Abstract
This experimental study was conducted with a turbocharged diesel engine fueled with dimethyl ether (DME) and combustion and emissions characteristics of DME engine were investigated. The results showed that higher torque and power could be achieved with DME compared to diesel fuel operation of the base engine at full load. At full load, the fuel consumption at low engine speeds with DME was lower than diesel fuel. The results also showed that the peak values of cylinder pressure, heat release rate and in-cylinder mean temperature of the DME engine were lower than those of diesel engines. NO_x and HC emissions of the DME engine decreased while CO emission increased slightly. Effect of exhaust gas recirculation (EGR) on emissions of DME engine was observed. The results showed that, by means of EGR, NO_x emissions decreased significantly, especially at high load, and HC emission increased. When EGR rate was below a certain value, CO emission presented little change, and CO emission increased considerably while EGR rate was over a certain value. CO and HC could be lowered to a considerably low level with oxidation catalyst converter (DOC). DME city bus powered by DME engine exhibited a low combustion noise, fuel economy and good drivability.
