Design of a novel impulse turbine for exhaust energy recovery in a commercial load carrier single cylinder diesel engine

Abstract

A significant fraction of the fuel energy supplied in a diesel engine is wasted into the atmosphere through the exhaust gases. Although most modern-day diesel engines are turbocharged, a few remain naturally aspirated. Due to technical challenges, single-cylinder engines are not turbocharged and remain naturally aspirated (NA). The intermittent and pulsated exhaust gas flow tends to choke the turbine and increase the back pressure. On the other hand, supercharging a single-cylinder engine leads to superior performance at the expense of fuel efficiency, as a significant fraction of the energy is wasted in the exhaust. The current study employs a novel crank shaft coupled impulse turbine for effective exhaust energy recovery in a supercharged, high-speed, commercial single-cylinder diesel engine. This novel impulse turbo-compounded and supercharged engine layout was simulated using a 1D model developed using AVL BOOST software. Based on the results of the 1D model, the impulse turbine design was carried out. A CFD simulation of the impulse turbine was carried out using commercially available CONVERGE. The major design parameters, including blade profile, blade width, nozzle shape, size and angle, blade angles, blade speed, number of blades, and turbine outlet port opening, were optimized using the CFD software. The simulated results showed that the designed impulse turbine generated 2.67 kW of power, enhancing the power output of the supercharged engine by 21% at the rated operating condition. The turbine efficiency was 68%, considering the available kinetic energy at the exhaust. Simulation results indicate that the impulse turbine compounded supercharged engine could generate 15.4 kW of power, 45% higher than the base NA engine brake power output.