Abstract: The combustion process and emissions of diesel with 10% of diesel/methanol blend or 10% of port-injected methanol are studied. 4B26 turbo-charge DI engine without any change in its original structure is test at a constant speed of 2 200 r/min under the conditions of four different engine loads, which is equipped with an electrically-controlled port injection system. The result shows that the in-cylinder pressure of DI engine has no great difference in the use of diesel/methanol blend and port-injected methanol. Compared with diesel/methanol blend, the port-injected methanol gives a lower intake air temperature, contributing to a further lower exhaust temperature. The ignition delay period becomes longer at low load, and NOx and soot emissions are reduced significantly, meanwhile, HC and CO emissions are high. In both cases, compared with diesel, the maximum pressure hardly changes, the in-cylinder temperature decreases, and the ignition delay postpones at low load; NOx and soot emissions are reduced, and HC and CO emissions are increased.

Key words: power machinery engineering, methanol, combustion process, emission