【作者】

Mingfa Yao

【摘要】

论文已在中国上海举行的2013年CIMAC大会上发表。论文的版权归CIMAC所有。Exhaust Gas Recirculation (EGR) is used widely due to its efficiently impacts on the NO x reduction with the increasingly stringent emission regulations. However, the introduction of EGR can lower in-cylinder oxygen concentration and increase combustion losses, which will increase soot and brake specific fuel consumption (BSFC) simultaneously. In this paper, the integrate optimization for the combustion system and fuel injection parameters, the introducing way of EGR, turbocharger matching, fuel injection strategy was conducted in a heavy-duty diesel engine with common-rail fuel system. The results showed that, soot, BSFC and the maximum in-cylinder pressure can been lowered by properly reducing compression ratio, optimizing the structure parameters of combustion chamber (shrink diameter and bowl depth,etc.) as well as the usage of Bosch injector with eight taper holes. Relative to high pressure EGR (HP-EGR), low pressure EGR (LP-EGR) can significantly enhance EGR recyclability and air/fuel ratio (AFR) at low speed conditions, thus improving soot and BSFC performances. Conversely, HP-EGR can reduce pump losses and BSFC at the medium and high speed conditions. Compared to constant pressure system, the EGR recyclability and the NOx-BSFC trade-off can be improved by pulse boost systems for HP-EGR. The trade-off between NOx , soot and BSFC will worsen with the increased intake charge temperature at high load cases under the low speed. However, the effects of intake charge temperature on the engine performance and emissions can been weaken via optimizing turbocharger systems, EGR system, fuel injection strategy, etc. With increasing engine power, two-stage turbocharger (2TC) can obviously improve EGR recyclability and the trade-off between NOx , soot and BSFC compared to single-stage turbocharger at full load conditions under medium and low speed, which showed obvious advantages and potential in the case of meeting Euro IV and Euro V regulations without any after-treatment. At low load conditions, the NOx ,soot emissions and the maximum pressure rise rate (MARR) can been efficiently reduced by lowering in-jection pressure and postponing injection timing under single injection strategy. At high load conditions under low speed, soot and BSFC can been improved by the same control strategy used at low load. At high speed conditions, it is necessary to employ post injection and higher injection pressure to reduce engine emissions and BSFC. Keywords: Diesel engine; Turbocharger;Exhaust gas recirculation (EGR); Combustion; Emissions

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

2

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