The effect of different diesel fuels on the exhaust emissions of a diesel engine-powered generator

In this study, the effect of alternative fuels like bioethanol, n-butanol and biodiesel on the performance and exhaust emissions of a diesel engine powered generator set was investigated. Bioethanol, n-butanol and biodiesel were added to petroleum based diesel fuel by 10%, %16 and 30% (v/v), respectively, to obtain the alternative fuels having similar oxygen content. The blended fuels obtained and petroleum based diesel fuel were tested in 4-stroke and 4-cylinder naturally aspired diesel engine powered generator set at constant speed (1500 rpm) under different power outputs. In the tests, the measurements of cylinder gas pressure for each test fuel and operating conditions was performed and by using these data net and cumulative heat release were calculated. Experimental results have shown specific fuel consumption increased at the rate of about 10% by using biodiesel added fuel blends while no significant change was observed in the efficiency when compared with petroleum diesel. However, in case of using alcohol added blended fuels; specific fuel consumption reduced by about 8-10%, efficiency increased at the rate of 5%. In use of alternative fuels mean NOx emissions reduced in comparison to petroleum diesel and also this reducing was higher for alcohol blended fuels than for biodiesel added one. On the other hand, an opposite trend was observed for unburnt HC emissions; they reduced at the rate of 20% with biodiesel blended fuel while about 15% increase was observed by using alcohol blended fuels. Smoke emissions were not to be measurable levels at low-mid loads when alternative fuels were used. Maximum cylinder gas pressure was higher for alternative fuels than for petroleum diesel and the start of combustion was earlier for biodiesel blended fuel while it was later for alcohol blended fuels than for petroleum diesel.