This paper presents a simulation study of hydrogen leakage from an onboard
hydrogen supply system in open, closed, and semi-closed spaces. The simulations
investigate the effects of environmental factors and conditions such as
obstacles on the diffusion process of hydrogen leaks. The results show that when
hydrogen gas leaks, the direction of the leak determines the potential risk. If
the leak is directed toward the cab, the gas will accumulate in the gap between
the cab and the hydrogen supply system, posing a significant risk to the driver.
On the other hand, if hydrogen leaks toward the rear, a combustible cloud forms
mainly behind the vehicle at a safe distance of 3.8 meters. The study also
investigated the effects of wind speed, wind direction, and ambient temperature.
It was found that headwinds can cause hydrogen to spread near the vehicle,
increasing the risk of an accident. The paper also investigates the effect of
obstacles that inhibit the horizontal diffusion of hydrogen, causing the gas to
accumulate in front of the obstacles and increasing the risk of explosion in the
vicinity. This paper also investigates the effect of vent area and vent location
on the diffusion of hydrogen leaks in enclosed spaces, and the results show that
the vent location factor has a more significant effect on the magnitude of
hydrogen concentration in enclosed spaces after a hydrogen leak compared to the
vent area. The simulation results can help improve society's understanding of
hydrogen energy, the development of related safety standards and emergency
response measures for accidents, as well as provide insight into the risks
associated with hydrogen systems. The results of this study will be useful for
policymakers, engineers, and researchers who are committed to the widespread use
of hydrogen energy.