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A technique is verified for mapping the exhaust emission levels of a diesel engine during transient operation. Particulate matter, oxides of nitrogen, hydrocarbons, and carbon monoxide emissions were sampled for discrete segments of various transient cycles. Each cycle consisted of four distinct segments. The discrete segments are described by average engine conditions, rate of change variables, and segment length. Regression analysis was used to develop equations relating the emission levels during each segment to the engine parameters. The regression equations were then used to obtain estimates of composite emission levels of several complex transient cycles that were subsequently tested. These cycles included the EPA heavy-duty transient cycle and two simulated heavy-duty cycles developed for underground mine vehicles. Comparison of the predicted and measured cycle emissions are made for the EPA heavy duty cycle and the simulated mine cycles.

Diesel exhaust emission levels have been measured during discrete transients in speed and load, and with changes made to the engine and fuel. Particulate, oxides of nitrogen, unburned hydrocarbon, and carbon monoxide measurements were made for two fuels, DF2 and 5 percent water-in-fuel microemulsion, for both a standard Caterpillar 3304 and a modified 3304 engine. Engine modifications included increasing compression ratio and retarding injection timing. This paper examines the effects of the water addition and engine modification on the steady-state and transient emission levels. In general, the addition of water decreased the particulate and oxides of nitrogen emission levels for the standard engine, but increased the levels of hydrocarbons and carbon monoxide. For the modified engine, the water addition resulted in a slight decrease in oxides of nitrogen and particulate matter at high speed and load conditions.

The possibility that NO2 artifactually converts polynuclear aromatic hydrocarbons to biologically active species in diesel particle sampling is explored. NO2 was injected into dilution air upstream of the exhaust mixing point at varvinq concentra-ting levels with both passenger car and truck driving simulations. Ames test specific activity and nitropyrene levels were seen to increase above base levels when the NO2 level exceeded 5 to 10 ppm. Extract responses to added NO2 in transient drivinq appeared to initially increase, then level off above about 20 ppm. It is suggested that some requestering of nitratable orqan-ics may be responsible. Reexposure of filtered particles to diluted gas phase diesel exhaust caused little increase in nitroaromatics or Ames activitv. It appears that NO2 levels below about 5 ppm are relatively safe from filter artifacts.