72-14 EMISSIONS FROM THE WORCESTER POLYTECHNICAL INSTITUTE (WPI) HYBRID October 1971 H. Anthony Ashby Test and Evaluation Branch Mobile Source Pollution Control Program Office of Air Programs Environmental Protection Agency ------- Background The WPI Electric Hybrid was entered in the 1970 Clean Air Car Race by students from Worcester Polytechnic Institute and was the \vinner of the Hybrid Division of the Race.. A contract was arranged so that the car could be more thor- oughly evaluated, using the 1972 Federal Test Procedure, at EPA facilities in Michigan. Control Techniques The WPI Hybrid is basically an electric car with on-board charging capability. Power is stored in 20 six-volt batteries wired in series, and is transmitted via a DC traction motor and heavy duty propeller shaft and differs ential to the rear wheels. The generator for recharging the batteries is powered by an internal combustion Jeep V6 engine of 225 cubic inch displacement. Emission controls on the engine include air injection into the exhaust mani- folds, catalytic reactors, and exhaust gas recirculation. The engine burns lead-free gasoline to protect the catalysts. Engine speed is maintained between 1800 and 2200 rpm. The load on the engine is also kept relatively constant because the demands for power, such as during accelerations, are met by drawing from the batteries. Such a design has the poten- tial to produce low emissions. The vehicle weighed about 4500 pounds and was tested at an inertia weight of 4500 pounds. Test Program The vehicle was delivered to the EPA laboratory at Willow Run Airport on April 7, 1971. The students who delivered the car demonstrated the vehicle operating procedures to GAP test personnel. Dynamometer testing required a driver to follow the speed-time schedule and another person to control engine speed and various electrical parameters. Testing concluded on May 8 due to increasing amounts of heat and smoke from the vehicle's electrical apparatus. ------- 2. The car was run on the 1972 Federal Test Procedure and on the 7-mode procedures using an inertia weight of 4500 pounds. The 1972 FTP is a chassis dynamometer procedure consisting of a cold start, the LA-4 driving schedule and the constant volume sampling (CVS) method for collecting a diluted sample of the exhaust over the entire start and driving operation. The 7-mode procedures employ a repeating 7-mode driving cycle. The 1970 Federal Test Procedure uses continuous analysis of the undiluted exhaust over seven repeats of the cycle. The emission concentrations are averaged at several discreet intervals during each cycle and then multiplied by factors reflecting fuel-air ratio, engine air flow rates and time in each mode during actual driving to yield an average concentration during each cycle. The mass emissions are calculated from the concentration data using a formula based on vehicle weight. The 9x7 test uses nine repeats of the 7-mode cycle, with the CVS method of sample collection. In the 1970 FTP, all exhaust constituents are analyzed by NDIR instruments. In the CVS procedure NDIR is used for determining CO and CC>2 , a flame ionization detector (FID) for unburned hydrocarbons (HC) and a chemiluminescence (C.L.) Instrument for nitrogen oxides (NOX). Results The mass emissions data, presented in Table 1, were relatively high. This may have been due to failure or poisoning of the catalysts or to malfunction of the air pumps or EGR system. The high emissions could also have been caused by a malfunction of the electrical controls resulting in the I. C. engine being operated at too high a load or at some other non-optimal condition. Mass emissions of NOX from the C. L. instrument are presented as NC>2, corrected to a humidity of 75 grains. On test number 12-1521, the lower HC emissions are due to the fact that it was a hot start test. ------- TABLE 1 WPI Electric Hybrid Mass Emissions Test No. 12-1456 ^-1457 12-1502 12-1520 12-1521 12-1567 6-0632 Type 72 72 72 72 72 Hot 9 70 FTP FTP FTP FTP FTP Start x. 7 FTP HC gm/mile . 3.46 5.84 1.08 1.14 .32 2.85 .35 CO gm/mile 12 11 20 15 15 3 1 .06 .04 .39 .68 .12 • 99 .27 C02 gm/mile 1053 1182 1763 1542 1707 869 .2 .7 .8 .0 .0 .6 -gm/mlle 6 6 11 11 •« 13 9 .53 .94 .26 .44 .0.0 .82 .16* * NO only., determined by NDIR. ------- |