BED含氧燃料在不同海拔下对柴油机PM和NOx排放的影响

为研究生物柴油-乙醇-柴油(简称为BED)含氧燃料在不同海拔下对柴油机微粒(PM)和氮氧化物(NO_x)排放的影响,在一台高压共轨柴油机上分别燃用纯柴油和BED含氧燃料,在两种大气压力(81和100 k Pa)下进行了排放试验研究.结果表明,燃用纯柴油和B15E5(15%生物柴油+5%乙醇+80%柴油,体积比)燃料后,在中、低负荷时的PM排放在高气压下基本高于低气压下,最高增幅分别达到26.2%和19.0%;在全负荷时的PM排放在高气压下降低,最高降幅分别达到6.1%和17.0%.燃用B25E5(25%生物柴油+5%乙醇+70%柴油,体积比)燃料后,PM排放在高气压下降低.燃用纯柴油后,柴油机在高气压下的NO_x排放低于低气压下;燃用B15E5和B25E5含氧燃料后,在中、低负荷下的NO_x排放在高气压下降低,在全负荷下的NO_x排放在高气压下升高.在中、低负荷下NO_x排放最高降幅分别达到12.1%和15.3%;在全负荷下,NO_x排放最高增幅分别达到6.5%和5.8%.在不同大气压力下,柴油机燃用纯柴油和BED含氧燃料后,PM与NO_x排放均呈现明显的trade-off关系.相比于在低气压下,随负荷增加引起的PM排放降幅和NO_x排放增幅在高气压下增加.

Effect of BED oxygenated fuel on the PM and NOx emissions of a diesel engine at different altitude levels

In order to study the influence of the biodiesel-ethanol-diesel (abbreviated as BED) oxygenated fuel on the particulate matter (PM) and nitrogen oxides (NO_x) emissions of a diesel engine at different altitude levels, experimental investigations of PM and NO_x emissions were performed on a high pressure common rail diesel engine fueled with pure diesel and BED oxygenated fuels at different atmospheric pressures of 81 kPa and 100 kPa. The experimental results showed that the PM emissions basically increased at medium and low loads with the greatest growth of 26.2% and 19.0% at high atmospheric pressure, and decreased at full-load with the greatest drop of 6.1% and 17.0% when fueled with the pure diesel and B15E5 fuels. And the PM emissions decreased at high atmospheric pressure when the B25E5 fuel was used. Compared with the NO_x emissions at low atmospheric pressure, the NO_x emissions decreased at high atmospheric pressure when the pure diesel fuel was used. And the NO_x emissions also decreased at medium and low loads, but increased at full-load when the B15E5 and B25E5 oxygenated fuels were used at high atmospheric pressure. The greatest drops at medium and low load were 12.1% and 15.3%. The greatest growths at full-load were 6.5% and 5.8%. When the pure diesel fuel and the BED oxygenated fuels were used, the PM and NO_x emissions were presented obvious trade-off trend at different atmospheric pressures. At high atmospheric pressure, the drop of PM emissions and the growth of NO_x emissions with the rising load both increased.