Experimental study on effects of DME premixed ratio on performance of a PCCI engine

The experimental investigation on the effects of DME premixed ratio on the combustion characteristics, emissions characteristics and fuel economy was conducted in a PCCI engine modified from a 2105 diesel engine. The results showed that the igniting timing advanced, and the maximum cylinder temperature and pressure increased with an increase in the DME premixed ratio. The rate of the pressure rise developed from two peaks to three peaks, and the maximum rate of the pressure rise increased first and then decreased and increased again with an increase in the DME premixed ratio. The heat release process changed from two-stage heat release to three-stage heat release, and the overall heat release rate curve moved forward with an increase in the DME premixed ratio. The cumulative heat release rate increased gradually; the position of the rise also advanced; the combustion duration shortened; the NO_x and smoke emissions decreased. The equivalent fuel-consumption rate b_eq gradually decreased, and the effective thermal efficiency gradually increased.