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柴油机是客、货牵引车的最重要动力源。从全球温室效应的影响看,降低柴油机排放的任务十分紧迫。随着对日益增加的氮氧化物(NO_x)、颗粒(PM)和二氧化碳排放的关注,提出了严格的排放法规。未来的排放法规要求采用先进的排放控制技术,如选择性催化还原、稀氮氧化物捕集器和废气再循环技术。废气再循环被广泛用于降低排放。用一种低压废气再循环技术降低轿车柴油机排放,改善发动机的燃油经济性。对1台排量为7 L、装备有低压废气再循环系统的轿车柴油机开展了试验研究。在稳态和瞬态运行工况下,使用低压废气再循环系统比使用常规高压废气再循环系统更能获得改进燃油耗的效果。在发动机处于中速、中等负荷时,使用低压废气再循环系统可降低燃油耗,而NO_x和PM排放并不受影响。
Diesel engine is the most important power source for passenger and cargo tractor. From the global impact of the greenhouse effect, the task of reducing diesel emissions is urgent. With the growing concerns about nitrogen oxides (NOx), particulates (PM) and carbon dioxide emissions, stringent emission regulations have been proposed. Future emission regulations require the use of advanced emission control technologies such as selective catalytic reduction, lean NOx traps and exhaust gas recirculation technologies. Exhaust gas recirculation is widely used to reduce emissions. Using a low-pressure exhaust gas recirculation technology to reduce emissions from passenger car diesel engines and improve fuel economy of the engine. A test study was carried out on a diesel engine with a displacement of 7 L and equipped with a low-pressure exhaust gas recirculation system. Under steady-state and transient operating conditions, the use of a low-pressure exhaust gas recirculation system provides better fuel economy improvements than conventional high-pressure exhaust gas recirculation systems. Low-pressure exhaust gas recirculation systems reduce fuel consumption while the engine is at medium-speed and medium-load, while NO x and PM emissions are unaffected.