Investigation on the effect of port-injected methanol on the performance and emissions of a diesel engine at different engine speeds

This study is aimed at investigating the effect of port-injected methanol on the performance and emissions of a diesel engine under different engine loads and engine speeds. Experiments were performed on a fourcylinder diesel engine operating at three engine speeds and five engine loads for each speed. The results show that when methanol is injected into the intake port of the diesel engine, the brake thermal efficiency decreases at low engine loads but has no significant change at medium to high engine loads. There is also a reduction of NOx and particulates but a significant increase in CO, HC, NO2, unburned methanol, and formaldehyde emissions. The application of port-injected methanol shows potential greenhouse benefits only at high engine loads with a high level of fumigation methanol. With a diesel oxidation catalyst, the HC, CO, unburned methanol, and formaldehyde emissions are significantly reduced when the exhaust gas temperature is sufficiently high. The results are consistent at each engine speed.