柴油预喷量对甲醇-柴油双燃料发动机NOx和颗粒物排放的影响试验

Effects of pre-injection quantity on the emission of NOx and particles of a methanol-diesel dual-fuel engine

【目的】研究柴油预喷量对甲醇-柴油双燃料发动机NOx和颗粒物的排放变化规律。【方法】以一台电控共轨四缸柴油机改造的甲醇-柴油双燃料发动机为试验对象,选取30%和70%负荷,10%~40%掺烧比工况,调节不同预喷量,测试NOx和颗粒物的排放数据,分析总数量浓度、平均粒径、粒径谱等指标。【结果】30%和70%负荷,预喷量为2 mg/cyc工况下,超细颗粒物的总数量浓度、平均粒径均处于一个较低水平;此工况下30%负荷大颗粒物的数量浓度最低,70%负荷大颗粒物数量浓度也处于引入预喷后的最低水平,NOx排放量有所下降。【结论】小负荷工况下,优化预喷量2 mg/cyc后,NOx和颗粒物的排放性能可以同时达到最优;大负荷下,NOx排放随预喷量增大而增大,颗粒物排放在预喷量2~3 mg/cyc附近达到最优。

【Objective】To study the effects of pre-injection quantity on the emissions of NOx and particles of a methanol-diesel dual-fuel engine.【Method】A methanol-diesel dual-fuel engine modified by an electronically controlled common rail 4-cylinder diesel engine was used as the test object to test ultrafine particulate matter and NOx emission data,different load(30%and 70%),co-combustion rates(10%~40%)and pre-injection rates were selected.Additionally,thetotal number concentration,average particle size,particle size spectrum and other indictor were analyzed.【Result】The total number concentration and average particle size of ultrafine particles were at a low level at 30%and 70%load,the pre-injection volume was 2 mg/cycle.The concentration of large particles was at the lowest level at 30%load,and at 70%load was also at the lowest level after the introduction of pre-injection,at the same time NOx emissions decreased.【Conclusion】Under light load conditions,the emission performance of NOx and particulate matter can be optimized at the same time when optimized the pre-injection amount to 2 mg/cycle.Under heavy load conditions,NOx emissions increase with the increase of pre-injection amount and the particulate matter emissions are the lowest when pre-injection amount is between 2 to 3 mg/cycle.