Effect of injector flow rate on heavy-duty DI diesel engine performance and emissions for various injection pressures

Abstract

A computational study to examine the effect of injector flow rate at various injection pressures on the combustion process and mainly, on pollutants emitted from a heavy duty DI diesel engine was conducted using a multi-zone combustion model. The relation of injector flow rate with injection duration and mean injection pressure was taken into account in the present analysis to assess the overall effect of injection parameters. As observed, injector flow rate affects the combustion and pollutants formation mechanism through its effect on the fuel-air mixing rate. Higher injection rates are more beneficial to the improvement of bsfc-NO and soot-NO trade-offs at low engine speed whereas the opposite occurs at high engine speed. Overall, it was revealed that considerable improvements in terms of engine performance and pollutant emissions can be attained using low injector flow rates at the entire engine operating range and significantly increased injection pressures to keep the injection duration constant.