Combustion characteristics of a dual fuel diesel engine with biodiesel as ignition fuels

在一台以进气管道供应的天然气(CNG)为主要燃料的双燃料柴油机上，研究了工作参数对发动机性能、燃烧特性和排放的影响。结果表明：(1)在高负荷下，双燃料燃烧需要十六烷值大于45的点火燃料；(2)当反应速率较高的化合物二甲醚与CNG预混时，不同的CNG供应比例下，燃烧模式有很大的不同；(3)双燃料柴油燃烧采用进气中的氮气或二氧化碳气体稀释，可以显著改善NOx与烟度之间的权衡关系。

This study investigated the influence of operating variables on engine performance, combustion characteristics, and emissions with a dual fuel diesel engine powered by natural gas (CNG) supplied from the intake-pipe as the main fuel and an ignition fuel sprayed into the combustion chamber. The results showed that: (1) at high loads the dual operation requires ignition fuels with cetane numbers higher than 45; (2) when DME (di-methyl ether) a compound with a high reaction rate is premixed with the CNG, the pattern of the combustion is very different for different CNG supply ratios; and (3) remarkable improvements in the trade-off relation between the NOx and smoke emissions are possible when N2 or CO2 gas dilution of the intake air was employed with dual fuel diesel combustion.