Achieving Biodiesel Standards Through Saturation Level Optimisation

Abstract

Biodiesels made from waste feedstock are viable sustainable fuels for compression ignition engine use. However, biodiesel produced from single waste source do not always comply with the European biodiesel standard. This study investigated the fuel quality and engine performance when two biodiesels with different characteristics were blended at various proportions. Waste cooking oil biodiesel was blended with sheep fat biodiesel which has a lower unsaturated fatty acid content. The engine performance, combustion and exhaust emission characteristics of the neat biodiesels and their blends (at 60/40, 50/50, and 30/70 ratios) were analysed. The results showed that 60/40 and 50/50 blends met the core parameters of BS EN 14214 biodiesel standard and improved the combustion and emission characteristics as compared to their neat biodiesels and diesel. The 50/50 blends gave up to 5% and 14% improvements in the in-cylinder pressure and maximum heat release rate respectively, when compared to the same results for neat biodiesel operation. Reduction of up to 73% in CO, 96% in smoke and 3% in CO2 emissions were observed. However, NOx emission was 2.5% higher than diesel. The results revealed that carefully selected biodiesel-biodiesel blending could meet fuel standards, improve engine performance and reduce exhaust emissions.