天然气燃料特性对CNG汽车动力性能的影响

由汽油车改装的既能用汽油又能用压缩天然气作燃料的CNG汽车，在使用天然气作燃料时，要在发动机进气系统增设一套燃气装置。这不仅加大了进气阻力，同时在进入气缸的可燃混合气中天然气所占体积比汽油雾化后所占体积大，由此共同影响了气缸的容积效率。CNG汽车为了兼顾汽油和天然气的不同燃料特性，一般对发动机的压缩比、进排气道尺寸等结构参数不作改变，其结果是天然气的优良燃料特性不能得到充分发挥，从而导致发动机输出功率下降9％～15％，输出扭矩下降4％～10％，影响了汽车的动力性能。

Influence of fuel property on dynamic behaviour of CNG automobiles

In remaking a conventional automobile into a CNG automobile that takes natural gas besides gasoline as fuel, the structural parameters of the engine for compressed natural gas automobiles, such as the compression ratio, sizes of inlet and outlet, are not changed in consideration of tLhe different properties of gasoline and natural gas. When natural gas is taken as fuel, its good properties will not have full scope, and this results in a reduction of 9% ~ 15% of power output and 4% ~ 10% of torque output of the engine, and in an effect on the dynamic behaviour of the automobile.