新扩散模型下温度对煤粒瓦斯动态扩散系数的影响

升温促进煤基质中瓦斯快速大幅解吸/扩散是热激励法增产瓦斯机理之一，其首要关键科学问题是探明温度对扩散系数的影响规律和影响机理。采用恒温与升温方法进行了3种不同条件下的扩散实验：（1）初始同压不同温吸附后恒温扩散；（2）同初始吸附量条件下（高温高压、低温低压吸附后）恒温扩散；（3）同初始温压吸附后的升温扩散实验。实验结果表明：实验（1），（2）中用单孔隙经典扩散模型计算的常扩散系数随温度升高呈现无规律的波动形态，经典模型无法解释这一现象。原因是经典模型不能精确描述全时段扩散过程，误差极大，继而发现了扩散系数随时间延长而衰减的特有现象。为此，提出了能精确描述全时扩散过程的动态扩散系数新模型。新模型分析表明，煤基质中多尺度非均质孔隙形态决定了多级孔隙扩散系数分布，进而导致了扩散系数随时间延长而衰减。新模型下动扩散系数随温度升高单调递增，符合阿雷尼乌斯关系，规律惟一，经典模型常扩散系数是新模型动态扩散系数的平均值。新模型涵盖了经典模型，前者是后者的推广。

Influence of temperature on dynamic diffusion coefficient of CH4 into coal particles by new diffusion model

Promoting gas diffusion/adsorption rapidly and sharply by use of warming coal matrix is one of mechanism of improving gas production by method of thermal excitation.The principal key science issue，the influence law and mechanism of temperature on diffusion coefficient is need to be studied.Three type of diffusion experiment under the condition of equal temperature and heating was researched.(1) Isothermal diffusion after adsorbing at equal pressure and different temperature；(2) Isothermal diffusion after adsorbing at equal adsorptive capacity (high temperature and pressure and low ones)；(3) heating diffusion after adsorbing at equal initial pressure and temperature.The results show that：the constant diffusion coefficient calculated by unipore classical diffusion model varies irregularly with temperature increasing.The unipore classical diffusion model can not explain that and has large error because the model can not precisely fit full-time gas diffusion process.And then，the phenomenon，diffusion coefficient decreasing with time increasing，was found.A new dynamic diffusion coefficient model which can precisely fit full-time gas diffusion process had been proposed.The results analyzed by new model indicated that diffusion coefficient decreasing with time increasing is due to the multi-pore coefficient distribution which is controlled by multi-size，heterogeneous pore in coal.The dynamic diffusion coefficient increases with temperature increasing in new model，which can be fitted by Arrhenius equation.The constant diffusion coefficient of classical model is the average value of dynamic diffusion coefficient of new model.The new model can contain and generalize classical model.