PROGRESS REPORT NO. 12 KINETICS OF OXIDATION AND QUENCHING OF COMBUSTIBLES IN EXHAUST SYSTEMS OF GASOLINE ENGINES D. J. PATTERSON PERIOD: February 1, 1970 to February 28, 1970 February 1970 This project is under the technical supervision of the: Coordinating Research Council ARPAC-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. GENERAL February 23 marked the completion of the first year of this three-year program. As yet a contract has not been executed for the second year. We will be working on a month-to-month basis until a contract is negotiated. PHASE I PROGRESS Baseline evaluation of the 550 CID engine is virtually complete. Installation of the duPont reactors may begin in March. The two-tank reactor

system fabrication has still not been completed. We expect delivery during March from Walker Manufacturing. The hydrogen meter fabrication has been completed and this unit has been checked out with calibration gases for response to hydrogen and interference from other combustion products. No major problems are anticipated in the measurement of hydrogen as part of the exhaust gas mix. The exhaust system of a single cylinder engine has been modified to permit installation of a laser-schlieren system. Temperature and flow data obtained will be used as inputs for the computer model. PHASE II PROGRESS A simulation on a single arm of an exhaust manifold (7.5 cu in. volume) receiving exhaust from a single cylinder has been completed. Inlet exhaust conditions entering the manifold were the same as those previously used for exhaust gas entering the 300 cu in. exhaust reactor; i.e., temperature cycling between 1200 and 2000'F, hydrocarbon (as methane) cycling between 250 and 2500 ppm, and carbon monoxide constant at 0.8%. Air was introduced at 100~F to achieve an overall dilution ratio of 1.4 as before; however, flow rate of air was staged to give 10% of the average rate over the 75~-interval of crank angle of maximum exhaust flow and a higher rate which resulted in the correct average over the remaining 645~ of a 720~-cycle. Resulting temperatures, pressures, and concentrations as a function of crank angle were observed to exhibit periodic oscillations of wide amplitude, as would be expected from the pulsing input and small manifold volume. Changes

in hydrocarbon and carbon monoxide during the period after exhaust flow ceased for a cycle were represented by an exponential-type decline as combustion and dilution by the continuing flow of air dropped concentrations to near zero at the end of each 7200-cycle. Perhaps the most significant finding was that conversion of CH4 was 70% and the conversion of CO 20% within the small volume of the exhaust manifold. It should be remembered that these conversions are based on selected literature values of kinetic constants (Yuster for carbon monoxide and Koslov for methane) and are subject to an unknown error for the conditions of this problem. However, the tenative conclusion is that the manifold may be highly important in predicting overall conversions between the exhaust port and the tailpipe of an exhaust system. Its importance may however be less than that shown due to imperfect mixing of air and exhaust within the small volume of the manifold. Modeling of the 300 cu in. CSTR reactor is continuing at higher levels of CO and with H2 added as an additional combustible species. For exhaust containing several percent CO, the amount of H2 entering is assumed to be predicted by equilibrium for the water-gas shift reaction at a K of 3. 5 correeq sponding to a reaction temperature of 26400F. A similar assumption has been used by Eltinge in computing fuel/air ratios from exhaust analyses and by Schwing in studies of exhaust oxidation. No applicable values of kinetic constants have been found in the literature for oxidation of hydrogen; and an assumption will be made that its oxidation in the CSTR reactor is essentially complete. Calculations were performed on the mass balance for CC, based on the kinetics used previously, to predict conversion versus reaction temperature. The

conversions calculated were in close agreement with those obtained in previous simulations of the CSTR reactor, which predicted a conversion of 56% for CO at 1200~F reactor temperature. This method of determining conversions for CO from intercepts between the mass balance and the energy balance (the method used by Schwing) is being used here to identify the inlet temperature below which conversions of CO drop precipitously (blowout). A range of temperature close to the calculated value will then be investigated using the CSTR simulation at the higher percentages of CO and H2 mentioned earlier to confirm that the simulation correctly predicts the blowout phenomenon. PHASE III PROGRESS No progress this month.

OVERALL FINANCIAL SUMMARY Program Total: February 24, 1969 - February 23, 1970 $106,455 Cumulative Expenditures through January 23, 1970 98, 103 Balance $ 8,352 110 100 L Lbor - - - Projected -K Actual Total - Projected --— Actual 90 80 70 60 Dollars Thousands5 0 so 50 30 / M A M J Ju209 190 0 Months 19~9 1970

DISTRIBUTION LIST No. of Contract Distribution 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 1 Chevron Research Company 576 Standard Avenue Richmond, California 94802 Mr. R. L. Bradow, Senior Chemist 1 Research and Technical Department Texaco, Inc. P. O. Box 509 Beacon, New York 12508 Dr. E. N. Cantwell 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 Motor Vehicle Research and Development Bell Tower Hotel 300 South Thayer Street Ann Arbor, Michigan 48104 Dr. H. Niki 1 Scientific Laboratory Ford Motor Company P. O. Box 2053 Dearborn, Michigan 48121

DISTRIBUTION LIST (Concluded) No. of Contract Distribution copies Mr. R. C. Schwing 1 Research Center Laboratories Fuels and Lubricants Department General Motors Corporation General Motors 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 Professor D. J. Patterson, Dept. of Mech. Eng., Auto. Lab., N.C. 2 Project File 14