Emission and Combustion Characteristics of a MethanoI/Dimethyl Ether Dual-Fuelled Compression Ignition Engine

摘要

This paper investigates the combustion and emission characteristics of a compression ignition engine fuelled on methanol as the main fuel and dimethyl ether (DME) as ignition promoter. Tests were conducted at constant speed with increasing load. The DME contribution to the total combustibles was varied from some 25 to 55% by mass. The DME was found to release energy in two stages, each occurring before top dead centre. A limited number of exhaust emission species, CO, CO{sub}2, NO and NO{sub}2 were measured. It was found that with methanol/DME fuelling the concentration of NO showed a significant reduction and it was consistently less than that of the corresponding diesel fuelling tests throughout the fuel equivalence ratio range. In particular, at maximum load the concentration of NO was less than half of that of the corresponding diesel tests. The smoke density was reduced in the worst case from 85 HSU on diesel fuelling to 9 HSU on methanol/DME fuelling. Thus methanol/DME fuelling contributes to a cleaner environment.