压缩比对电热塞引燃甲醇发动机的影响研究

Effects of Compression Ratio on Glow Plug Assisted Methanol Engine

在1台由DH1115单缸柴油机改装而成的电热塞引燃式直喷甲醇发动机上,使用CFD模拟软件Converge耦合甲醇氧化详细化学动力学机理,研究了压缩比对甲醇发动机燃烧及非常规排放的影响。结果表明,压缩比对甲醇在电热塞引燃燃烧方式下的燃烧及非常规排放有着重要影响:提高压缩比,有利于甲醇的蒸发,提高甲醇混合气均匀性;较高的压缩比可以使甲醇着火时刻提前,缩短滞燃期,甲醇着火更加稳定,同时也有助于促进甲醇完全燃烧;甲醛及未燃甲醇排放均随着压缩比的提高而降低,但降低幅度随压缩比增大而逐渐减小,在压缩比提高到19及以上时,甲醛及未燃甲醇排放分别小于0.4 mg/(kW·h)和3.1 mg/(kW·h)。

The effects of compression ratio on combustion and unregulated emissions were researched on a glow plug assisted direct-injection methanol engine retrofitted from DH1115 single-cylinder diesel engine by using Converge module of CFD software and the methanol detailed chemical kinetic mechanism.The results show that compression ratio has a significant effect on the combustion and unregulated emissions.Increasing compression ratio can improve the homogeneity of methanol-air mixture due to the induced evaporation of methanol.A high compression ratio can advance ignition timing,shorten the ignition delay period,improve the ignition stability and promote the complete combustion of methanol.Formaldehyde and unburned methanol emissions decrease with the increase of compression ratio,but the drop amplitude decreases with the increase of compression ratio.The formaldehyde and unburned methanol emissions are less than 0.4 mg/(kW·h)and 3.1 mg/(kW·h)respectively when the compression ratio increases to 19 or higher.