Experimental study of effects of exhaust gas recirculation on combustion, performance, and emissions of DME-biodiesel fueled engine

Abstract

The effects of exhaust gas recirculation (EGR) on the combustion, performance, and emissions of a six-cylinder turbocharged common-rail dimethyl ether engine with biodiesel blends were experimentally investigated. The proportions of biodiesel were 0% (B0), 5% (B5), 10% (B10), 15% (B15) and 20% (B20) by weight, and the effect of the engine load was considered. The results indicate that a higher EGR rate increases the ignition delay and combustion duration. The peak rate of heat release increases as the EGR rate increases at low loads but decreases at high loads. The present investigation shows that the EGR strategy is effective for suppressing NOx formation and the NOx emissions approximately linearly decrease as the EGR rate increases. The retardation of the combustion phase by external EGR effectively reduces the rate of pressure increase. The effect of the biodiesel proportion on the combustion and performance of an engine is complex, and the B5 blend showed the shortest ignition delay and the highest brake thermal efficiency. The influence of the biodiesel proportion on the EGR is not obvious. The disadvantages of EGR and biodiesel addition include the resultant increases in the CO and HC emissions and the particle number concentration.