Emissions characteristics of a diesel engine fueled with biodiesel and fumigation methanol

Currently, considerable attention has been given to the investigation of biofuels, including biodiesel, as alternative fuels for internal combustion engines. This study is aimed to investigate the effects of fumigation methanol on the emissions of a diesel engine fueled with biodiesel as the baseline fuel. The biodiesel used in this study was converted from waste cooking oil. Experiments were performed on a 4-cylinder naturally aspirated diesel engine operating at a constant speed of 1800 rev/min for three engine loads. The results indicate no significant change in brake thermal efficiency and carbon dioxide (CO2) emission, an increase in both carbon monoxide (CO) and unburned hydrocarbon (HC) emissions, and a decrease in both nitrogen oxides (NOx) and particulate matter (PM) emissions. In particular, there is also an increase in nitrogen dioxide (NO2) in the exhaust gas. The results obtained at a fumigation ratio of 0.1 are compared with those obtained with the engine operating on ultralow sulfur diesel: there is still an increase in CO and HC, by a factor of up to two, and an increase in NO2, by a factor of up to 5, while the NOx is reduced by up to 8% and the particulate mass is reduced by up to 50%, depending on the engine load.