摘要
以某186FA柴油机为研究对象,对比分析喷油嘴用不同加工方法的喷孔及流量变化对小型柴油机燃烧和排放性能的影响。试验结果表明:减小喷油嘴流量,同工况下柴油机的最大燃烧压力降低,燃烧始点提前,预混燃烧比重减小,扩散燃烧阶段燃烧速度加强。合理匹配喷油嘴的流量参数能有效降低柴油机的排放。喷油嘴喷孔用电火花打孔与用机械钻孔相比,能明显的改善柴油机排放性能。186FA柴油机用电火花打孔、流量为0.959 L/min的喷油嘴和原机机械钻孔的喷油嘴试验对比,整机HC、CO和PM排放分别下降了45.1%、27.7%和10.4%;NO_x上升11.3%;但HC+NOx仍下降2.4%(八工况排放试验循环)。用喷油嘴优化匹配后整机排放能达到中国非道路柴油机第三阶段排放标准的要求。研究表明:柴油机在中、小负荷工况的燃油消耗率、HC、CO明显减少是整机排放降低的主要因素,其机理是喷油嘴流量系数大,喷孔燃油流道表面质量改善,提高了喷油压力和喷雾质量,每循环喷雾形状稳定,改善油气的混合和燃烧质量,说明喷油嘴喷孔参数和流量是影响非道路小型柴油机性能和排放的重要因素。
With a certain 186 FA diesel engine as the research subject,influences of nozzles with differentlyprocessed orifices and changes in flows on combustion and emission of small diesel engines were compared.The results indicate that the maximum combustion pressure decreases,combustion starting point gets earlier,proportion of premixed combustion decreases and combustion rate is enhanced in the diffusion combustion stage with the reducing of nozzles＇ flow.And properly setting flow parameters of nozzles effectively reduces emission of diesel engines.Nozzles with electrospark-perforated orifices perform better in emission than those with mechanically-perforated orifices.Overall HC,CO and PM emission of 186 FA diesel engines with electrospark perforated orifices and flow of 0.959 L/min reduce relatively 45.1%,27.7% and 10.4% than those of engines with original mechanically-perforated orifices.Though NOxemission increases by 11.3%,the total percentage of HC and NO_x is still 2.4% lower（eight-mode emission test cycle）.After optimization of nozzles,overall emission meets limits for exhaust pollutants from diesel engines of non-road mobile machinery（China Ⅲ）.The study reveals that fuel consumption ratio under middle and small load working condition and evident decrease in HC and CO are main factors of decrease in overall emission.The reason involved is that big flow parameter of nozzles and improved quality of runner surfaces increase pressure of fuel injection and improve quality of fuel injection.On the one hand,smog shape remains stable in every cycle;on the other hand,combinations of gas and oil and combustion quality are improved.These prove that orifice parameters and flow quality of nozzles are important factors that influence performance and emission of nonroad small diesel engines.
出处
《科学技术与工程》
北大核心
2017年第30期56-62,共7页
Science Technology and Engineering
基金
江苏高校优势学科建设工程(苏证办发[2014]37号)
江苏省重点研发计划(BE2015188)资助
关键词
非道路
柴油机
直喷式燃烧
喷油嘴
流量
排放
non-road diesel engine direct injection combustion nozzle flow emission
