运用米勒循环与生物柴油对柴油机性能优化分析

Optimization analysis of diesel engine performance with Miller cycle for biodiesel

本文基于GT-Power软件,对比分析了B20生物柴油在1000 r/min转速、2种负荷工况(100%和50%)下的2种米勒循环最佳方案,找到关于动力、经济、排放性能最佳的进气门提前关闭角;再基于米勒循环方案,对其性能进行了优化和分析,得出了B20生物柴油发动机在2种工况下功率、油耗、soot排放与NOx排放最佳性能的进气正时方案。结果表明:变气门重叠角米勒循环在整体性能方面优于变凸轮型线米勒循环,变气门重叠角米勒循环燃用B20生物柴油在2种不同负荷工况下,当处于进气门提前关闭角30℃A时功率性能最佳,并且通过模型优化后2种工况分别在进气门正时179.0℃aA和排气门正时174.0℃aA、进气门正时224.5℃aA和排气门正时119.0℃aA区域内有功率极大值;同理,油耗、soot与NOx排放也同样存在相对应的最佳进气门提前关闭角与优化后相对应的区域。

Based on GT-Power software,this paper compared and analyzed two optimal schemes of Miller cycle for B20 concentration biodiesel under 1000 r/min and two load conditions(100%and 50%),and found the best inlet valve closing advance angle for power,economy and emission performance.Then,based on the Miller cycle scheme,its performance was optimized and analyzed,and the intake timing scheme with the best performance of power,fuel consumption,soot emissions and NOx emissions of B20 biodiesel engine under two working conditions was obtained.The results show that the overall performance of the Miller cycle with variable valve overlap angle is superior to the Miller cycle with variable cam profile.The power performance of the Miller cycle with variable valve overlap angle is the best under two different load conditions of B20 biodiesel when the inlet valve is closed at 30°CA in advance.After model optimization,there are maximum power in the areas of intake valve timing at 179.0°CaA,exhaust valve timing at 174.0°CaA,intake valve timing at 224.5°CaA and exhaust valve timing at 119.0°CaA in the two load conditions,respectively.Similarly,fuel consumption,soot and NOx emissions also have corresponding optimum inlet valve closing angle in advance and corresponding areas after optimization.