汽油机冷起动过程富氧燃烧试验研究

Research on oxygen-enriched combustion during the cold start phase in a gasoline engine

为了研究进气中O2体积分数对汽油机冷起动过程燃烧与排放特性的影响,试验对一台单缸汽油机分别提供O2体积分数为21%、23%、25%、27%和29%的富氧空气,对比分析冷起动最初60 s内的缸内压力、放热率和排气温度,以及HC、CO和NOx排放.研究结果表明,随着进气中O2体积分数的增加,汽油机冷起动过程燃烧与排放状况均有明显改善,着火更早、燃烧更快、缸内压力峰值和放热率峰值更大;同时,富氧燃烧可提高排气温度,大幅降低HC和CO排放量,减幅分别达88.5%和93.6%,但NOx排放量随O2体积分数增加而加速增大.

In order to study the impact of the air intake O2 percentages on combustion and emissions during the cold start period in gasoline engines, a single-cylinder gasoline engine was supplied with 21% , 23% , 25% , 27% and 29% oxygenated air respectively. Pressure, heat, and exhaust gas temperature were simultaneously analyzed. This produced different emission levels of HC, CO and NOx during the initial 60 s period after starting. The results showed that when the O2 percentage increases during the cold start period, combustion and emissions are significantly improved, auto-ignition occurs earlier, ignition duration is shorter, peak pressure and heat generated in the cylinder are higher. At the same time, the oxygen-enriched combustion increases the exhaust temperature and reduces the emissions of HC and CO by 88.5% and 93.6% respectively, but NOx emissions increase with the O2 concentration.