Numerical Study On Leakage And Diffusion Of Indoor Combustible Gas

The gas leaking from indoor gas pipeline can mix with enviormental air, and indoor gas concentration changes contantly. The dangerous accidents will happen when indoor gas concentration achieves explosion limits. The explosion accidents happened in recent years due to gas leakage, which caused great casualties and serous economic losses. The gas and liquefied petroleum gas were taken as research objects, the concentration distribution and variation with different boundary conditions were obtatined by simulating calcaultion and experiment study on leakage and diffusion of indoor combustible gas. The research results were contribute to safety design of indoor gas pipelines and could supply theoretical basis for preventing explosion accidents of indoor combustible gas.In this paper the mathematical model which was solved by the finite volume method was established based on continuity equation, momentum equation, energy equation, no reaction multicomponent transport model and the turbulence model equation which modified by buoyancy, and combining with boundary conditions and initial conditions.The effect of gas species, leakage opposition, leakage diameter, leakage pressure, outdoor wind speed and obstacle on leakage and diffusion of indoor combustible gas was studied by numerical simulation. The simulation results showed the gas concentration formed by liquefied petroleum gas leakage was bigger than that formed by natural gas leakage at the same time. The gas concentrations of different leakage oppositions are different, the concentration field was bigger when the leakge hole is at opposite with outlet and more far away from outlet. Indoor gas concentration was proportional to leakage diameter and leakage pressure and inversely proportional to outdoor wind speed. The obstacle changed indoor flow motion and block leakage diffusion of combustible gas. It was easy for leakage gas to accumulate near the obstacle, the higher obstacle height, the bigger the concentration field. The concentrations of different leakage oppositions were furthermore obtained.The concentration distributiones of indoor combustible gas at different conditions were experimental studied. The simulation cabinet was built and the experimental system was designed. The experiment was carried on taken carbon dioxide as experimental gas instead of liquefied petroleum gas and got the concentration distributiones of different leakage oppositions, different leakage diameters and different leakage rates. The deviation of simulation results and experimental results was within 10%, but the variation trends of them were same, which verified effectiveness of simulation results.