The effect of multiple fuel-injections on emissions of NO{sub}x and smoke with partially-premixed diesel combustion in a common-rail diesel engine

摘要

The aim of this study is to quantify, using partially-premixed combustion, the effect of fuel-injection schedules on the NO{sub}x-smoke trade-off. Steady-state tests were conducted, between 1200 - 2000rpm and 3bar BMEP with conventional (two-injections) and partially-premixed combustion (three-, four- and five-injections). Compared with conventional combustion, partially-premixed achieved up to 61% reduction in NO{sub}x, for similar smoke. However, four-injections, compared with three- and five-injections, gave the lowest NO{sub}x-smoke trade-off and 19.5% increase in Specific Fuel Consumption (SFC) compared with conventional combustion. The most effective fuel distribution was achieved when high quantities were injected earlier and smaller ones later i.e. closer to TDC. The last fuel-injection quantity made the greatest contribution to combustion noise. The general level of three-injection partially-premixed combustion noise, compared with conventional at 2000rpm and 2bar BMEP, was more spectrally uniform with frequency.