The blending of hydrogen
in natural gas may have effects on the
safety of its usage in a domestic house. In this work, the leakage
accident of hydrogen-blended natural gas (HBNG) in the kitchen of
a domestic house is analyzed by CFD with a hydrogen blending ratio
(HBR) ≤ 30%. The whole process is divided into the gas accumulation
process and the ventilation process. In the initial leakage stage,
the influence of heights and the HBR on the gas distribution is analyzed.
HBNG concentration increases with increasing height. Based on the
exit Froude number, the formation of a gas cloud in the kitchen is
significantly influenced by the initial momentum and buoyancy, while
it is more driven by the concentration gradient beyond the kitchen.
In contrast to height, the variation of HBR on the HBNG distribution
is not significant. In the ventilation process, the evolution of the
hazardous gas cloud volume is analyzed. With windows and doors closed,
the hazardous gas cloud fills the house in approximately 3600 s after
the leakage occurs. When windows and doors are open for ventilation,
the volume of the hazardous gas cloud first declines rapidly and then
slowly. The reasons for the variation rate of hazardous gas cloud
volume are analyzed according to ventilation conditions. The difference
during the decline stage for different HBRs is analyzed according
to the gas layering properties. Under a lack of convection condition,
the ventilation process finally reaches a stagnant stage. In addition,
another ventilation process has been investigated after extending
the gas accumulation time. After extending the gas accumulation time,
the effect of different HBRs on the ventilation process remains the
same as before. However, it postpones the time point to enter the
stagnation stage. As gas accumulation time extends from 3600 to 5400
and 7200 s, the ventilation time into the stagnation stage increases
from about 4800 to 5400 and 6000 s, respectively. This study has implications
for the establishment of a risk assessment system based on hazardous
gas cloud volume.