DME/CNG双燃料均质压燃发动机性能试验研究

Study on the Performance of HCCI Engine Fueled with DME/CNG Dual Fuel

研究了二甲基醚和天然气双燃料均质压燃发动机性能和排放特性.结果表明,采用高十六烷值燃料二甲基醚和高辛烷值燃料天然气,可以拓宽均质压燃的运行工况范围.均质压燃发动机在中等负荷工况,热效率比传统压燃式发动机高.小负荷工况,采用二甲醚和大比例EGR方案可以提高热效率.和传统压燃式或点燃式发动机不同,均质压燃发动机的着火始点对经济性影响不大.均质压燃发动机的NOx排放极低,比原机降低95%以上.随着二甲基醚浓度增加,NOx排放增加,HC和CO排放降低;接近爆震燃烧区域,NOx排放急剧升高,而接近稀燃极限区域,HC和CO排放急剧升高,发动机热效率降低.

The performance and emission characteristics of HCCI (homogeneous charge compression ignition) engine fueled with DME (dimethy ether)/CNG (compress natural gas) have been investigated. The results indicate that the operation region of HCCI engine can be extended by using DME with a high cetane number and CNG with a high octane number. Operating at middle load, the thermal efficiency of HCCI engine fueled with DME/CNG is higher compared with the conventional CI engine. Different from both conventional CI engine and SI engine, the onset combustion timing doesn't have much influence on the efficiency of HCCI engine. The NOx emission of HCCI engine is much lower, and compared with the original diesel engine, it can decrease by more than 95%. When the concentration of DME increases, NOx emission increases while HC and CO emissions decrease. Near the knocking limit, NOx emission increases rapidly, and near the lean burn limit, HC and CO emissions increase rapidly in compliance with the efficiency decrease.