Experimental and Simulation Study on the Dispersion of Hydrogen-Enriched Natural Gas Leaks in Residential Buildings

Hydrogen-enriched natural gas (HENG) is an important pathway for the low-carbon transition of urban energy systems. Understanding its leakage dispersion characteristics and hazardous gas cloud evolution is essential for residential safety management. In this study, a full-scale residential leakage experimental platform was developed, and a validated computational fluid dynamics (CFD) model was established. The effects of kitchen layout, hydrogen blending ratio, and leakage orifice diameter on indoor gas accumulation and hazardous gas cloud evolution were systematically investigated, with hazardous gas cloud volume adopted as the risk indicator. The results show that enclosed kitchens restrict gas migration and promote local accumulation near the leakage source, whereas open kitchens accelerate gas transport into adjacent rooms. Increasing the hydrogen blending ratio from 0% to 20% increased the hazardous gas cloud volume from 52.1 to 59.2 m3 at 3600 s, mainly due to the reduced flammability threshold and enhanced volumetric release characteristics of HENG. Leakage orifice diameter exhibited a more significant influence on hazardous gas cloud expansion; the hazardous gas cloud volumes were 37.4, 30.5, and 6.36 m3 for 10, 6, and 2 mm orifices, respectively, with the 10 mm orifice producing a hazardous region approximately 5.9 times larger than that of the 2 mm orifice. These findings provide quantitative insights for HENG leakage risk assessment, gas sensor placement, and emergency response strategies in residential buildings.