Studies on the optimizations with regard to relationships between performance and emission characteristics in dimethyl ether (DME)-fueled engines using common-rail fuel injection systems

摘要

Dimethyl Ether (DME) seems to be one of the most attractive alternative fuels for heavy-duty engines. Many researches and developments have been carried out on DME engines. However, the principal technical problems have not yet been solved enough. One problem is related to finding safety fuel supply systems able to suppress vaporizations. To search for these systems, we have studied optimization of injection equipment in terms of the relation between performances and emission characteristics by using common-rail injection systems. We have found that thermal efficiency and emissions is satisfactory when the engine is operated at 50 MPa, 14 degree BTDC. Also, when the pilot injection by common rail is 10%, NO{sub}x emission reduced up to 30%. And the brake thermal efficiency is optimum when the nozzle needle lift is 0.21 mm for test engines.