A comparative study on methanol/diesel and methanol/PODE dual fuel RCCI combustion in an automotive diesel engine

In the present work, an attempt was made to study and compare the effect of Methanol/Diesel and Methanol/PODE RCCI combustion in a 3-cylinder, turbocharged, CRDI, diesel engine. The test engine was suitably modified to use dual fuels by incorporating methanol port fuel injection system and an open electronic control unit. Experiments have been conducted at 3.4 bar BMEP and 1500 rpm by varying methanol premixed mass fraction at a constant CA50 of about 10°CA aTDC. The results show that increasing methanol mass fraction prolonged the ignition delay, decreased the in-cylinder pressure for both Methanol/Diesel and Methanol/PODE RCCI operation. At a premixed mass fraction of 80%, the maximum brake thermal efficiency of both Methanol/Diesel and Methanol/PODE is about 31% which is 3.5% higher than the conventional diesel combustion. Brake specific oxides of nitrogen and soot emissions are significantly reduced for both dual fuel RCCI combustion with increased methanol mass fraction. However, Brake specific hydrocarbon and carbon monoxide emissions are slightly increased. At a constant premixed mass fraction, Methanol/PODE dual fuel RCCI combustion resulted in more BSNO emission than Methanol/Diesel RCCI combustion. However, lower BSHC, BSCO and soot emissions are observed with Methanol/PODE dual fuel RCCI combustion compared to Methanol/Diesel RCCI combustion.