Combustion characteristics and performance of a methanol fueled homogenous charge compression ignition (HCCI) engine

Under the pressure of energy crisis and environmental pollution, a new combustion mode, homogenous charge compression ignition (HCCI) combustion, combined with a renewable alcohol fuel, methanol, was studied on a four-stroke HCCI engine. Intake charge temperature, fuel–air equivalence ratio and engine speed, were varied during the experiments. The results show that the intake charge temperature influences both the combustion phasing and heat release rate significantly, which is the most sensitive parameter among tested parameters for methanol HCCI combustion. Equivalence ratio has obvious influence on IMEP and cyclical variation but has little influence on thermal efficiency. The engine speed scopes are dominated by operation conditions and the optimized speed where highest thermal efficiency obtained increases gradually with equivalence ratio increasing. The maximum thermal efficiency can be obtained when CA50 locates near 7.5 °CA and combustion duration is less than 11 °CA on the experimental setup.