 +.4 10-40 sec. 10-15 sec. --- --- 45 sec. 55 sec. Figure 5.8e. Run No. 7. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 73

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for STS-47 Run #8, q"total=3.5 W/cm2 4000 T - ---- -- --- --- ----— 160 3500. —- --- -D Analytical surf, emp. 3000 - -—. —_-.. - ------ -- ---- 1 - 120 U 2500 - __.~ _1 EV, | ///'/ l...Measure surface temp. 2000 | -f _. - -80 i U 1500 ---------- __ _ —------ - - 60 u "h" computed from measurer ents 1000 40 1- Ana yticai "h"1, 500 - - _ --------- 20 0 $ —-— __ -.______ _ — - -- ------ -__-t - ---- - - ------- ----—... 0.. 0 10 20 30 40 50 60 70 Time, sec Figure 5.9a. Run No. 8. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #8 3.8 E 3.6 P13.4 3.2 0 10 20 30 40 50 60 70 Time, sec Figure 5.9b. Run No. 8. PBE-IA. STS-47. Heat flux input.

Heat Flux toward Liquid and System Pressure vs.Time For Space Experiment #1 Run #8.................. ------ 109 F 6 1.......' |'.............. 108..............7,........ 107 10 0 102 0 10 20 30 40 50 60 70 80 Time, sec Figure 5.9c. Run No. 8. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature U 140 -, 50 E I'o, 0 10 20 30 40 50 60 70 80 Time, sac B. Local Fluid Temperatures 75 - - TM01. lmm TM02. 5mm - - TM03. 10mm 5 65, 45 0 10 20 30 40 50 60 70 80 Time, sec C. Far Field Bulk Temperatures 5- TM04. 23.4mm TM05. 48.9mm - TM06. 74.4mm 551,f 5 50! 45 0 10 20 30 40 50 60 70 80 Time, sec STS 47 - RUN#8 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 4.5.4 10-70 sec. 15-25 sec. 65 sec. ------ 80 sec. Figure 5.9d. Run No. 8. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 77

A. Mean Heater Surface Temperature u 140 4, 110. ~ 80 50 0 10 20 30 40 50 60 70 80 Tinme, sec D. 52 1 1 - TM07 o TM08M09.2 0 49.5 47 0 10 20 30 40 50 60 70 80 Tine, sec E. ~55 TM~ I~ ITM. TM12 TM13 E 35 0 10 20 30 40 50 60 70 80 Time, sec STS 47 - RUN #8 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLux (F) ON/OFF ON/OFF START START TEST TIME 4.5 ~.4 10-70 sec. 15-25 sec. 65 sec. ------- 80 sec. Figure 5.9e. Run No. 8. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 78

Convection H.T. Coeff. ai d Mean Surface Temperature vs. Time for STS-47 Run #9, q"total=1.8 W/cm2 4000.... - 160 1 D Analy calsurf. t mp. 3500 |. 140 3000 120 25020 40 60 80 100 120 E — 2000,~~~~~~Time, sec0 1500 60 derivedfmputed from mefficisurent. 0 20 40 60 80 100 Timo, sec Figure 5.10a. Run No. 9. PBE-IA. STS-47. Mean heater surface temperature and derived heat transfer coefficient.

Total Heat Flux vs. Time for STS-47 Run #9 1.8 - -- _.__....... -- o E 1.6 o 1.4 1.2 1 Llt I | | 1 I -+..... 1 1 I -—,........ i ~......;. 0.00 10.00 20.00 30.00 4().00 50.00 60.00 70.00 80().()( 90.0() 1()0.00 1 1().0()() 12().()() Time, sec Figure 5.10b. Run No. 9. PBE-IA. STS-47. FHeat flux input.

Heat Flux toward Liquid and System Pressure vs. Time for Space Exp. #1 Run #9 8 112 7.."110 CY 6: ___ -- ___ - 108 co0 106 4~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 oo ~: 5 —+ —t ~ tf —t —- 1060f ~3' 1.... 984 0 96 0 20 40 60 80 100 120 10 Time, sec Figure 5.10c. Run No. 9. PBE-IA. STS-47. System pressure and fluid side heat flux.

A. Mean Heater Surface Temperature 120 - 0 i i 40 1 0 20 40 60 80 100 120 140 fime, sec B. Local Fluid Temperatures TM01. 1mm - TM02, 5rm TM03. 10mm 65 U ~. 55'i 45. 0, 20 40 60 80 100 120 140 nme, sec C. Far Field Bulk Temperatures 50 0 49 49 TM04. 23.4mm TM05,48.9mm.1 T M06,74.4mm o / 48. 0 20 40 60 80 100 120 140 Time, sec STS 47 - RUN#9 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLux (F) ON/OFF ON/OFF START START TEST TIME 2.5:.4 10-1 15 sec. 30-50 sec. 105 sec. -------- 125 sec. Figure 5.lOd. Run No. 9. PBE-IA. STS-47. Fluid temperatures near primary heater and far field bulk. 82

A. Mean Heater Surface Temperature 120 U 100 E 80t +.' C 60 / 40 0 20 40 60 80 100 120 140 Time., ec D. 55 1 TM07 TM08 TM09 L _50 t. ----------- ---- ------ -- —, E 45 0 20 40 60 80 100 120 140 rime, sec E. 60 r T' - TM'l TM12 - TM13 j ~ 50......... _ _- - -------------— ~'. -------- E 40 _ 0 I 30 0 20 40 60 80 100 120 140 Time, sec STS 47 - RUN #9 HEAT SUBCOOLING HEATER POWER 100 FPS STIRRER REPRESS TOTAL FLUX (F) ON/OFF ON/OFF START START TEST TIME 2.5 ~.4 10-115 sec. 30-50 sec. 105 sec. -------- 125 sec. Figure 5.10e. Run No. 9. PBE-IA. STS-47. Fluid temperatures near back up heater. Quartz substrate underside and ambient vicinity temperatures. 83

STS-47 Run #1.'' i..................., ~t ~ ~~' v * f_ _-....... - ~~-. ~\M';~~~~~~~~~~~~~~~~~~~~~~i,j~f~;''.x..~ ~~~ xr~low~,~wxu~::.:: ~:............... =.~~~~~~~ _ F~~~'r, ~... A- |<~_ -, ~..~":.:.~:' "...... Frame#O 1 63 time= 11.62 sec. Fram egO 1 66 time= 11.65 sec. X.. —;....................... I. I~......................... I.- i'ii'' "......:t...,..!.........:.. -................r~ =:ui~s,:v..:..'~- ~ ~'' -.- ~-"s:;*(.................I......i* "'..:.. "..'.''...'.':'..'.'';'.:.':............''.'.''.::-.''.. "::'..','. -'.':',:!':.~!~:`~:~..`...:...........:.:~:::::.:....:'::.'.:.~.i::::;~.:'.:~?.~:~.:':.~:'~.~::.;:' ~:i~:~,..~,.*.'~:.'.... _b; _~ Frame#O 169 time= 11.68 sec. Frarne#0166 time=l 11.9 sec... w -:. -...... -..R,.N. -~~~~~~~~: ~~:-..........-::,::X....:.,:.......: Frame#O 158 ~~~~~~~~~~~~~time=1, sc rm# 161 iel.93 sec.', i"',,'': ~;'' ~:'':' *:::;- ^'::[' i E* it F~gure.11..Run. 1... PB,;- — /4 7. t:d P:o Iages 8. - i1 11iA~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.t ~~:: I~~~~~~~~~~~~~c::x Frame#0169 time-1 1.68 sec. Frarne#0194 time=1 1.93 sec.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~I 1~;:; Figure 5e 11 Run~ No 1. PBE ~ IA. SS47 eece hoorahcImgs 84;Z~I~~r-~

STS-47 Run #1 _~ _ a. At~~~~~~~~~~~~~~~~ W:t.......":........... I~',:_ i ~: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~z~~~~~~~~~~~~~~~~~r: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ w.7.................... "~~~~~~~~~~?" Frame#()51 1 time= 15.09 sec. Frame#0)000 time= 17.20 sec..~'~'/~~'.',.-..',-?.: =,z.........................;,, *,, i.. Frame#00 13 time= 1 8.50 sec. Frame#0?42 time=36.98 sec.' _:6........... _. _:.. A'....::..' 4..,:.Q ~.......... A i!i.. *. z j's4 A.,:~:,,.,.j' t.. Frame#0859 time=418.067 sec. Frame#0970 time=6.977 sec. I~~~~~~~~~~~~~~ e t: oM6XltGX.~~,~'_,,,,,: - <o +S:':::':':: ~:iS~ i.:';:i:' 9~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Figure 5.l1. Cont::Lnued. 85

STS-47 Run #2.to.0 l. |...e.....,-....,.1. i.4.aI- *,.,'-.-~X. r-..^...... 7.,. oe ~ _ _ -. -<.' — - _. ".''........''' -. ". -''""":,-a.'............................ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..............'......:.''..... ~~~~~~~~~~~~~~~~~~~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~....:-..:.....$ I~~~ ~ ~ ~ ~~~~,,%,_,.~~ ~~~~~~~~ r _~f~:~............... i ~-.....~xi i...l',';. | 0* w> *w *> | > - - - - 1s''::~ —- -. -x............. *~< ~'"7'-'' ~' <..''.4i5......... "..~.................... 04.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~f -~ ~:~7j~~~~~~~~~~~~~~~~ i ~~~; ~, ~r.,~~~ p.~~~~~~~~~~~~~~~~~~~i~ i~ ^,,,,......................, -: — t - -—,: o~iX,-,_- L.- _l..........................................................:::.::'.:::..:.,!.:.....,:...!: _, -...; ^ S'._.'".'..;...... ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.......... - a......................................:.....;-......i... - - -.>. t ~~a~i; Cu"~''SC'+<''<-z v b t ~' ~~ t 1 _................... ~: ~x: ~-.: ~.~ ~. - ~x...... v...................... ~:i..,...... Frame#0785 time=22.40 sec. Frame#0786 time=22.41 sec. Figurej~~~~~ 5.12~~. Ru*n ~ No.s~ 2. PBE-vIA.~~~~~~~ STS —47 i ~. Selected1~~ Phol~ographic. -- ~' ~....... ~...........:'''','"'~,' i.' Q:: 1 I I A I; Q All li? 6t I:,~hi~~~~~~~~~~~~~~~~~~~~ Frame#0787 time=22.42 sec. Frarne#0788 ti me-22.43 sec. Figre.12 Ru No 2 BE-A. TS 7. eletedPhoogrphi Imges ~I.":i:-~c::"x~u:~6~

STS-47 Run #2':-........;.. _ ~ ~~ _, ~~~~~~~~~~~~~~ ~........'............ M. *- _l~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......... ~....._. -FraeO79 t''ime=22.50 sec. Fr a m e r)8 17 ti'=___ I_............-..........c:., ~~~~~~'m; I- -.i*-x - r) v, L r1r~ | ~:~;.....~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.ii:';~J: -?''..-?"...' —........I...../..-. Fae95tme2.0 sec Faef)38 tie=.3 s ec. J.v~~Fv/-,wg_.., L-ir-. K; j -,jsi _L;;:.:r-.............. i;; _ o 4 a. ^ w -_...................................... I_- i I _............ Frame#0795tm=254ec 4 rm#87tie2.2sc -....:......................................;^.. _ 4 > v _ -'~~~~:::*:. ",,,9l Frame#0952 time=97.81 sec. Frarne#10385 time=612.99 sec. s~~,'Z_ r i 8.:~ L~rv: Ig-:,S~::<:>* -~.<^ T f' 9n'..~j~ucra ib-~-~io ~~~crir j~ia * -:u. -'~o~~~ C i.:.^ Q.".......:.......,........... Figure 5.2. -'onyt:~ued........ 8 70,,, 0,,,,,,,,;,,,,,........................................................................~~p. ~. Frame#0744 _ Frarne#0744 time=97.81 sec. Frame#1016 time=124.99 sec.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~: Figure 5.12. ontiued I ~-L-~'87~~

STS-47 Run #3 II _=.... ----- --- - L-s -tr - ~~~~~~~~~~~... ~\-,,..,~; )~ —~~~~~C C Frame# 1233 time=41.39 sec. Frame# 1236 time=41.42 sec... - - -,,%,:;-........ t -- _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.................... -.....:.~~~~~~:.'' -, t........................................................~:. t; /.....,' _ }t, g~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~zA.-,.......... I'b''^ "'''"; <QE 9X,..... -;g g _.....'''-:e' $ A................................... a............................,,~'~:.:Q^r,,- A',........:....:.s'..r:' -. -......,....,,. ~ ~ ~ ~ ~ ~ ~ ~ ~....... ~~~~~~~! k.......~:~..1:i:::.~.....!.i:.......... 3.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~ ~_.......~...,:.i ~:,'-:.~-.':.~::,:.~.~,::. >..... " ii~~~~~~~~~~ii~~i~.~::~i:'~'..:!.~,':!~:~.!::.::......,.,....... E~~~~~~~~~rame 1258~~ Frame#1233 time=41.64 sec. Frame#1256 time=41.65 sec....::::. *.:.svxsu>: R~~~~~~~~~~~~~~~~~~~~~~~w:4fx.4 se~~~~~~~~~yy W. X o l.9. >.: * NI:,~.,.,~..~x,,~.-~..:.,,- ee..:...,. z....-,..:~.,~.~..:..: - - - -: w::. *',. ",.''.''''.',','",,@o., _ a a j _.,..X, S,_~~~~~~~~~~~~~~~~~:5.: ~......~....v..,.:..~-.:...,.-...::s.-..~... ~Lr1-W:" "': L."":-x:;' 7:'S;;;:';;; >.;_Q ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~" -''"" ~' t' o-,. *i- l~ i:::* S.................... i::C: CL. ~~~icj~ia~~c-:s ~:i ~~~CIW~t~~L~ ~~.~~.:: i.....~.... ~.:.:~.~-~~~~ Frame# 126 0 time=41.66 sec. Frarne# 126 4 time=41.70 sec. F~~gure 5.13o.":sPLRu No 3 PE-. ST-4. Selec"i)ted"~~Y~ htgrp~ Images r rl- 8 -rK -;::~-at'i::-~ *;'~z~i";"i S S Ai~, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i~~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Frame#1260 time=41.66 sec. Frame#1264 time=4 1.70 sec. Figure 5.13. Run No. 3. PBE-IA. STS-47. Selected Photographic Images.~~~~~~~~~~~~~~~~~~~::,I,~.~e?~~r ~~~~:i ~~ ~ ~ 8

STS-47 Run #3 Frame# 1 27 6 time=41.82 sec. Frame# 1408 time=43.13 sec..........:........>.' ~::'~...........:......... ~:'.'..'.'~. ~~......''.:4~ ~ —— ~-~..''.:: -:.:................' o -A~ ~~..............'....:. ~ Frame#2603 time=98.60 sec. Frame#2717 time= I110.00 sec. Fsur 5.3 Cn:~ud ~-~ ~ —~-1: ~ ~ ~89

STS-47 Run #4 Frame#O 1 34 time= 1 1.34 sec. FramnerS 1 35 time= 1 1.35 sec. ~~~~~~~~~~~~~~~~~.......2.....'....:7.2............... —.:-..' ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-.'...-.............. }................ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i.::151i!:!!.!:. 5'~ E::iii:::ii!:ii E-i:~~:~i.~: —~C:L.-.~-~.>6: ~::..'.:........,......~.:.:..:...:.:...'...''.:.~:...:...:..... ~:.i..yii~:.'~..i:............*...... 5 _' ~ w Zw ~~~~~~~~~~~~~~~~~~~L~ — _........................................ iIL —-:........... e_.._.. -.......~'"' " ~"~~""~""~' ~..:~~~~~~~~~~~~~~~~~~~~_~.L~-L..'.,~..~."*,~".: ~~~~~P~L ~ ~ ~ ~ C I:J`I~~WW Wd I O.~.,Y~.. ~ 3,,\''.,''._,-,>:!,......i~'~~:~::,~~..,;. "' ~.Z...... _V...,'........ ~r:!_,,,::.~.....'.:;t ~~~ Y_''x~esq tU X_;,, -., - s, z s@G~~~~~ime 11.0 s ec Frm # 143 tie 11.3 sec. >N:1 ~i~~'R Fsgue 5.4 R u No.- 4. PBE-I:. STS-~7. Sele.5-~ctedir~ Phtgrp-cIags 90... _..w.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.........i: -g-xooty~~~~~~~~~~~~~~.>.............................;2_,>,ij,,,W'^'','',;'^\YjXV44si o..................... o,,s j,,:j_,,_E.4.iiXY_,,,,,,,,,,,_a>4 3 ~~~~~~~~~~~~~~~~~~........:; — r~:,a~v,,,i; j-. X,, ~:ajb........... ~ —,.,,'"',',','::`'~~:' -' -'~'''.'''''^''S-c ~ ~ I7S|..........:'............................................... s_...........__x _'S....;'..;'..:... 8::..:: Frae#0143 time=',, 1.4 sec. Frameff'O 143 time= 1 1,43 sec. I'""-''"li's xx:'~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~a-i.s:j~~~~Pn ba;~ _z:w~ee~ _ |~~~~~~~~~~~~~I I' c' f;.::',:.,':.:,: —:::,:.,",E,''',:,,,t,,::.."'':~::~,,,,,,,,,,,,,,,.,,::,C' w~ci -' e~~-X'.;- N ~i.}, - - ~ ~;s_ -~:,i ~ Figure 5.14. Run NoO 40 PBE-IA. STS-47:~~:~~~:~:~. Cs:P F Selecced ~~~ Phoogrphi Imagese.:,~;:ji~~ ~~~~~~~~~~~~~~ ~iX ~..-..90~

STS-47 Run #4 Ev a #r; =,, I,..j ~1~;........,...... 1.........7...., Z.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~' r-;' I~~~~~~~ ni;; ~ Y! q'.. 0.-D i _ i -...... _........' A ~~~~~~~~~~..................... -..',''..__........... I. i3Cdl-:", r..3P.;~ jK wz ~ ~ ~ ~' t.........r.. Xvw........ ~~~~~~~~........... /~~ ~ ~00m 0-:: t — * fl tt# s I w:-_,_.....,...-........:. r[ff'i-j~ -^~~~~~i-, II ~~~~0^~~~::e''.'.::":'"7,~'tg;,..:~....'........-....... ~~~~~~~~~~:ii............ Figure~c' 54 C tu 91 15~i 7~,~:1.....:....:::.....:....::.... Frame#0153 ~time= 12.45 sec. Fae 1 time= 14.22 sec....-'e.::........:::::::::::::::::.'...... ~ ~ ~~~~~~~~~~~~~~~~~~~~~?i;iii;?:.............==......====.=.........................................................>....'......:::.;<:;:::....~.....::...:.............. iZ:Z.''''.'..'...:2'.'.'....'~'\i:.Y:.:.:..~~~~~~~~~~~~~~.....:.i.~.-.;.........-..........-..~;.?..~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.:L.I: 3...... Frame#0567 ~time= 19.82 sec. Frm#02time=29.00 sec. F:i. gre5.4 Cntnud 2;~~-~:~:~;~~~:91

STS-47 Run #5.. - -..,,........ I':::' "i:'i.?~ij:!?~~: ~~~'.~2~?:~i.................... ". Frame#21 IO0 time=26.35 sec. Frame#2102 time=26.55 sec. t lY Xt et..~7 I..; -?' "-:''':'t:.-i~i::.: -" 1 d, ~~~...~..~:~..~.:~~~~~!....!..' __! l ~ ~~~":~iI',X0';4':................:.T:.::."! 1;::~ ~1 I: _S~.~:~iiiiii~i::~:~":.....::.;.:j~;!!~~ ~r?'".:~:.:. i!........ ~;.ii!:i;:.'.iii'i~ii~!isi~':.,'""- a... t |. -.9. -. M-. w M 8za.k, i s i............................... E; #F~~~~~~~~~~~~~~~~................. -...el ~.:x~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..... t.,,0. - -. i.;... f...... i.................................... [ l:: - -- *|_~~~~~...................... Fram1e=26 sec Fram210 tim=2.1 se F-igure 5.15. Run No. 5. PBE-IA. STS-47. Select~~~~~~~~~~~~~~~~~~~~~ed Phot~~~~ograph~.....Images... 92.........ffi.A S L X.. ] L~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~........ _ I~~~ ~- _::'- ~c J....: X ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......., X t, *; * g e t 1>): z >.........:..... 5!E )~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~........ ) \ oX E l' g 5 2 - A ^,........,,;.,,,,,,~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~............ 292~~~~~~~ ~r Htffl. -,~:.:. n!.~:~ 1:" I_.~:|,|~~: ~.~~~~ Frame#2 104 time=26.75 sect Frame#2 108 time=27. 1 5 sec.~~~~~~~::~ Figure7~ 5.~.15;.~~?aki*rij:~, Ru N. 5. PE-A SS 47 elctdPhtgrpic Iags:~:~ V~T~:.~r~~~. r92

STS-47 Run #5 Frame#21 11 time=27.45 sec. Frame#2119 time=28.25 sec.::........'";:-.:-.:'::;'- "'. ~;~:.:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..........-.:~~.:...:...~~"..' ".:....::i:::?:.~" " "". ~.:~;'~.;::;'.:;.:.................... ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~..............;:::!:~'~!::',,..... Frame#2144 time=30.75 sec. Frame#2250 time=41.36 sec........... v~~~~~~~~~~~~~~~~~~~~~~~~~~..........-ac_+ e 04~~~u LL'''~:'*'"~:~,... + c.~. ~i- -Y-Q ) ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ rl~~~~~~~~~~ L~~~~~~~~~~''~~~~~~~~~~~~~~~~~Ful,, ~~i~~~~~~~~~~~~~~':~"TM'.i:i~:::::~..''' C:?:~..~j %r ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~il;~~*`;:....... -----— i - ----.... t~~~~~~~~~~~e -' >P i- x'Ei yl_ I tS- - Frame#24K6 time=06.88 sec. Frame#2708 time=8 6.2 2 sec. FIgu.5 nu J:I~ r i f9 Frame#2465 t ime=62.88:4 ~ sec Frae#70 tie862 sec."" Figure 5.15. Continued. ~i~~:csi~Yi::::~:~:~~ry:~6'i93

STS-47 Run #6 " ~;I;_ |.4.. o FrAme{ N# 1.843 time=47-46 se'. Frre 1s 844 ti,,=47.4 sec.A._.ti..- -..... I i —- -- ~ ~.... ~~~~~~~~..'..~....... r.;.S 5^> c.,;i-;,4............................::..:........-.........."'.'.'!.::';.'.:!.......:;:.:.:..!..'.',:... z:';......-..... s -, ~~.....,,. ~::.....::.......-..".......::,.:.. A.:..:.:...... | _I Frame# 1843 time=47.46 sec. Framne# 1844 time=47.47 sec............... |~~~ f 0 - -, |~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:''''..'' W~ +' "'".........'....:........................, Frame# 1848 time=47.48 sec. Frame#1846 time=47.49 sec. 1~~~~~~~~~~~~ - _. h......................,,,,.,.......................................................................;, -'...':i;.~.:.,.'',.:;:i:...-......................,........:-'.:.:;.:.-.a. ".,,.:': —:.i': i:.:'.. -:<: -:..-.........-.-: -..:,!!!!:?:i,,!!!?:?!':i:;i;i~~,: ~i::i.~? i~!;''9 ~~ci.... ~5~~~~~3 9~~~~~~i~~~rX~~~~'"i;t.... "~:-~ -\cr-:~.~~ ~E.;:;i}~,:~: ~~~~~~~~~~~~~~~~~....~cr~z..~p~'~~r~qD?~p ~ Frame# 1848 time=47.51 sec. Frame# 1854 time=47.57 sec. Figure 5.16. Run No. 6. PBE-IA. STS-47. Selected Phot~ograph-ic Images. 914

STS-47 Run #6................, ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~!.........~. ~ ~~ ~~~ ~~~ ~~ ~~~ ~~ ~~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Frm#60tm=1005 se.Fa#26 time 11.2 sec ~` lf~:~~~11 Fre ame116. iCo#tiue5.0 b`Y _E~ ~~9. _ ~~~~~~~~~~~~~~~~~~~~~~~~~~ w_~~~~~~~~~~ U i.- >we v~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *IIC Ifj ura i'5- _~- ~s -: ^., >... ~....;;M9 -x;',.'. _.'r:'<>' _,,- *4_ Jb'a i: <_ _.. Frarne#2962 time= 81005 sec. Fraune#2726 time= l1.00 sec. Figure 5.16. Continued.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.;.~'~~~~:18~ ~~~~~~~9

STS-47 Run #7 ---- ----- -~~- - l)-~~r)~~ FramegO~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-L7~ 164_ _~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. Frameff''v 1 64 time= 11.34 sec. Frame31 66 time= 11.36 sec. _st Z ^ +'' 443Rl F + t<-sa,^> __............E:-.. — aiC~t:':'s-,lt.............'_.. -......'......; ".....................'.''''' s''S W ~~~~ ~....-..............Frm. 1 0... t.. 1.... i~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~f`~h:':"i~ _ a | ti _ _ ~~ —,xt~ur-'I _' Frame#O174 time=l 11.4 sec. Frarne#0016 time=l 11.7 sec. u...7.B-. So:d h orp Iges 96 W==>s' >''<'' a \ " 0 0 < *~~,.,e,., >, __.,.:..,,.,,,,, ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~;oI1-;rpu~*r lr~~e.'T;Eg_: ] 1:: io fC'''d'8U0Y]:a... -..:~~ a~: i-il o;i I, l |U a)^"i:~~Y~i lP S ~~~lrr~:::::.~~~~~~~~~~~~~~~~~~:M,~~~.MM Frame#O 169 time=l 1.39 sec. Frame#0170 time=l 1.40 sec. w.'.xsw.o,,,.......... &.,.:.,, Z. ~.,.................. r,...,,.::....'.i, -.s.....; x, >. -s.;. S Si - w........................... E c;,:,i,,x,,,,:,,0::',,.....:....'''>'-''4':'',>''.''''''''''':_'=.R::.........:::.....-:'i_ " ~ ~ ~ ~ ~ ~i~:~~~~~~....... =,.,;,,.,,.,n,^., s,~~~~~~~~t X........ -,_D.-...,.,, [::.'!:.......... s-~.:::..X,:X':.:~:'-:~:,,~.,,,. -. D k'.r' ame#0:1-' 4ime1: i''::14 s::c.: F. rn'.#.0:: > 0 tim:.71 sec. w. i. * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i3 Frame#0 174 time= 1 1.44 sec. Frame#020 1 time= 1 1.7 1 sec.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:~ Fiur 51. unN.7. PE —: TS47e Seece Phtgrpi Iae e:x:2~::,c`~p~~i~::8'.~;''::96~

STS-47 Run #7 _ _p t -. _.....E~~:..... _.i..................~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~..~i-~.,..,\,......:1,...,,t,u, *s ^...... W.#~~~~~~~~~~~~~~~~~~~~:i- ~- -' ": - A.. - AIC. f ~~ i~ Fram1ne#0323 time= 11.83 s Frame#0c56 time= 12.24 sec. I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ t., dvK 9...i.,s- Y:;........... — t-.i~uns o... -.........._. s -? > * -......'. * * b * s w; [:: V * - - - - - - * - - - - A.:..':.:..~,,.......... S' —....................i...:'.."::................. Frame#0650 time=25.10 sec. Frame#0841 time —44.23 sec. F~i.gure 5.17. Cont'inued. 97

STS-47 Run #8.. w~............ >.'.........- -.-r............,:. I- " s *s x -N-.X )40 -F~~~~~~~v s ~~~~~~~..............-.......' -. e -............ __.,_;_............... L- " — i+: v.........*....A,::.......;.....' ~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~~~. ec. -;..; Y'0.;i',">&'C~ i~i-x*~U-ilLU~rY-~~~~OII~ ~ ~4~1:-........- @...*F...~.....,xr,... -A La: a _~QZrH~ rnpq~ _T _s rl n;'_ e - l S. - _ _ Frame#06141 time=20-66 sec. Frame#0612 time=20.64 sec. _~""~~,"ipal l ca x"41r....... _ _...........................,.........'..gV..,.',j'....A s z<. i;..... X-~ ~~~ ~~~~~~~~<::9-...................:',,,,,,,,, - V. t Mis~~~~~~~~~~~~~~~.................................... X-............ "t -4 xx~~~~~~~~~~~~~~~~ i - - - -a: ~v:;:t I... Frame#0614 time=20-76 sec. Frame#0634 time=20.71 secE~~~~.;hi;W~~~n~~L~* - - I B 8';= i; 2*~~~~~~~~~~a: os-:.<.^wes.SA:>::u~y x... NsSF~I E x.I S, X,X's,Q"~.'4'>.'.5.'':*' "4.':"'..Y XXCwut9~,sv; veXX _SSZ:::i.:_'S'X' X, a,, t t,.'Z'>,.::.....,;,:':.::'.>.':.'.,,.:............................ e Ii~r.~rS* [':_.d,:',, i,,,'',, [',~~~~~~~~:'.4.''.oo'.' ~'.'..'.'''-'-'-'':.4: [',=' [ [:SX,'^<,.;.",'''''-.','.''' —'-'',''.''"','.'.'':,'............',".-'~~~~~~~~~~~~~~~~~~~~~~~~~:~: 11 t_ j @ ~~~~~~~~~~~~~~~ f................... _ * _ rs /irii WriC~Cr~3~ii~Pr~~t....~ hjQ~~ stetn *^o / trn- wg | ^ con........... p-n *o wA +sn_ aG l wh on~~-i~;~ c~*~);~~: 1 lablllWsr J~VJO-V VVVVVVVVVVV'~11119-'J 9....... ~lWrJJft11- JUJO Figue 5e18s un N. 8ePBE-A. SS~47 SelctedPhotgrapic Iages b~:~;jy~~Q~Q~rr-J;~898

STS-47 Run #8 _1 _ ~; __~~..'. I c;. 0;Iw t-.ZW;it~~~~~~~~~~~~~~~~~~~~~~~ i~~~~~~~:a Frame#0671 time=21.22 sec. Frame#0827 time=22.78 sec. Av ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.......:",~-'::w.-.'.'......v....?~~~~~~~~~~~~~~~~~~~~~~~~~...........; 1:: s j'.,':l [X'S 3 I.[. -. A.'.,,,... 51@1..~~~~~~~~~~~~~~~~~~~~~~~~~~~~.D...''.~ ~'. i: i:....:..' ~:~:.-':~:~::!~":'..... "ii.'i~.......!i:.~ ~~~ ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.......... ~~~~~~~~~~~~I i *_rr ~s~~~ ~x~~/..r r ~rX*: ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 3'~~~~..........':':!.:..~:':.:'..:'.::'.'.'.':.~ c:'!~:~:.'................ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......~.'...;.'":::i,'.....!;if:.' i'i:~'~ "a-~ - ~ ~f:, ~. > * * * *, 9. Figure 5.18. Conti:nued. 99 ~..,.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~......................~'O., 4.;1:: Frme139 im=5.2 sc.Frme143 im=6.6 sc

STS-47 Run #9 Frame#2229 time=51.48 sec. Frame#2230 time=51.58 sec......... M-......... ~~~~~~~~~~>....:.... ~~~~~~~~~~: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~ ~ ~ ~ ~ ~ ~ ~ J.. _s........ I'' i _I Is -- 1 1 Wfflq Frae#23 tim=17 sec Frae23 tie5.98 sec.-... E...'.f A. _s,~~~~~~~~~~~~~~~~~~.......................s-::~l~ ~:._....... Frame#2238 time=52.39 sec. Frame#2256 time=54.19 sec. Fgur:.19. Run o., 9. PB-IA. STS-,.. Selected Photograp. ma.e_ 100ra;So: sr TJ wlllr >'XX-:-: - - -- ---- _ [... ii.. ~-..F: t... _ l lE~"~"~"~"~~F,.. I,5:~ ~; T A 77;- f Fb...................... ~:........ Ii:~~J t'i -' {:`~.,.: ~~.~-I E C C'i~ ~~ x" Frame#2238 time=52.39 sec. Frame#2256 time=54.19 sec. Figure~:. 5.19 RulN.PEI.SS40 SeetdPoorpi mgs 100~~~''9~~-: ~

STS-47 Run # c ~~~~~~~~~~~~~~~~~~ ~k:~~~~~~~~~~~~~~~~. /.'~.' Frae#3 0 2 t m = 8 8 e.Fae20ie6.4sc Fram#245 tme=8.1 se. Fame260 tie=8.42sec i.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i}:'~~:~' Frm#73t i m e = 0.07sc rm#88 ie 1.3sc F~~~gure 5.1. Gotnud ~~31, i~~10

6.1 Conduction Effects In the absence of buoyancy and forced convection, heat transfer in fluids takes place by pure stationary conduction, as in solids. This was confirmed for relatively short periods in microgravity, in solids and in fluids before nucleation takes place, by the measurements of Ervin and Merte (1991), also appearing in Ervin et al (1992). In this case the physical processes of conduction conformed closely to the analytical solution for two semi-infinite solids, initially at a uniform temperature, with a uniform step in a plane heat source at the interface. 6.1.1 Conduction in Substrate The analytic solution of the interface temperature between the two semi-infinite solids, which corresponds to the gold film heater surface temperature in the physical system, is plotted as the 1 -D Analytical Surface temperature for reference purposes for each of the Runs of the matrix in Figs. 2.2a - 5.10Oa. The discrepancy between the analytical and the measured values increases for the lower level of heat fluxes, for which longer periods of conduction heat transfer in both the solid and fluid domains take place before nucleation occurs. This discrepancy is attributed to three-dimensional conduction effects during this period, primarily in the quartz substrate domain, which has a larger thermal diffusivity, a = k/pc = 8.34 x 10-7m2/s, compared to a = 5.24 x 10-8m2/s for R-113. Comparisons of the short 5.1 second drop-tower ground based testing were excellent with the one-dimensional solutions. In this case the quartz substrate was less massive than that in the PBE, and the single heater surface on the substrate was located symmetrically. To confirm that three-dimensional effects were operating in the PBE a 3 - D finite element model was developed for the particular geometry of the PBE. It was computationally intensive, requiring about 10 hours on a 486 base machine, and the results are presented here for demonstration purposes. Fig. 6-1 shows the measured mean heater surface temperature for Run No. 3 of the PBE-IA on STS-47 from Fig. 5.4a. Also shown are the measured underside surface quartz temperatures under the center of each of the heaters from Fig. 5.4e, with the active heater side measurement being TM1 1, the larger increase of the two, as anticipated. Also indicated are the 1 - D analytical heater surface predictions from the semi-infinite solid solution, and the 3 - D predictions of both the heater surface and the quartz undersides using the finite element solution procedure with the heat flux input up to the nucleation point, followed by an imposed uniform surface temperature, which approximates quite well 102

the measured value following nucleation. It is noted that the 3 - D computation closely approximates the measured surface temperatures up to the nucleation point. The measured temperature rise occurring at 85 seconds was not incorporated into the 3 - D finite element model. Nevertheless, it is noted that the measured quartz underside temperatures follow the computed changes. The difference of 20C between the measured and computed quartz underside temperatures is a consequence of taking the initial quartz temperature to be uniform at the initial bulk liquid temperature, in the computational process. An initial difference of 20C across the quartz existed as a result of the heat transfer from the quartz to the surroundings, which were about 100C cooler than the quartz surface. This had little effect on net heat losses from the heater surface itself because of the low thermal conductivity of the quartz. Fig. 6.2 is an isometric plot of the 3 - D temperature distribution in the quartz substrate computed by the 3 - D finite element model, at the onset of nucleation at 40 seconds on Fig. 6.1. This shows clearly the conduction taking place as departures from the 1 - D semi-infinite solid model. The potential influence that 3 - D conduction effects might have on the computation of the heat transfer coefficient to the fluid will be considered in the next section. The upper part of Fig. 6.2 is a central section showing the 2 - D temperature distribution in the R-1 13 after 30 seconds of heating, and demonstrates that the extent of the penetration of the temperature disturbance is quite small. Fig. 6.3 presents an isometric plot of the 3 - D temperature distribution in the quartz substrate at 90 seconds in Fig. 6.1, using a constant mean surface temperature of 750C as measured, following nucleation at 40 seconds. The 2 - D central section temperature distribution in the R-113 is also given at the top, but has no physical significance, since boiling has begun at 40 seconds. 6.1.2 Conduction in Fluid Fig. 6.4 shows the measured mean heater surface temperatures as fitted from the measurements of heater current and voltage at 10 Hz. Also repeated from Fig. 6.1 are the 1 - D and 3 - D computed heater surface temperatures prior to nucleation. The heat transfer coefficients to the fluid are computed from the measurements with the 1 - D finite difference procedure for the case where a polynomial fit is used between each of the measurement points for interpolation purposes, and results in the oscillations observed. The 3 - D finite element computation of the heat transfer coefficient during the conduction phase up to nucleation provides a reasonable fit to the heat transfer coefficients computed by the finite difference method when some visual filtering is applied. Once nucleation occurred the 3 - D finite element model used a constant imposed temperature, which approximates the 103

measurements out to about 85 seconds when dry-out begins. The heat transfer coefficient computed from the 3 - D finite element model during the 40 second to 85 second interval follows the smoothed version of that computed from measurements with the 1 - D finite difference model. This is a consequence of the relatively low thermal diffusivity of the quartz, which means that the penetration depth of the disturbances taking place at the surface with these frequency levels are not influenced by three dimensional effects. In order to determine the effect that filtering of the measured mean heater surface temperature would have on the heat transfer coefficient computed with the 1 - D finite difference model, two different degrees of filtering techniques were applied, presented in Figures 6.5 and 6.6 for the same Run No. 3 of PBE-IA on STS-47. Fig. 6.5 presents the mean heater surface temperature and computed heat transfer coefficient taking three (3) successive heater surface temperatures at 100 ms intervals averaged to provide the temperature at the middle point on the time scale. This procedure was advanced for each 100 ms data point. The smoothing obtained is noted by comparison with Fig. 6.4. Fig. 6.6 is similar to Fig. 6.5, except the averaging process was conducted over five (5) successive measurements, advancing also in 100 ms steps. Excessive filtering is to be avoided, since it is possible that a real transient might be eliminated. The results presented in Figs. 5.2 - 5.10 were obtained without the use of any filtering. Future data reduction will take place using the 3 point averaging technique. However, a polynomial fit for interpolation between data points is necessary in both cases. One further assessment of the procedures followed in the numerical computation of the heat transfer coefficient from the measured mean heater surface temperatures is necessary. In carrying these computations out it is assumed that the heat flux input to the heater surface is constant, at some interpreted mean value. That this is not the case can be noted by examining Figs. 5.2b - 5.10b. A detailed examination of the effect of taking a constant heat flux was conducted for PBE-IA Run No. 3, using the 3-D finite element model developed here. In one case a curve is fitted to the measured variation in the input heat flux, while in the other case the input heat flux is taken to be constant. The results are given in Fig. 6.7, and it i oted that any discernible discrepancy occurs only in the immediate vicinity of the nuclea.. I1 point, where the largest temperature change occurs, with the maximum variation in the inr lit heat flux. At this point the peak computed heat transfer coefficient is reduced from.')0 to 1600 w/m2K. Actual two dimensional variations over the heat transfer surface make such distinctions between the mean input heat fluxes difficult to justify. Furthermore, the 3 - D element computational time required for the constant heat flux is two (2) hours for a 2 104

minute test run with 0.5 sec. time steps, compared to six (6) hours with a variable input heat flux. As a result, a constant mean input heat flux is used here throughout. 6.2 Nucleation Fig. 6.8 is a plot of the nucleation delay times obtained in the early ground based testing, including the tests conducted in the 5.1 second NASA-Lewis drop tower, for a particular heater surface designated as Q5. Nucleation delay time is defined as the interval between the onset of heating and the moment when the first vapor bubble appears. For a given input heat flux a distinct relationship exists between the nucleation delay time and the heater surface superheat and liquid temperature distribution at the onset of boiling. The latter quantities govern the character of the early bubble dynamics and the spread of the boiling across the heater surface. Such processes are described in detail in Ervin and Merte (1991), Ervin et al (1992), and Lee and Merte (1993). Based on these ground tests an optimum correlation was developed, as shown in Fig. 6.8, in order to estimate the delay times expected in the flight experiment. A number of the drop tower data were neglected in this process, marked by asterisks, because the heater surface superheats at nucleation, plotted in Fig. 6.10, appeared unusually high. All nucleation delay times measured with the PBE-IA are plotted in*Fig. 6.9 together with the identical correlation from Fig. 6.8. The comparison with the flight data is quite good. Fig. 6.10 is a plot of the mean heater surface superheats at nucleation for the same tests plotted in Fig. 6.8. It was not possible to conduct these tests in the drop tower with the lower levels of input heat flux, since nucleation did not take place in the 5.1 second drop tower test. An intermediate heat flux level was introduced, and it is noted that the heater surface superheat on nucleation at a/g 0 O appears as a maximum at the heat flux levels between the highest and lowest values, even with different subcooling levels. Fig. 6.11 is the corresponding data obtained from all the PBE-IA tests conducted, including preand post- flight. It is noted that a corresponding peak exists in the mean heater surface superheat on nucleation between the high and low levels of heat flux, and is particularly high in microgravity. In addition, for the most part, as the subcooling level increases the heater surface superheat on nucleation is smaller. This is quite opposite to what intuition would provide. No explanations for the above behaviors appear reasonable, as yet, unless the nucleation becomes a function more of the absolute temperature rather than the superheat. The heat flux levels selected for these experiments vary by factors of two, in order to cover the widest range possible with the limited testing available. A proposal has been submitted for further flights to include heat flux input levels of 0.5, 1.0 and 2.0 w/cm2 with the same subcooling as in Fig. 6.11, and subcoolings up to 220C with the same 105

heat flux input levels as in Fig. 6.11, so that the explanation mentioned above about the role of the absolute temperature on nucleation rather than the superheat could be explored further. In addition, the role of the liquid temperature gradient at the heater surface interface at nucleation, along with bulk liquid subcooling, is being examined. It was demonstrated by Ervin and Merte (1991) that nucleation of R-1 13 can occur at heater surface superheat levels on the order of 40C if a sufficiently rapid heater surface temperature increase can be instituted. In this latter case, approximations to step changes in heater surface temperatures were being attempted. On the other hand, as reported by Iida et al (1993), high rates of heating for ethyl alcohol at atmospheric pressure by a small (0. 1 mm x 0.25 mm) platinum film 20 Angstroms thick on quartz, to 1070C/s, produced nucleation at the theoretical homogeneous nucleation point of 1290C superheat. In this case the liquid subcooling was 530C, and the formation of the vapor bubbles was described as "Caviarwise bubble generation". 6.3 Bubble Dynamics Based on both observations and measurements conducted in earth gravity at a/g = +1, a/g = -1, and in the 5.1 second NASA-Lewis drop tower, once nucleation occurred the propagation of the boiling across the heater surface and the bubble growths could be classified into one of six categories, termed as follows: A. Advancement of interface by irregular protuberances. B. Growth of mushroom-like bubble with spreading along heater surface. C. Orderly growth of bubble with a "smooth" interface. D. Orderly growth followed by onset of interface instabilities. E. Energetic growth of bubble with unstable interface. F. Slow motion of bubbles toward region of higher temperature. The circumstances under which these took place with R-113 are given in detail in Ervin and Merte (1991) and in Ervin et al (1992), and will be summarized here: A took place only at a/g = +1 with qT >2 7 w/cm2. B occurred only at a/g = +1 with 2 < qT < 7 w/cm2. C took place at a/g = -1 with high levels of heat flux qT- 7 w/cm2. D was observed with a/g = -1 with q < 7 w/cm2and a/g 10-5, also with qC < 7 w/cm2' However, the lowest heat flux level possible in the drop tower was qi 6 w/cm2. 106

E was observed only with a/g 10-5 and gave rise to the explosive growth with protuberances appearing over the entire liquid-vapor interface. The lowest heat flux possible was qT = 6 w/cm2. F occurred at a/g = -1 and a/g 10-5 with q > 7 w/cm2. The motion is attributed to thermocapillary effects. Although the initial bulk liquid subcooling was expected to play a part in these categories, its effect is not yet clear. From examination of the photographs from the PBE-IA on the STS-47, with samples given in Figs. 5.11 - 5.19, all boiling propagations are in either categories D or E, depending on the combination of heat flux and subcooling. The difference between these two categories lies in whether the bubble growth and/or propagation takes place relatively slowly or dynamically (explosively). The maximum camera speed of 100 pps in the PBE-IA was not capable of following the dynamic cases of category E. It is estimated that a framing rate greater than 3000 pps would have been necessary. Another manifestation of the distinction between categories D and E lies in the absence or presence of measured pressure spikes in connection with nucleation. The rate of data acquisition for the system pressure was limited to 10 Hz (100 ms between readings), and the peak pressure can occur at any time between these measurements. Such pressure spikes can be noted in Fig. 5.3c for Run No. 2, in Fig. 5.6c for Run No. 5, in Fig. 5.7c for Run No. 6, and in Fig. 5.10c for Run No. 9. The pressure control system was not capable of responding to this nucleation spike, nor was it intended to. From the films, Category D takes place with the highest heat flux and for all subcoolings, in Run Nos. 1, 4, 7, and in Run 3, with the lowest heat flux and the largest subcooling. All other Run Nos. 2, 5, 6, 8, 9 result in very energetic or explosive initial vapor bubble growths, Category E, which include all Runs at the medium heat flux qT 4 w/cm2 for all subcoolings, and at the low heat flux qT- 2 w/cm2 for low or zero subcooling. The behavior in Run Nos. 2, 5, 8, with qT -j 4 w/cm2 is related to the high heater superheat at nucleation demonstrated in Fig. 6.11, relative to that for the other heat flux levels. It is also noted in Fig. 6.11 that the nucleation heater surface superheat for the lowest heat flux and highest subcooling, Run No. 3, is about the same as in Run No. 1, which also was in Category D. The energy content in the superheated boundary layer thus is not as high as in the other Runs, in microgravity. 107

It is believed that the dynamic growths taking place in certain cases can result in vapor bubble departures from the heat transfer surface due to the momentum imparted to the liquid, causing rewetting of the heater surface and sustaining the nucleate boiling process. Such a departure appeared to take place here only in Run No. 2. The initial growths in both Run Nos. 6 and 9 were quite dynamic, with dryout but not momentum produced bubble departure, and followed by a relatively slow rewetting process. The heater surface never did dry out completely in Run No. 3, and is believed to be due to the low heat flux together with the large subcooling. All three cases with the lowest heat flux level, Run Nos. 3, 6, 9 appear to produce a sustained steady-state nucleate boiling in microgravity, for all levels of subcooling. This is set forth in Table V, which summarizes the mean heat transfer coefficients obtained with PBE-LA, both at a/g = +1 and in the STS-47 Space Flight. Dry out occurred in all Runs at a/g = -1 because of buoyancy effects. It is noted in Table V that nucleate boiling takes place at a/g = +1 only for the highest levels of heat flux, in Run Nos. 1, 4, 7, and also in Run No. 2, for the medium heat flux level but with the highest level of subcooling. Even here, subcooling appears to be playing an anomalous role in pool boiling. The heat transfer coefficient is the largest at h = 2500 w/m2K with the largest subcooling, in Run 1, while those for Runs 4 and 7 are slightly lower but identical at h = 2300 w/m2K. The measured mean natural convection non-boiling heat transfer coefficients are on the same order as predicted by the correlation, as indicated. The maximum discrepancies are on the order of the generally accepted levels of + 25%. The decreases in heater surface temperatures., accompanied by increases in the heat transfer coefficients, as noted: in Fig. 5.2a for Run No. 1 at 65 seconds, in Fig. 5.4a for Run No. 3 at 110 seconds, in Fig. 5.5a for Run No. 4 at 50 seconds, in Fig. 5.9a for Run No. 8 at 65 seconds, in Fig. 5.10a for Run No. 9 at 105 seconds, are a result of activating the stirrer motor before the test is completed. This can be confirmed from the test matrix given in Table II. However, on examining certain Runs it is noted that distinct increases in surface temperature take place, accompanied by decreases in the heat transfer coefficient: in Fig. 5.4a for Run No. 3 at 85 seconds, in Fig. 5.6a for Run No. 5 at about 80 seconds, in Fig. 5.9 for Run No. 8 at about 55 seconds, in Fig. 5.10a for Run No. 9 at about 80 seconds. 108

q" A Tsub Run Ww/nm2K | w/rn2K No. Aprox. Approx./ a/g + ag = 10-5 No Appox Post Flight 11/4/92 STS47 T 7.0 10o7 25 700 Nucleat Boiling Drv Out 2) ~ 306 11o5 1300 1250' Nucleate Boilina Steadiv State + Oscallatimg 1.8 11.0 450 (350)* 1 100 = O0 Non-Boiling Convection Steady State - Dry Out 4 7.0 { 273 200 Nucleate Boiling Dry Out 5 3.6 2.8 550 (430)* 400 -= 200 Non-Boiling Convection Increased Dry Out 6 1,8 550 (350)* 1150 Non-Boiling Convection Steadv State + Osci11atin (Rewet) 7 7.0 0.6 j 23 200 _Nucleate Boiling Drv Out 8 3.5 0.4 600 (400)* 3 = 20 0 NonBoiling Convection Incsed Drv Out 9 1.8 0.2 500 (350)* 1100 = 200*~ _Non=BoiinE Convection Stvead State + Drv Out & Rewet Computed from natural convection correlation Nu = 0 15 x Ra /3 Table V. PBEolA. Comparison of measured mean heat transfer coefficients between ag =+1 and STSA47 Space Flight. 109

Looking at the photographs in Fig. 5.13 for Run No. 3, with the lowest heat flux and highest subcooling, it may be noted that the dryout area begins to increase over the surface, without any significant amount of nucleate boiling taking place over the wetted portion of the heat transfer surface. It is possible that the subcooling inhibits the nucleation process in the vicinity of the meniscus, so that the agitation of the liquid-vapor interface by the absorbing of these small bubbles is reduced sufficiently that the rewetting of the heat transfer surface by the meniscus becomes inhibited, promoting the dryout process. For the other Run Nos. 5, 8, 9, it is believed that the distinct increases in surface temperature are due to the vapor bubble growing sufficiently large so that it becomes pressed against the heater surface. It can be seen in Fig. 3.5 that the largest size vapor bubble that can be accommodated in the test vessel before contact is made with the walls is about 12 cm in diameter. If all the heat transfer to the fluid produces vapor, as would take place with a saturated liquid, the size of the vapor bubble in a microgravity environment can be calculated as approximating a sphere. The resulting vapor bubble radius is plotted in Fig. 6.12 as a function of time for the 3 nominal levels of heat flux used. For q j' 2 w/cm2 a radius of 6 cm is reached at about 85 seconds, which agrees approximately with the behavior of Run No. 9; For qT _ 4 w/cm2 the time is about 55 seconds, which agrees with Run No. 8. Run No. 5 at qj= 4 w/cm2 has a time of 80 seconds, which is larger than the estimated 55 seconds, because of the nominal subcooling of the liquid which reduces the bubble growth rate as a result of condensation. 6.4 Heat Transfer to Fluid As described previously, the mean fluid heat transfer coefficients computed from the measured mean heater surface temperatures are plotted in Figs. 5.2a - 5.10 a for each of the respective Runs of the matrix. A definite relationship exists between the transient mean heater surface temperature and the heat transfer coefficient. These serve to indicate, qualitatively at present, the modes of heat transfer between the heater surface and fluid: conduction to the liquid; nucleate boiling; conduction to the vapor phase (termed dryout); and combinations of the three forgoing mechanisms based on the fractional part of the heater surface over which each is acting. For the time being the conduction heat transfer mode to the liquid will be neglected in the interest of simplicity. For the heat flux levels used to date, nucleation and its propagation across the heater surface take place early in the process, so that the major part of the heat transfer surface is either covered by vapor or influenced by the nucleate boiling phenomenon itself. For future cases where the heat flux levels are sufficiently low such that relatively smaller portions of the heater surface are 110

influenced by the presence of either nucleating sites or significant amounts of vapor, the heat transfer to the stagnant liquid regions then will be incorporated. From the photographic data taken through the transparent heating surface from the underside, it is possible to discern quite distinctly those portions of the heater surface on which dryout has taken place. Examples are abundant in Figs. 5.11 - 5.19. It is observed that under some circumstances this is a time varying phenomena, and is related in some fashion to both the transient mean heater surface temperature and heat transfer coefficient. If measurements of the time varying fractional area of the heat transfer surface in contact with vapor, which will be termed the fractional dryout area, can be made with sufficient temporal detail, it is felt that the possibility exists for quantifying the contributions to the total heat transfer of the different modes of heat transfer taking place. Since only mean heater surface temperatures and heat transfer coefficients are measurable at present, only spatial mean parameters can be determined: local measurements in the future would permit determination of these parameters on a spatially local basis. In order to provide an efficient means for quantifying the time varying fractional dry portion of the heater area from the 16 mm films, an optical processing system has been set up in which the 16 mm film is projected on a screen with a motion picture projector; the motion is stopped at the desired frame; the time noted; the image picked up with a video camera, which can then be stored on a VCR and/or immediately digitized with a frame grabber for greater resolution; the digitized data is stored on an optical disc for later processing. The following will demonstrate how the measurements of the fractional dry portion of the heater area and the spatial mean heater surface temperatures T and heat transfer coefficients liT may be related. Fig. 6.13 is a representation, from the underside, of the heater surface on which boiling is taking place in microgravity, and may be considered to be typical of, for example, Fig. 5.12 - Frame #0952 and Fig. 5.13 - Frame #2603, reproduced from digitized 16 mm frames from the STS-47 Flight of the PBE-IA, Run Nos. 2 and 3, respectively, and are runs with the largest subcooling used. The dry portions of the heater surface are readily discernible in both cases, as is the nucleate boiling taking place over the remainder of the surface in Frame 0952 of Fig. 5.12. These bubbles are then "absorbed" by the larger overlaying vapor bubble due to the action of the surface tension. In Frame 2603 of Fig. 5.13, on the other hand, with the lower heat flux, part of the domain between the dry portion appears to be inactive in this frame. In reality, nucleate boiling is also occurring in these domains, but with a significantly smaller frequency and nucleation site density. It should be kept in mind that the pool boiling process in microgravity is inherently transient, because of the changing local subcooling and changing 111

size of the overlaying vapor bubble, and consequently the nature of the local and average boiling processes will be changing as well. Fig. 6.14 is a simplified representation of Fig. 6.13, and illustrates how the mean heater surface temperatures and heat transfer coefficients are defined for the dry and nucleate boiling areas as TD, hD and TB, hB, respectively. The following additional definitions are made: AT = AD+AB (2) 1 = A+ AT = FD + FB (3) where FD and FB are the fractional dry and nucleate boiling areas of the heater surface, respectively. qT = qT/AT (4) Tw = FD x TD + FB x TB (5) The overall mean heat transfer coefficient: hT = qi/(T w - Tsat) = q"/-Tw (6) qT = qD + qB (7) a -a-_X_ qD +B_ AD of AB of qT AT AT +AT_ ATX qD + ATX qB= FDXqD + FB XqB (8) The mean heat transfer coefficient on the dry portion of the heater surface is: hD = qbj/(TD - Tsat) = qD/ATD (9) The mean heat transfer coefficient on the nucleate boiling portion of the heater surface is: hB = qi/(TB -Tsar = qB/ATB (10) From Equations (6), (8) - (10): qT = hT x ATW = FDX hDXATD+FB x hBx ATB (11) From Equation (11): 112

hT = FD x hD x + FB x hB X B (12) ATw ATw If, as an approximation, hB can be considered constant for a given heat flux input and bulk liquid subcooling, and also if hB >> hD and ATB/ATw 1=, then from Equation (12): ohT (13) =FB (1- FD) (13) Both hT and FD are independently measurable quantities, and the supposition as to the constancy of hB thus can be tested. Should this prove to be the case, then the total heat transfer rate could be approximated, from Equations (4), (6) and (13) as: qT = AT x (1 - FD) X hB X ATw (14) The heat transfer coefficient hB defined by Equation (13) could be viewed, in these circumstances, as a microgravity nucleate pool boiling heat transfer coefficient. The assumptions made in its development are summarized: (a) hB = constant (b) hB >> h (c) ATB/ ATw = 1 An additional assumption was implied: (d) FB # = O This last condition is related to the fact that FD is measured, and in Equation (13) the measured hT is divided by FB = 1 -FD. If FD is close to unity, then FB is close to zero, and the relative uncertainty can become quite large. The limit to which FD can approach unity for these calculations is as yet unknown; as will be shown below, measurements up to FD = 0.95 have been made. 113

Upon examining the transient mean heater surface temperatures and mean heat transfer coefficients of the PBE-IA on STS-47 microgravity flight, in Figs. 5.2a - 5. 10a, photographic candidates were selected from the nine test points of the matrix for detailed measurements of the dry spot areas in order to compute a microgravity boiling heat transfer coefficient. These are tabulated in Table VI, together with the current status. In the early stages of such computations the individual frames were digitized, individual prints of each made, and the dry spot areas measured by hand with a planimeter - an admittedly laborious process. However, it was desired to explore the feasibility of the process, and to examine the results so obtained before investing further resources. In addition to an external optical drive with storage capacities of 600 MB/cartridge, software for computing the manually defined dry spot area has been obtained to bypass the manual area measurements. Estimates of the time required to digitize and measure the dry spot fractional area for each frame have been made, and require approximately 10 minutes per frame, which includes the time required to identify the time from the LEDs on each frame. This is necessary in order to synchronize these measurements as closely as possible with the mean heater surface temperature measurements. Of the total of about 18,000 frames in the 400 foot roll of 16 mm film exposed in the experiments, the times selected in Table VI correspond to about 2400 frames. As indicated in Table VI, about one-fourth of this has been completed, with 1800 remaining. Computational results will first be presented for PBE-IA Run No. 9, since examination of Fig. 5.2a shows both heater surface rewetting and dryout taking place in the same Run, not associated with the initial transients of nucleation. The effects of heater surface rewetting and dryout beginning at about 62 seconds and 82 seconds, respectively, are noted. In these domains the 16 mm film is running at 10 pps. It was discovered that defining the dry-out portion of the heater surface requires a certain element of human interpretation since the automatic measurements based on a defined gray scale in conjunction with the processing software available tended to produce much larger fractional dry areas than was deemed reasonable. Nucleating sites produce light shaded areas similar to dry areas, but make significant contribution to the heat transfer, and must be discounted in the area evaluation. Fig. 6.15a shows the measured heater surface fractional dry area and.-e mean surface temperature for the time interval of 61.5 to 67.5 seconds in Fig. 5.-. The temperature changes in Fig. 6.15a do not appear as extensive as in Fig. 5.2a because of the considerably expanded time scale. It is noted that the heater surface temperature decreases as the fractional dry area decreases. Fig. 6.15b is a plot of the measured heater surface fractional wet area, obtained from Fig. 6.15a, and the mean heat transfer coefficient 114

Run No. Times Selected Status l. l Nucleation - 20 Seconds 2. 20 Sec.-+ 30 Sec. 65 Sec. -- 75 Sec. 95 Sec. -* 100 Sec. 3. 42 Sec. - 50 Sec. Completed 55 Sec. - 60 Sec. 83.5 Sec. + 90 Sec. Completed 4. Nucleation - 20 Sec. 5. Nucleation - 35 Sec. 70 Sec. 90 Sec. 6. Nucleation - 65 Sec. 50 Sec. -e 58 Sec. Completed 7. | Nucleation -- 15 Sec. 8. 8. | Nucleation - 35 Sec. 50 Sec. -- 60 Sec. 9. Nucleation -* 70 Sec. 61 Sec. -e 69 Sec. Completed 80 Sec. -e 90 Sec. 80.5 Sec. - 85.5 Sec. Completed Table VI. PBE-IA on STS-47. Candidates for heater surface dry spot area measurements and computation of microgravity nucleate pool boiling heat transfer coefficients. 115

replotted from Fig. 5.2a. If the assumption that hB = constant, made above, is valid, then the two quantities plotted in Fig. 6.15b should vary in a similar manner, according to Equation (13) above. As can be seen, this appears to be the case. hB can be computed from the data of Fig. 6.15b, and is obtained by dividing the mean heat transfer coefficient by the fractional wet area. This is plotted in Figure 6.15c, together with the measured mean heat transfer coefficient and wet ratio from Figure 6.1 5b. For convenience eight (8) photographic images showing the rewetting process are included here as Fig. 6.15d. the microgravity boiling heat transfer coefficient in Fig. 6.15c is noted to be approximately constant during the period from 62 seconds onward, with a value of about h - 1250 w/m2K. It is also to be noted that the mean heat transfer coefficient converges toward the nucleate boiling heat transfer coefficient as the heater fractional wet area approaches unity, as it must since one is derived from the other. In this connection it should be pointed out that the seemingly large variations in the boiling heat transfer coefficient occur only when the heater fractional wet area is quite small, and is a result of inherent uncertainties in both the mean heat transfer coefficient and the measured fractional dry area. This uncertainty is amplified when dividing the measured mean heat transfer coefficient by the fractional wet area, which is obtained by subtracting the fractional dry area from unity. There is a further contribution to the uncertainty because of the uncertainty of 0.1 second in time in the measurement of the dry area when the camera speed is 10 pps. It is also possible that the boiling heat transfer coefficient is a function of the fractional dry area, but the determination of this must await more accurate local measurements of heater surface temperature. Figure 6.16a is a plot corresponding to Fig. 6.15a, except for the time interval of 80.5 to 85.5 seconds in Run No. 9, while Figs. 6.16b and 6.16c correspond to Figs. 6.15b and 6.15c for this same time interval. The difference in the boiling heat transfer coefficient between Figs. 6.15c and 6.16c is that the heater fractional wet area is increasing in Fig. 6.15c, while it is decreasing in Fig. 6.16c. In spite of this, the boiling heat transfer coefficients have mean values of approximately 1250 w/m2K and 1200 w/m2K, respectively. These are surprisingly close values, within 4%, when the various total uncertainties involved are acknowledged. Fig. 6.16d shows eight (8) images of the dryout process taking place in this same interval. Figs. 6.17 (a-d) - 6.19 (a-d) present the results of measurements and calculations in the same format as Figs. 6.15 (a-d) and 6.16 (a-d), for two parts of Run No. 3 and one part of Run No. 6, respectively. Figs. 6.17 ( a-d) show the oscillatory behavior following the initial dryout associated with nucleation, while Figs. 6.18 (a-d) follow the dryout related to possible effects of subcooling on nucleation in the vicinity of the meniscus, as 116

discussed earlier. The nucleate boiling heat transfer coefficient decreases slightly to h 900 w/m2K in Fig. 6.18c, whereas it is larger, hB= 1200 w/m2K earlier in the same Run No. 3, during the rewetting process shown in Fig. 6.17c. It should be noted that both Run No. 3 and Run No. 9, included in Figs. 6.17 (a-d) - 6.18 (a-d) and Figs. 6.15 (a-d) - 6.16 (a-d), respectively, have the same low level of heat flux, with the former having the large degree of subcooling. The results for Run No. 6, also with the lowest level of heat flux but with a moderate subcooling level, are given in Figs. 6.19 (a-d), also for the rewetting phase following the initial dryout resulting from nucleation. It is seen in Fig. 6.19c that the nucleate boiling heat transfer coefficient remains constant at a level of hB 1000 w/m2K even though the wet ratio varies from 40% to 80%. 117

Comparison of temperatures between measured and computed for STS47 Run #3 100 - Z -- ________ _ ____ _ _________- --- 66 A.8 W/cm2, Tinitial=49.0 __ 90 - 3Dcmptto Measured Surface Temiperature 6 90 - D computation U 70 -1 — 1 ~6 0 From here 3-D temperature regarded to be coritant Cd 60 H 50 Measured quartz temperature, TM 11 and TM 12 56 00 cA 40 3-D computed quartz temperature, TM 1 I and TM 12 U &Y = 30 t 5 20~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5 10~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5 o t~~~~~~~~~~~~~~~~~~~~~~~tj 0 -t —----— 1 — -- — t —— 1- V ---- ---— t -- ---— t- I — - ----— F — --— 1 —- 1t --- -4 —— t —--- - 46- J 0) 20 40 60 80 100 120 14() Time, sec Figure 6.1 Comparison of 1 - D and 3 - D predicted temperatures with measurements. PBE-IA on STS-47. Run No. 3. qj" = 1.8 w/cm2, ATsub = IO.90C.

STS-47 Run#3 q"=1.8 W/cn2, Tini=49 0C, time=40 Sec. 1.100E+02 Max..~ R-113 - 9.780E+O1 8.560E+O1 7.340E+O1 6.12E0 Min./-) L 4.900E+O1 33q Figure 6.2. PBE-IA on STS-47. Run No. 3. Isometric plot of 3-D temperature distribution in quartz substrate at 40 seconds.

STS-47 Run#3 q"=1.8 W/cm2, Tini=49 0C, time=90 sec. 1. 100E~02 9.780E~O1 8. 560E+O1 Q Max 7.340E+O1 4.900E+O Min. Figure 6.3. PBE-IA on STS-47. Run No. 3. Isometric plot of 3-D temperature

3000- 100 I-D Atalytical Surf. Temp. 1 3-D computed Surf. Temp. 90 Measured Surface Temperature 250080 -.I 70 2000 | g rom here 3-D surface temperature regarded to be constant 2000 O 60 o 1500 ||.|- h,computed from Measurement(I-D) 50 1500 Oe i H- I I I I I I - 0 () 5000 [., ~~~~~~~~0~~~~~~~~~~~~~~~~~~~~~~~ 0 20 40 60 80 100 120 Time (sec) Figure 6.4. PBE-IA on STS-47. Run No. 3. Comparison of fluid heat transfer coefficients computed from measured mean heater surface temperatures using 1-D finite difference and 3 - D finite element models.

Heater Surface Temperature and Heat Transfer Coefficient for STS-47 Run #3 (3 point average) 3000 100 1-D Analytical Surf. Temp. Measured Surface Temperature (3 point average) 90 2500 80 70 0 2000 60 E v O.~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. N ~~~~~~~~~~~~~~~~~~~E, 1500 50. In, -J ~~~~~~~h, 1-D Analytical 0~~~~~~~~~~~~~~~~~~ 40:3 1000 12 Time (sec) Figure 6.5. PBE-IA on STS-47. Measured heater surface teinperature filtered by 2averaging three (3) consecutive measurement points sequentially. 5~~~~~~~~~~~~~~~~~~~~~00 h, 1-D Analytical 1 0 ~~20 40 60 80 100 120 Time (sec) Figure 6.5. PBE-IA on STS-47. Measured heater surface temperature filtered by averaging three (3) consecutive measurement points sequentially.

Heater Surface Temperature and Heat Transfer Coefficient for STS-47 Run #3 (5 point average) 3000 / 100 1-D nalytical Surf. Temp. 90 l | \ / \ ~~~~~~~~Measured Surface Temperature (5 point average)l 2500,,~~~~' ~~~ | | i l l t~~~~~~~~ 80 700 2000 6O,I1500 50 filtered byaveragingfiveh, comp uted from m easurement pn 40 s 1000 30 " 20 500 h, 1-D Analytical 1 0 I — 4 —-- I 0 0 20 40 60 80 100 120 Time (sec) Figure 6.6. PBE-IA on STS-47. Run No. 3. Measured heater surface temperature filtered by averaging five (5) consecutive measurement points sequentially.

2500 0 _ _ _ _ — 1.9 3-D computation for STS-47 Run #3 Hleat flux curve fitted 2000 -- - P r c(Y 1.8 Constan heat flux (1.8 W/cm2) Hleat flux measured h foor constant heat flux 1500 I 1.7 h for variable heat flux.r. 1000 1.6 500 1.5 0 I — _ —------- I I —--— +-t -- ---- tt- - 1.4 0 20 40 60 80 100 120 140 Time (sec) Figure 6.7. PBE-IA on STS-47. Run No. 3. Comparison of the fluid heat transfer coefficients obtained by taking the input heat flux as constant or variable.

Delay Time vs. Heat Flux (or QS 100 0 If Boiling~~~~~~~~~~~~~~~~311m Propaao Au t*=145.083 exp(-().6969cq ) i nal B0111 C) 0 /~ IrBSubcl() 2 /7 10 uA Subl)Col 2 7 A Siilc I 1 Ao * o J Subtcoo~l 0) 0C, a/gO ( 0.1 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 0 Saa I i U Suhol ~~,,2 7 tE~~~~~~~~~C 13 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ SuI~,coo~l Is Suhlcoo~cl 0'(7, a/~g+;- Exceptional Drop Tower Data * Shc1hol I I 0.01 iL ___Li~~.~~-~- ______ [ ___ - 0 1 2 3 4 5 6 7 8 9 Total Heat Flux, W/crni Figure 6.8. Nucleation delay correlation developed during ground based and 5.1 second drop tower testing.

Delay Time vs. Total Heat Flux for Flight System (STS-47) 100.00 A... _ a\ Subcool 0 ~C, g t*=145.083 exp(-0.6969q") E I 00 | \ | uA S)ubcool 2.7 "C 10.00 / Y F t~~~~~~~~~~ I I *~~A Subcicool I j 0.10 - Subc()ol II "( * STS-47 Microgravity Data 0.()1 0 -. ___.. L. I. I __... L.. 0.00 1.00 2.00 3.00 4.00() 5.00()() 6.00() 7.00(() 8.00()( 9.()( Total Heat Flux, W/cm2 Figure 6.9. Comparison between nucleation delay times of PBE-IA prior to, during, and following STS-47 Flight with ground based and 5. 1 second drop tower

Heater Superheat vs. Total Heat Flux for Q5 80 _.. 70 1, u Io- -/ -]lliill oilita g 60 1- (? A S'bco l 0I Caol() lag-l 0' AA20_ _ = t | Stubcwool( 2 7 50 -0 | *ExceptionaloropFower)ata;, l l I "- A * Sluhcool II a 40'! I Tol Sublc()(l 0 "'C, a/g () 20 - DropoweDaaS ol0drop tower Data 20 Subcm(l II 10 - O\ *Exceptional Drop Tower Data Suh l 0 1 1 1 ~ I I i I -...... - - I - I _ _ J I -I...'...._ L_ i.... 0 1 2 3 4 5 6 7 8 9 Total Heat Flux, W/cm2 Figure 6.10. Heater surface nucleation superheat during ground based and 5.1 second drop tower testing.

Heater Superheat vs. Total Heat Flux for Flight System (STS-47) 80 -_1 __~_- Subcool 0 ~C,Pre-Flight, -I g I. I.. —-. Subcool 2.7 ~C 70 - B*: First Test in Pre-Flight A| —- Subcxool 11 ~C 60 - - - Subcool 0 ~C,Post-Fligh, -I g U 30|- A -\ Subcool 2.7 "C O 50,~ ~ 30..-..Subcool 2.7 "C *r - — *- Subhcool II 9C) 200 SubcoolCI/4/92, II g SubcoollII0C o - j...L, I, I I'N I I, _ _______ _ 2 C 0.00 1.00 2.()0 3.00 4.)00 5.(00 6.00 7.0() 8.0() 9.00 Total Heat F'lux, W/cm2 Figure 6.11. Heater surface nucleation superheat of PBE-IA prior to, during, and

Bubble Growth Prediction Assuming that all energy applied consumed in forming a vapor bubble -— dR d,i4 3 R3. " - Vapor bubble Aq-hfg-' -— R 3-p \ Fluid: R-1 13,\ dry "b —heater T =60 A =7.27710'4 hfg = hr(T) pv = pvr(T) t = 1.. 100:3'A'q' 10000 R(q,t):-.t 4.t1.hfg.pv Maximum possible growth 0.1 8 W/cmA^2_ 0.08 4 W/cmA2' 0.06 R(2. t) 2. 2 W/cmA2 R (m) R(4,r 0.04 o/ 0.02 0 0 20 40 60 80 100 Time (sec) Figure 6.12. Prediction of spherical vapor bubble growth in saturated R-113, corresponding to PBE-IA Run Nos. 7-9. 129

Vapor bubble I Nucieate boiling at drvout peruneter SktcV 111_iCe~ S ubstrare I -Dryout area I___/_ heater // Figure 6.13. Schematic representation of boiling observed on heater surface in microgravity, from PBE-IA on STS 47. 130

Typical nucleation site Dry Area TD, hD, AD o' ~ -': ~ t6 o 0a~ C)~0 0 o OO ~ -. o 0 0 o C 0 00 0 Nucleate Boiling Area TB, hB, AB Figure 6.14. Heater surface representation from underside with defined terms. 131

Dry Spot Ratio and Measured Mean Surface Temperature vs. Time for STS-47 run #9 1()0 f).9 0-8~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~( /()I 0. 1( 0.6. 0 I0 0.5 1 4'0 2 (33<'i 1 C Dry Raio 30 0.4 I La(.. SlJrfoce Tem-Up [] 3 ":";.'I 0.2 20 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 0/ - _-. —... -. 0 60 61 62 63 64 65 66 67 68 69 70 Time, sec Figure 6.15a. PBE-IA on STS-47. Run No. 9. Transient measured mean heater surface temperature and fractional dry area. Time interval: 61.5-67.5 seconds.

Wet Ratio and Heat Transfer Coefficiert vs. Time for STS-47 run #9 100 0 0.7 ~~~~~~~~j~~~~~~800.2~~~~~O E 0.5w 600 400 Wet Ratio 0.3 200 01 0vt- t1 - --- --- I I -__ _ ----- - - -— / —------ -- -- 0. 60 61 62 63 64 65 66 67 68 69 70 Time, sec Figure 6.15b. PBE-IA on STS-47. Run No. 9. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 61.567.5 seconds.

Boiling Heat transfer Coefficient, Total Heat transfer Coefficient and Wet Ratio vs. Time for STS-47 run #9 2500 2000 0. ('I () i 0.7 v 1500 0.6 E 0. " | 9 >,P16 A g o'"~ t'l- t i@ E - t~Mean Heat Tranrsfer Coeff. 500Q |5....- Boi I inrl tieat Transf er (',t t. 0.2 O Wet Ratio O.J O W --— t- l- t - - - t- I —---- -----.. -.... —-t —- -...... t -- - -..- -. O. 61. 63 64 65 66 67 68 Time, sec Figure 6.15c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 61.5-67.5 seconds.

STS-47 Run # 9 (S 1) ~~ ~~~~~3(~~.' | a. 9~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~, ^~~~~~~~ A..... t=61.92 sec t=62.72 sec t=63.52 sec t=64.32 sec'~~~~~~~~~~~U~~ ma~~~~~~~~~~~~~~~~~~~~:1:~1:: Aid;;; _.i:~...............: t=65.13 sec t=65.93 sec t=66.73 sec t=67.54 sec Figure 6.15d. PBE-IA on STS-47. Run No. 9. Sample images showing rewetting. Time interval: 61.5- 67.5 seconds. 135

Dry Spot Ratio and Measured Mean Surface Temperature vs. Time for STS-47 run #9 (region #2) ([) ( /1 oime y() 0.8 - 0.7 70 a'Fg 60 0.teprtr adfatoadyae.Tmierl:8555sc5s 0.4..................... 40 0.3 - Dry Ratio Surface Temperature 0.1 10 79 80 81 82 83 84 85 86 87 Time, sec Figure 6.16a. PBE-IA on STS-47. Run No. 9. Transient measured mean heater surface temperature and fractional dry area. Time interval: 80.5-85.5 seconds.

Wet Ratio and Heat Transfer Coefficient vs. Time for STS-47 run #9 (Region 2) 0.8 1000 0.7 0.6 800 M~ | Wet Ratio "~ ~ 0.5 oi /. 600 E: 0.4 n \, 0.3 400 0.2 0.1 200 0 - t -t I T V t —- -t t —- I... t 79 80 81 82 83 84 85 86 87 time, sec Figure 6.16b. PBE-IA on STS-47. Run No. 9. Relation between measured heat transfer coefficient and heater fractional wet area. Time interval: 80.5-85.5 seconds.

Boiling Heat transfer Coefficient, Total Heat transfer Coefficient and Wet Ratio vs. Time for STS-47 run #9 60(jUu " __ 0.9 5000' | Bo~i ~irlcg Heat'ransf,,r (:(eft 07 | ) ) Wet Ratio 4000 1 0.6 00 80.5 85284 0.58. E 3000 2000 10.3 0.2 1000. 0,'i O - -0 —- 0 80.5 81 81.5 82 82.5 83 83.5 84 84.5 85 85.5 86 Time, sec Figure 6.16c. PBE-IA on STS-47. Run No. 9. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 80.5-85.5.e.nndrl

STS-47 Run #9 (S2) t=80.59 sec t=81.19 sec t=81.79 sec t=82.39 sec t=82.99 sec t=83.59 sec t=84.19 sec t=84.79 sec Figure 6.16d. PBE-IA on STS-47. Run No. 9. Sample images showing dryout. Time interval: 80.5 - 85.5 seconds. 139

Dry Ratio and Surface Temperature vs. Time for STS-47 run #3 (region #1) 1 1 ---- __ - __ —---- __ __ - 100 0.9 0.8 o Dry Ratio 0.7 Surface Temperature O 0.6 __'" 0.5 0.4 80 0.3 0.2 19 0-~ —- i I- I i 70 40 41 42 43 44 45 46 47 48 49 0 Time, sec Figure 6.17a. PBE-IA on STS-47. Run No. 3. Transient measured heater surface temperature and fractional dry area. Time interval: 42-50 seconds.

W W R a flo a nd Hesa~ Ym ran s g wCO Coosff~n~ vs.o T0me g fo SYS-47 T un 1 3 X Ts g 0on gM 1.4 1800 1.2 00 1400 1200 De~~~~~~~~~~~ =0.8 1000 e~ ~0.6 800 n0~~~. o Wet Ratio 600 0.4 02.....Mean Hleat Transter Coeff. 400 0.2 0 ~00 — t- ~ ~ ~ ~ ~~~I t I --- ~.... -- - I O -0 40 41 42 43 44 45 46 47 48 49 50 Time, sec Figure 6.R7bo PB1E-EA on STS-47. Run No. 3. R eation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 42-50 seconds.

Boiling Heat transfer Coefficient, Total Heat transfer Coefficient and Wet Ratio vs. Time for STS-47 run #3 2()(J)() i.'1 1800 1.2 1600 1400 ~Ao oOk)Q( 1200 Wet Ratio 0. 41 42 43 44 45 46 47 48 49 < U E 1000sec 400nucleate boiling heat transferng coefficieatnt. Time inransfer Coeff42-50 seconds. 200 O C, -Wet Ratio 41 42 43 44 45 46 47 48 Time, sec Figure 6.17c. PBE-IA on STS-4?. Run No. 3. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 42-50 seconds.

STS-47 Run#3 E 3iS ~~~~~~~~~~~~~~~L:~ b~~~ ~ ~~ ~ ~~~~~~ ~~~~~~. = _.................,.: = __ >s _,, Sn~Y. {S i gv, - |a,. -':'e s I:. t=44.48 sec t=45.38 sec t=462.8 sec t=47.18 sec ~~~~~~~~~1143 -u' _iNE D~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ag *~~~~~~~~~~~~~~~~:: 4~~:. --.: _ _ _ 9....................,,z.'N.:.. -.:.w -: _st__ffil, __fiZD *Wl _R~~~~~~~~~~~~~~~~~~~~~~~~~~~~eP=ES / -~K-:~~;::: -a _ _ _ _ = = r - f -' o:~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~:r. 4w;';e > i2_ ==== = m _:az.::::^ >:Z:,::: _ i~~~~~~~~~~~~~~~:; E a t=44.48 sec t=45.38 sec t=426.8 sec t=47.18 sec Fiue61d B-Ao T-7 RnN.3 apeiae hwn rewetting: osilaios Tieitrvl 2-50scns ~~~.I; ~ ~ ~ ~ ~ 4

Dry Ratio and Surface Temperature vs. Time for STS-47 run #3 (region #2) 0.5 _ 1 _..1-.- - 79 Dry Rcftio 0.4 Surrface lermlperJ lureo 78 0.3 77 E 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~02 - ~~~~~~~~~~~~~~~~~~~~~76 ~U 0O C]~~~~~~~~~~~~~~~ 11:: -~~~~~~~~~~~~~~~~7 0. - -I __ ---- -~ -, -, J -t -— 1 82 83 84 85 86 87 88 89 90 91 Time, sec Figure 6.18a. PBE-IA on STS-47. Run No. 3. Transient measured heater surface temperature and fractional dry area. Time interval: 83.5-90 seconds.

Wet Ratio and Heat Transfer Coefficient vs. Time for STS-47 run #3 (region#2) 1 r - 1400 0.6 | ^ Wet Ratio 1 2 0 | to _ t leat Tansfer Coeff | l 0.5 400 82 83 84 85 86 87 88 89 90 Time, sec Figure 6.18b. PBE-A on STS-47. Run No. 3. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 83.5-90 seconds.

Boiling Heat transfer Coefficient, Total Heat transfer Coefficient and Wet Ratio vs. Time for STS-47 run #3 1600 ), O* (;, ( O' 0.i)' 1400 0. |.-l3oi l ing [eat Transfe Ci t. 02 0'8 200 [ () Wet Ratio j 0. 83 84 85 86 87 88 89 90 Time, sec Figure 6.18c. PBE-IA on STS-47. Run No. 3. Relations between the measured mean heat transfer coefficient, measured hater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 83.5-90 seconds. nucleate boiling heat transfer coefficient. Time interval' 83.5-90 seconds.

STS-47 Run #3 t=83.49 sec t=84.49 sec t=85.49 sec t=86.49 sec t=87.49 sec t=88.49 sec t=89.49 sec Figure 6.18d. PBE-IA on STS-47. Run No. 3. Sample images showing gradual dryout. Time interval: 83.5 - 90 seconds. 147

DoMy Raio and Suoogace Uamps~oa~dum vs. Uloma liov SUS-k47 Run a 6 0.9 0.8 - ~~~~~~~~~~~~~~~~~~Dry RafloD(J 0.8~~~~~~~~~~~~~~~~~i Surfice Terner(Alre~o 0.7 U 80 Q 0.6 00 C 0.5 40~ 0.3 0.2 20 0.1 -____________________ ____________ ____ ____t -- -.1 —- I —- ___ —---- 1 —---------- -- --- -- 49 51 53 55 57 59 YBMe, sec Figure 6A19a. PBE-IA on STS-47. Ruin No. 6. Transient measured heater surface temperature and fractional dry area. Time interval: 50-58 seconds.

Heat Transfer Coefficient & Wet Ratio v:. Time for STS-47 run #6 1.6 —----- -—, 1600 1. 1 11400 WMt latio 1.2 1 0_ 2 1000.2 0 " 0.8 800 0 C 0.6 - 600 2 I0.4 r1-00 0.2 200 0 I — - -----------— t - t- ---- - -I t —- ------ t — 0 50 51 52 53 54 55 56 57 58 59 60 Time (sec) Figure 6.19b. PBE-IA on STS-47. Run No. 6. Relation between measured mean heat transfer coefficient and heater fractional wet area. Time interval: 50-58 seconds.

Boiling Heat transfer Coefficient, Total Heat transfer Coefficient and Wet Ratio vs. Time for STS-47 run #6 16001.8 14( 1 1 1.6 1200.4 1.2 U2 1000 1 E 800, Time,,~~~~~ se0.6 400 nui Mean bHeat Transfer Coefs0.4 4oi IMing Heat Trans fer Coef f0. 200 0 Wet Ratio 49 50 51 52 53 54 55 56 57 58 Time, sec Figure 6.19c. PBE-IA on STS-47. Run No. 6. Relations between the measured mean heat transfer coefficient, measured heater fractional wet area, and derived nucleate boiling heat transfer coefficient. Time interval: 50-58 seconds.

STS-47 Run # 6 r: ~::;: ~i-~.. - - --........,.......' sv -.................'ii':i i::i ii.i.ii i' i ii::::::':'.......... 9. d.t........ -.... t=50.79 sec t=51.79 sec t=52.79 sec t=53.79 sec ~~::::::...........::... [ _I ~~~~~~~~~~~~~~~~~~~::::: i wetting. Time ieva: 50- 58ri se c o n d s.v 151:.:::::.. ~iiiil...... W - ~~~~~~~~~~~~~~~~~~~~~~~~~~...... X.'...............................................,........................... t=54.79 sec t=55.79 sec t=56.79 sec t=57.79 sec Figure 6.19d. PBE-IA on STS-47. Run No. 6. Sample images of increase in wetting. Time interval: 50 - 58 seconds..::::::::.:::~;::(:5:

7. CONCLUSIONS When considered historically over a sufficiently long period of time, the study of a subject as complex as nucleate boiling can be viewed as a continuing evolutionary process. The understanding of the various elements which constitute nucleate boiling has been enhanced considerably as a result of improvements in measurement capabilities, and the use of microgravity is another step in this direction. Two additional experiments, already completed and similar to that described herein, one with different hardware (identified as PBE-IB) and the other with the identical hardware of the present work (identified as PBE-IC) will hopefully serve to settle uncertainties about the reproducibility and repeatability of nucleate boiling in microgravity, respectively. With the completion of one phase of this study of pool boiling in microgravity, represented by the current work, questions might be posed as to what has been learned and discovered, and what remains: (a) It appears that long term steady-state nucleate boiling can take place on a flat heater surface in microgravity with a wetting liquid, but only under quite special conditions of heat flux and subcooling, the boundaries of which are as yet unknown. (b) Related to (a) above, surface tension has an important role in producing dryout and/or rewetting on a heated surface. The circumstances describing this remain to be explored further. (c) Two new and interesting heretofore unobserved phenomena have been disclosed in the current work: (i) The effect of the heating rate on the heater surface superheat at which nucleation takes place, with the complicating influence of bulk liquid subcooling. It seems that the heater surface superheat at nucleation goes through a maximum as the imposed heat flux is reduced in microgravity. Furthermore, increasing the bulk liquid subcooling reduces the heater superheat at nucleation in microgravity, all other conditions being held constant. 152

(ii) An extremely dynamic and unusual initial vapor bubble growth has been observed under certain conditions in microgravity, which appears to be associated with an instability problem, producing an unusual interfacial behavior. (d) A microgravity nucleate boiling heat transfer coefficient has been determined, which to this point appears to take on an almost constant value. 153

Ervin, J.S. and Merte, H., Jr., (1991), "A Fundamental Study of Nucleate Pool Boiling under Microgravity," Report No. UM-MEAM-91-08, Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor..-11., Final Report on NASA Grant NAG3-663. Ervin, J.S., Merte, H., Keller, R.B., Kirk, K., (1992), "Transient Pool Boiling in Microgravity". Int. J. Heat Mass Transfer, Vol. 35, pp. 659-674. Iida, Y. Okuyama, K., Sakurai, K., (1993), "Peculiar Bubble Generation on a Film Heater Submerged in Ethyl Alcohol and Imposed a High Heating Rate over 107 k/s," Tech. Note, Int. J. Heat Mass Transfer, 36, No. 10, pp. 2699-2701. Lee, Ho Sung and Merte, H., Jr., (1993), "Vapor Bubble Dynamics in Microgravity," Report No. UM-MEAM-93-10, Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, MI., Pool Boiling Experiment Report on NASA Contract NAS3-25812. Mastroianni, M.J., Stahl, R.F., and Sheldon, P.N., (1978), "Physical and Thermodynamic Properties of 1, 1, 2 - Trifluorotrichloroethane (R-113)," J. of Chemical and Engineering Data, 23, 2, pp. 113-118. Merte, Herman, Jr., (1967), "Liquid Metal Boiling in Agravic Fields," in Investigation of Liquid Metal Boiling Heat Transfer, Air Force Aero Propulsion Lab., Wright-Patterson AFB, OH, AFAPL-TR-66-85, Jan. 1967. Merte, Herman, Jr., (1989), "Study of Nucleate Pool Boiling under Microgravity," Science Requirements Document to NASA. Merte, Herman Jr., (1992), "Pool Boiling Experiment," Report No. UM-MEAM-91-19, Department of Mechanical Engineering and Applied Mechanics, University of Michigan, Ann Arbor, Michigan, status Report for period 2/1/91 - 9/30/91 to NASA Lewis Research Center on Contract NAS3-25812. Weinzierl, A., and Straub, J., (1982), "Nucleate Pool Boiling in Microgravity Environment," Proceedings of the 7th International Heat Transfer Conference, September 6-10, 1982, Munich. 154

Appendix A Specific Technical Reauirements Parameter Requirement Test Fluid Fluorocarbon R- 113 Heating Surfaces 19.05 mm x 38.1 mm (3/4" x 1-1/2" Gold on Quartz (7.25 cm2) Nominal thickness corresponding to a resistance of 3.8 + 0.2 ohms (Approximately 400 Angstroms), uniform to + 5% desired. Test Heat Flux 2 watts/cm2 14.5 watts 4 watts/cm2 29.0 watts 8 watts/cm2 58.0 watts Test Chamber 15.2 cm (6") Dia. x 10.2 cm (4") High Temperature Uniformity + 0.220C (L 0.40F) Nominal Test Temperature 48.90C (1200F) Pressure Control + 690 N/m2 L( 0.1 psi) Heater Power Constant voltage + 1%. Heater calibration current should not raise heater temperature more than 0.11 ~C (0.20F). Temperature Sensor 12 Sensor Locations 3 Vicinity of each Heater Surface 3 in Bulk Liquid 2 on the Rear of Heater Substrate 1 in surrounding area behind substrate. Data Requirements V, I, Time... (19 parameters). Heater V & I + 0. 1% Meas. Accuracy, but with a sensitivity of + 0.03% x a full scale. Temperatures + 0.060C (L 0. 1 F) Meas. Accuracy Pressure + 345 N/m2- (L 0.05 psi) Meas. Accuracy. Acceleration (3 Axis) Levels less than 10-3g desired. Time correlated to experimental elapsed time Data Requirements Sample Rate - 10 Hz Accuracy - + 10-4 Range - 10-2 thru 104 g Frequency - D.C. thru 2.5 Hz Photography 100 pps, 10 pps, 0.18 mm (0.007") Resolution Clock Nearest 0.01 Sec. Elapsed Time 155

Appendix B Coefficients for the Vapr-Pressure Curve for R- 113 (From Mastroianni et al, 1978) en p = A + + C + DT2 + (E) T [n (F-T)] where: p = pressure = psia T = Temperature in ~R -F + 459.67 A = + 23.428348 B = - 9095.6033 C = - 0.012548607 D = +5.S391227 x 10-6 E = + 0.14025795 F = + 878.48416 En x = Natural logarithm of argument xo 156

Appendix C. Plots of the X, Y, Z accelerometer measurements for each run of PBE-IA in the STS-47. 157

Acceleration Level vs. Time Run #1 0.25 0.2 AIkIlIMULh IIfiILuI 0. 15 0.1 - 0.05 0 000 -0. -0.15 - - - - - - - - - - - - -- - - - - - ~ -- - - - - - -0.2 -- --- * —. Time, sec I ~~ACCX - ACCY ACCZ Figure C I PBE-IA accelerometer measurement. Run No. 1.

Acceleration Level vs. Time Run #2 0.25 0.2 0.15 I 0.1 U1 0.05'IO C 4-..~~~7 - -0. I. I ~ r I -0.15 Time, sec I ~~ACCX ACCY ACCZI Figure C2. PBE-IA accelerometer measurement. Run No. 2.

Acceleration Level vs. Time Run #3 0.25 0B.2 0. 15 0.1l l 0.05 0 0 O - I- I I0 I- - I —--- ~~~~. ~. ~. 1O ~.: —-,.-. ~; - 0 l,:.....-.,-,...r.,,, -;; l~s -0 1;r 1- II iII L 0.:.::::.:::::...... X;;; t..........;,:::::::::::.....:... i -::; I::::: CD o O 0 5.0...........................L...........*....___._.._.__...__._.___.._._._...._._._._ _ _ _ __ = _ _ 4 _ _ _ ~ _ _ _ _ _ _5 _ __ _ _ _._.........1;'11I..'; l I -0.} IS ISO"|1| -0.15 l ~~~~~~~~~~~~~~~~~~~.,....,................, ~,......... l ~. — -0.2 Time, sec.-.-. ACCX - ACCY ACCZ Figure C3. PBE-LA accelerometel measurement. Run No. 3.

Acceleration Level vs. Time Run V4 0.25 0.2 A 0.15 1 114VAJ ~AiAt1~iwww~:~I ~V I~~A&NwnV!I'rIfM1~ E 0.1 0.0 C) 01 0\~~ ~il" (,((~~.. I il -0. I~I_. Time, sec I.~~ACCX ACCY ACCZ Figure C4. PBE-IA accelerometer measurement. Run No. 4.

Acceleration Level vs. Time Run #5 0.3 0 10 0)2 -0.3 Figure C5. PBE-IA accelerometer measurement. Run No. 5.

Acceleration Level vs. Time Run #6 0.5 0 4 0.3 0 E 0 0.2 -— A -U --------- -- -- — _ _ - - a' 0 ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1 04 CD T sec 41 AC AYC 0Fe -0. r ~ ~ ~ -. -0.4 Time, sec ACCX - - ACCY ACCZ Figure C6. PBE-1A accelerometer measurement. Run No. 6.

Acceleration Level vs. Time Run #7 0.25 0 2 I V A 0. ir 5 ull' liIkrllV WM V I H i 2 0.05 801 ~00 aC) 01 -0. I~~~~~~~I Time, sac ACCX ACCY ACCZ Figure C7. PBE-IA accelerometer measurement. Run No. 7.

Acceleration Level vs. Time Run #8 0.3 0.1 U)~~~ ~ ~ ~ 2 AI Al A Al IAI Al IAI A1 Ij WII I r —~ C O ~~~~ —IrT — 1 ~~~~01~~~~~~ -111)( 0 0 0 < -0.2 -0.3 Time, sec ACCX ACCY ACCZ Figure C8. PBE-IA accelerometer measurement. Run No. 8.

Acceleration Leiel vs. Time Run #9 0.3 0.25 0.2 ill 1 41 l G 0.15 IM-IIW-I II, 0 05 1 |. _,,,.; _ _ U 0 se 0 -0.15w.1 -0 -— __ —----..I.,','"' - -: -- ACC- ACCY ACCZ j Ir 0. 5Figure C9. PBE-LA accelerometer measurement. Run No. 9. Time, sec

Appendix D. Plots of results of Pre-Flight test conducted for PBE-IA at a/g = -1 on 4/28/92. 167

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #1, q"total=6.7 W/cm2 3000 300 1 — Analytical surf. temp. 2500 250 2000 - _ —20 a'0 --- --—. - - --- ---- - 1- -I --—' I: II( n co LM (isuied surface emp. E 1500 150 looo I I~~~~~~~~~~~~~~~I 1) Ai - ly I I i "I i 100 -1() 0 1-_ —------ -— 1 —- ------- -s —-__ --- -- - --------- --.-. - 0 0 10 20 30 40 50 60 70 Time, sec Figure DIa. Mean heater surface temperature and derived heat transfer coefficient. Run No. 1

Total Heat Flux vs. Time for 4/28/92 Run #1 7.5. 7. -\ o, > 6.5 6 5.5 0 10 20 30 40 50 60 7() Time, sec Figure Dib. Heat flux input. Run No. 1

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #1 C4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5. 4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~5 0 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0 10 20 30 40 50 6H 7 Time, sec~~~~~~~~~~1250 X ~~~~~~Fgr Ic yse rsueadha lxint lidiu N.1

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #2, q"total=3.65 W/cm2 2500.... 250 I-D Analytical Eurf. temp.. u 2000 -- -______ ________ -------- ______- - 200 ~ r~E 1500 5 Measured sur ace temp. 1000 z _______ __ —i- t —-- -- ---— _- ____ —-- -- ---—. —-.-. t-.. —. —-- - --- - 10.goo, 1 -D An/ lytical "h" lIit COrTputed fro mT(Jirei ionk 500 ------.. ft ——.- —.. -. —-—. —. —— ~ —.-.- - -- - t — -.- -. — - 50 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure D2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2.

Total Heat Flux vs. Time for 4/28/92 Run #2 3.8 - _ )3.6 u 3.4 3.2 0 10 20 30 40 50 60 7() 80 9( 1()() Time, sec Figure D2b. Heat flux input. Run No. 2.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #2 8- 153 152.5 -- e 1~ 152 01 i"~~,,,~~~,~, 1 I~~qrlllninl~~~ki~~li 151.5 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~111 I II I I a~~~iih __ _______ 150.5 a. _ LlL A-0 22 l149.5 0 ~~~~~~~~~~~~~~~~~~~~~~~~~~149 0 20 40 60 80 100 120 140 Time, sec Figure D2c. System pressure and heat flux into fluid. Run No. 2.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #3, q"total=3.65 W/cm2 2000 - r- -— __. —- ----------- --- 1. i. 200 1750 -.. --— __. ——. -.' 175 71-D |nalytica surf. te 1500 - -..... -. —-------- - ---- - - -- 150 1250... 125 1000 0 20 -0 4 100 150ure Mean ha'Measu d surface temp. 750 75 o "h" cor )LJted froI r nesec ern erlets 500 50 1 -D Analylcal h" 250 0 10 20 30 40 50 60 70 80 90 100 110 Lu Time, sec Figure D3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3.

Total Heat Flux vs. Time for 4/28/92 Run #3 21.8 -.. E 1.6 t1.4 1.2 1- I I' t t I I I f I E-} t 4 tI_ t 1 -I 0 20 40 60 80 100 120 Time, sec Figure D3b. Heat flux input. Run No. 3.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #3 8 -_ _ v_ _ _ _ _ __ - - - - _ ___ _it -- - __ - - - a - - - X 156 155.5 E 6 —155 I illilgill 5~ ~ ~ ~~~~Fgr inRIVI Syte presueadhatfunofui.RnN.3 153.5o'o- -4 _................................. 153' O: 4 0 ___'4f-~ 5. 152 0 20 40 60 80 100 120 140 Time, sec Figure D3c. System pressure and heat flux into fluid. Run No. 3.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #4, q"total=6.5 W/cm2 i-D An lytica surf. temp,- 2000 200. Me sured surface tem. - ~ 1500 - --- I 150 2 E ~ 100010 1 I _ _ I _. I j 1 500 1 -D Analytical "h" "I" CO [ /Jtd fromII roTrsn ir5rnes 50 o - ____ -.. _______ --- -, —----- -. -- - o 0 10 20 30 40 50 60 Time, sec Figure D4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4.

Total Heat Flux vs. Time for 4/28/92 Run #4 7.5 7 / 6.5 4) 65.5..... 0 10 20 30 40 50 6() Time, sec Figure D4b. Heat flux input. Run No. 4.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #4 8.__ _ ____ _ _ 118 117.5 E6 A|l lj 0 i; fi t A e 119 1glliiw2i0 # 4~~~~~~ 0V o 2......... ~AAA~P~M 117 0*.2 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1145. 0.. _ _ _ _........... _ _ _ _ _......... ~. 11 4 0 10 20 30 40 50 60 70 Time, sec Figure D4c. System pressure and heat flux into fluid. Run No. 4.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Fun #5, q"total=3.4 W/cm2 1250..t..T - -.....-.I -- -T —-- - - T -. — t 250 1000 200 20 ic: | | |, i Meas red surface temp. E ~ 5001 00- r — -- _ -- - 100. "h" c mrnputed fr)rn r)measur mrnents 1 -D Anlylical "h" 250 50 0- 0 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure D5a Mean heater surface temperature and derived heat transfer coefficient. Run No. 5.

Total Heat Flux vs. Time for 4/28/92 Run #5 4 3.8 E 3.6 3.4 ---. 3.2 3.2 — I -1 ~ {; t -- -I — 11 0 10 20 30 40 50 60 70 80 9() () Time, sec Figure D5b. Heat flux input. Run No. 5.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #5 8 r —- - --- r- - --- -- - ----- - -;- ~ - 1 19 118.5 C%4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~1 ~~~~~~~~~~~~3 ~~~~~~~~~~~~~~~~~~~~~117.5 cr:a a~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~a U-O ~2 ------- ---...-. —--- ____ -16 115.5 0 -.. —-~~ —-— t —._________ - -. ——.- — t. — --- 1 15 0 20 40 60 80 100 120 Time, sec Figure D~c. System pressure and heat flux into fluid. Run No. 5.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #6, q"total=1.76 W/cm2 3000 - 150 1 D Analytl al surf. te p. 2500 - - L: "' " _- ------ - 125 2000 100 2 E 1500 A| Me ured surfice temrp 1500 75 I 1000 u 0-D n lylicalc "ll" l "I" I collip lted laroiT lllleu sicostr(oei s l 500 --.. __.... - __.. - 25 0 10 20 30 40 50 60 70 80 90 100 110 Time, sec Figure D6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6.

Total Heat Flux vs. Time for 4/28/92 Run #6 E 1.6 \U 1.4 1.2 0 20 40 60 80 1u0 120 Time, sec Figure D6b. Heat flux input. Run No. 6.

Heat Flux toward Liquid and Systt m Pressure vs. Time; PBE 4/28/92, Run #6 18 ---- --- -- 4 —-- ------— 118 117.5 E 6 g' X=I ( I 1'0t'l1eR1t-\b#V iLr E U1 6 2 115'd Iy es ic 114.5 0 20 40 60 80 100 120 Time, sec Figure D6c. System pressure and heat flux into fluid. Run No. 6.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #7, q"total=6.7 W/cm2 3000 - __ _ _ _ _ _-. — - - 300 2500 250 1-D Analytical surf. tmp. r;~~~~~~~~~ 0 2000 20 Q C4~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4 2 0100 Measured sLurfa e temp. 1000~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1000 I —-------— ___ _ ____- t —- __ ---— __ —-- --- 10 I l g 1 -D Analylical "h" "h" cornrpulted from rneasureMents 500 3 0- 0 10 20 30'1 Time, sec Figure D7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7.

Total Heat Flux vs. Time for 4/28/92 Run #7 7.5 6.5 5.5 0 5 10 15 20 25 30 35 40 Time, sec Figure D7b. Heat flux input. Run No. 7.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #7 8 ----- I T — — ram - - T -- - - - - — I 180 160 E 6- 1 0 12_ 240 o - o 4 1W0 S 4 -0-0:2 80 o 2 60 40 0 + —— I --- -- - ____f —- --- -- - ----- - - - -.- - --- f - - f 20 0 10 20 30 40 50 60 Time, sec Figure D7c. System pressure and heat flux into fluid. Run No. 7.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #8, q"total=3.5 W/cm2 2500 - - 250 2000 1-D Analytical surf. temp. - 1500 _ -~........ 150. 00~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 1500~~~~~~~~~~~~~~~~~~~~~~~~~~~ I~~~~~~~~~~~~~~~~~~~~ II',I"-.c* l1000 - - _ —- __ —-_ -__ _n _Me_ ____ | Measured surface temp 1000.................. 10 t 1 -D /nalytical "h" "h" cormput from measure rnents 500 5O 0~ ~ ~ ~ ~ ~~~'......+J Ws' O _.................... — - -... 0 0 10 20 30 40 50 60 70 Time, sec Figure D8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8.

Total Heat Flux vs. Time for 4/28/92 Run #8 4 - 3.8 E 3.6 o 3.4 3.2 3-' " _...... 0 10 20 30 40 5() 60 70 80 Time, sec Figure D8b. Heat flux input. Run No. 8.

Heat Flux toward Liquid and Systum Pressure vs. Time; PBE 4/28/92, Run #8 109.5 109 E 6| i| | 108. "- *a l l W Reve.s r-' 107.5 o o ______. 17 d nh1065.5 ]2 105.5 104.5 0 10 20 30 40 50 60 70 80 Time, sec Figure D8c. System pressure and heat flux into fluid. Run No. 8.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for pbe42892 Run #9, q"total=1..8 W/cm2 1750 ------'- - __ -_______ - ___ - 175 1500 —- - _ __-15 1 -D An lytical su f. temp 11250 2 01 E ME asured s rface te p. 750 _ 0 1- Analytical "h" "h comput d from P easure ents 500 — t5 250 25 0- 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure D9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9.

Total Heat Flux vs. Time for 4/28/92 Run #9 2 1.8 E 1.6 1.2 0 20 40 60 8() 100 120 Time, sec Figure D9b. Heat flux input. Run No. 9.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 4/28/92, Run #9 8 -__-_ __ ___ -------------. —--- 108 107.5 E 6 ~I- e|____|___ _____ _ ______ -. - - -- __| —----- - t | 107 IIILUJIIU 106.5 - 10 0 0 20 40 60 80 100 120 140 Time, sec Figure D9c. System pressure and heat flux into fluid. Run No. 9. Figure D>9c. System pressure and heat flux into fluid. Run No. 9.

Appendix E. Plots of results of Post-Flight test conducted for PBE-IA at a/g = +1 on 11/4/92. 195

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBEU 114/92, Run #1 q"otal=7.02W/cM^ 2 60M0. 120 1-D nalytical Surf.Te perature Measure Surf. Temperature ~~~~~~~~~~-VIA — 5000!/..- 1-D v I _. -. _ CI,~M~~hls~nrV_ 10 4000 - L. || 800 "h" camputed from rreasurement,. 3000. —----- 60 2000_ t i4 1 -ID Ar alyical "h" 1000 - 20 0 + F - -0 t: B I 1 l 0 0 10 20 30 40 50 60 70 Time, sec Figure Ela. Mean heater surface temperature and derived heat transfer coefficient. Run No. 1

Total Heat Flux vs. Time for 11/4/92 Run #1 8 7.5 6.5 0 10 20 30 40 50 60 7( Time, sec Figure Elb. Heat flux input. Run No. 1

Heat Flux toward Liquid and System Pressure vs. Time for PBE11/4/92; Run#l 1 14 ~ _ _ _ _ _ --- 149 12 -A 4 148 < 4 ---- --- - - - - | 140 E'0 X ---- -_ -__ —-- i - 1 146' 04 6144 X 2........ 143 0 2 ----- - --- -— f —- - _____ -- _ -- -- - 142 0 10 20 30 40 50 60 70 Time, sec Figure Elc. System pressure and heat flux into fluid. Run No. 1.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #2 q"total=3.6W/cm 2 6000 * 120 1-D,nalytical S rf.Temper ture 5000 _ 1 100 4000 ----- -- - --- 80 Measurec Surf. Temrl erature 3000............ 60 0 2000 -'40 "h" cor puted from measurenent 1000.... ---- 20 1 -D Analytical'h" 0010 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure E2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2.

Total Heat Flux vs. Time for 11/4/92 Run #2 3.8.. _ 3.6 3.4 3.2............' " t' r I' t_. 1...... t - i4...........~ —-- -- _ 0 10 20 30 40 50 6() 70 80 90 1)0 Time, sec Figure E2b. Heat flux input. Run No. 2.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 11/4/92, Run #2 20 -__- _ _ ------- - 148 16 I _ _ _ _ i Y 4 7 12 X8 ---— f —t —-t —- -- ___-_- ____ _ --. ——. — _-__ -_ —--- ---- - - 4 Z~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4 a.. 0 4l 144/ 0 -t —--— t-l —-.- t —— f — -— f —fI — I1143 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure E2c. System pressure and heat flux into fluid. Run No. 2.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #3 q"total=1.805W/cmA2 3000 _ _ 120 1 -D A alytical urf.Ter erature 2500 - -- -- Meascred Surf Temper ture 100 2000 ___ _____ _____ ____ —- __ __ _ f- — ~~ 80 Qj 2000~~~~~~~~~~~~~~~~~~~~~~~~~~ 1500 60 0 r: 1~~~~~~~1-D Ar alytical "h"" "h" co puted fr m measL rement 0 1000 40J 500 r4W4 ~ 20 0 - _ _ _ 0 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure E3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3.

Total Heat Flux vs. Time for 11/4/92 Run #3 2 1.8 E 1.6 cl 1.4 1.2 0 10 20 30 40 50 60 70 80 90 100 110 12() Time, sec Figure E3b. Heat flux input. Run No. 3.

Heat Transfer to Liquid and Pressure vs. Time; PBE 11/4/92, Run#3 8 -- E __ rv _ --- - - 149 C14 < 6 E! 0 "d 2 B~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ __ 0 2 —.... -............ 1475 O 0 _47 i_0 0 20 40 60 80 100 120 Time, sec Figure E3c. System pressure and heat flux into fluid. Run No. 3.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #4 q"tokal=7.05W/cm^ 2 6000 120 /1-D Anal tical Surf Temperc ture l Mea ured Surf. Temper ture 5000,, - - 1 0 U 4000 -, ___,______._-_____- -~' =.= —-u- -,-'-;:,-~............. -~......~ N... ~ 80 o 3~~~~~ 3000~~~~ |"h" computed from measurement 3000 - -- - -- __ -- 6 0 U 2000 40u I -D Anal~ fical "h" 1000 - -- _ 20 0 0 0 10 20 30 40 50 60 Time, sec Figure E4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4.

8 7.5 6.5 0 IDO 21) 30 40 50 60) Time, sec nFigur E4b. Heat flux input. Run No. 4.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 11/4/92, Run #4 20 -- 112.5 16 12 - - -- __ _ __ _ _ I —---—. — - - -- - - - - - - T - - -.- T 111.5 eI X82 ------ 1 —--- I ----- 1115 &'A..~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~/ 0 I 4 112 0 o' 4~~~ 0............................. -— 1 X8`~~~~~~~~~~~~~~~~~~~~~~~~~~~~~110 0 10 20 30 40 50 60 Time, sec Figure E4c. System pressure and heat flux into fluid. Run No. 4.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #5 q"total=3.54W/cm^ 2 3000..,"'...... 1 20 -D iAalytical Sulrf.Te mpera ure 2500 -.... --—.-.-. —.. _.,-t.-,t —--.-. ^.-" —t-'- -,-, "1 100 AO 2000- — I --—... --— 1 80 Z o S Me sured Surf. Temperatere 2 1500 60 I D Analytic I "h"'h" comput d from mrasuremen 1000 40; 500 1- - - -- - - 20 - Io 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure E5a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 5.

Total Heat Flux vs. Time for 11/4/92 Run #5 4 3.8 3.6 _ 3 3.4 3.2 0 1 0 20 30 40 50 60 70 8( 90 10() Time, sec Figure E5b. Heat flux input. Run No. 5.

Heat Flux toward Liquid and System Pressure vs. Time; PBE1I 1/4/92, Run #5 Io~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~.5.2i 0 - - - _ -- - 1 aO. 0 X -1 1 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure E5c. System pressure and heat flux into fluid. Run No. 5.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #6 q"total=1.81W/cm^ 2 3000 l.. l -1 l. l.. 120 1-D Ar lytical S rf.Temperoture 2500 - MH astJred S.rf. Temnperattire 100 1 11-D An llytical"h" l | "h" omputed from mea urement 2000.......... -- i -11 80 500 - 60 E 1000 - 40: 0 10 20 30 40 50 60 70 80 90 100 110 Time, sec Figure E6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6.

Total Heat Flux vs. Time for 11/4/92 Run #6 1.8 1.2 0 10 20 30 40 50 60 7() 80 90 1()() I 1() Time, sec Figure E6b. Heat flux input. Run No. 6.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 1/4/92, Run #6 8 --— _ _I-___ __ _ -- - ---- __- - 113.5 _2 40 1123 2'2~~~~~~~~~~~~1 ft 0 20 40 60 80 100 120 Time, sec Figure E6c. System pressure and heat flux into fluid. Run No. 6.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 11/4/92, Run #7 "total= 1.806W/cm^ 2 7000... 120./ 1-D Analytical Su f.Temperature 6000.. 100 Measured Surf. lemperature 5000 1- - - -; — 80 9 1 4000 60 E;h" computed from- measurement E. 3000.... 40 2000 20 1 -D Ar/ lylical "tV' 0 10 20 30 40 Time, sec Figure E7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7.

Total Heat Flux vs. Time forl 1/4/92 Run #7 7.5 E: 7 6.5 6 0 o ~~5 10 15 20 25 30 35 40 Time, sec Figure E7b. Heat flux input. Run No. 7.

Heat Flux toward Liquid and System Pressure vs. Time; PBE I 1/4/92, Run #7 28.... 180 24 16 C~4 < 20 -. — -- 140 E'd 16 - 0 13''O- 12- -....10 X I'3 0 ~08 -80 4. - _ _ _ _ _ _ _ _ - - -.. _ _.. - - ~.. -.. -......... 6 0 0 ~~~~~~~~~~~~~~~~~~40 0 10 20 30 40 50 60 Time, sec Figure E7c. System pressure and heat flux into fluid. Run No. 7.

Convection H.T.Coeff. and Mean Surface Temperature vs. Time; PBE1 1/4/92, Run #8 q"total=3.55W/cm^ 2 3000 120,-,,!Measured Su f. Temperature 1500 60 2500: 1~ ~~1 -D Analytical "h" "h" compute from measure nent i 1000 40'/C, 500 - 0 0 0 10 20 30 40 50 60 70 Time, sec Figure E8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8.

Total Heat Flux vs. Time for 11/4/92 Run #8 4 3.8 r., S3.6 o 3.4 3.2 3 -{ 0 10 20 30 40 50 60 7() Time, sec Figure E8b. Heat flux input. Run No. 8.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 11/4/92, Run #8 10 rX l _a_- ---— _- - -------- 104 103.5 E aD'0, 1, ---- M 2A lILA A ~~~~~~102.5 101.5 0 - 100 0 10 20 30 40 50 60 70 80 Time, sec Figure E8c. System pressure and heat flux into fluid. Run No. 8.

Convection H.T. Coeff. and Mean Su. face Temperature vs. Timne; PBEI 1/4/92 Run #9, q"total=1.806 W/cm2 3500 _ - 140 ro t i_ 1' | 1-D nulyt~~culsurf temp |,Measuredi surf ce temp.| | 3000 ----- ---- -- - --- - _ 120 2500. —: 2 1500 | — ____ X __ _ —-. — 100 — t —l a..-" 1-D Analy aticl "h"surf. ted from measureents p. 1 2000 0 2 0. E ___ __ ______,,, _._ - 6 500~~~~~~~~~~~~~~~~~~~~~~~~~~ 1 -D nalytcal "" "h_ mputed from measurements U 1000.................... 40~ 00 0 20 40 60 80 100 120 Time, sec Figure E9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9.

Total Heat Flux vs. Time for 11/4/92 Run #9 2-. 1.8 1.4 ____ _ ____ _ 1 1.2 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure E9b. Heat flux input. Run No. 9.

Heat Flux toward Liquid and System Pressure vs. Time; PBE1 1/4/92, Run #9 1 -------- I —-- ___ -___ —r — ---- _-_ ---—. —7 — I___ ____~. 106 6- C6 105 _ _ _ _ _ _ __ —— + —--— g- )- _ _ l~t —-- -~-t - ~-t 104 01 3 I i%02~~JAnP.M 3= - 4-' - 0 4-2~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~a 0) 20 40 60 80 100 120 Time, sec Figure E9c. System pressure and heat flux into fluid. Run No. 9.

Appendix F. Plots of results of Post-Flight test conducted for PBE-IA at a/g = -1 on 12/22/92. 223

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #1, q"total=6.2 W/cm2 2500 -------— T t —- - -: —- --- - 275 2250.-... - —. - --—..- - - - - 250 1I-D Analytical surf. temp. 2000- ---------- - -- - > 225 1750 - 3 - - - 200 6 1500 175 Figure Fla. Measured surf ce temp. " 1250 150:1000 125 / h" computed from measurements 750 100 u 500 75 250~ 0 25~-~,r ~,-&~...,,.,,.,,..,,' -. —- -- --- - v 2' 1-D Analytical h" -250 0 0 10 20 30 40 50 60 70 Time, sec Figure Fla. Mean heater surface temperature and derived heat transfer coefficient. Run No. I

W | ~~~~~~~~~~~~~~~~i r — * I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ i~~~~ i~~ I-~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ L/L ~~~~~~~~~~~~~~E -_ C~~~ * I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 0~~\0u I~~~~~~~~~I~ ~ __ I ~225

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run# 1 10 -- -- -....... 153.5 ____ 8 4\"UIIH 153 2o 6 - 152.50 O40152 x~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 10 CN 2 i~yi~KI~~~~~~~~~1Y~.-''6 151.5 0 10 20 30 40 50 60 70 X 0 10 20 30 40 50 60 70 Time, sec Figure Flc. System pressure and heat flux into fluid. Run No. 1.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #2, q"total=3.4 W/cm2 3500t -_ _.-..-. -, _ - ~.: 200 00 1- Analytic I surf. tem 3000 - ___ ----- --- - --- 175 2500-t - - _ - i —- - 150 O 2000 -—.'. 1 -- -1 —- -- i 25 C. 1500..... Measured surface t mp. E C~i 1500 -- ----- --- -_ 10 1000 | _- _-_-____ | —— ft;~,;'~' —--— r+ —----- L- __ ---- - --- | — l-D Anal_ ical "h" 0 -500 70 8 90 100 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure F2a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 2.

Total Heat Flux vs. Time for 12/22/92 Run #2 4 - 3.8 N. 3.6..... 00 3. 3.2.......................... 3 I I - 1 l l l l l l | — + —--- 0 10 20 30 40 50 60) 70 8( 90) 1()() Time, sec Figure F2b. Heat flux input. Run No. 2.

Heat Flux toward Liquid and System Pressure vs. Time; PBE1 2/22/92, Run #2 I- -cu~~~~~~~~~~~~~~~~~~~~~~~~~~~- - - iMm152.3 2N~~~~~~~~~~,AM'$it LA\I152 o 2 _ A: 151 -2 - - ___ ___ — ----------- -- I - 150.5 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure F2c. System pressure and heat flux into fluid. Run No. 2.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE12/22/92 Run #3, q"total=1.8 W/cm2 3500-....-. __- _ 120 1 -D Ana tical surf. temp. 3000 -___ - -c. 105 2500 - t t," — - - -'~~' ~! Measured surface temp. 150 2 4 6 10 -500 0 0 20 40 60 80 100 120 Time, sec Figure F3a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 3.

Total Heat Flux vs. Time for 12/22/92 Run #3 2 1.8 - _ __ E 1.6:u 1.4 1.2 - O 10 20 30 40 50 60 70 8( 90 100 11 12() Time, sec Figure F3b. Heat flux input. Run No. 3.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run #3 8,; ____ A - -.. 155 E6 4 6 ni~ri~iti~u~. 154.5.~~~~~~~~~~~~~~~~~~~J 1t41yg;15011 11llmll I~ll~iJ~l 4111 __ __ ___ __ __ _ _ — ~-~~-~ ~- -- (o >' 2 _ - 1 5 x U.... ___ - W on __40 __ -r q sy tj, 153. 0 - - _ _ _ - - - -1 5 3 0 20 40 60 80 100 120 Time, sec Figure F3c. System pressure and heat flux into fluid. Run No. 3.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE12/22/92 Run #4, q"total=6.3 W/cm2 2000 250 1750 - - 225 1500 - -- 200 1250 -. - - ____ _ -- ___ - Measurec surface temp. 150 1 000 150 1 -D Analytical rf. temp. C 500 100 "h" comp ted from measure -ents 250 -75 0 50 1 -D Anal (tical "h" -250 ----------- _____ -------- 25 0 10 20 30 40 50 60 Time, sec Figure F4a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 4.

Total Heat Flux vs. Time for 12/22/92 Run #4 7.5,4 6.5 5.5 - _ l _ I E | + -- -__ _ __ | - _ _ _. -. 0 10 20( 30 4() 50 6 Time, sec Figure F4b. Heat flux input. Run No. 4.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run #4 7 118 CY~ ~ ~ ~ ~ ~ ~ ~~~~~~~~~~~~V to -cl 5 ~~~~~~~~~~~~~~~~~~~~~~~116 a 33 Ln 3 X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~,o 3 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~114 0 10 20 30 40 50 60 Time, sec Figure F4c. System pressure and heat flux into fluid. Run No. 4.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #5, q"total=3.4 W/cm2 3500- - -D.m.. —. - -. 200 200 -500 ___t —- - L - | — _ — t —---. - _ I.. l.., __''"-. - 750 —-— | — - || 0 1-2 1500 ()) 1000..... 125. 1 -D Analytical "'b -500 - _____ __ __- ______- __ --- - -- -- - - 0 0 10 20 30 40 50 60 70 80 90 100 Time, sec Figure F5a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 5.

Total Heat Flux vs. Time for 12/22/92 Run #5 3.8 E 3.6 3.4 3.2 3 -40 50 60 70 80 90I I 0 10 20 30 40 50 60 70 80 90 1()() Time, sec Figure F5b. Heat flux input. Run No. 5.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run#5 77- _ _ _ 4 - 120 <6 I:: 6' ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~118 U 5~~~~~~~~~~~~ -i'6..................... - -- 1 1 6 o co 0 - 1.......... 114 0 0 10 20 30 40 50 60 70 80 90 Time, sec Figure F 4c. System pressure and heat flux into fluid. Run No. 5.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #6, q"total= 1.8 W/CM2 2750- - - - _ _ - _ _ - - -- -12 1 -D Ana ytical surf. temp. 2500 -- - - -- - - - -- - - - ~- - - - - - 2000 - _ _ v -_ _ _ - 1750 - _ _ - - - V - _ _ _ _ - - - - - - - - - 0 ( ____ / _______ ~~Measured s rface temp.. ~e1500- 1250~~~~~~~~~~~~~~~~~~~~~~~~~~. 1000____ _1 750~~~~~~~~~~~~~~~~~~~~~~~~~~ h"computed rom measurene s 500~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~, 250 - Pb4Y*t' 2 1 -D Anc lytical "h"0 0 20 40 60 80 10012 Time, sec Figure F6a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 6.

Total Heat Flux vs. Time for 12/22/92 Run #6 1.8 1.8 -EX 4=16 _ _ _=- _ _ -.. E 1.6 1.4 _.2 10 20 30 40 5 6 0 7 0~ 80 90- ---- 0 10 20 30 40 50 60 70 80 90 i ()() I I() Time, sec Figure F6b. Heat flux input. Run No. 6.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run#6 5 _...... 118 5u 4 117.5 E 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure F6c. System pressure and heat flux into fluid. Run No. 6. Figure F6c. System pressure and heat flux into fluid. Run No. 6.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #7, q"total=6.4 W/cm2 2750 - ___ —-— __________ —— ~ —— ~ — - -___ ---- --- - --------- --- - - - ---- - 240 2 -D Analytical surf. temp2 2250 200 2000 - - - - - 180 so 1750 -t —- -------- ---- --------------- tl —---— * —-- - - — _ - - -- 160 *i Measured surface temp. C4 1500 10 Ea 1250 2 1000~~~~~~~~~~~~~~~~~~~~~~~~~~ i 100 I- - -__ —--- ------— t ~ -------- -- — t —------ - - -- - -— 10 ~ 750~~~~~~~~~~~~~~~~~~~~~~~~~~ "h" computec from measurements 500 -_ 250 -------- ------ ------------ -- --- - -- - 40 0 -- - - 20 1 -D Analytical "h" -250 - ---- 0 10 20 30 40 Time, sec Figure F7a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 7.

Total Heat Flux vs. Time for 12/22/92 Run #7 7.5 7 6.5 6 5.5 0 5 10 15 20 25 30 35 40 Time, sec Figure Fib. Heat flux input. Run No. 7.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run#7 10 107.r>c~ o8 4 anFiur - yse E0 2 / - 105.8 Figure F7c. System pressure and heat flux into fluid. Run No. 7. x ~ ~ ~ ~ ~ ~~~~~~~~~ie e lUL~~~~~~~igueFc.Sserssrnea.lxinofud RnN.7

Convection H.T. Coeff. arnd Mean Surface Temperature vs. Time for PBE 12/22/92 Run #8, q"total=3.4 W/cm2 2000. __.- 225 1750 - -:- 200 1500 1- |__| l-D Analytical surf. temp. 175 1500 \ --- - 175 ~., 1250 ---— t —--- - --- 150 E 1000- — |_ _ _- —. -- 125 0 E a. Measured surf ce temp. E ~~~~~~~~~~~~~~~~~750 loo ~~~~~~~~0 500. _|"h" computed from measurements 500 75 o 250 1 -D Analytic i"h" -250 - 0..1. 0 10 20 30 40 50 60 70 Time, sec Figure F8a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 8.

Total Heat Flux vs. Time for 12/22/92 Run #8 4 3.8 E 3.6 3.4 _ 3.2 3 -L 0 10 20 30 40 50 60 7() Time, sec Figure F8b. Heat flux input. Run No. 8.

Heat Flux toward Liquid and System Pressure vs. Time; PBE 12/22/92, Run#8 5 E - _- 1 _ ---- - _ ----- -— T 1 8 cu 4 ----- kdlJ,~irl~w117.5 55 ~ ~ ~ ~ ~ ~ _ —11.5 E 2L 0'~ 13.. —-----— t —-1 0 20 40 60 80 100 120 Time, sec Figure F8c. System pressure and heat flux into fluid. Run No. 8.

Convection H.T. Coeff. and Mean Surface Temperature vs. Time for PBE 12/22/92 Run #9, q"total=1.8 W/cm2 3250 -- - ----- ------------- -.140 1-D A alytical surf. templ __l\._7 -: 2750 - ------ -- 120 __- - _ _ _ _ 0EI' oo gL 2750 40 60 80 Figur F~Measn red surface temp 1250. 6 —____ _ -----— _- --- - ---- 0 "h" computed fr rn rneoasurernonls 250 20 _______ ____I -D Analy cal "h" -250 _' 0 20 40 60 80 100 120 Time, sec Figure F9a. Mean heater surface temperature and derived heat transfer coefficient. Run No. 9.

Total Heat Flux vs. Time for 12/22/92 Run #9 1.8 E 1.6. 1.4 _.. 1.2_ __ tkil I'l I I, l! I! I I -I- -4 1 0 10 20 30 40 50 60 70 8() 90 100 11() 12() Time, sec Figure F9b. Heat flux input. Run No. 9.

Heat Flux toward Liquid and System Pressure vs. Time: PBE 12/22/92, Run#9 5 _B-~- --- r~-' - -I.. 108 Cu J'tT'I" r U1 3 UL- - 3-.... 107 o 01 -Iio_ 2 106.5.,~ P i ~ 6 0 10 20 30 40 50 60 70 80 90 100 110 120 Time, sec Figure F9c. System pressure and heat flux into fluid. Run No. 9.

UNIVERSITY OF MICHIGAN 3 9015 02827 4747