Study On The Behavior Of High-pressure Hydrogen Jet Fire Impinging Upon Barrier Wall

As a zero-emission energy,Hydrogen energy has attracted a large number of investors and researchers all over the world.Compared with the traditional fossil energy,hydrogen energy has a series of advantages,such as no pollution,high calorific values and so on.In the hydrogen economic system,the hydrogen refueling station plays an irreplaceable role of providing power for fuel cell vehicles.And the number of hydrogen refueling stations in the world is rapidly growing.At present,the hydrogen storage mode in the refueling station is mainly high-pressure gaseous storage.In case of leakage,it is easy to form jet flame and cause serious fire if ignited by an open fire or self-ignited due to shock wave.Therefore,how to effectively mitigate or block the high-pressure hydrogen jet flame is a major research topic in the field of hydrogen safety and sustained utilization.The barrier wall is a very common means of fire prevention.In order to study the flame characteristics of high-pressure hydrogen jet fire impinging upon barrier wall at different conditions,the author investigated the flame shape,flame temperature,radiant heat flux,etc.,by numerical simulation.The numerical model is established based on the open-source CFD software Open FOAM,which is an object-oriented class library.The specific research work as following:The numerical simulation platform Exfire Foam is established based on the C++ class library provided by the open-source CFD code Open FOAM.The platform adopts the eddy dissipation concept combustion model based on large eddy simulation and fv DOM radiation model.In this article,the author simulated 13.5 MPa hydrogen blow-out experiments carried out by Schefer et al.of Sandia National Laboratory,USA and 90 MPa hydrogen blow-out experiments conducted by Proust et al.of INERIS research institute,France.The simulated flame shape,flame length,flame temperature,radiant heat flux,etc.,are in good agreement with the experimental data,respectively.It is proved that the Exfire Foam numerical platform can reasonably predict the behavior of high-pressure hydrogen jet fire.The research revealed the effect of hydrogen storage pressure on the behavior of hydrogen jet fire impinging upon barrier wall.The working pressure of bundle truck,station cylinder and hydrogen fuel cell vehicle were adopted to simulate the hydrogen jet fire.The height of barrier wall was set to 3 m.The author compared and analyzed the flame shape,flame length,flame temperature and radiant heat flux.The results show that the existence of barrier wall greatly reduces the size of the high-pressure hydrogen jet fire.And behind the barrier wall,hazardous area with temperature over 70℃ is basically limited within 1 m.The research revealed the effect of height of barrier wall on the behavior of hydrogen jet fire.The hydrogen storage pressure was set to 70 MPa and the diameter of leakage orifice was 8 mm.The author simulated the behavior of hydrogen jet fire impinging upon barrier wall of different heights(0 m,1 m,2 m and 3 m).It is found that the wall of 1 m,2 m and 3 m can reduce the horizontal length of flame by 33.3%,81.0% and 81.2% respectively.When the height of barrier wall is larger than 2 m,the flame cannot cross it directly.And in the area 0.5 m away from the back of barrier wall,the temperature is basically same with the ambient temperature.While the harm of the heat radiation behind barrier is greater than high temperature,and the hazardous area behind the wall where the radiant heat flux exceeds the limit of 4.7 k W / m2 for personnel is about 6 m.The research revealed the effect of horizontal distance between jet exit and barrier wall on the behavior of hydrogen jet fire.When the height of barrier wall is 3 m,the author simulated 70 MPa hydrogen jet fire by changing the horizontal distance between jet exit and barrier wall(2 m,4 m,6 m and 8 m).The simulation results show that when the distance is less than 6 m,the flame flows reversely to the jet exit after being blocked by barrier wall.The high temperature caused by flame will further increase the pressure of hydrogen storage equipment and may cause explosion.