PROGRESS REPORT NO. 23 KINETICS OF OXIDATION AND QUENCHING OF COMBUSTIBLES IN EXHAUST SYSTEMS OF GASOLINE ENGINES D. J. PATTERSON PERIOD: January 1, 1971 to January 31, 1971 January, 1971 This project is under the technical supervision of the: Coordinating Research Council APRAC-CAPE 8-68 Steering Committee and is work performed by the: Department of Mechanical Engineering The University of Michigan Ann Arbor, Michigan Under Contract No. CAPE-8-68(1-68)-CRC and Contract No. CPA-22-69-51-HEW

LONG-RANGE OBJECTIVES It is well-known that a significant amount of CO and unburned fuel may be consumed in the exhaust system of gasoline engines. Such combustion phenomena in exhaust reactors may be used to advantage to reduce the emission of these undesirable constituents. This process is the basis of exhaust air injection systems currently installed on some automobiles. The overall objectives of this three-year research program are: To determine the chemical and physical processes which affect the emission characteristics of exhaust reactors installed on selected typical engines operating at various conditions on a dynamometer test stand. *To identify the chemical species and significant chemical reactions present before, within, and after the reactor. *To obtain information which will be helpful in predicting the design of the next generation of gasoline engine exhaust reactors. PROGRESS PHASE I MULTICYLINDER REACTOR Last month, an unexplained increase in hydrocarbon emission arose from the 5'50 in. engine. Upon inspection severe scoring was evident in most cylinder bores. We have no explanation for the cause of the scoring, but feel it is probably not associated with the thermal reactors. A new 350 in. engine has been obtained from Chevrolet and is currently being installed. The old cylinder heads,intake manifold, carburetor, and exhaust reactors have been installed. The comparison ratio of this

new setup will be nominally 8.8:1 as opposed to 9.0:1 previously. Thermocouples have been received for measuring the reactor warmup characteristics. These will be welded to the surfaces of the righthand reactor. Currently emission equipment and personnel have been shifted to the single cylinder reactor. SINGLE CYLINDER REACTOR The temperature control system described in the previous progress report was installed this month, the reactor system was reinsulated, and a series of runs was begun to determine the degree of uniformity of temperature in the reactor, the repeatability of the kinetic data, and the importance of wall effects. Early results indicate that the temperature in the reactor is reasonably constant and that the wall temperature is quite close to the gas temperature. The sum of the measured flow rates of air and fuel to the engine and injection air to the reactor agreed quite well with the measured flow rate through the sparger tube, and the system was checked after running and found to be free of leaks. The regression program to determine the kinetic constants has not been applied to the new data as yet, but will be when more runs are completed. PROGRESS PHASE II Primary efforts during the month involved literature research on mixing and turbulence, and finalizing the regression routine to be used

for the single cylinder reactor. Emphasis will next be concentrated on "second generation" models. These models will not endeavor to simulate the detailed performance features of the DuPont reactor per se. Alternatively, models which permit evaluation of importance of design factors on performance will be employed. Second generation models will likely treat only steady inputs. The alternative of treating time and spatial variation simultaneously is judged to be a formidable computational problem. Models built up from components will assume premixing of air and exhaust. Extremes of micromixedness after premixing can be computed. The first step in this category will be the writing of a program for a simple steady-input tubular reactor, which gives the opposite extreme from the well-mixed model with respect to both micro- and macromixedness. The random-coalescence-type model will treat the problem of intermediate micromixedness. It will derive its mixing parameters from the theory of turbulent mixing-subject to limitations on the size and permissible pressure drop in a reactor. The model will likely assume complete macromixing, as done by Curl. Evangelista had applied this model to combustors for arbitrarily selected kinetics. His approach for solving the integral differential equation for the model requires that all rate dependence (including temperature effects) be expressed as a polynomial with respect to extent of conversion. This is overly restrictive, aTnd it is likely that a Monte Carlo solution will rather be employed. The mixing theory for jets used by Evangelista will be our starting point

in this ef[fort. This being att:ribut-;,ble to Cousin::s:nd e:nl'lier to Batchelor. A continuing literature survey is being conducted in thi:: area. A reasonable extension of the theory would be to add a distribution for the size of the eddies undergoing mixing. PROGRESS PHASE III MEASUREMENT OF EXHAUST GAS VELOCITY A new device to record the schlieren image, utilizing photodiodes as a light detector, was developed during the month of January in order to eliminate difficulties associated with the timing synchronization and manufacturing of a fast moving shutter for the measurement of the exhaust gas temperature. Instead of using the streak photograph technique for the time measurement, several photodiodes will be mounted on the film plane with a fixed distance apart and the signal from the photodiode will be amplified and swept by an oscilloscope which is triggered by a signal from the engine. Since the photodiode gives a continuous signal over any engine position and only the desirable portion of this signal is to be seen from the oscilloscope, the problem of complicated timing synchronization can be eliminated and the system does not require a shutter. While two pin Hewlett-Packard Pin fhotodiodes (response time less than 1 nsec) are ordered and the troubled laser unit was sent to the

factory for repair, a photodiode as;embly equipped with an amplil'ier is being fabricated. As soon as the ordered parts are received some preliminary data will be obtained from the new recording device. GAS CHROMATOGRAPH Work continues to upgrade our gas chromatograph.

CRC CAPE 8-68 PROGRAM OVERALL FINANCIAL SUMMARY PrL,-,;ramr Total: February 24, 1970 - February 23, 1971 $106,o00 Cumulative Expenditure through December 1970 82,000 Balance $ 24,500 110 I I 00 | Labor -— Projected x —x Actual Total -Projected. — Actual 90 80 70 Dollars / 50 40 30 - 20 10 o - F M A M J Ju A S O N D 3 F M Months 1970 1971

DISTRIBUTION LIST No. o01 Contract Distr i buti(ln copies Mr. Alan E. Zengel 3 Assistant Project Manager Coordinating Research Council, Inc. 30 Rockefeller Plaza New York, New York 10020 Dr. P. R. Ryason Chevron Research Company 576 Standard Avenue Richmond, California 94802 Mr. R. J. Corbeels 1 Research and Technical Department Texaco, Inc. P. 0. Box 5Q09 Beacon, New York 12508 Dr. E. N. Cantwell 1 Automotive Emissions Division Petroleum Laboratory E. I. DuPont de Nemours and Company, Inc. Wilmington, Delaware 19898 Dr. J. B. Edwards Research Section Chrysler Corporation 12800 Oakland Avenue Detroit, Michigan 48203 Mr. G. D. Kittredge 15 Department of Health, Education, and Welfare Motor Vtehicle Research and Development 5 Research Drive Ann Arbor, Michigan 48103 Dr. H. Niki Scientific Laboratory Ford Motor Company P. O. Box 20'55 Dearborn, Michigan 48121

DISTRIBUTION LIST (Concluded) No. of Contract Distribution Copies Mr. R. C. Schwing 2 Research Center lJaboratories Fuels and Lubricants Department General Motors Corporation General Mutors Technical Center 12 Mile and Mound Roads Warren, Michigan 48090 Mrs. Mary Englehart. 1 Department of Health, Education, and Welfare National Air Pollution Control Administration 411 W. Chapel Hill Street Durham, North Carolina 27701 Internal Distribution Professor J. A. Bolt, Dept. of Mech. Eng., Auto. Lab., N. C. 1 Professor B. Carnahan, Dept. of Chem. Eng, East Eng. Bldg. 1 Professor J. A Clark, Dept. of Mech. Eng., West Eng. Bldg. 1 Professor D. E. Cole, Dept. of Mech. Eng., Auto Lab., N. C. 1 Professor N. A. Henein, Dept. of Mech. Eng, Auto. Lab., N.C. 1 Professor R. Kadlec, Dept. of Chem. Eng., East Eng. Bldg. 1 Professor H. Lord, Dept. of Mech. Eng., Auto. Lab., N. C. 1 Professor J. J. Martin, Dept. of Chem. Eng., East Eng. Bldg. 1 Professor W. Mirsky, Dept. of Mech. Eng., Auto. Lab., N.C. 1 Mr. E. Sondreal, Dept. of Chem. Eng., East Eng. Bldg. 1 Professor D. J. Patterson, Dept. of Mech. Eng. Auto. Lab., N.C. 2 Project File 14