A Study on Combustion and Emission Characteristics of Small DI Diesel Engine Fuelled with Dimethyl Ether

An investigation has been carried out to evaluate the combustion and emission characteristics of dimethyl ether(DME) using a small direct-injection diesel engine. The fraction of the fuel leakage from the fuel pump plunger pinion to the supplied fuel is determined by the fuel injection experiment under engine motored conditions. The effects of engine configuration and operation parameters on engine performance, regulated and unregulated exhaust emissions are investigated. The unregulated pollutants of formaldehyde, methyl formate and formic acid from a DME fueled engine are measured by gas chromatography and FT-IR analyzers. The test results show that the performance and regulated exhaust emission characteristics of DME are superior when compared to the original diesel engine. The formaldehyde is the principal component of unregulated pollutants. The behaviors of formaldehyde, methyl formate and formic acid emissions to engine design parameters and operation conditions are clarified. The experimental results demonstrate that the DME fueled engine should have an appropriate nozzle opening pressure and advanced angle of fuel injection. Retarded opening of the exhaust valve is found to result in a decrease in oxides of nitrogen emission.