Study on methanol premixed coupled with EGR to achieve ultra-low emissions in diesel engine

In this paper, an experimental investigation on achieving ultra-low emissions in diesel engine was carried out using intake premixed methanol and EGR technology. The influence of EGR introduction method on combustion and performances were studied comprehensively. The results show that ultra-low NOx (<0.4g/kWh) and PM (<10mg/kWh) emissions can be achieved simultaneously in diesel methanol dual fuel (DMDF) highly premixed low-temperature combustion mode. Compared with low-pressure EGR (LP-EGR), the excess air coefficients under high-pressure EGR (HP-EGR) drops more significantly. At the same EGR rate, the in-cylinder mean temperature and equivalent of mixture are higher under HP-EGR conditions, which results in higher combustion efficiency, lower CO and THC emissions. The maximum brake thermal efficiency of high-pressure EGR is 9.6% higher than that of low-pressure EGR.