Study on dynamic diffusion characteristics of methane in coal matrix

The approach to modeling coal matrix methane transport is based upon the solution to Fick's first law or Fick's second law.This paper presents an experimental method for determining diffusivities from high-pressure methane adsorption-desorption volumetric isotherm data.The numerical model of this method is based on Fick's second law for spherically symmetric flow.The example of this measurement method is given through Jincheng's coal sample.The result shows that adsorption-rate is consistent with desorption-rate,both increasing with pressure.