混合气浓度对CNG发动机性能影响试验研究

在CA4102增压中冷电控多点喷射单燃料天然气发动机上进行了不同混合气浓度对发动机性能影响的试验。试验结果表明:当过量空气系数(a)从1.1变化到1.54时,小负荷工况下发动机的最大燃烧压力变化不大,大负荷时发动机的最大燃烧压力降低,放热率峰值降低,燃烧速度变慢,燃烧滞后。随a的增大,CO排放先减少后缓慢增加;NOx排放减少,在a=1.5时,NOx排放接近于0;a较小时HC排放基本没有变化,在a>1.5时,HC排放急剧上升。燃气消耗率随a的增大呈现增加的趋势,当a>1.4以后增加显著。

Experimental Research on the Influence of Mixture Concentration on CNG Engine Performance

On a CA4102 turbocharged intercooled electronic controlled multi-point injection CNG engine, the influence of different mixture concentration on CNG engine performance was tested. The result shows that the maximum combustion pressure shows no change under low load conditions and a decrease under high load conditions when the excessive air ratio a is increased from 1.1 to 1.54. The maximum heat release rate decreases, the burning velocity becomes slow and the combustion delays under high load conditions in the excessive air ratio range from 1.1 to 1.54. The CO emission reduces first then slowly increases when the excessive air ratio a is increased. The NOx emission reduces with the increase of excessive air ratio a and is nearly to zero when the excessive air ratio a is equal to 1.5. The HC emission shows no change when the excessive air ratio a is smaller and a remarkable increase when the excessive air ratio a is larger than 1.5. The specific gas consumption increases with the increase of excess air ratio and increases significantly when the excessive air ratio a is larger than 1.4.