Hydrogen Jet Fire from a Thermally Activated Pressure Relief Device (TPRD) from Onboard Storage in a Naturally Ventilated Covered Car Park

Abstract

Hydrogen jet fires from a thermally activated pressure relief device (TPRD) on onboard storage are considered for a vehicle in a naturally ventilated covered car park. Computational Fluid Dynamics was used to predict behaviour of ignited releases from a 70 MPa tank into a naturally ventilated covered car park. Releases through TPRD diameters 3.34, 2 and 0.5 mm were studied to understand effect on hazard distances from the vehicle. A vertical release, and downward releases at 0°, 30° and 45° for TPRD diameters 2 and 0.5 mm were considered, accounting for tank blowdown. direction of a downward release was found to significantly contribute to decrease of temperature in a hot cloud under the ceiling. Whilst the ceiling is reached by a jet exceeding 300 °C for a release through a TPRD of 2 mm for inclinations of either 0°, 30° or 45°, an ignited release through a TPRD of 0.5 mm and angle of 45° did not produce a cloud with a temperature above 300 °C at the ceiling during blowdown. The research findings, specifically regarding the extent of the cloud of hot gasses, have implications for the design of mechanical ventilation systems.

Proactive Emergency Response Strategies for First Responders to Hydrogen Gas Leakages in Vehicles

“…Another article indicated that inside a tunnel, the size of the flammable vapor cloud decreases with increasing wind strength yet remains unchanged beyond a certain wind speed [12]. Furthermore, a study investigating the risks in indoor spaces following jet flame generation due to the operation of a TPRD in hydrogen vehicles parked in compartmentalized underground spaces indicated that maintaining the TPRD outlet angle at 45 • or less was safer [13]. This orientation minimizes the risk to passengers during rescue operations, as jet flames discharged perpendicular to the floor pose greater hazards.…”

Jet Flame Risk Analysis for Safe Response to Hydrogen Vehicle Accidents

“…Much research is being conducted on ensuring the safety of hydrogen facilities and equipment, such as hydrogen tanks and hydrogen refueling stations [10][11][12]. Hussein et al investigated temperature variations in the release direction of a jet flame in a parking area and found that it was difficult for passengers to escape when the jet flame was released vertically [13]. Accidents that can occur in hydrogen passenger vehicles include leaks, jet flames, and explosions, but the one most likely to cause damage is a sudden burst of flame from the activation of the TPRD.…”