Study On The Application Of Diesel Oxidation Catalyst And Particulate Oxidation Catalyst To DMCC Engine

In order to make the DMCC engine better applied to the actual,and meet the higher emission regulations,there must be corresponding post-processor in the DMCC engine.At present,the most common and effective post-processor on the DMCC engine is DOC and POC.Therefore,the study of DOC and POC on the emission characteristics of DMCC engine was carried out.In this study,an in-line 4-cylinder turbocharged,electronically controlled unit-pump diesel engine installed a methanol injection and control system to convert it into a DMCC engine,and chose one DOC and four different POC for testing.Research indicates that:The inlet temperature of DOC has a significant effect on the catalytic efficiency.When the DOC inlet temperature is too low,the catalytic efficiency is low.As the inlet temperature increases,the catalytic efficiency of DOC increases for gas emissions.When the inlet temperature exceeds 250?,HC and CO emissions become very low after DOC.Overall,the catalytic temperature of CO is lower than that of HC.With increasing load,the exhaust temperature after DOC become lower about 20 in pure diesel mode.On the contrary,in the DMCC mode,the exhaust temperature after DOC increased to some extent,and the higher the methanol replacement rate,the higher the temperature after DOC.In the DMDF mode,with the increase of methanol replacement rate,the emission of particulate matter gradually reduced through the DOC in most conditions,and the particulate emissions at 25% load and 100% load were higher than the medium load(50%,75%).The NOx emission decreases with the increase of methanol replacement rate.Methanol emissions related to the exhaust temperature closely.At small load there are much more methanol emissions.Different lengths of POC play an important role in effect of exhaust gas purification.The longer the POC length,the higher the catalytic efficiency of PM and gaseous emissions in both pure diesel and DMCC modes,but the catalytic efficiency in DMCC mode is higher than that of pure diesel fuel model.POC caused 25%-40% reduction in particulate matter,HC and CO reduced by more than 90%.However,the addition of methanol caused higher formaldehyde emission,the oxidation effect of formaldehyde needs to be improved.The effect of different POC density has very little effect on diesel engine exhaust gas.Both in the pure diesel and DMCC modes,the higher the pore density,the little higher the catalytic efficiency.Select the best POC and DOC for the DMCC engine in this study and test under ESC cycle conditions.After DOC + POC,the weighted smoke emissions of country?and dual-fuel country ?are 0.0379 g/(kW·h)and 0.0189 g/(kW·h)respectively,with an average reduction of 50.2%.The NOx weighted emissions were 4.69 g/(kW·h)and 3.34 g/(kW·h)respectively,with an average decrease of 28.7%;HC,CO,methanol,formaldehyde and other gases are at very low levels.