正丁醇/生物柴油高预混压燃燃烧及排放特性的试验

Experiment on Combustion and Emission Characteristics of n-Butanol/Biodiesel Dual Fuel HPCC

在一台改造的单缸柴油机上,研究了正丁醇/生物柴油高预混压燃的燃烧和排放特性.缸内直喷生物柴油,进气道喷正丁醇,合理选择喷油时刻和正丁醇比例,实现了高预混燃烧.试验中生物柴油的喷油轨压固定为100,MPa,循环油量为60,mg(当量生物柴油循环油量),研究了正丁醇热值比例、生物柴油喷油时刻和EGR率对燃烧和排放特性的影响.结果表明,正丁醇比例、EGR率和喷油时刻通过缸内混合气活性和混合气活性分布影响正丁醇/生物柴油双燃料高预混燃烧的燃烧和排放特性,燃烧呈现多种燃烧模式组合的复合燃烧现象,适当调整正丁醇比例、EGR率和生物柴油喷油时刻可以获得较高的热效率和极低的NOx和碳烟排放.正丁醇比例为80%～85%时,较早的生物柴油喷射时刻可以获得较高的热效率(47%以上)和低的NOx和碳烟原始排放.

Combustion and emission characteristics of n-butanol/biodiesel dual fuel HPCC（high premixed charge combustion）in a modified single cylinder diesel engine were conducted.Biodiesel is injected into cylinder and n-butanol is injected into the intake port.Reasonable choice of injection timing of biodiesel and ratio of n-butanol realizes the HPCC.The rail pressure of biodiesel is fixed at 100,MPa,and cyclic fuel flow-rate is fixed at 60,mg（equivalent biodiesel cycle consumption）.The effect of n-butanol ratio,biodiesel injection timing and EGR rate on the HPCC and emissions was studied.Results show that n-butanol ratio,EGR rate and biodiesel injection timing affect the HPCC and emissions through influencing the chemical reactivity and the chemical reactivity stratification of cylinder mixture.HPCC is a compounded combustion model comprised of multi combustion modes.Ultra low NOx and soot emissions along with high-efficience could be achieved by varying the injection timing of biodiesel,EGR rate and n-butanol ratio.At n-butanol ratio of 80%—85% with early biodiesel injection timing,the indicated thermal efficiency reaches 47% while maintaining ultra low NOx and soot emissions.