丁醇汽油混合燃料在缸内直喷发动机中的燃烧特性研究

Combustion Characteristics of Butanol-Gasoline Blends for GDI Engine

为探究丁醇对发动机燃烧的影响,选取甲苯标准参考燃料(TPRF)与各类丁醇的同分异构体的混合燃料进行了发动机可视化试验研究。试验基于直喷点燃式光学发动机,结合高速摄影及缸内压力测试等手段,进行了不同TPRF-丁醇燃料的火焰图像处理及分析,并结合燃烧分析仪测试了发动机的燃烧性能。试验结果表明:正丁醇与TPRF的混合燃料的火焰速率及火焰面积扩张速率最高,而叔丁醇与TPRF的混合燃料最低;丁醇的添加会抑制TPRF的着火倾向,导致燃烧持续期和着火延迟期明显延长,延长效果由大到小依次为叔丁醇、仲丁醇、异丁醇、正丁醇;由于丁醇的热值更低,黏度和汽化潜热更高,掺混丁醇后发动机平均有效指示压力也有显著降低。

In order to explore the influence of butanol on engine combustion, engine visualization experiment was conducted with the mixture of toluene standard reference fuel(TPRF) and various butanol isomers. On a direct-injection ignited optical engine, the high-speed photography and in-cylinder pressure testing was conducted to process and analyze flame images of different TPRF/butanol fuels and a combustion analyzer was used to test the combustion performance of engine. The test results show that the flame velocity and flame area expansion rate are the highest for the blends of n-butanol and TPRF and are the lowest for the blends of tert-butyl alcohol and TPRF. Moreover, the addition of butanol will inhibit the ignition tendency of TPRF, and the combustion duration and ignition delay hence prolong. The prolonging effects from small to large are tert-butyl alcohol, sec-butyl alcohol, isobutyl alcohol and n-butyl alcohol. Besides, the mean effective indicated pressure of engine decreases after blending with butanol due to the lower calorific value, higher viscosity and vaporization latent heat of butanol.