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在一台改制的发动机上进行了异辛烷、乙醇及其混合燃料HCCI燃烧的研究。发动机性能用缸内压力评估,研究用的参数包括放热率、平均指示压力和热效率。试验结果表明,乙醇着火时刻早于异辛烷;在乙醇中加入异辛烷可以推迟着火,并导致平均指示压力和热效率的降低;对某种特定燃料,HCCI燃烧的发生主要取决于进气充量温度,初始充量温度的增加将导致HCCI燃烧提前;充量温度低或发动机转速低时,混合气形成质量差,对HCCI燃烧有不良影响;指示热效率为30%~43%,其值高于火花点火发动机;预燃室的存在有利于稳定的HCCI燃烧;超稀充量运行可以显著降低NOx排放。
HCCI combustion of isooctane, ethanol and their co-fuel was carried out on a modified engine. Engine performance was evaluated using in-cylinder pressure. The parameters used for the study included heat release rate, mean indicated pressure and thermal efficiency. Test results show that ethanol ignition timing is earlier than that of isooctane; addition of isooctane to ethanol can delay the ignition and lead to lower average indicated pressure and thermal efficiency; for a particular fuel, the occurrence of HCCI combustion mainly depends on the inlet charge The increase of the amount of temperature and the initial charge temperature leads to the early combustion of HCCI. When the charge temperature is low or the engine speed is low, the formation quality of the mixture is poor, which has an adverse effect on the HCCI combustion. The indicated thermal efficiency is 30% -43% In the spark ignition engine; pre-combustion chamber is conducive to the stability of HCCI combustion; ultra-dilute operation can significantly reduce NOx emissions.