Coupled variation of pressure and temperature for methane adsorption in coal seam under three initial pressures

Abstract

The methane adsorption test on coal was conducted under three initial pressures of 0.50 MPa, 0.75 MPa, and 1.00 MPa using the coal bed adsorption simulation test system. The focus of this study is to analyze the evolutionary characteristics of CH4 pressure and coal seam temperature under three different initial pressures. The distribution law of methane gas pressure and coal seam temperature on the inner plane of a coal seam, as well as the coupling relationship between them, are studied by interpolating and plotting the collected data using MATLAB software. The results indicate that methane pressure decreases over time, while the coal seam temperature increases. There is no linear correlation between the decrease in pressure and the increase in temperature. When coal is adsorbed, the pressure and temperature in the central region are lower, while the temperature in the region with high pressure is higher. The distribution of pressure and temperature is synchronized. The higher the initial pressure, the higher the temperature of the coal seam, and the more methane is adsorbed by the coal. However, the strength of the coal's adsorption capacity cannot be simply measured by the magnitude of the pressure drop. The research content can be used as the basis for further investigation of the methane occurrence rule in coal seams and the evaluation of methane adsorption capacity of coal.