Effect of EGR on combustion and emission of methanol HCCI engine

In order to deal with the problem that the combustion of homogeneous charge compression ignition (HCCI) is difficult to control, the impacts of external exhaust gas recirculation (EGR) on methanol HCCI combustion and emission characteristics were investigated on a modified engine by modifying intake and exhaust system, adding HCCI fuel supply system and intake-heating system. The results show that the EGR has a remarkable influence on the combustion and emission of methanol HCCI. As the EGR ratio increases, CA10 and CA50 gradually delay and the combustion duration prolongs, the change level varies with the differences of mixture concentration, the emissions of unburned hydrocarbon and monoxide carbon quickly increase. Nitrogen oxide can only be detected at the condition of relative richer mixture (air-fuel equivalence ratio less than 1.5), and its quantity decreases quickly with the EGR ratio going up.