Investigation of the operational and combustion performance of in-service gas cooktops fueled by hydrogen-enriched natural gas

Injecting hydrogen into natural gas pipelines is regarded as a cost-effective and practical pathway toward a low-carbon energy future. As the most widely used domestic gas appliance, the operational performance and safety of cooktops are essential. In this study, over 500 in-service cooktops with different service lives are tested under hydrogen ratios ranging from 0 to 25%vol to investigate the effects of hydrogen addition on gas flow rate, heat load, flame structure, ignition performance, and flame stability. The influence of service life on heat load, ignition performance, and flame stability is also evaluated. The results show that with increasing hydrogen ratio, the gas flow rate increases while the heat load decreases, and the additional heat load reduction exhibits a strong correlation with service life. Ignition instability and flashback are mainly observed in long-service-life burners with structural deformation or improper air shutter adjustment. No flashback occurs below 15% hydrogen, whereas limited flashback appears at 20-25%vol. In contrast, yellow flame and lifting are mitigated with hydrogen addition. Finally, practical approaches for compensating heat load variation and mitigating unstable combustion are proposed, providing technical support for hydrogen injection into natural gas pipeline projects.