Reducing emissions of a diesel engine using fumigation ethanol and a diesel oxidation catalyst

Experiments were conducted on a four-cylinder direct-injection diesel engine with part of the engine load taken up by fumigation ethanol, which was injected into the air intake of each cylinder, to investigate the combustion and emissions of the engine under five engine loads at an engine speed of 1800 rpm. Fumigation ethanol was injected to top up 5, 10, 15, and 20% of the engine loads under different engine-operating conditions. In comparison to Euro V diesel fuel, fumigation ethanol gives a higher peak in-cylinder pressure and heat release rate. Increasing the fumigation ethanol would increase the ignition delay. More fuel is burned in the premixed mode, and less fuel is burned in the diffusion mode. The brake thermal efficiency decreases with an increase in fumigation ethanol at low and medium engine loads but does not change significantly at high engine loads. On the emission side, the application of fumigation ethanol results in a significant increase in hydrocarbon (HC), carbon monoxide (CO), and nitrogen dioxide (NO2) emissions. However, there is a decrease in nitrogen oxides (NOx), smoke, and particulate mass and number concentrations. The diesel oxidation catalyst is able to reduce the high emissions of CO and HC arising from fumigation ethanol and, in addition, further reduce the particulate emissions.