Indoor Diffusion Of Natural Gas Concentration Field Under Temperature Gradient

In the backdrop of the world’s energy crisis, as a clean, efficient energy, natural gas is attracting more and more people of all ages. The development of natural gas industry has started to become a common choice for the world energy conservation and promoting sustainable economic development. A large number of delivery pipes are needed in the development and utilization of natural gas. By2006, the total length of China’s natural gas pipeline has reached nearly3million meters. As the urban gas transmission and distribution facilities are often located in dense areas of population and public facilities, it would result in death or serious injury and property damage, once a gas fire and explosion accident happens. Gas pipeline leakage is one of the main causes of city gas safety accidents. This paper focuses on probing the law of the gas pipeline leakage and diffusion. The emphasis is on the effect of temperature gradient on the gas leak diffusion.Three parts are included in this paper. First from on macroscopic analyzes the diffusion regulation of indoor gas leakage. Then, a systematic research on the influence of leakage dispersion under various factors, looking for the corresponding mathematical equations. Finally, the effect of various factors on the gas leak diffusion was validated by numerical simulation, compare the effect of each factor, find out the powerful one.①Before the analysis of the influence factors of gas diffusion in the first part, this paper put forward two factors to measure the effect of various environmental factors on gas leakage diffusion and the applying conditions:diffusion velocity in the initial time and area of influence when diffusion is steady. This paper first divide the influencing factors of the indoor gas diffusion into four categories:pressure gradient, temperature gradient effect directly,density buoyancy, thermal buoyancy.②Seeking the basis of the theory put forward in the previous paper from the derivation in part two, the effect of various influencing factors on gas diffusion were expressed by four mathematical formula. Compared the impact of various influencing factors on gas diffusion weight by magnitude analysis. This paper comes to the conclusion that diffusion term based more on components pressure gradient effects, the density buoyancy could obviously strengthen or impede the pressure gradient effects, temperature gradient and thermal buoyancy also affects the pressure gradient effects to certain extent, play less of a role but could not be ignored.③In part three, based on the numerical simulation, one can draw a conclusion that temperature gradient and thermal buoyancy affects the effect of pressure gradient independently, The trend of gas diffusion with the effect of temperature gradient and temperature gradient are in the same direction,that is to say, it diffused to direction with higher temperature. As temperature gradient interaction term and thermal buoyancy are in the same order of magnitude, the effect of thermal buoyancy on the gas leak diffusion is stronger.