燃油预热改善直喷柴油机性能与排放研究

Improvement of performance and emissions of DI diesel engine using preheated diesel fuel

为了在传统柴油机上实现同时降低NOx和碳烟排放的准均质预混合燃烧,采用在高压油泵后加热流经高压油管柴油的方法,在一台单缸柴油机上就高温柴油对发动机燃烧和排放的影响开展了台架试验研究.通过在进气中添加低比例的二氧化碳气体,对采用燃油加热实现柴油准均质混合气压燃燃烧过程进行了探索性研究;同时应用KIVA3V对高温燃油喷射对混合气形成的影响进行了模拟研究.结果表明:高温燃油能够促进喷雾雾化和预混合气的形成,且对应一个最佳的温度范围,通过适当增大供油提前角到上止点前32°,采用大流量的多孔喷嘴缩短喷射持续期,以及进气中添加少量二氧化碳等措施,可以实现直喷式柴油机准均质预混合燃烧,达到同时降低NOx和碳烟的目的.

In order to reach low emission combustion, high temperature fuel injection and exhaust gas recirculation were used in a single-cylinder direct injection diesel engine. Furthermore, the high temperature fuel spray behavior and mixture process were studied using KIVA3V code. The results indicate that high temperature fuel injection can improve the fuel-air mixture in an optimum diesel fuel temperature range. The premixed combustion of diesel engine was realized by high temperature spray, while enlarging the fuel supply advance angle to 32° before top dead center （BTDC）, and using a multi-hole injector, and the fuel consumption rate and exhaust emissions were improved to a certain extent.