Based on the operation cycle in internal combustion engines, a novel mode was proposed to improve the fuel economy of diesel engine by burning diesel fuel in methanol mixture. Methanol was injected into the manifold to form a homogeneous air/methanol mixture which was then ignited by diesel fuel spray under the diesel/methanol compound combustion (DMCC) mode. When the engine operated in this mode, its power increased by 2% and its brake specific fuel consumption decreased by 2.2%, compared with those of the baseline engine. And a 15% decrease in intake air temperature and a 9.3% drop in exhaust temperature were also gained. Besides, both Nox and paniculate matter (PM) emission were remarkably reduced. Therefore, in terms of emission level, a Chinese II diesel engine can be upgraded to a National Ⅲ, with its original injection system unchanged. Furthermore, the results of road test showed that fuel economy was improved by 10%, higher than that of the baseline engine. The mechanism of the engine operating in this mode was analyzed with p-V operation diagram. It indicates that the DMCC mode can improve efficiency dramatically and reduce exhaust emissions for diesel engine. Meanwhile, it also provides a novel way to make use of methanol in compression ignition engines.%根据内燃机燃烧循环的特点,提出用柴油在甲醇混合气中燃烧以大幅度提高柴油机燃料效率的模式.在柴油机上采用柴油/甲醇组合燃烧模式,甲醇通过进气道喷射与空气混合形成均质混合气由柴油引燃.与原杌相比,该模式下发动机的动力性提高2%,比油耗减少2.2%,排气温度降低15%,进气温度降低9.3%,同时实现了NOx和微粒(PM)的大幅度下降,使得在不改变原机机械式喷油系统的前提下,将仅满足国Ⅱ排放的发动机提升到了国Ⅲ排放水平.道路试验结果表明,柴油在甲醇氛围中燃烧,其燃料效率比原机提高了10%以上.结合采用此种模式工作的发动机p-V图对其实现高效燃烧的热力学机理进行详细分析.结果表明,该模式可大幅度提高柴油机效率,减少有害气体的排放,同时也为甲醇在压燃式发动机上的应用提出了一种方法.
展开▼
