Uniformity of temperature variation in coal during methane adsorption

• The combination of micro CT and SEM was used to test the meso-structure of coal.
• Test coal temperature variation by infrared thermal imager during methane adsorption.
• Non-uniformity of coal temperature variation during methane adsorption are studied.
• The temperature variation laws in different meso-structure of coal are revealed.

Uniformity of methane adsorption by coal is important for assessing both the maximum storage capacity and damage caused by nonuniform thermal expansion. Therefore, this study examines the structural characteristics and temperature variation on the surface of coal during methane adsorption at 1 and 1.5 MPa. The results showed that the temperature increase in different surface regions associated with methane adsorption obeys the normal distribution law, and it is closely related to its meso-structure characteristics. That is, the vitrinite of the coal matrix has a fast adsorption rate and a better developed microscopic structure, resulting in a higher adsorption capacity and more pronounced temperature rise. In contrast, clay minerals present in coal have a lower methane adsorption capacity and slow adsorption rate, resulting in a smaller temperature rise.