scope:

Mapping projections indicate that light-duly diesel vehicles wigh-ing up to 3000 pounds can approach the 1982 emission requirements of 1.0 gram per mile lor NO. and 0.6 grams per mile for particulates. This can be accomplished with innovative, optimized engine control systems. Turbochtirgin|> does not appear to reduce particulate emissions. Limited modifications of the combustion system have not resulted in significant reductions of envisions. Test results from an experimental particulate trap have shown collection frequencies of more than SO percent; this indicates the potential to approach a p»r-lstallage emission level of 0.2 grams pet mile at low mileage in vehicles up to 3500 pounds. Traps can be regenerated by high-speed/high-kxid engine operation, by throttling the engine intake air. and by operation of a diesel-fueled burner. Inn none of these techniques lias been developed for tltc entire range of engine speeds and loads that would be required for a pioduction-feasible system. The durability of these (taps lias not been prosen. The addition of lend to the diesel fuel reduced the ignition temperature of particulates on a trap hv about 300 F.

Compared with ihe homogencous-charge gasoline engine, the divided-chamber diesel engine has the potential to provide improvements in volumetric, or tank, fuel economy at today's emission requirements. The average improvements for an indircct-injcction diesel range from 27 to 33 percent for inertia weights from 1500 to 4000 pounds (1). I lowever, emission regulations for 1985 will require a significant reduction in NO, and particulate levels of diesel engines, which are currently designed for optimum fuel economy.

Figure 1 shows the general trends in CVS-CH par-ticulagc emissions^ versus NO, emissions for diesel-powered vehicles with inertia weights ranging from 2250 to 4500 pounds. Figure 1 was constructed from published data on emissions from diesel vehicles, test results from diesel vehicles equipped with exhaust gas recirculation (EGR), and projections based on engine dynamometer data. The NO, and particulate emissions of production vehicles, represented by the right-hand termination points of the curves in the graph, increase significantly as the vehicle's inertia weight increases. The use of EGR to reduce NO, emissions to the 1981 requirement of 1.0 gram per mile increases particulate emissions.