预喷射和掺混乙醇对柴油机性能及排放的影响

Influence of Pilot Injection and Blending Ethanol on Performance and Emission of Diesel Engine

本文利用GT-Power软件建立了单缸柴油机的仿真模型,模拟研究了预主喷间隔、预喷油量和乙醇掺混比例对发动机性能和排放的影响。计算结果表明,预喷射能明显改善发动机的燃烧特性和排放性能,但扭矩和燃油消耗率变化不明显;预主喷间隔对发动机性能和排放的影响较小,预喷油量的增加会提高缸内压力和放热率峰值,造成NOx和碳烟排放增加;掺烧乙醇可以显著减少NOx和碳烟排放,提高缸内压力和放热率峰值,不过发动机的扭矩减小,油耗率增加;随着乙醇掺混比例增加,这些趋势进一步加强。柴油机采用预喷射和掺混乙醇相结合的策略,可以改善发动机的排放性能和燃烧特性,而且不会恶化动力性和经济性,是一种有效的技术方法。

The paper established a simulation model of single cylinder diesel engine using GT- Power software to calculated the influence of pilot-main injection interval, pilot injection quantity and ethanol fraction on performance and emission of diesel engine. The results showed that it can im- prove combustion and emission performance of the diesel engine significantly using pilot injection, while the torque and brake specific fuel consumption change was insignificant. Influence of pilot- main injection interval on performance and emission of engine was small. Increasing pilot injection quantity can increase the peak of cylinder pressure and heat release rates, causing NOx and soot e- mission increase . Blending ethanol can decrease NOx and soot emission significantly , increase the peak of cylinder pressure and heat release rates, but the torque decreased and brake specific fuel consumption increased. When ethanol fraction increased, these trends would be enhanced. Using pi- lot injection combined blending ethanol on diesel engine could further improve combustion and emis- sion performance, and the power performance and economic performance would not deteriorate ap- parently. Therefore this strategy was one effective technical method.