作为降低柴油机废气排放的一种方法,对均匀充量柴油燃烧技术(HCDC)进行了试验,将一部分燃油喷入进气道以形成均匀预混合气,这样,在直接喷入气缸的柴油着火之前,这种均匀预混合气从进气道进入气缸。试验结果显示,能显著降低NO_x和排烟。如果柴油预先与空气混合,预混合气会过早地自燃,从而难以保持在上止点附近着火定时,从而限制了柴油机的运行工况。虽然,降低排放的主要目标是实现高负荷工况下的稳定低排放燃烧,但是柴油机实际运行大多包括部分负荷工况。因此,即使在部分负荷运行范围内,如果HCDC能够实现低排放燃烧,则能够大大降低柴油机废气排放。因此在本研究中,在低负荷和中等负荷运行范围内,试图通过直喷燃油喷油定时的控制和EGR来改善燃烧和降低排放。对于全负荷工况,力求通过燃用高抗爆震性能的含氧化合物的柴油来优化HCDC。试验结果表明,在油门半开和低预混合燃油比的条件下,通过延迟(优化)直喷燃油喷油定时,能大大降低NO_x,而不增加排烟。这与在高预混合燃油比条件下所获得的效果是相同的。还发现通过优化预混合燃油比和EGR率,能降低NO_x排放,而不增加排烟。此外,能够确认,经在柴油中混入MTBE(甲基特丁基醚),当HCDC在柴油机整个运行范围起作用时,NO_x和排烟都能得到降低。通过延迟直喷燃油喷油定时,NO_x和排烟还能得到进一步降低。 As a method to reduce exhaust emissions of diesel engines, a uniform charge of diesel combustion technology (HCDC) was tested and a portion of the fuel was injected into the intake duct to form a uniform premixed gas. Thus, before the diesel fuel directly injected into the cylinder ignited This homogeneous premix enters the cylinder from the intake port. The test results show that can significantly reduce NO_x and exhaust. If the diesel is pre-mixed with air, the pre-mixture will prematurely ignite, making it difficult to maintain ignition timing near TDC, limiting the operating conditions of the diesel engine. Although the main objective of reducing emissions is to achieve stable, low emission combustion under high load conditions, the actual operation of diesel engines mostly includes part load conditions. As a result, diesel exhaust emissions can be greatly reduced if HCDC is able to achieve low-emission combustion even over a part-load operating range. In the present study, therefore, attempts were made to improve combustion and reduce emissions through direct fuel injection timing control and EGR at low and medium load operating ranges. For full load conditions, the aim is to optimize HCDC by burning oxygenated diesel fuel with high resistance to knocking. The experimental results show that NO_x can be greatly reduced by delaying (optimizing) the injection timing of direct injection fuel at the condition of semi-open throttle and low premixed fuel ratio without increasing exhaust emissions. This is the same effect as achieved with a high premixed fuel ratio. It has also been found that by optimizing the premixed fuel ratio and EGR rate, NO x emissions can be reduced without increasing exhaust emissions. In addition, it was confirmed that with the incorporation of MTBE (methyltetramethylether) in diesel fuel, NO x and smoke emission were reduced when HCDC was activated over the entire operating range of the diesel engine. By delaying the timing of direct fuel injection, NO_x and smoke exhaust can be further reduced.