The flame mitigation effect of vertical barrier wall in hydrogen refueling stations

Abstract

Reliability and safety of hydrogen refueling stations directly affect the public acceptance of hydrogen energy. Due to high storage pressure (up to 90 MPa), the firefighting measures in hydrogen refueling stations are different from those in traditional gas stations. The mitigation effect of barrier walls against jet flame, the reduction ratio of flame length and flame deflection angle were studied by an in-house version of FireFOAM solver. The code employed a modified eddy-dissipation concept combustion model within the framework of large eddy simulation. A real-gas state equation of hydrogen in a simplified form was adopted to describe the complex behavior of high-pressure hydrogen. The notional nozzle approach was applied to replace the actual hydrogen jet exit based on mass and momentum conservation. The simulation results show that the visible flame length decreases with the growth of height difference between the barrier wall and hydrogen jet exit, which can be fit using the power function. The flame deflection angle is proportional to the height difference, which means the barrier wall can greatly reduce the dangerous area behind the wall. However, the increase of the wall height can also cause a significant increase in the flame radiation fraction, because the surface area of the flame grows after impinging on the barrier wall. When the height difference is larger than 1 m, further increase in the height of barrier wall cannot significantly promote the fire resistance effect.