Performance and emission characteristics of preheated and blended thumba vegetable oil in a compression ignition engine

•Thumba straight vegetable oil is used as a fuel in CI engine.•Engine waste heat is used to reduce the viscosity of thumba oil.•Preheating improves thermal efficiency by 1.27% (24.66–25.93%).•Preheating reduces emissions significantly as compared to unheated thumba.•Drastically reduction in emissions as compared to diesel also. This research is motivated for making the rural areas of developing countries self-reliant in energy production. Rural areas are endowed with enormous amount of vegetation that is used to produce edible and non-edible vegetable oil. In the present study thumba oil which is non-edible vegetable oil, having high viscosity and low volatility has been used as a fuel in CI engine. Viscosity of thumba oil is reduced by blending with diesel fuel along with preheating through waste heat of engine’s exhaust gases instead of transesterification, that requires chemicals and process heat, which is not available in rural area due to logistic problem. Experiment has been conducted with a single cylinder diesel engine to obtain performance and emission characteristics with various blend ratio of heated and unheated thumba oil with diesel. It has been observed that preheated thumba oil B-20 blend (20% thumba oil+80% diesel) gives better performance and less emission as compared to all other blending combinations among all preheated and unheated thumba oil and diesel. Preheating of optimized thumba blend results an improvement in break thermal efficiency by 1.27%. It also gives reduced smoke opacity, CO, HC emissions by 2.6%, 0.2%, and 5PPM respectively.