柴油机部分均质预混燃烧模式下混合与化学控制参数对指示热效率的影响

摘要

A hybrid combustion control strategy based on partially premixed combustion （PPC） diesel en- gine was developed for high thermal efficiency and near zero emissions in a wide engine-operation range up to IMEP of 1.1 MPa.The combustion control parameters of mixing and chemical, including fuel injec- tion timing, injection rate pattern （such as multi-pulse injection）, boost pressure and exhaust gas recirculation （EGR）and in-cylinder temperature regulated by intake valve closing timing, must be deliberately matched for pursuing the combustion paths of equivalence ratio and temperature, avoiding of entering the formation zones of soot and NOx.In this study the effects of mixing and chemical parameters on thermal efficiency were investigated by energy balance analysis from first law of thermodynamics. It was found that thermal efficiency is more sensitive to combustion control parameters than emissions in clean PPC.%基于部分均质预混燃烧（PPC）的柴油机研究开发和优化了一种混合燃烧控制策略，在平均指示压力（IMEP）高达1．1MPa的负荷范围内实现了高的指示热效率以及超低排放．燃烧过程中的混合与化学控制参数包括了喷油定时、喷油模式（如多脉冲喷射）、增压压力、EGR率以及进气气门关闭定时等，通过优化耦合以上控制参数可以优化控制当量比与温度的变化路径，从而避开NOx与碳烟（Soot）生成区．基于热力学第一定律，通过能量平衡的分析方法研究了混合与化学控制参数对热效率的影响．研究表明，相对于排放而言，热效率受控制参数的影响更加敏感．