Effect of fuel injection pressure on the characteristics of single cylinder diesel engine powered by butanol-diesel blend

•Effect of fuel injection pressure on diesel engine run with butanol-diesel blend.•ID and CD decreased with the increasing of injection pressure.•Increasing the injection pressure caused the higher maximum CP and HRR.•BTE increased while BSFC decreased as fuel injection pressure decreased.•NOx increased while smoke decreased with the increasing of injection pressure. In the case of the use of an alternative fuel in an engine, some changes in engine operating parameters may be required to achieve the same or higher engine performance. Fuel injection pressure is one of the most important operating parameters effecting the characteristics of diesel engines. In this study, the impact of fuel injection pressure on combustion, engine performance and exhaust emission of a single cylinder diesel engine fueled with butanol-diesel fuel blend was examined. The test results indicated that butanol-diesel blend (Bu10) started injection earlier than diesel fuel and had a longer ignition delay and shorter combustion duration. Ignition delay and combustion duration decreased with the increasing of injection pressure. The higher cylinder pressure and heat release rate peaks for Bu10 were obtained due to the rapid burning of the accumulated fuel in the cylinder during longer ignition delay. With increasing injection pressure, the maximum cylinder pressure and heat release rate increased. As the engine speed increased, the maximum cylinder pressure and heat release rate decreased. Brake thermal efficiency increased while brake specific fuel consumption decreased as fuel injection pressure decreased. In addition, Bu10 blend caused slightly higher brake thermal efficiency and brake specific fuel consumption. Bu10 blend caused a decrease smoke emission while slight increase NOx emissions. As the fuel injection pressure increased, NOx emission increased while smoke emission decreased because of the smaller diameter of the injected fuel droplets and better mixing of air with fuel.