POC的结构参数对DMCC发动机排放影响的试验研究

在一台直列4缸增压中冷电控单体泵柴油机的进气道上增加甲醇喷射装置,实现柴油甲醇二元燃料燃烧(DMDF)模式.利用废气分析仪对其主要气体排放进行测量,研究在排气管上加装的柴油颗粒氧化催化转化器结构参数对尾气催化效率的影响,试验结果表明:POC长度越长,对碳烟、THC、和未燃甲醇的转化效果越好,甲醇替代率为30%、POC长度为100 mm时,对碳烟、CO、THC和未燃甲醇的平均净化效率分别为15.00%、91.61%、75.56%、66.96%,长度增加至200 mm后,上述效率明显提高,分别提高到30.37%、99.29%、67.55%、95.44%;POC孔密度增加,POC对碳烟、CO及未燃甲醇的转化效率有小幅增加,甲醇替代率为30%时,孔密度从200目增加到300目,对碳烟、CO和未燃甲醇的催化效率分别从19.61%、94.66%、86.07%提高到23.06%、97.44%和88.56%;POC结构参数的改变对NO_x的转化效率影响不大.

Effects of the structural parameters of particle oxidation catalyst on emissions of diesel/methanol compound combustion engine

Experiments were conducted on a four-cylinder turbo-charged, inter-cooling electronic unit pump diesel/methanol dual fuel (DMDF) diesel engine, which was equipped with a methanol port injection system. By measuring the main emissions with an analyzer, the effects of the structural parameters of particle oxidation catalyst (POC) on emissions of DMCC engine was studied. The results showed that the longer the POC was, the higher the catalytic efficiencies of soot, CO, THC and unburnt methanol were. The average catalytic efficiencies of soot, CO, THC and unburnt methanol were 15.00%, 91.61%, 75.56% and 76.07% respectively, as the length of POC was 100 mm and the methanol substitution ratio was 30%. After the length of POC was extended to 200 mm, the efficiencies were improved sharply, and reached to 30.37%, 99.29%,67.55% and 95.44% respectively. The increase of POC cell density led to a small increase in the catalytic conversion efficiency of soot, CO and unburnt methanol. The efficiencies reached to 23.06%, 97.44% and 88.56% from 19.61%, 94.66% and 86.07% as the cell density increased from 200 to 300 meshes and the methanol substitution ratio was 30%. Effects of the structural parameters of POC on the catalytic conversion efficiency of NO_x were negligible.