Performance and emission characteristics of a diesel engine fuelled with waste cooking oil/diesel fuel blends

Abstract

Vegetable oils (neat or used) have the greatest promise to be used as alternative fuels for diesel engines due to very significant fact that they are renewable energy sources, low cost fuel raw material and they are environmental friendly. To use vegetable oils in diesel engine without modification, it is necessary to make sure that the vegetable oils properties must be similar to diesel fuel. In this study, waste cooking oil (WCO) that has been used several times for frying purposes is investigated for the utilization as an alternative fuel for diesel engines. Two different WCO with different previous uses were blend with diesel. The various blends of WCO and diesel were prepared and its important properties such as viscosity, density, calorific value and flash point were evaluated and compared with that of diesel. The blends were tested in a direct injection diesel engine in 10% and 30% v/v blends with a reference diesel fuel. Tests were performed under a set of engine operating conditions. It was found that blending WCO with diesel reduces the viscosity and different previous uses of WCO significantly affected the properties of the blended fuels. Blending of WCO with diesel has been shown to be an effective method to reduce engine problems associated with the high viscosity of WCO. The experimental results also show that the basic engine performance such as power output and fuel consumptions are comparable to diesel and the emissions of CO and NOx from the WCO/diesel blends were also found slightly higher than that of diesel fuel.