碳酸二甲酯对烷基化汽油燃烧性能的影响

在四缸直列四冲程增压直喷汽油机上，研究了添加体积分数为10%的碳酸二甲酯(DMC)对燃用烷基化汽油在典型工况下发动机性能的影响及其燃烧过程原理。结果表明：在所有工况下，添加DMC后燃油消耗率均有明显增加，增幅最高可达20.53%，有效热效率变化不明显。在外特性工况下，添加DMC对汽油机动力性影响不大，均不超过3%；在稳态工况下，DMC的加入降低了燃料的总碳氢化合物(THC)和氮氧化物(NOx)排放，碳氢化合物(HC)的排放最大降幅为13%，NOx排放最大降幅为32%；在低转速工况下，DMC的添加可引起总颗粒物排放增加，最大增幅为103%，其中核态颗粒物增加是主要因素，最大增幅为113%。燃烧过程分析表明，加入DMC会造成燃烧始点最多推迟1.24° CA，燃烧重心最多推移1.98° CA，燃烧持续期最大延长2.32° CA，从而引起定容性下降，热效率降低，后燃量增加，颗粒物升高，燃烧温度下降，NOx排放降低。

Effect of Dimethyl Carbonate on Combustion Performance of Gasoline From Alkylation Unit

With using a four-cylinder on-line four-stroke turbocharged direct-injection gasoline engine, effect of adding 10% volume fraction of dimethyl carbonate (DMC) on the combustion performance of gasoline from an alkylation unit under typical operation conditions were investigated. In addition, the combustion mechanisms involved in the above process were also studied. Experimental results showed that, under all operation conditions, the fuel consumption rate could increase up to 2053% after adding DMC, but the effective thermal efficiency did not change much. Under the condition of external characteristics, addition of DMC had little effect on the dynamic performance of the engine, e.g., less than 3%. Under steady-state operating conditions, addition of DMC could reduce fuel total hydrocarbon (THC) and oxynitride (NOx) emission, e.g., up to 13% for HC compound emission and up to 32% for NOx emission. Under the condition of low rotation speed, addition of DMC could increase the total particulate matter emission up to 103%, in which the increase of nuclear particulate matter was the main factor, up to 113%. The combustion process analysis indicates that DMC addition can cause combustion start point postponed up to 1.24° CA, combustion gravity center shifted 1.98° CA, and combustion duration length extended up to 2.32° CA.Therefore, DMC addition in gasoline can cause reduced constant capacity, thermal efficiency and combustion temperature, increased post-combustion and particulate matter, and reduction of NOx emissions.