中速柴油-甲醇双燃料发动机试验

在未对原机燃油系统进行改动的情况下,为一台中速柴油机加装甲醇喷射装置,组成了柴油-甲醇双燃料系统,分析了该发动机在变速和恒速工况下的甲醇替代特性,以及个别工况下喷油正时对上述特性的影响。试验数据显示,随着甲醇替代率的增加,NO_x排放和热效率会出现拐点；发动机HC排放的增长在低负荷时可控制在原机的2.3倍,中高负荷时普遍在10倍以上,最大时达22.4倍；推迟喷油在热效率上的负面影响会随着甲醇替代率的增加而逐步减少,而其在NOx排放方面的优势却能得以保持；在恒速发电工况下,中低负荷时甲醇的部分燃烧倾向增加,限制了甲醇替代率的提高；变速变载的运用形式下,柴油-甲醇双燃料系更容易取得较高的热效率,而恒速变载的运用方式下,双燃料系统更容易获得较低的NOx排放。

Experimental Study of a Diesel-Methanol Dual-Fuel Medium-Speed Engine

An intake branch methanol multi-point injection system was installed on a medium speed diesel engine without modification on existed fuel system to form a diesel-methanol dual-fuel system. Effect of the dual-fuel system on engine operating characteristics at both various speeds and constant speed application was studied; the effect of injection timing is also studied at one of the working conditions. Test result indicates: along with the increase of methanol substitution ratio there will be an inflection point of NOx emission and thermo efficiency; HC emission increased by 130% at low load, generally over 1700% at medium and high load, and 2140% at maximum; for late injection, Diesel-Methanol Dual-Fuel System can gradually decrease the disadvantage in efficiency while maintaining its advantage of lower NOx by increasing methanol substitution ratio; methanol substitution ratio was limited by the tendency of partial combustion of methanol at medium load rate when the engine is used for generator; operation mode with various speed help the dual-fuel engine to achieve higher efficiency while the generator mode helps the engine to achieve lower NOx emission.