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对一台装有米勒系统、新开发的高压废气再循环系统、共轨供油系统以及变截面喷嘴涡轮增压器的中型中速直喷柴油机的排放和性能进行了测量,并与基准型发动机进行了比较。当功率、燃油耗、烟度和其他排放保持不变时,随负荷和优化组合方法的不同,NO_x排放可减少30%～50%。放热率分析解释了发动机在烟度和NO_x排放方面优化的原因:变截面喷嘴涡轮增压器为燃烧过程提供更多的氧气(降低烟度),并降低最高燃烧温度(减少NO_x排放)。共轨供油系统适应性强,能产生较高的喷油压力,因此,燃油与空气的混合更完善(降低烟度),同时,在相同的燃油耗下可允许燃烧时刻推迟,从而降低了最高温度(减少NO_x排放)。因此,灵活的供气系统和供油系统的组合可对发动机总体性能产生一种叠加优化的效果。
The emission and performance of a medium-speed medium-speed direct-injection diesel engine equipped with Miller system, a newly developed high-pressure exhaust gas recirculation system, a common rail fuel supply system and a variable-cross-section nozzle turbocharger were measured and compared with the baseline The engine was compared. When the power, fuel consumption, smoke and other emissions remain unchanged, NO_x emissions can be reduced by 30% to 50% depending on the load and method of optimization. The heat release rate analysis explains why the engine is optimized for smoke and NO x emissions: The variable-section nozzle turbocharger provides more oxygen (reducing smoke) and lower maximum combustion temperature (reducing NO x emissions) for the combustion process. Common rail fuel system adaptability, can produce a high injection pressure, therefore, the fuel and air mixture better (reduce smoke), at the same time, with the same fuel consumption allows the combustion time to postpone, thus reducing the Maximum temperature (NO_x emission reduction). Therefore, the combination of flexible air supply system and fuel supply system can produce a superposition optimization effect on the overall performance of the engine.