• Energy Research

Experimental, thermodynamic, and DFT analyses determine optimal conditions for maximizing BTX yields from LCO and provide mechanistic insights.

Experimental, thermodynamic, and DFT analyses determine optimal conditions for maximizing BTX yields from LCO and provide mechanistic insights.

Abstract A single cylinder hydrogen fuelled internal combustion engine was experimentally evaluated and a model was developed. The optimized hydrogen engine developed a peak power of 4.8 kW @ 3600 rpm while operating under lean conditions. Lean operation in the equivalence ratio range of 0.47–0.59 resulted in low NOx emissions. The spark timing, equivalence ratio, and fuel injection timing were optimized to achieve high torque and low NOx emissions for different engine speeds at wide open throttle. A one-dimensional model was developed for the single cylinder engine, which was able to predict the trends in brake torque, brake power, brake thermal efficiency and NOx emissions for different engine speeds. It was found that the Woschni's correlation, which was originally developed for gasoline and diesel fuels under-predicted the convective heat transfer coefficient and the predicted coefficient was multiplied by a factor of 2.2 in order to simulate the actual heat losses with H2 fuelled IC engines. This is due to the high burning velocity as well as a low quenching distance of hydrogen flame which presumably results in higher cooling losses in a hydrogen engine. Using the model, a sensitivity analysis was further performed to study the effect of operating conditions such as engine speed, spark timing and equivalence ratio on the performance parameters and NOx emissions. The model was able to predict the reported trends of an increase in torque and a maximum in exhaust NOx concentration with an increase in the equivalence ratio. An increase in the exhaust NOx concentration with spark advance for all engines speeds was predicted. It was found that in order to achieve high torque, the spark energy must be provided closer to TDC for low speeds but should be advanced away from TDC for higher engine speeds.

Abstract A single cylinder hydrogen fuelled internal combustion engine was experimentally evaluated and a model was developed. The optimized hydrogen engine developed a peak power of 4.8 kW @ 3600 rpm while operating under lean conditions. Lean operation in the equivalence ratio range of 0.47–0.59 resulted in low NOx emissions. The spark timing, equivalence ratio, and fuel injection timing were optimized to achieve high torque and low NOx emissions for different engine speeds at wide open throttle. A one-dimensional model was developed for the single cylinder engine, which was able to predict the trends in brake torque, brake power, brake thermal efficiency and NOx emissions for different engine speeds. It was found that the Woschni's correlation, which was originally developed for gasoline and diesel fuels under-predicted the convective heat transfer coefficient and the predicted coefficient was multiplied by a factor of 2.2 in order to simulate the actual heat losses with H2 fuelled IC engines. This is due to the high burning velocity as well as a low quenching distance of hydrogen flame which presumably results in higher cooling losses in a hydrogen engine. Using the model, a sensitivity analysis was further performed to study the effect of operating conditions such as engine speed, spark timing and equivalence ratio on the performance parameters and NOx emissions. The model was able to predict the reported trends of an increase in torque and a maximum in exhaust NOx concentration with an increase in the equivalence ratio. An increase in the exhaust NOx concentration with spark advance for all engines speeds was predicted. It was found that in order to achieve high torque, the spark energy must be provided closer to TDC for low speeds but should be advanced away from TDC for higher engine speeds.