Applicability and parameter sensitivity of gas desorption-diffusion model in coal particles
Study on the law of gas desorption-diffusion in coal is of great significance for fully understanding the mechanism of gas migration in coal,gas resources scientific utilization,and gas disasters precise control and prevention.Based on the numerical simulation method,the applicability of the unipore model,the bidisperse model and the dynamic diffusion coefficient model in the gas desorption-diffusion of coal particles was compared and analyzed.The gas pressure distribution law of the bidisperse model and the dynamic diffusion coefficient model and the sensitivity of the model parameters to the metamorphic degree,particle size and adsorption equilibrium pressure of the coal sample were studied.The results show that compared with the unipore model,the bidisperse model and the dynamic diffusion coefficient model will more accurately describe the gas desorption-diffusion law in the whole stage.The bidisperse model and the dynamic diffusion coefficient model describe the gas desorption-diffusion process in different ways.Compared with the bidisperse model,the dynamic diffusion coefficient model has a larger radial gas pressure gradient.The degree of coal sample metamorphism,particle size,and adsorption equilibrium pressure have a significant impact on the various parameters of the model,and its essence is the difference in pore structure of coal.The research results can provide a guidance for the rational selection of gas desorption-diffusion model and parameters.
gas diffusionbidisperse modeldynamic diffusion coefficient modelpore structurenumerical simulation
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