Theoretical And Experimental Study On Leakage And Diffusion Rules Of Indoor Combustible Gas

The concentration field distribution of indoor is non-uniform changes, the dangerous accidents of deflagration or explosion will happen when indoor gas concentration achieves explosion limit and encounters with ignition source. Taking the leakage and diffusion process of indoor combustible gas for research object in this paper, the following aspects were studied:(1) The influence factors and calculation methods of combustible gases'explosion limits were analysed in this paper, and calculation methods of purely one-component combustible gases', purely combustible gas mixtures'and multicomponent combustible gas mixtures' explosion limits were studied. In the end, the calculation method of purely combustible gas mixtures'explosion limits was choosed to calculating combustible gas's explosion limit.(2) The mathematical models were established based on continuity equation, momentum equation, energy equation, no reaction multicomponent transport model, density equation and the turbulence model equation which modified by buoyancy. Initial conditions and boundary conditions were presented and discrete model and solution method were presented based on finite volume method and SIMPLE algorithm.(3) The liquefied petroleum gas was taken as research object, and the experiment platform researching on indoor gas leakage was built based on existing laboratory condition. The effects of leakage rate, leakage time, large vent, ventilation velocity and obstacle on leakage and diffusion of indoor combustible gas were studied. The following diffusion rules and explosive concentration distribution with different influential factors were obtatined by simulating calcaultion and experiment study on leakage and diffusion of indoor combustible gas. The greater the leakage of gas, the more gas leaking into the interior space at the same time, the dangerous accident will happen in shorter time. The spread of leakage and distribution of concentration field is proportional to the leakage time. The gas concentration nearby large vent can be diluted, so explosion concentration field will last longer. Changing the ventilation velocity had the few influence on gas diffusion trend, and will only dilute concentration nearby velocity opening. The changed indoor flow motion and block leakage diffusion of combustible gas. It was easy for leakage gas to accumulate near the obstacle and the explosion concentration field on left of obstacle lasted longer. There was large concentration difference on both sides of obstacle.The deviation of simulation results and experimental results was about 20%, but the variation trends of them were same. Some prevention measures of gas leakage accident were given based on diffusion rules. The research results were contribute to preventing deflagration or explosion accidents and could supply theoretical basis for formulating fire safety measures.