Three-dimensional Simulation of Wet Combustion of Hydrogen-methane Mixture in the Annular Combustion Chamber of a Microturbine

This study presents a three-dimensional simulation of wet combustion in the annular combustion chamber of a C30 microturbine using a hydrogen-methane fuel mixture. The research aims to minimize exhaust emissions, including nitrogen oxides (NOx) and carbon monoxide (CO), and reduce fuel consumption. A partially premixed combustion model has been utilized to accurately simulate the combustion process within the chamber. The impact of steam addition (wet combustion) is also analyzed. The simulation employs the k-ε Realizable turbulence model and probability density function (PDF) for chemical reactions. The fuel mixture is adjusted by adding hydrogen in increments of 10%, resulting in a final composition of 40% hydrogen and 60% methane. With hydrogen’s high heating value, the chamber temperature reaches 2376 K, significantly increasing NOx and CO emissions. To control the temperature and maintain turbine operating conditions, the fuel mass flow rate is reduced by 35%, ensuring a consistent turbine inlet temperature. At this temperature, CO and CO2 emissions decrease by 16% and 61%, respectively, while NOx emissions increase due to hydrogen’s flame characteristics. The introduction of humidity levels of 2.5%, 5%, 7.5%, and 10% in the inlet air reduces NOx emissions by 68% in the case where the fuel mixture contains 10% hydrogen, with this reduction occurring at 10% humidity. Additionally, a 48% reduction in CO emissions was observed when the fuel mixture contained 40% hydrogen, and this reduction also occurred at 10% humidity. Wet combustion also enhances temperature uniformity in the chamber. These findings highlight the potential of hydrogen-methane mixtures with wet combustion to enable low-emission, efficient microturbines, supporting sustainable energy goals.