煤层气发动机燃烧稳定性试验

摘要

为研究燃料组分变化对煤层气发动机性能的影响,在一台火花点火发动机上进行了煤层气发动机运转稳定性试验研究,探明了稀燃极限以及燃料当量比、煤层气各组分混合比对发动机的经济性及运转稳定性的影响,并采用掺氢燃烧的方式研究了掺氢量对煤层气发动机稀燃极限及循环变动的改善作用.试验结果表明:煤层气中CO2含量对发动机的经济性及运转稳定性均有较大影响,随着CO2含量的升高,有效热效率逐渐下降、并在较高CO2含量时急剧恶化,发动机的循环变动系数增加;掺氢能够有效拓展稀燃极限,随掺氢量的升高煤层气发动机的工作稳定性有明显改善,即使在较低当量比条件下采用较高的H2含量仍能获得较理想的循环变动系数(COVIMEP小于5%).%We conducted experimental research on the operational stability of coal-bed gas to study the effect of component variation on performance of an SI (spark ignition) engine.The lean-burn limit and the influence of the equivalence ratio and component mixing ratio of the blended fuel on the engine economy and operation stability were obtained.The lean-burn limit and cyclic variation were improved via hydrogen additives.The results showed the composition of carbon dioxide (CO2) greatly influenced both engine economy and operation stability.As CO2 concentration increased,there was a gradual decrease in brake thermal efficiency.However,there was a sharp decline in the brake thermal efficiency in the high CO2 concentration range.It also led to higher cyclic variation.Hydrogen additives resulted in a wider lean-burn limit,and the operation stability of the coal-bed gas engine improved with increasing H2 concentration.Ideal operation stability could be obtained when the COVIMEP (coefficient of cyclic variation of IMEP) was less than 5%,even under low equivalence ratio conditions due to high H2 component.