Development of an Oxy-Hydrogen Engine for Power Generation Application Using Simulation and Experiment

Hydrogen is a zero-carbon fuel suitable for the de-carbonization of power generation and the industrial sector. Green hydrogen produced via the electrolysis of water is the most sustainable fuel to achieve a net-zero carbon economy. Oxy-hydrogen (hydrogen and oxygen) generated onsite from the electrolyzer can be fed to engine with the intake air to enhance power and combustion efficiency with near-zero exhaust emissions. In this study, a 15 kVA two-cylinder natural gas spark-ignition generator set was used. The engine was retrofitted to operate on an oxy-hydrogen-air mixture. A maximum of 43% of rated engine load was achieved during the preliminary experiments. GT-Power software was used to calibrate the 1D model using experiment data and generate the burn profile of oxy-hydrogen-air mixture. The calibrated and validated 1D model was used for further predictive simulations. The power limiting factors were identified via simulations for flow and power improvement. The simulations revealed that boosting the intake air through supercharging is necessary to achieve the power targets and lean engine operation (for lower NOx emissions). A suitable supercharger was selected based on the maximum airflow requirement and was modeled for further analysis. The maximum operating limits of air-fuel ratio and oxygen volume percentage in air for predictive simulations were fixed at 80 and 40%, respectively. The airflow management and power achievement becomes critical at high-altitude conditions due to lower ambient pressure and density. The results revealed that the selected supercharger is suitable for high-altitude conditions as well. However, NOx emissions increased drastically at high-altitude conditions due to higher oxygen concentration, in-cylinder temperature, and heat flux. Selective catalytic reduction (SCR) is necessary for oxy-hydrogen engines at high-altitude conditions. This study would be helpful in the development of oxy-hydrogen engines, aiding in the transition towards a zero-carbon economy.