PROGRESS REPORT NO. 6 KINETICS OF OXIDATION AND QUENCHING OF COMBUSTIBLES IN EXHAUST SYSTEMS OF GASOLINE ENGINES D. J. PATTERSON PERIOD: AUGUST 1, 1969 to AUGUST 31, 1969 AUGUST 1969 This project is under the te&hnical 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. PHASE I PROGRESS A group of preliminary engine tests were run in order to check out procedures and equipment, and determine emission levels from the standard 350 CID Chevrolet engine. NDIR and FID hydrocarbons, CO, CO2, and oxygen concentrations were measured by continuous sampling at the tailpipe, wye, and exhaust ports for a variety of engine operating conditions. The General Motors test code was followed for performance testing. Water out temperature was set at 190 F and oil temperature was limited to 230 F. Tailpipe emissions from two data sets are discussed below.

ENGINE SPEED Data was taken to study the effect of engine speed on emissions. Operating conditions were: Speed: 800 to 2400 rpm at 200 rpm increments Load: constant at about 17 Bhp (calculated road load at 45 mph) Ignition Timing: minimum advance for best torque Air-Fuel Ratio: approximately 15.5:1 Figure 1 shows the hydrocarbon concentrations measured at the tailpipe. Both FID and NDIR readings are shown. As expected, the HC concentration decreased as speed was increased. Figure a shows tailpipe, CO, CO2, and oxygen concentrations. All three remained constant because the air-fuel ratio was held constant. The manifold vacuum as a function of engine speed is plotted in Figure 3. For this constant horsepower test, vacuum increased at the higher engine speeds. BSFC is plotted in Figure 4. As expected increased friction at higher speed increased BSFC. IGNITION TIMING Data was also taken to study the effect of ignition timing on performance and emissions at constant load. Operating conditions were: Speed: 1200 rpm Load: road load, 10.44 Bhp Ignition Timing: 10,18,26,34,42,50 degrees before TC Air-Fuel Ratio: 15.5:1 Figure 5 shows tailpipe NDIR and FID hydrocarbons as influenced by ignition timing. The data at 50 BTDC is not included as poor combustion sent hydrocarbon

readings off scale. Hydrocarbon concentration increased markedly when the spark was advanced beyond MBT (34o). As a result, at this operating condition small errors in timing while having practically no effect on load, have considerable effect on hydrocarbon emissions levels. Figure 6 shows tailpipe CO, CO2, and 02 concentrations. All are nearly constant for advances up to about MBT since air-fuel ratio was held constant. The decreases in CO2 and increase in 02 when the spark was over advanced arose from incomplete combustion. Figure 7 shows manifold vacuum and bsfc as a function of ignition timing. ALDEHYDES The DNPH method has been set up for aldehyde measurements. Calibration tests have been run using standard formalin solution as the formaldehyde source. Limited analysis of engine exhaust gas has been made also to assess repeatability. OTHER Construction of the subtractive column analyzer is underway. PHASE II PROGRESS Preliminary studies aimed toward developing a first generation reactor model continue. A literature search is underway. A trip to Mobil Scientific Laboratory will be made to discuss their modeling approach.

PHASE III PROGRESS Studies of both timed and continuous sampling techniques continue. An electronic control has been built up for the Cox timed sampler. The control is being debugged at the present time. A student studying for his Ph.D. in Chemistry has been hired to do chromatographic analysis of exhaust hydrocarbons.

A /F -- 5.5/1 BBip.MP 7.2 Ignition O\ 600~~~~~~0 0 2 peo(Rm OL ~~~~00eNI~ 5 Zd~~~~~~~~~~~~~~~~~~~~~~~~~~~pe. o~~~~~~~~~~~~ 40 ~ ~ ~ ~ ~~-esl elia ~~~~Z 13~~~~~~~~~~~a (3 ~~~~~J:~~~~ —-— ll~rcabo OZ~~~~~~~~~~Fgi

O - C02 A - 02 144t 0 - CO 14.0 -4 14.0 o <. 800 1200 1600 2000 2400 ENGINE SPEED (RPM) Figure 2. CO, C02, 02 concentration versus engine speed.

o 15 A~~~~~~~~~~~~A/F hr15. / 5 SBHP ~U /1 EL~13C Ignit-o ii 222 9 o~~~~~~~0'o i~n t IM.ST 800 c 1200 1600 ENGINE Sp (Rm 2000 Figure _3. Mn Lfld Vc 2mre0r egne speed'.

A/F- 15.5/1 1.0 BHP~ 17.2 Ignition Timing at MBT.9 03 z~~~ I.6.5 800 1200 1600 2000 2400 ENGINE SPEED (RPM) Figure 4. Brake specific fuel consumption versus engine speed.

A/F,- 15.1/I 1200 BHP 10.44 RPM - 1200 z o 1000 O FID -- 800 A LNDIR wz 800 Z X 0. z 6600 0 a.0 o 400 I 200 0 I I I It 10 18 26 34 42 IGNITION TIMING(DBTDC) Figure 5. Tailpipe hydrocarbons versus ignition timing.

A/F 15.5/1 O-CO2 BHP 10.44 a- 02 RPM 1200 CO 14.0 13.0 12.0 Z 0 $ 5.0 W. 3.0 z 0 1.0 z 0.41 10 18 26 34 42 50 IGNITION TIMING (DBTDC) Figure 6. CO, C02, 02 concentration versus ignition timing.

O Manifold Vacuum A BSFC 19 I' z D o3 17 z. 0 16 U.9 M I 9.9 I I I I I I,w 10 18 26 34 42 50 IGNITION TIMING (DBTDC) Figure 7. Manifold vacuum and brake specific fuel consumption versus ignition timing.

CRC CAPE 8-68 PROGRAM OVERALL FINANCIAL SUMMARY Program Total: February 24, 1969 - February 23, 1970 $106,455 Cumulative Expenditures through July 24, 1969 33,290 Balance $ 73,165 110 100 Labor - - - Projected * - K Actual Total - Projected - Actual 90 80 70 60 Dollars / Thousands 50 40 30 20 10 00~ -,,'' F M A M J Ju A S Months 1969 1970 12

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 1 Automotive Emissions Division Petroleum Laboratory E. I. DuPont de Nemours and Company, Inc. Wilmington, Delaware 19898 Dr. J. B. Edwards 1 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. C. H. Ruof 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 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 15