稀燃点燃式天然气发动机的燃烧特性

Combustion Characteristics of Lean-Burn Spark-Ignition Compressed Natural Gas Engine

通过对一台6102型稀燃点燃式天然气发动机在不同混合气浓度和不同点火提前角下的燃烧特性进行试验,深入分析了点火提前角和混合气浓度对天然气发动机燃烧特性的影响.结果表明,当进气压力和转速一定时,随着混合气变稀,NOx排放降低,但输出转矩有减小趋势,耗气率升高且燃烧稳定性变差;适当增大点火提前角,可以使输出转矩增大,耗气率降低,提高燃烧稳定性,但NOx排放会有所增加.因而需综合考虑动力性、经济性和排放来选择最佳的混合气浓度和点火提前角.找出了在满足动力性、经济性和排放的特定工况点的适宜浓度和点火提前角范围,为进一步标定全工况下的MAP图也提供了参考依据.

The study of combustion characteristics of different mixture concentrations and ignition advance angles was conducted with a 6102 lean-bum spark-ignition CNG engine. The effects of ignition advance angle and mixture concentration were further analyzed. The study results are shown as follows. When intake pressure and engine speed are constant, with the decrease of mixture concentration, both NOx emission and torque are reduced, while gas consumption rate increase and combustion process get unstable. If ignition timing is properly advanced, output torque will be increased, gas consumption rate will be reduced and stability of combustion process will get better, but NOx emission will slightly rise. At last, the work scope of satisfactory output power, gas consumption and NOx emission was determined by the experiment, which will be helpful to the further MAP determination.