A Numerical Simulation Study on the Combustion of Natural Gas Mixed with Hydrogen in a Partially Premixed Gas Water Heater

To investigate the impact of blending natural gas with hydrogen on the combustion performance of partially premixed gas water heaters, a framelet-generated manifold (FGM) was employed for lower-order simulation of combustion processes. Coupled with the 30-step methane combustion mechanism simplified by GRI3.0, a three-dimensional computational fluid dynamics (CFD) simulation of the combustion chamber of a partially premixed gas water heater was carried out. A numerical simulation was performed to analyze the combustion process of a mixture including 0–40% natural gas and hydrogen in the combustion chamber of a partially premixed gas water heater. The results indicate that the appropriate hydrogen blending ratio for some premixed gas water heaters should be less than 20%. Furthermore, it was observed that after blending hydrogen, there was a significant increase in the combustion temperature of the water heater. Additionally, there was a slight increase in NOx.