Evaluation of Some Factors Controlling DI Diesel Combustion and Exhaust Emissions

The combined effects of turbocharging, high fuel injection pressure, and reduced oil consumption on diesel exhaust emissions were investigated using a single-cylinder research engine. The influence of these exhaust emission control concepts on particulate composition was determined using a new particulate analysis method. In addition, the dependence of particulate composition on engine load and air utilization was examined using the microfumigation technique. Simultaneous application of these emissions control concepts reduced exhaust particulates by 70 percent. High injection pressure reduced the insoluble component of particulates, while reducing oil consumption and turbocharging the engine lowered both soluble and insoluble particulates. Reductions in oil-derived particulates with increasing engine load were partially attributed to increases in volumetric air utilization. Ninety percent of the lube oil found in exhaust particulates was unburned; however, similar concentrations of unburned and partially oxidized components were observed in fuel-derived particulates.