ENGEERING RESEARCH INSTITUTE UNIVERSITY OF MICHIGAN ANN ARBOR REPORT NO0 33 USE OF FINNED TUBES IN CONDENSING BUTYL HEAD!S AND ISOPROPYL ALC(OIOL GAREN AEKJIAN Researc?- s is tant EDWIN H* YOUNG.. Assistant Professor of'Chemical and Metallurgioal'Engineering Project 1592 WOLVERINE TUBE DIVISION CALUMET AND HECLA, INC. DETROITy MICHIGAN Aune, 1954

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TABLE OF CONTENTS Page SUMMARY ii INTRODUCTION 1 PROCESS REQUIREMENTS 1 DESIGN PROCEDURE 1 DESIGN OF THE BUTYL-HEADS CONDENSERS 7 DESIGN OF ISOPROPYL-ALCOHOL CONDENSERS 7 CONCLUSIONS AND RECOMMNDATIONS 8 APPENDIX A CALCUlTATION OF THEORETICAL OVERALL EAT.-TRANSFER COEFFICIENTS FOR TEE CONDENSATION OF BUTYL HEADS ON 7/8-INCH OD FINNED AND PLAIN TUBES 13 APPENDIX B DESIGN CALCULATIONS FOR BUTYL-HEADS CONDENSERS BASED ON CALCULATED OVERALL COEFFICIENTS 24 APPENDIX C DESIGN CALCULATIONS FOR BUTYL-fEADS CONDENSERS 27 APPENDIX D CALCULATION OF THEORETICAL OVERALL HEAT-TRANSFER COEFFICIENTS FOR THE CONDENSATION OF ISOPROPYL ALCOHOL ON 7/8-INCH OD FINNED AND PLAIN TUBES 32 APPENDIX E DESIGN CALCULATIONS FOR ISOPROPYL-ALCOHOL CONDENSERS BASED ON CALCULATED OVERALL' CEFFICIENTS 33 APPENDIX F DESIGN CALCULATIONS FOR ISOPROPYL-ALCOHOL CONDENSERS 36 NOMENCLATUR 48

This study was carried out to investigate the applicability of low-fin 19-fins-per-inch tubes in exchangers designed for the condensation of butyl heads and isopropyl alcohol. Six plain-tube and six finned-tube condensers were designed to establish a basis for comparison of the economics of plain-tube and finned tube units, The results of the study are summarized in Table I,: The results indicate that the condensation of butyl heads and isopropyl alcohol are good applications for finned tubes+ Trufin tube No. 196049-01 is specifically recommended for this purpose* For the specific heat duties and flow rates under consideration the finned-tube units cost about 30 percent less than units utilizing plain tubes of the same nominal size, The more compact finned-tube condensers are identified as designs 1 and 3 (Tables IV and V) for butyl heads and designs 7 and 9 (Tables IV and VI) for isopropyl alcohol. This report presents in detail a recommended procedure for the design of condensers utilizing finned tubes. iii

TABLE I SIMMARY~ OF DESIGN AND COST CALCULATIONS Overall Length Design Shell-Side Tube Coefficient of Cost, No. Fluid U0, Btu/hr-~F-ft2 Tubing, Dollars outside area ft 1 butyl heads 7/8-inch OD 134 1150 2590 finned copper 2 butyl heads 7/8-inch OD 180 2320 3650 plain copper. ~. -... -.............. 3 butyl heads 7/8,-inch OD 70 2208 3432 f inned copper 4 butyl heads 7/8-inch OD 100 3980 4635 plain copper I! L.l I,.I r I. J, I -i. 5 butyl heads 3/4-inch OD 70 3162 4005 f inned admiralty 6 butyl heads 3/4-inCh 01 100 4640 5467 plain admiralty 7 isopropyl 7/8-inch OD 125 1582 3236 alcohol finned copper 8 isopropyl 7/8-inch OD 149 3400 4730 alcohol plain copper 9 isopropyl 7/8-inch OD 80 2472 3760 alcohol finned......... p. e r............,........., 10 isopropyl 7/8-inch D 5100 5540 alcohol plain copper 11 isopropyl 3/4-inch 01D 80 3520 4277 admiralty 12 isopropyl 3/4-inch OD 100 5920 6495 alcohol plain admiralty iv

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN USE OF FINNED TUBES IN CONDENSING BUTYL HEADS AND ISOPROPYL ALCOHOL INTRODUCTION Finned tubes have been successfully used in a wide variety of industrial vapor-condemnsation applications, It has been suggested that finned tubes could be used to advantage in the condensation of isopropyl alcohol and butyl heads in petrochemical processes~ The investigation of the possible usage. of finned tubes in such applications requires a comparison,of the economics involved in plain- and finned-tube units designed to handle specific heat duty requirements, This report presents design procedures, sample calculations, and specific recommensdations for plain-tube and finned-tube exchangers for specified conditions of isopropyl-alcohol and butyl-heads condensation. PROCESS REQUIREMENTS The processes require the design of a shell-"and.-tube condenser to handle 27,00 lb per hour of isopropyl alcohol coming from an evaporator and an overhead shelnand.-tube condenser to handle 18,670 lb per hour of butyl heads coming from a fractionating column,, Table II gives the condenser requirements in detail for the two applications. DESIGN PROCEDURE The condensation heat duty, Q(Btu/hr), is related to the shell side heat transfer area A(sq ft) and to the mean overall temperature difference.e driving force AT ('F) by the following relationship: Q = UoAAT, (1) where Uo is the overall heat transfer coefficient in Btu/hr-F-1sq ft outside area and iss defined as follows. U = 1 + r0 + k+ (2)A UO hg km Am Ai hiAi where all other symbols used in this and subsequent equations are defined in the nomenclature table at the end of this reports The evaluation of each of the terns in equation (2) i carried out in d.tail for the condensation of butyl heads and is summarized for isopropyl alcohol in Appendires A and D. ____ ___ ___ ___ ___ ___ ___ ___ ___ ___ 1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN TABLE IT CONDENSER REQUIREMENTS (1) (2) Service of Unit Isopropyl alcohol Butyl heads Heat duty, Btu/hr 8,68o,oo0 6,560,000 Log mean AT, tF 75 72 Shell side: vapor 98% IPOR Butyl heads quantity, lb/hr 27,000 18,670 latent heat of vaporization, Btu/lb 320 352 inlet temperature,'F 180 184 outlet temperature, OF 165 160 allowable AP, psi 0W5 0, 5 condenser pressure, psi atmospheric atmospheric Tube side* fluid water water quantity, lb/hr 348,oo000 263,000 inlet temperature, OF 85 85 outlet temperature, "F 110 110 allowable AP, psi 10 10 Design pressure, psit tube side > 200 200 Design temperature, OF: shell side 250 250 tube side 160 160 The condensi coefficients were computed from a modified form of NusseltHs equation for fined and plain tubes, A modified form of Nusselt0s equation which gives the condensing coefficient for the average tube in a multitube condenser is: ho = O%725 CN (r (3) tcf Atf ND where for plain tubes D represents the outside diameter (DO) of the tube; for finned tubes this length dimension is the equivalent diameter (Deq) which varies with the fin efficiency and condensing coefficient and C is a con densate correction factor which brings the hepretical relationship of Nusselt into aggment with experinental results. __outlet__temperature__ ____~__1!0 ___1 0

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Figure 4 presents CN as a function of the average number of tubes in a vertical row'(N) for condensing Freon-12, Nusseltts theory, which depends upon laminar flow of the condensate depreciates the performance of the single tube by a factor (1/N)1/4 to obtain the average coefficient for N tubes in a vertical row, Experimental work has shown that this depreciation factor is too severe, evidently because the flow of the accumulated condensate on the tubes is not laminar It should be realized that the use of CN in equation (3) will therefore result in the design of a more compact condenser as comi pared to awunit designed on the basis of the Nusselt equation, The formulas suggested for finding the value of N for exchangers having more than twenty tubes are:1 N 0,815 x0'52, for square pitch1 (4) N 0.,40 x 54r for triangular pitch, (5) The latent heat of vaporization of the vapor is the value at the condensing temperature* The other physical properties identified by subscript f are obtained at the condensate fi1Jm temperature, Tf, which is defined as follows: Tf Tsv -a 1/2 Atcf, (6) Figures 2 and 3 were prepared for butyl heads and isopropyl alcohol respectively to facilitate the computation of the theoretical overall coef:. ficients by multiple trial-and-error solutions, Inside water-film coefficients were calculated by use of the follows ing relationship given by McAdams.: hw 150 (1 + OOllo tw) v 2 (7) Figure 5 presents fin efficiency as a function of the outside film coefficient h6$ the outside fouling factor ro: the finned-tube dimensions and the thermal conductivity of the metal., To facilitate the succeessive-approximation computation required for determining condensing film.coefficients, Fig 1 was prepared for Truin tube No 196949-01. This figure was obtained by plotting a series of values of(l/Deq)1/ as a function of the& utside film coefficient ho, The difference between h and ho is that h- is based on the equivalent outside area and ho is based on the outside area, The equivalent i KatzD,'I L*, and Williams, R, B., Oil and Gas Journal, July 28, 1949, 2 MeAdams, W, H,,, Heat Transmission 2nd edition, McGraw-Hill Book Company, 1942, p,1853 3 Gardner1 K A,, Trans: A;SME,, Vol _ No, 8, p, 625 (1945),

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN outside area is a function of the fin efficiency as indicated by equation (12) and ho is related to ho as indicated by equation (13).. 0 In general, the valu of ho in equation (2) may be computed by either of two methods, ibe,e from equation (3) or by first determining ho using equation (8) and then applying equation (13). hi = 0.725 CN4 ( f gC:X 81/4 (8) if equation (8) is used in the trial-and-error calculation of Uof.the following outlined procedure may be used. This procedure parallels that used in this study which used equation (3). The calculatios based on equation (3) are given in section 2 of Appendix A. The following is an outline of proceduire using equation (8): (1) Assume ho f (2) for r = 000005, find = + ro (3) determine ef from Fig.5 (4) calculate Ae from equation (12) (5) calculate, Al1/4 from the following equation: A ). / - z"1X3 ef +_ 1 1/4 +_ Ieq'Ae Aee (6) calculate ho from equation (13) (7) calculate Rt = from ho and the other resistance terms uof determined in equation (2) (8) fi-nd dAtcf from Atcf( ) I (10) (9) calculate from equation (8), where N and CN are determined from the assumed Uof and the- tube-side arrangement. If the Calculated and the assumed values.of h- check -satisfactorily, the corresponding value of ho is-~brrect. For design work, the recommended procedure presented in detail in Appendix A is preferable to the above method because for a given tube and outside fouling factor a plot such as Fig. 1 enables one to reiduce the various steps involved in the successive approximation of Uof.

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN The following sample calculation illustrated how Fig. 1 was prepared: Assume ho = 500 Btu/hr-~F-sq ft of equivalent area Mean fin thickness, y 0.016 inch Fin height = (do- dr) = (0.864 - 0.749) = 0.0575 inch 2 2 km = 220 Btu-ft/hr-~OF-sq ft for copper ro = 0.0005 hr-~F-sq ft/Btu do - 0.864 = 1.152 dr 0.749 The abscissa for fin efficiency curves given in Fig. 5 is H 2 (11) + ro) Therefore, + r + 0.0005 = 0.0025, 500 and the abscissa = 0.0575 () (12) =0.250. 12 (0.0025) (220) (0.016) The corresponding fin efficiency, ef, as read from Fig. 5, is 0.977. Of the total outside area 80 percent is on the extended surfaces and 20 percent is on the root of the finned tube. Therefore, Af = (o.588)(0.80) = 0.470 sq ft/ft, and Ar = (o.588)(0.20) = 0.118 sq ft/ft. The equivalent outside area for condensation is defined as Ae = efAf + Ar (12) Therefore, Ae = (0-977)(0.470) + 0.118 = 0.577 sq ft/ft. By definition, ho is related to h6 as follows: = hAo (Ae (13) Therefore, ho = (500) (X) = 491. 1/4 \0.588/ The value ofl 1 \ is obtained from the;-ollowing relationship: (j =De efq ( 1.5)=1 A A0 Dr, (14) S~A

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN where L _ af 2Do and af = Af =,470) = 0,00206 ft2 f (12) (N) (12)(19) fin L - ( 402o )(6 o0,0143 ft (2) (0o864) 7-0 =' ~I (1 3)(0* 977) ~47~ g 1 4 1188 \Deq1 to*588) |oe043 o.5880 079 (.L)l/4 = 2w942 + 0.401 53.343 (1)1/ The computed value of 3.343 fori which corresponds to the outside condensing coefficient of ho = 491 ts plotted in Fig- 1 as the or dinate against ho as the abscissa4 This procedure was repeated and points were obtained to cover the range of ho from 0 to 1000. Table III contains a summary-of these points, It may be seen that once a curve- has been established for a particular tube it has general application, and a series of curves for different sizes of finned tubes made from various metals may be conveniently prepared.| TABLE III CALCULATED RESUITS OF ho and (i)l) FOR WOLXVERINiEUTRUFIN TUBE NO. 96049-01.... I.....A 1.4 Abscissa in A hot h + r0 Figh5 ef Ae e 25' 24.7 0o0622 1000 0*588 lo0 25 35411 100 95.53 0.122 0,995 0.586 0.996 99.6 3.397 200 182 0,1688 0.990 0.583 0 991 198,2 3,381 300 26l 0,202 0,988 0.582 o0 990 297 3-~376 400 353 0,228 0*982 0. 579 o0984 3935,5 35560 500 400 0,250:0.977 0.577 0,981 491 35343 650 490 0*277 0.974 0.575 0,.978 635 3331 1000 667 0323 0o,965 0,572 0.974 974 35305, _ -, _._.*.1. _, _, _, _, _. _ ~ _. _,, _, _.,, _ ~ _- 6.... _. _...............................

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN DESIGN OF THE BUTYL-HEADS CONDENSERS Butyl heads at atmospheric pressure are condensed on the shell side of units using tle following different types of tubes, (a) Wolverine Trufin tube No, 196049-01 (b) Wolverinei Trufin tube No, 195065-26 (C) o0875 in O0D 16 BWG plain copper tube (d) 0,750 ins OD 14 BWG plain admiralty tube, Tables IV and V present the summary of the calculated results, All units are of conve1tional shell-anld-tube condenser design; the low-fin tubes having 19 fins per inch were selected because these tubes have plain ends and can be rolled into tuibe sheets in the conventional manner, and give favorable performance in the condensation -of organic vapors.' The composition of butyl heads was estimated from the given specific gravity and latent heat of vaporization data, It was assumed that the mixture contains essentially n-butyl and isobutyl alcohols in equal proportions and water, On this basis the. conposition of butyl heads was found to be 85*5 weight percent butyl alcohols and 14*5 weight percent water.. Theoretical overall heat-transfer coefficients were calculated for both the finned-tube and plain-tube units to establish the relative performance of the two tubes, Fouling factor:s recommended by TEMA were used both for the organic vapors (0*o005) and for plant water (0,OO001) One set bf design calculations based on the recommended procedure is presented in Appendices A and B and summarized in Table IV.,.A more conservative design is presented in Appendix C and the results are summarized in Table V- These designs are based on the application of the Nusselt equation (3) without the inclusion of the. condensate drip factor CN for the plain-tube units, The design coefficient for the conservative finned-tube units was obtained from the plain-tube overall coefficients by multiplying by Uof/Uop obtained by the recommended -prQcedureo These — designs are in accordance with the usual conservative coefficients employed in industrial designs and represent considerable available overcapacity for the four units so designed, Appendix A gives the overall coefficients used in..both the recomended And more conservative designs. DESIGN OF E ISOPROPTL-ALCEOHO CONDENSERS Isropyl alcoehol is condensed on the shell side of units using the same tubes specified for the butyl-heads condensation units.

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Tables. IV and VI give the summary of the calculated results and the shell and tube specifications for finned-tube and plain-tube condensers~ The design calculations based on the recommended procedure are presented in Appendices D tand E and are summarized in Table IV. The more conservative design is presented in Appendix F and the results are summarized in Table VtI Appendix D summarizes the overall coefficients'calculated by the recommended procedure and the more conservative Coefficients based on NTusseltls equation. CONCLUSIONS AND RECONMEDATIONS Tables I, IV V, and VI indicate that finned tubes can be u.sed to definite advantage in the condensation of butyl heads and in the condensation of isopropyl alcohol* The finned-tube units recommended n thet basis of the procedure used in this report are given in Table IV. These designs (nqnbers 1 and 7) result in substantial econmic savings, The finned-tube units recommended for isopropyl-alchohol and butyl-heads condensation cost 31 percent and 29 percent less than the plain-tube units having the same nominal size tubing.'Based on the more conservative- design -with an oveia;ll coefficient of lO0 for the plain tu.be and the corresponding finned-tube coefficient with compara-be performance,,'the recommended designs for finned-tube units are 5 in Table V and 9 in Table VI. The overall coefficients, Uoy for the finned tubes are 80 percent,and 70 pereent of the overall coefficients for the plain-tube units for! isopropyl alcohol and butyl heads respectively. These coefficients can be expressed in terms of unit length of tube and are identified as UL. On this basisy the overall coefficients per foot of tube/ length for the finned tube are 105 perce':and 80 percent greater than the corresponding plain-tube coefficients for isopropyl alcohol and bUtyl heads, From Tables V and VI the finnedtube units recommended. for isopropyl-alcohol and butyl!-heads condensa' tion cost 33 percent and 26 percent less than the plain-tube units having the same nominal size tubingsw The.,condensation. of isopropyl alcohol and butyl heads are good applications for low-fin 19-fins-per-inch tubes,

TABLE IV SUMMARY OF CONDENSER DESIGNS Service of Unit Specifications Butyl Heads Isopropyl Alcohol 1 2 7 1. Total heat duty, Btu/hr 6,560,000 6,560,000 8,680,000 8,680,000 2. Lb vapor per hour 18,670 18,670 27,000 27,000 3. Lb water per hour 263,000 263,000 348,oo000 348,000 4. Shell fluid and pressure, psig Butyl heads, 0.5 Butyl heads, 0.5 Isopropyl alcohol, 0.5 Isopropyl alcohol, 0.5 5. Tube fluid and pressure, psig Water, 70 Water, 70 Water, 70 Water, 70 6. Tube characteristics Trufin No. 196049-01 7/8 in. OD 16 BWG Trufin No. 196049-01 7/8 in. OD 16 BWG 7/8 in. OD Cu. finned tube plain copper tube 7/8 in. OD Cu finned tube plain copper tube 7. Length of tube in bundle, ft 8 10 8 10 8. Number of tubes in bundle 144 232 198 340 9. Total length of tubing, ft 1150 2320 1582 3400 10. Total outside heat-transfer area, ft2 677 531 931 780 11. No. of exchangers 1 1 1 1 12. Shell inside diameter, in. 18 23 21 27 13. Shell-side pressure drop, psi 0.5 0.5 0.5 0.5 14. Tube-side pressure drop, psi 5.1 9.6 4.8 8.0 15. Cross-sectional area for flow 0.1662 0.1757 0.2284 0.2575 inside tubes, ft2/pass 16. Shell-side passes 1 1 1 1 17. Tube-side passes 2 4 2 4 18. Shell thickness, in. 3/8 3/8 3/8 3/8 19. Shell and tube side nozzles, in. 3(4) 4(4) 4(4) 6(4) (total number required) 20. Tube arrangement 1-1/8 in. square pitch 1-1/8 in. square pitch 1-1/8 in. square pitch 1-1/8 in. square pitch 21. Overall heat-transfer coefficient, Btu/hr-"F-ft2 outside area 134 180 125 149 22. Logarithmic mean temperature difference,OF 72.4 72.4 75 75 23. Excess heat-transfer area, percent 0 5.4 0.6 0.5 24. Water velocity, ft/sec 7.1 6.72 6.81 6.05 25. Estimated unit cost. dollars 2590 3650 3236 4730

TABLE V SUMMARY OF BUTYL-HEADS CONDENSER DESIGNS Condenser Number Specifications 3 4 5 6 1. Total heat duty, Btu/hr 6,560,000 6,560,000 6,560,000 6,560,000 2. Lb butyl heads per hour 18,670 18,670 18,670 18,670 3. Lb water per hour 263,000 263,000 263,000 263,000 4. Shell fluid and pressure Butyl heads, 0.50 psig Butyl heads, 0.50 psig Butyl heads, 0.50 psig Butyl heads, 0.50 psig 5. Tube fluid and pressure Water, 70 psig Water, 70 psig Water, 70 psig Water, 70 paig 6. Tube characteristics Trufin No. 196049-01 7/8 in. OD 16 BWG Trufin No. 195065-26 3/4 in OD 14 BWG 7/8 in. OD Cu finned tube plain copper tube 3/4 in. OD admiralty plain admiralty tube finned tube 7. Length-of tube in bundle, ft 12 14 10 8. Number of tubes in bundle 184 284 264 464 9. Total length of tubing, ft 2208 3980 3162 4640 10. Total outside heat-transfer area, ft2 1298 911 1298 911 11. Number of exchangers 1 1 1 1 12. Shell inside diameter, in. 20 25 21 29 13. Shell-side pressure drop, psi 0.5 0.5 0.5 05 14. Tube-side pressure drop, psi 4.0 8.0 6.2 8.0 15. Cross-sectional area for flow inside tubes, ft2/pass 0.212 0.215 0.1872 0.216 16. Shell-side passes 1 1 1 1 17. Tube-side passes 2 4 2 4 18, Shell thickness, in. 3/8 3/8 3/8 3/8 19. Shell and tube side nozzles, in. (total number required) 4(4) 6(4) 4(4) 6(4) 20. Tube arrangement 1-1/8 in.square pitch 1-1/8 in. square pitch 1 in. square pitch 21. Overall heat-transfer coefficient, Btu/hr-~F-ft2 outside area 70 100 70 100 22. Logarithmic mean temperature difference,~F 72.4 72.4 72.4 7?.4 23. Excess heat-transfer area, percent 0 0.4 0 0.4 24. Water velocity, ft/sec 5.56 5.49 6.30 5.46 25. Estimated unit cost, dollars 3432 4635 4005 5467 Cost of Unit 6 using 3/4 in. OD 16 BWG plain admiralty tubes: 5207 dollars

TABLE VI SUMMARY. OF ISO PRO? Y L -AL C ORO L CONDE NS ER DES I G N-S Specifications Condenser Number 9 10 11 12 1. Total heat duty, Btu/hr 8,680,000 8,680,000 8,68,0,000 2. Lb isopropyl alcohol per hour 27,000 27,000 27,000 27,000 3. Lb water per hour 38+8,000 348,ooo 31+8,o-o 308,000 4. Shell fluid and pressure Isopropyl alcohol, 0.50 psig Isopropyl alcohol, 0.50 psig Isopropyl alcohol,-0,50 psig Isopropyl alcohol, 0.50 psig 5. Tube fluid and pressure Water, 70 psig Water, 70 psig Water, 70 psig Water, 70 psig 6. Tube characteristics Trufin No. 1960+9-01 7/8 in. OD 16 BWG Trufin No. 195065-26 3/1 in. OD 11 wG plain 7/8 in. OD Cu finned tube plain copper tube 3/1 in. OD admiralty admiralty tube finned tube 7. length of tube in bundle, ft 12 11 12 10 8, Number of tubes in bundle 206 364 291 592 9. Total length of tubing, ft 2172 5100 3520 5920 10. Total outside heat-transfer area, ft 2 1152 1168 1446 1162 11. Number of exchangers 1 1 1 1 12. Shell inside diameter, in. 22 28 23 31 13. Shell-side pressure drop, psi 0.5 0.5 0.5 0.5 1:4. Tube-side pressure drop, psi 5.5 8.1 8.3 8.1+ 15. Cross-sectional area for flow inside tubes, ft2 /pass 0.238 0.2756 0.209 0.275 16. Shell-side passes 1 1 1 1 17. Tube-side passes 2 4 2 1 18. Shell thickness, in. 3/8 3/8 3/8 3/8 19. Shell and tube side nozzles, in. (total number required) 4(4) 6(4) 4(4) 8(1) 20. Tube arrangement 1-1/8 in. square pitch 1-1/8 in. square pitch 1 in. square pitch 1 in. square pitch 21. Overall heat-transfer coefficient, Btu/hr-F-Pft2 outside area 80 100 80 100 22. Logarithmic mean temperatare difference, F 75 75 75 75 23.' Excess heat-transfer area, percent 0.1 0.7 0 0.2 24. Water velocity, ft/sec 6.54 5.65 7.45 5.66 25. Estimated unit cost, dollars 3760 551+0 1+277 61+95 Cost of Unit i~g using 3/4+ in. OD 16 BWG plain admiralty tubes: 6160 Aol1ar

APPENDICES

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN APPENDIX A CALCULITION OF THEORETICAL:OVERAL HEAT-TRANSFER COEFFICIENTS FOR THI CONDENSATION OF BUTYL HEADS ON 7/8 INCH OD FINNED AND PLAIN TUB3ES ~1. Specifications Average bulk shell-side temp,,y Tav = 172'F Average bulk tube-side temp., tw 97 5~F Log-mean temp, difference ATI = 72.40F Heat dutyQ 6y,560,000 Btu hr Water flow rate 263,000 lb/hr or 1.18 ft3/sec. Allowable tube-side APt = 10 psi 2, Calculation.of for Wolverine Trufin 196049-01 tubes The overall heat-transfer coefficient is evaluated by trial-anderror procedure. A value of Uof is assumed and a su.itable tube layout pre:pared on the basis of the assumed Uof. >The individual resistances are computed for the assumed condenser design and the Uof is determined, The correct Uof is obtained when the computed UOf checks with the assumed value. The following fQuling factors are used as recommended by TEMA: o = oo h-F-.f fta r = O0005 Btu ri = 0.001...,.,.., Btu Metal resistance, Rih (see tube characteristics for isopropyl-alcohol eondenser design, Appendix F): Ap = o,-96 Pt2/ft 12 AmL A - Ai a,~ = 996 - 0.171 = 0,18 ft2/ft 0,171 i3

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Rm Xf A = (oo (o.,0419)0588). km Am (12) (220) (0.1833) Rm = 0,ooo00006 hrFift2 outside Btu Ass Uf = 130 Btu hr-0Fft2z outside A 6,60,000 697 ft (130) (72,4) Total tube length = 697 = 1185 ft 0,.588 Using 8-ft-long tubes,1 number of tubes in bundle, x = 1 148 For two tube passess ~A0st = 03(148)(ooo ) 0.37) ft2 (2) Water velocity = 8 6,9 ft/sec 0,171 Compared to the res-ults for design No, 3 in Table IVT the tube'-side pressure drop corresponding to this water velocity is less thai. 10 psi. For square-pitch tube arrangements N = o0815 x0,,52 (4) N = (o0,85) (148)~'052 1094, The outiide condensing oefficient for the average tube in.a multitube condenser is giVen by -3.2 = 0725 N (kf gP h (3a),\f Deq Atcf From Fig, 4. CN = 1.42 Substituting.. = (>2, k p gc 1/4 14

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN ho -= o0566 ( PS C f ) (15) From equation (7)t O68 h - 150 (1 + 0,,011 x 97*5) 2 (0.651,r, 62 hw = 1588 Btp./hr-*F-ft2 inside A~ 3,44.AD = 0, ", 002164 Ai h h 1588 A- rI = (5(3.44)(Q0,oo ) = 0,00344 Ai Ri = 0*002164 + 0.00344 = oo005604 1 = t R + R;m+ Ri U~of where Ro = 1 + ro h Therefore, ~(t".L W) =+ r! i + Ri (Rt 1- ) = 0.0005 o000oooo6 + oo005o604 ho — t * ) - =t0061i. hP outside The condensing coefficiernt Is determined by trial and error by assundng ha, finding Rt, &tcf, l/De/4, and.t 1culating ho from equation (15), Assume ho = 940 0.o001064 ho 940 Rt = 0.006164 + oo001064 = 0.007228 AQftcf =T, ( = (0,001064) (72,4) = 10.66~F (0,,007228) 15.

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN (Atf )1/4 (10o66)1/4 1.808 From Fig. 1 /, $1/4 = 3.308 Condensate film temperature Tf = Tsv 1/2 Atcf (6) Tf r 172 1/2 (10*66) = 166,70F. From Fig. 2. ki;~~ic = I" 780. From equation (15) "h = (o (866) (33o8O) = 809 Since the calculated h0(809) is consid.rably less than the assumed h(940), for the second trial select h- = 770,+ h 0.00130 Rt = 0*006164 + 0.00130 = 0.007464 tcf r " (0000130)(72,4). = 12.600F (0oo07464).1/4 t/4 (~tt) / (12,60) - 1z6884 1/4 3*320 (Fig, 1) eq 3 2 1/4 (k.. g.) = 778 (Fig.2).ho = (o.566) (778) (,32o) 775 (l.884) The agreement between assumed and calculated ho is satisfactory. 16

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Therefore, Uof = = = 134 tu R t 0..007464 hrO~Fft2 Outside The caleulated value agrees closely with the assumed value of 130. 35. Calculation of Up for 7/8-ineh OD 16 BWG Plain Copper Tubes Metal resistance, Rm (see tube characteristics for isopropyltwalcohol condenser designj Appendix F): 0..229- 0.195 2.303 log 0.229 o.195 (o.065) (0o229) = (l2)(220)(0 210) 0,.000027 Assume Uop = 175 A = 56 o,oo000 519 ft2 (175)(72.4) Total tube length. 51 = 2260 ft 0.229 2260 Using 10-ft long tubes, number of tubes in bundle 1 = 226 10 For 228 tubes and four tube passes, ACs-t =...... (0,003025) - 0.1726 ft2 (4) Water velocity = = 6.85 ft/sec. 0,1726 The tube side pressure drop is computed for this unit;: Mass velocity, Gi = 263,0ooo 1,f523,000 lb 0,1726 hr.ft2 Re = (.745)(1,523,000) = 52900 17

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN From p. 836, Kern, Process HIeat Transfer ft = 0.000174 AP tubes = ft Gi (tube length) n2 psi (5.22 x 1010) Di S g where CIg = 1.0226 (See Appendix F) S = 0.995 APtubes (.ooo0174)(1.523 x 106) (10)(4)(12) (5.22 x 101~)(0.745)(0o995)(1.0226) AP tubes = 4.90 psi AP headers 4(V) n2 (S)(2ge) From Kern, p. 837 2 V =- 0.32 2gc AP headers = (4)(0.32)(4) 5.15psi (0 995) APt = 4.90 + 5o6 - 9.96 or 10.0 psi approx. This pressure drop agrees with the allowable. For square-pitch tube arrangement, N = 0.815(228)'5 = 13.6 (by equation 4) and CN = 1.5 (Fig. 4). Therefore, 1/4 kf. 2 12 ho = (0#725)(1 5) 1 -k- ) lp+ 0.875 X 13 f At0f 2 1/4 ho 1=.+09l Of, f gc (16) k = 150 (1l +0-0ll x 97~5) 20. = 1558 _18

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN' o.-1,175 = 0Q*000764 Ai hw 1538 Atr~ = (,l7?3)(ooo l) = oo001173 Ai Ri.ooo000764 + 0.001173 = 0.001937 (Rt.i = 00005 + 0.00003 + 0.001937 - 0,002467 Assume ho = 315 = 3 = 000318 515 Rt 0.0oo2461 + o.oo00318 0 00564 At (00=18) (72.4) 40,8~F (0o05.64) l(tf/4 - (40,8i1/4 ~(Atl = (40.8) 2,526 Tf = 172 - 1/2(40.8) 151,6:~F.. From Fig, 2, (3 2 1/4 kf Pf gc 7 From equation (16). ho (1. 09) (. = 323. (2~526) A value of ho = 324 Would be the correct one on the btasis of the second triali'i 324, h 1 0400309 Rt = 0.*002467 + 0,00309 = 0,005557........55 h ~I Btu. UOP = 0.005(557 1=80 hr.F"Pf% Outside area _________ ________ _________ ______ 1

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN This valu.e of Uop is in close agreement with the- assumed value of 175. A more conservative d~esign i obtained by using a value of 100 for Uop which corresponds to a conde-nsing coeffi;eient based,on the Nusselt equation (3) without the reconmmended condensate drip correction factor of CN, The theoretically calculated overall coefficients based on the recommended procedure outlined in sections 2 and 3 of this dppendix are used for design calculations in Appendix By,and the results are summarized in Table IV;, In.addition, the overall coefficients calculated for plain-and finned-tube units are used to find the relative performance Uof/Uop and this ratio is used to obtain the overall design;:oefficient for finned.ube units on the same basis as the more conservative value of 100 for the plain-tube units* Thus -.....of 134 UOP,0- 745, An average alue. of this ratio: for butyl heas is computed in section 4 of this appendix. A set of condenser designs based on these conservative.overall coefficients is shomw in Appendix C for butyl heads and in Appendix F for islop-ropyl alcohol, The results are slummnrized in Tables V and VI for bu.tyl heads and isopropyl alcohol respectivelyW 4. Short-cut Method for Approximatixg and and The following method substitutes for the CN/N1/4 factor in equation ('3) a constant factor of 1/ll or 0. 91, Thus, the overall coefficients Uof and Uop can beestimated for a desirable water velocity without specifying tte condenser tube arrangement. For tWolverine Trufin 196049-01: ho =2 I,1 > 1/4 0.725 gf Pf g, x 1*1 1Lf Deq Atcf] For a water veloeity Vt. 6 ft/sec, hw = 150 (1 ( 0.011 x 6)8 = 1418 (o0651)0.2.~ ~~A0o~( * 1.44 Ai hw:1418 _ _ _ _ _ _ _ _ _ _ _ _ _ _ 20

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Rt 1 = 0000o5 o+ o00006 + O,0243 + O, 00344 = 0o006443 ho A.sume Ib _ 940, = 0.001064 ~ho 940 Rt' o.*oo643 ~ 0O,001064 - 0007494 Atcf (OO00~ 6) (72.4) 10-28*F (o0,:007494 ) )~/4 z/k _,te/4 (Atcf) (10,28) = - X791 From Fig, 21/ ('k]3f. l2f 1.X)6 ho = (o.66) (78o.5)(5..o8) Tff From, etation (17)i o ( 6692(79l) The calculated ho checks closely the ass.med ho. 1 Uo= 133*6 For 7/Winch OD 16 BWG plain copper tube: ho~;r (Q-2 i SL ~ghX1 1/4 (kf 0,2 ()/4 ho > 1*27 _o_ _P,_f (18) 21

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN For a water velocity Vt = 6 ft/ee, hw = 150 (1 + 0.011 x 97.5). ( 1380 Ao 1.173.=, 0,0085 Ai. 1380 ( 1R 1 t 4;) 0*0005 + 0000i03 + 0,00085 + 0*001173 0: o00255. i 1 Assume ho 380 o = = 0.002635.5 Rt = 000255 + 000Q2635 = 0.005185 Atcf = (o00o2355) (72.4) = 36.8F (0o005185) (At cf)l/4- (36.8)1/4 = 2,462 Tf = 172 1- 1/2(36v8) _ 153*,6~F From Fig.w, 27, (k3 2 1/4'kf pf ge k From equation (18), ho (1= 27)(754) 388 (2.462) A value of ho _ 390 would be the correct one on the basis of the second trial; hO 1 _ 390 I -- 1 0*002564 ho;390 Rt - 000255 + o,oo2564 = 0.05114 Uop1 -= 1956 0,o005114 The correspon'ding ratio Uof/Uop obtained by this method is Uo~f 6~- 0,.685. Uop 195.6

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN The average value of this ratio from the two methods given in sections 2, 3, and 4 is conservative and has the following value: Uof - ~0.745 o.6853 = 0.,714* 2~.. Uop 2 This, for the design of the bu.tyl-heads condensers the design overall coefficient for the finned-tube units, is conservatively taken as 70 perc-ent of that of the plain-tube unitS5 Hence, Uop = 100 Btu/hb- F-ft2 outside Uof = (100)(0,70) = 70 Btu./hr-'F-ft2 outiSide - Corresponding values of the overall coefficient per foot of tube length are Trufin. No. 196'049-011l ULf U0 Ao' (70) (0*.588) = 411l. For 7/8-inch OD 16 BWG plain tube7 ULP = (100) (0,229) = 22.9 ULf = 41:. = 1.795 ULP 22,9

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN APPENDIX B DESIGN CALCULATIONS FOR BUT-YL-HEADS CONDENSERS BASD ON CALCULATED ORAL COEFFICIENTS Design No Dl, Lesign of Condenser with Trufin No, 196049-01 Tubes 1l Tube S.peifications See isopropyl~alcohol condenser design (Appendix F), 2, - Tube Arranme nt Tube-side From Appedix Al section 2 for Trufin No, 196049-01 tubes, at Vt = 6,9 ft/sec Uof 134 Btu./hr-OF-ft2 outside area Required heat-transfer areat A (650,000) 677 ft2 Requiredt tube length = (677) 150 ft (o*588) length per tube = 8 f 1150 Number of tubes in bundle (!21) = 144 For tw, tube passes-~ Ast, =44 For tw be pases AC =( (0.00231) = 01662 ft Water velocity = 1 7*1 ft/ec 0.,1662 Mass velocity = 263o00 = 1,58o000oo b 0..1662 hr-fta Re(- (6) 1,5: 8000 0) 47,900, ft ='000018 (12) (1.79) AP` (0.00018)(:,s8 ),o8)a(8) (2)(12) - 2:,4 psi (5*22 x 10i~) (O,995) (0*651) (1L623) NP header losses (4;)(054)(2),.74 psi

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN APt = 2A4 + 2i74 = 5.1 psi For two tube passes* 144 tubes plaed on 1-1/8:incbhsquare pitch rtquire a shell with an inside diameter of 18 iinche-s xeess heat;transfer area n= one Design No*2. 2, fsign of condenser with 0%875-inch OD 16 BWG Plaint Copper Tbe| 1, Tube Specifications See isopropyl-aleohol condenser design (Appendix F). 2, Tube Arrangement and Tube-side AP From Appendix A, section 3 for 7/8-inch OD plain t'ubes at Vt 6.85 ft/$ee Uop = 180 Btu/hr-F-ft2 outside area A = (6,y56,ooo) = 5004 ft2 Requ.ired tube length = 2200: ft 0%229 Length bf tubes 10 t 22 2200 Nuber- of tubes in bundle = 220 10 Use 232 tubes to meet the allowable APt Actual A = (232) (10)(0229) 531 ft2 For four tube passes, (4) (1.18)..72 ft/aee Vt (2322) (0*oo3o25) Mass velocity (263,000); 1,196000,lb 1757 hr Re(05)0 =0) 52,ooo00 t = 0000175 (12) (~.79) AP~('71* (ooz)(9626. zo) (zo )(4) (x) 475 (s22 x 01'O )() 09) (0745)(lO:226) AP header losses - 4:10)()-:4.82 pzi (0,995) Ttal APt = 4.75 + 4*t82 = 9.57 or 9.~6 psi Shell inside diameter - 23 inches Excess heat-transfer area = (LQz054 ) ('00) 5i,4 pereent 25

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Cost Est.timation of Units T1. estirmated unit costs are based on the same conditions as those for the isopropy;-alcohol units (Appendix F),

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN APPENDIX C DESIGN CALCULATIONS FOR BUTYL-HEADS CONDENSERS For the computation of condensing and overall coefficients) the composition of the butyl heads was assumed to be n-butyl alcohol, isobutyl alcoa hol, and water. The two bu.tyl alcohols were assumed to be present in equal proportions, On this basis, two equations, one.utilizing additive densities and the other additive heats of vaporization, were solved simultaneously to give the following bu.tylheads composition: COmponent Wt. Fraction Butyl alcohol 0 855 Water 0O145 Total 1. 000 The design overall coefficients are taken as follows (see section 4, Appendix A): Uop = 100 Btu/hr -F-ft2 outside Uof = (0*70)(100) 70 Btu/hr-.'F-t2 outside Two sets of calculations were made for the following tube applications Design No, 3. Wolverine Trufin No, 196049-01 0*875-in. 16 BWG plain-end copper tube Design No. 4), 0.875-in. OD 16 BWG plain copper tube Design No, 5. Wolverine Trufin No* 195065-26 0,750-in: 14 BWG plain-end admiralty tube Design No. 6. 0*750-in. OD 14 BWG plain admiralty tube 27

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Design No. 3 Design of Condenser with Trufin No. 19604-01l Tubes 1. Tube SpecifiCations See isopropyl-alcohol condenser design (Appendix F). 2. Tube Arrangement and Tube-side APt' Allowable tube-side pressure drop = 10 psi Allowable shell-side pressure drop = 0,5 psi (160-85) - (184-110o)ATI 25303 log 75 72 F Heat duty, Q = (18,670)(352) = 6,560,000 Btu/hr Average water temperature = 85 + 110 97o50F 2 = 1.79 lb/ft-hr p = 62.0 lb/ft3 Water flow rate = 263,000 lb/hr or ( 56,000) = 1.18 ft3/see (62,oO) (3600) Required heat-transfer area, A - (6,56 00) oo 8t2 (72.4)(70) Required tube length = (128) = 2208 ft Length per tube = 12 ft 2208 Number of tubes in bundle 12 = 12 84 tubes For two tube passes, At = 231) = 0212 t Water velocity = 1.18 = 5.56 ft/sec 0o,212 Mass velocity (263,000) 1240000 lb (0,-212) hr,-ft2 Re *, (o r65l)(la4o,0o ) 37, 600 (12) (1*79)0600 ft = 0.00019 (ooool49) (124 x l8) (12) (2) (12) = 2,35 psi (5,22 x l0'o) (0o995) (0o651) (L.Q623) AP header losses _':)(::2.)(2) = 1.69 psi (0,995) 28

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Total tube-side APt = 2.34 + 1, 69 = 4.03 or 4,.0 psi For two tube passes, 184 tubes placed on l-1/8-inch-square pitch require a.shell with an inside diameter of 20 incheso Excess heat-transfer area = 0 percent. Design No. 4v Design of Condenser with o,875 in, OD 16 BWG Plain Copper Tube 1, Tube Specifications See isopropyl-alcohol condenser design (Appendix F). 2, Tube Arrangement and Tubeside APt Required heat-transfer area, A 6 *-0- =0) 907 ft2 (72.4)(loo) Required tube length = ((907) = 3960 ft (0o229) Length per tube 14 ft Number of tubes in bundle = 283 Use 284 tubes, four tube passes Number of tubes per pass = 284 71 Total tube length = (284)(14) = 3980 ft A = (3980)(0o229) 911 ft2 Acst - (71)(0oo003025) 0,215 ft2 Water velocity 1= 18 5,49 ft/sec 0,215 Mass velocity (265O 0 1=222,000 _ (Oa215) hr'ft Re =_ 3(0*745.)(l,2 22,.) 00 (12) (1.79) 42,4 ft 0o0000185 (0o,00085) (1.a222 x loe)2 (1)4() (4) ) (5*22 x l01 ) (0,995) (745) (1.0226) = AP header losses = (4)( )(4)38 (0o995) Total APt = 4,66 + 338 = 8084 or 8,0 psi.........._ 29 _.

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Shell inside diameter = 25 inches Excess heat-transfer area = (911-07) (100) 0.44 percent (907) Design No,e 5 Design of Cndenser with Trufin No* 195065-26 lubes 1. Tube Specifications See isopropyl-alcohol condenser design (Appendix F). 2. Tube Arrangement and Tube-side At Required A 1298 ft2 1298 Required tube length = 0,410 3162 ft Length per tube = 12 ft Number of tubes in bundle = 162 = 264 For two tube passes, Acst = 2 (0.00142) = 0.1872 ft2 1,18 Water velocity = 0182 A= 6.3 ft/sec Mass velocity =(263000) = 1,402,000 lb -(0.1872) hr-fta Re=(0olo) (l4o0,00o) Re =; 33,300 (12) (179) ft 0000198 A000l98) (1.402 x 106) (12) ()() (.1298 psi (5.22 x 1010) (0o995) (0,510) (1.o623) AP header losses = (4) (0.72)() = 2,18 psi.... (0995 Total APt X 3598 + 2.18 = 6,16 or 6.2 psi For two tube passes, 264 tubes placed on 1-inch-square pitch require a shell with an inside diameter of 21 inches. Excess heat transfer area = none 50>

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN Design No. 6. Design of Condenser with 0.750-in. OD 14 BWG Plain Admiralty Tube 1*. Tube Specifications See isopropyl-alcohol condenser design (Appendix F). 2. Tube Arrangement and Tube-side APt Required heat-transfer area, A = 907 ft2 907 Required tube length = 907 = 4610 ft 0.1963 Length per tube = 10 ft Number of tubes in bundle =... = 461 10 Use 464 tubes, four tube passes Number of tubes per pass = 116 Total tube length = (464)(lO) = 4640 A - (4640)(0.1963) = 911 ft2 Acst = (116)(0.00186) = 0.216 ft2 1.18 Water velocity = 1.18 5.46 ft/sec 0.216 Mass velocity = (263,000) 1, 218,000 -b rft (0.218) hr-ft2 Re = (0o.584)(l,218,oo) 35,100 (12)(1-79) ft = 0.0002 AP = (O.0002)(l.218 x 106o) (0)(4) (2) = 4.58 psi (5.22 x 101o ) (0995) (o584) (1.0226) AP header losses = (4)(0.2)(4) =8 psi (o.995) Total APt = 7-96 or 8.0 psi For four tube passes, 464 tubes placed on 1-inch-square pitch require a shell with an inside diameter of 29 inches. Excess heat-transfer area = (100) = 0.44 percent. Cost Estimation of Units The estimated unit costs are based on the same conditions as those for isopropyl-alcohol units. 31

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN APPENDIX D CALCULATION OF THEORETICAL OVERALL HEAT-TRANSFER COEFFICIENTS FOR THE CONDENSATION OF ISOPROPYL ALCOHOL ON 7/8-INCH OD FINNED AND) PLAIN TUBES A set of calculations similar to those for the bu.tyl heads were completed to determine the ratio Uof/Uop from which the design Uof could be determined. The following are the values obtained by the two methods outlined previously,. Method Vt Uof Vt Uop Uof/Uop CN/N1/4 6.78 125,2 5.85 149 0.84 Short-cut method(L 6 126.8 6 1i66.8 0,76 average Uo = o.84 + 0.76 o= 080 Uop 2 Hence i Uop = 100 Btu/hr-AF-ft2 outside Uof = (100) (0.80) = 80 Btu/hr-~F-ft2 ou.tside Corresponding values of the overall coefficient per foot of tube length are: Trufin No. 196049-01, ULf- UoA = (80o)(o.588) = 47*0 For 7/8-inch OD 16 BWG plain tube, ULP = (100)(o.229) = 22,9 U-f = = 2.05 ULP 22.9 32

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN APPENDIX E DESIGN CALCULATIONS FOR ISOPROPYLiALCOHOL CONDENSERS BASED ON CALCULATED OVERAIL COEFFICIENTS Design NO. 7 Design of Condenser with Trufin No* 196O0490 1 Tubes 1. Tube Speeifications See isopropyl-alcohol condenser design (Appendix F), 2, Tube Arrangement and Tube-side APt: From Appendix'Dj for Trufiin No,* 19604.9o1 tubes at Vt = 6,78 ft/see Uof 125,2 or 125 Btu/hr- F-ft outside area 8,680,0ooo0 (75) (25) Required tube length = 0: 588 = 1572 ft Length per tube 8 ft Number of tubes in bundle = 172 196,5 Use 198 tubes, 8 actual total tube length = (198)(8) = 1582 ft aetual A = (1582)(0o588) = 931 ft2 For two tube passes Aest = (99)(0.00231) =, 0,2284 ft2 Vt -. (.. i (3.8,.00 6.81 f t/see (36o0) (62,O0) (O02284 ) (0.2284) 348,oo,zlb maSS velocitY =... = 17520000 hrft 0,2284:' Re = (..6:")(l:).....46,000.,ft = 0..0008

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN AP (0.000 8)(1.52 x 0.).(8, (2)() = 2.21 psi (5.22 x 1010)(0o.995) (651)(10.o623) AP header losses (= )(...) (2) 2.57 psi (o0.995) APt = 2.21 4 2.57 = 4,.78 or 4*8 psi Shell inside diameter = 21 inches ExCess heat-transfer area (931 -925) (100) a0 65 percent (925) Design No. 8* Design of Condenser with 0&,875-inch OD 16 BWG Plain Copper Tubes i. Tube Specifications See isopropyl-alcohol condenser design (Appendix F). 2. Tube Arrangement and Tube-side APt From Appendix D, for 7/8-inch OD plain tubes at Vt = 5.85 ft/sec Uop = 149 Btu/hroF-ft2 outside area A:8,68 -,000 776 ft2 (75) (149) Required tube length = -76 = 3384 ft 0.229 Length per tube 10 ft Using 3400 ft of tubing Aactual = (3400)(0*229) = 780 ft2 Number of tubes in bundle = 400 = 340 10 For four tube pas.ses, A4st = 34 (0*005025) = 0*2575 ft2 Vt 16 - = 6,o5 ft/sec 0o.2575 548,ooo lb Mass velocity = = 1,350,000 -- 01*2575 hr — ft2 Re 7....5).(l5 00) = 46,80,,ft = 0.00018 34

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN (o.ooo18)(1.35 x 106) (10) (4)(12) A P 100 3....7 Ps. (5.22 x 10O)(O.995)(0o745)(1,0226) 5.97 psi AMP header losses = (099) = 402 psi APt = 3*97 + 4.02 = 7,99 or 8.0 psi Shell inside diameter = 27 inches Excess heat-transfer area =(7o-776) (100) = 0*52 percent (776) Cost Estimation of Units The estimated unit costs are based on the same conditions as those for isopropyl-alcohol units (Appendix F). _____________________________________ 55 _____________________________________~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN APPENDIX F DESIGN CALCUTLATIONS FOR ISOPROPYL-ALCOHOL CONDENSERS The overall design coefficients are taken as follows(from AppendixD): Uop = 100 Btu/hrt-F-ft2 outside Uof = (0o80)(100) = 80 Btu/hr-"F-ft~ outside Two sets of calculations were made for the following tube applications: Design No, 9, Wolverine Trufin No, 196049-01 0,875-in. OD 16 BWG plain end copper tube Design No. 10 0.875-in4 0D 16 BWG plain copper tube Design No: ll Wolverine Trufin No. 195o65-26 04750-in, 14 BWG plain-end admiralty tube Design No, 12, 0.750-in. OD 14 BWG plain admiralty tube Design No 9 Design of Condenser with Trufin No 196049-01 Tube 1, Tube Speccificati-ons Truf'in No, 196049-01 19 fins/in, do = 0.864 in. dr 0.749 in. Wall thickness = 0049 in, di: 0,749- (2)(0,049) = 0.651 in~ Ao 0*588 ft2/ft Ai = 04171 ft2/ft O/Ai - 35.44 Acs =..6 = 0.00231 ft2/tube (576),2; Tube rangement and Tube-side Pt Allowable tube-side pressure drop = 10 psi

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Allowable shell-side pressure drop 05W psi Tz ~ = (165-85) - (180-110) 75~F 2,303 log 8 Average water temperature = 110 + 8 = 97*5~F 2 At 97-5*~F5 = 0*74 cp, or 1*79 lb (Kern, Process Heat Transfer ft-hr 3 p = 62o0 lb/ft From previous calculations about 60 percent of the overall temper. atur e drop ocurs between the bulk water and t~he inside tube wall, Therefore average inside tube wall temperature, Tm = 97*.5 + (o-60)(75) = 97.5 + 45 142,5OF }w at tube wall temperature = 0,48 ep. (Kern, p.823) 0_14 4g (If)l (3 Heat duty, Q (27,,000)(320) = 8.68 x 106 Btu?hr Required heat-transfer areas A _ (8.68 x 10). 1446 ft (75) (80) Required tube length = _ 2460 ft (o0,5 88) Lenth per tube = 12 ft Number of tubes in bundle = 05 Use 206 tubes, two tubes passes Number of tubes per pass =.06 103 Total flow cross-seCtional area. Acst = (103)(0.00231); 02538 ft2 Water flow rates Wt ~ 348,000 lb/hr Mass velocityOGi (-4800) 60000 (0238)' hr-ft2 Water velocity i 460 I00 = 6.54 ft/sec (360oo) (62o0) DiGi (0.6151 ) (1~460, 000) 37

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN ft.= 0,00183 (p* 836, Kern) AP inside tubes ft G 2 (tube length) (5P22 x 1010) Di S [g (oo.000 )16 x 1)3),-, i2)().1 2) 5. 3,12 psi (5,22 x o101) (0,995) (o,65) (10623) where specific gravity S = = 0995 42. AP? tuvbe-side return pressure loss 4 nVt 2geS (I.4) (0,29) (2) 2.33 psi (0. 995) (Kern, p, 837) Total tube-side pressure drop APt 3.612 + 2,33 r 545 or 5.5 psi The' pressure drop is satisfactory. For two tube passes7 176 Trufin No, 196049-01 tubes placed on 1-1/8& inchsquare pitch require a shell with an inside diameter of 22 inches (Kern,, p, 841)., actual A * (206)(12)(0.:588) = 1452 ft2 145~2'1446 Excess heat-transfer area = -—..446 (100) = 0,42 percent 1446 Design No, 10, Design of Condenser with 0,875-in, OD 16 BWG Plain Copper Tube 1. Tube Specifications do = o:o875 in, Wall thickness = o*065 in, di 0-0o/875-(2) (0o65) 0o745 in. A ()( = 0.19 ft2/ft (12) ~Ai (X7Oel0,195 -ft2/ft (12) %/A i = 0,229 11.73 0. 195 (-,)....(057) 0.003025 ft2/tube -S (576) 58~r

ENGINEERING RESEARCH INSTITUTE' UNIVERSITY OF MICHIGAN 2. Tube A':rangement and Tlbe-side APt' Allowable tube-side pressure drop 10 psi From previous calculations about 21 percent of the overall temperature drop.oeurs between the bulk water and the inside tube wall,, Average inside tube wall temperature, T=, 97w,5 + (o-2l)(75) - l13,2:F p at l1352tF o063 p:, ~ ='> - tI 1,,o226 "g i. of'6- / Reqired heat-transfer area, A; 1160 ft2 1160 Requ.ired tube length 1160 = 5060 ft 0.229 Length per tube 14 ft Number of tubes in bundle = - 362 Use 364 tubes, 4 tube passes 364 Number of tubes per pass s - = 91 Total flow crossasectional area, Acst = (91)(0oo003025) = 0~2756 ft2 PMass velocity Gi l(b7),26.,000 -. (0.2756) hr Water velocity ( 1,262,o 0) 5.65 ft/seC (3600) (62o0) Re DiGi (O745) (1,262,000) 5 43,800 (12) (179) rft' 0,000183 (Kern, p* 836) A? inside tubes (o0ooo83)(1.262 x l0~)2(l4)(4 )(12) (5.22 x 1010) (0,995) (o*745) (1*0226) 4,,95 psi.A tube-side return pressure loss = ( 3*46 psi (00995) TOt1I tube-side p ressure drop, APt 4,95 + 3,46 = 8,41 or 8,4 psi. The pressure drop is satisfactory,._9

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN For four tube passes. 364 tubes placed on 1-1/8-inah-square pitch require a shell with an inside diameter of 28 inches, Actul A (364) (4)(0o29) - 1168 ft2 Exess area 0_ (-168-160) (100) = o069 percent (1160) Design No, 11, Design of Condenser with Trufin No,1 95065-26 Tubes 1,, Tube Specifications: T'ufin No, 1.9506526 19 fins/in, dO = 0.0737 in;7 dr 0o,640 in. Wall thickness = 0065 in. di o6 0640 - (2) (0065) 0,510 in,* A 0410 ft~/ft Ai= 06134 ft2/ft AO/Ai 5 306 $ (,)(O(~lo')2 = 00014i2 ft2(576) 2, Tube Arrangement and Tube-side APt Allowable tube-side pressure drop = 10 psi (i446) Required tu.be length (1) 520 ft (0,410) 3 Length per tube 12 ft (3520) Number of tubes in bundle = (12) = 294 Use 294 tbess two tube passes Number of tubes per pass 2 147 Total flow cross-sectional area, Ast (147) (000142) 0,209 ft2 Mass velocity Gi = (Oo209) = 1.662J000 r fthr-.ft2 (1p,662.000) Water velocity 600) (620) 745 ft/sec Re = (0510)(1,662,000) 9500 = ooo4.. __ _ __ _ __ _ __ _ __ _ __ _ __ _ 40 __ _ __ _ __ _ __ _ __ _ __ _ __ _

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN P? insie tu:bes - (0o00018_7)(1.662 x o10)2(12)(2)(2 5(227 psi (5,22 x 1010)(0,995)(0,510)(10623) AP tubeoside return p.resSre loss=.(4)(0.38)(2) = 3.05 psi 0.995 Total tubeoside pressre:dxop At 527 + 3q05 ~ 832 or 83 psi The pressure a.ro is sati-factoryt For two tue pasesW 294 Tr'uin No* 195(6526 tubes plated on!inch squre pitch reqyire a shell with an inside diauJrtete of'ti inches E.ss beat4'r-feare;a none Design No, 12 sign of Condenser with 0:750-ineh D 14 BWG Plain Admiralty Tubes 1. Tube Specifications W13.l thiekes = 0! 083 inaw.L = 0..:584 is ~Ao 01963 ft2/ft A*- 08f 9 /ft Ai. 0052>9 2/ft A/Ai = 0196 1285 0.1529's = 0,.268 ijtr or oQ00186 Pt2 2, TUbe Arrangement and Tu~be-side AP Alwable tubesaide p.resse drop = 10 psi Required. tbe! e ngth =(0968) 5900 ft T4ength per tube' 10 ft M~er of t-u.eS in bundle = 2. 5'90 10 Ue 592 tbe fo r tube 5s2s 2 be: r;Of t per ps 59 = 148 Total flo.w.Setioal area At 8 (1I8)(0086) 0~75 ft2..S~ "el —ity.G~i. -5k800 = 1,65000 hr-ft2 0:. 275..water Te'ity (1,265,-000) ='5'66ft/e. (36oo) (62.0)

~ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Re = =(34,4o (12)(1o79) ft = 0,000197 (o0oool97) (1265, x cPV( 1) ( Q4) (12 j (5.22 x 10i'o) (0o995) (0.584) (1e0226) = 487 psi A: tuwbe-side return pressure loss (4)()(4) = 3-54 psi (o.995) Total tube.side pressure drop1 APt 4k87 + 5I54 8*I41 or 8O4$ psi The pressure drop is satisfactory, For four tube passes, 592 tubes placed on 1-inch-square pitch require. a shell with an inside diameter of 31 inehes* Actual A = 9 (592)(10)(0o1'963) 1162 ft2 (1162'1160) Excess area (1160) (100) = 0*.17 percent Cost Estimation of Units The estimated unit costs are based on t;he fllowing conditions: 1 Condenser costs except the tube are based on September, 1950, values C'orrected to 1954 by cost indices of MarshalL and Stevens, 2, Cost of finned tubes- is based om March, l954 price list. 3 5 Cost of plain tubes is based on June) 1953'. price list, corrected to March1 19541.

3.4 3.3 3-2 jGl _ _ _ _ _ _ _ _ _ _l l 3.1 0 00 200 300 400 500 600 700 600 0 9000 hO, STU/(HR)(F)(SQ FT OUTSIDE AREA) 1/4 FIGURE I VARIATION OF (/DEQ) WITH OUTSIDE FILM COEFFICIENT FOR WOLVERINE TRUFIN 196049-01

840 L FIGURE 2 VARIATION OF PHYSICAL PROPERTY GROUP IN NUSSELT EQN. 830 WITH CONDENSING AND CONDENSATE FILM TEMPERATURES FOR 820 BUTYL HEADS 780 700' -....... ~~725~~~~~~0~I0 7!0 700 680 67 0, 8 660.F TMEAR, Tf. 65fi:' 120 - CON.DE NSATE FILM TEMPERATURE, TC, OF.

700 ago FIGURE 3 VARIATION OF PHYSICAL PROPERTY GROUP IN NUSSELT EQUATION WITH CONDENSING eo AND CONDENSATE FILM TEMPERATURES FOR I SOPROPYL ALCOHOL UO _ ___.... 420 410 SooC' So c. 570 820 -. 510. I00 120 140 160 Iso l 200 220 CONDENSATE FILM TEMPERATURKE,,.

24 /.6 z c I;2 t_ I IIA 2 0 I 1 2 3 4 5 6 7 8 9 10 20 NUMBER OF TUBES IN A VERTICAL ROW, N FIGURE 4 RATIO OF EXPERIMENTAL TO THEORETICAL CONDENSATION COEFFICIENTS FOR FREON-12

1.0 0.9 0.8 0.6 i' 0.4 0.2 d U0.o0 -. 2.0 - H + r,) iKMy FIGURE 5 EFFICIENCY OF ANNULAR FINS OF CONSTANT THICKNESS

ENGINEERING RESEARCH INSTITUTE ~ UNIVERSITY OF MICHIGAN NOMENCLATWRE A Total outside tube area in heat exChanger, fta, Acs I~Insid;. toseotilnal flow area of tube- ft2 &AC:4s- Total iVside Crosseietinatl flow a rO a of tubes, per pass, ft2 Ae Equivalent ou.tide area, it/ft, 4Ae efAf + Ar Af Outside finned-tube fin area ftp/ft af ea of one fin (both sides)j. ft2 Ai Inside tube area, ft2/ft of tube length Am Logarithmic mean metal area between Di and Dr,, ft/ft Ao Outside tube-surface area, ft2/ft of tube length A0/A1 Ratio of outside to inside surface areas Ap Outside surfae area of plain tube with same outside diameter as root diameter of finned tube, ft2/ft length of tube Ar Outside finned-tube root area1 ft2/ft CN Coreetion factor for condensing toefficient with N number of tubes in a v ertical row Deq Equivalent outside diameter for calculating condensing coefficients defined as follows: e1/4A Ar 1/1/4 l.5ef'' (") + 1/li' eq A0 L Ao(Dre eq E~qu.ivalent otside diameter for calculating condensing coefficient based on outside equivalent area, ft (..i )1/4 1= 3 ef ~ (~l/ +A11/4 ( ) 1/4 Di nsid u' deq AeeL Di Inside tube diameter, ft di Inside tube diameterr in. Do. DDiameter over the fins, ft do Diameter over the fins, in, Dr: Finned-tube root diameter, ft dr Fnned-tube root diameter, in,:ef Fin effiCiency factor, decimal equivalent ft Frietion factox.,t tube side -.'sf Subscript f attached to density, viscosity, and thermal icoiductivity of condensate represents fl.id properties at the film temperature of condenslng fluid, Tf ge Gravitational constant, 417 x 108 ft/hr2 or 32.2 ft/sec2 Gi Ma..'Mass velocity inside tubes lb/(hr)(ft2) H Fin height, ft ho.'Outside film coefficient corrected to base ff fin, Btu/(hr) ('F)(ft2) Outside film coefficient, Btu./(hr) (-F) (ft2) based on equivalent Outside area Inside film Coefficient for water, Btu/(hr)("F) (ft) k Thermal conductivity, (Btu.)(ft)/(hr) (F)(ft ) km The.rml con.ctit.of tube wall, (Btu.)(ft)/(hr)(:F) (ft2) L Mean effective fin height, ft, L = af/.io __8

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN Nomenclature (continued) N Number of fins per inch, or average number of tubes in a vertical row n2 Number of tube passes APt Total pressure drop through tube side, psi Q Total heat load, Btu/hr Ri Total inside resistance, (1/hi + ri)(Ao/Ai) ri Inside fouling resistance, (hr) (-F)(ft2)/Btu Rm Tube metal resistance, (hr)(*F)(ft2)/Btu' Ro Total outside resistance, (1/ho + ro) r0 Outside fouling resistance, (hr)(EF)(ft2)/Btu Rt Total resistance to heat transfer, (Ri + Rm + Ro) -= 1/Uo or 1/Ud Re Reynolds number S Specific gravity of fluid Tav Average bulk shell-side temperature, 4F Atcf Temperature drop across the condensate film, OF Tf Mean condensate film temperature, F, Tf = sv 1/2 Atf ATm Logarithmic mean temperature difference, 4F IT Average tube metal wall temperature, OF Tsv Saturation temperature of a condensing vapor,`F tw Average water temperature in tubes,: F U0fo Overall coefficient of heat transfer for finned tubes Btu/(hr)(`F)(ft2) outside surface Uop Overall coefficient of heat transfer for plain tube, Btu/(hr)(QF)(ft2) outside surface Vt Tube-side velocity, ft/sec Wt Total flow through tube side, lb/hr x Number of tubes required for condensing Xf Tube wall thickness, ft Xf Tube wall thickness, in. Y Mean fin thickness, ft y Mean fin thickness, in, Greek Symbols: Viscosity of fluid, lb/(ft)(hr) ktw Viscosity at tube wall temperature lb/(ft)(hr) Viscosity gradient g = ( g /lw) l p Density, lb/fts Latent heat of condensation, Btu/lb 99

UNIVERSITY OF MICHIGAN II3 9015 0252311 11 1113 3II9015 02523 1013