Research on the Combustion and Emission Characteristics for an Methanol/ICTL Diesel Engine under Low Load Condition
The influence of pre injection strategy coupled with EGR on combustion stability of a methanol/ICTL dual fuel engine under low load conditions was experimentally studied,which is modified by a four cylinder diesel engine that meets the national Ⅵ emission regulations.The results showed that under the study conditions,SOOT and NOx significantly declined by 66.3％and 33.5％compared to the pure ICTL mode when the methanol substitution rate was 15.2％.How-ever,COV(p)was close to the upper limit standard of 5％,which limits the further improvement of methanol substitution rate;Early pilot injection timing(-19℃A)is useful for improving the activity of methanol mixture and reduce SOOT emissions,but NOx emissions will increase.Early pre injec-tion timing(exceeding-29℃A)can further reduce SOOT emissions,while NOx emissions remain basically unchanged,but COV(p)exceeds 25％;Furthermore,the SOOT emissions are reduced with increasing pilot injection quantity,but the NOx emissions will increase and the COV(p)is 15.2％,when the pilot injection quantity is 2.1mg/cyc;NOx emissions greatly reduced and the combustion stability effectively increased with increasing the EGR rate.When the EGR rate is increased to 35％,the COV(p)is only 2.99％.
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