Effect of repeated heating of coconut, sunflower, and palm oils on their fatty acid profiles, biodiesel properties and performance, combustion, and emission, characteristics of a diesel engine fueled with their biodiesel blends

Using cooking oil multiple times is a common practice to reduce the food preparation cost, which causes many health issues, also simply throwing it away will cause environmental pollution. Hence, converting waste cooking oil into biodiesel is a solution to waste management with energy production. This study analyzed the effect of the number of heating cycles of coconut, sunflower, and palm oils on the fatty acid configuration and properties of biodiesel produced from them. A reduction in unsaturated compounds, increase in short-chain components, increase of 0.266%, 0.365%, and 0.347% in density, increase of 5.06%, 12.29%, and 8.83% in kinematic viscosity, increase of 0.266%, 0.365%, and 0.347% in calorific value are observed with five repeated heating of coconut, sunflower, and palm oils, respectively. Performance, combustion, and emission analysis of a diesel engine fueled with B20 blends of biodiesels showed a decrease of 0.27 %, 0.28 %, and 0.52 % in brake thermal efficiency, an increase of 2.44 J/deg, 3.43 J/deg, and 2.74 J/deg in peak heat release rate, an increase of 7 ppm, 65 ppm, and 60 ppm in NOx emission, and decrease of 4.5 %, 2.8 %, and 1 % in smoke opacity with five repeated heating of coconut, sunflower, and palm oils, respectively. Even though the brake thermal efficiency and emissions (except NOx) were found decreased for all biodiesel blends compared to diesel, coconut-based biodiesels were found to be the best alternative among all the biodiesels with reduced HC, NOx, and smoke as compared to diesel.

Automated summary

After heating coconut, sunflower, and palm oils five times, the unsaturated compounds in the biodiesel decreased while short-chain components, density, kinematic viscosity, and calorific value increased. B20 blends of these biodiesels in diesel engines showed decreased thermal efficiency and emissions (except NOx), with coconut-based biodiesels being the best alternative.