Reduction of gas desorption capacity by cooling coal samples seems a feasible way to improve the accuracy of gas in place estimation. To find an efficient refrigeration mode for the freezing coring technology, the freezing tests for coal containing gas (at 0, 1.09, and 2.15 MPa) are separately conducted based on the precalculation of dry ice dose. The evolvement of coal temperature and gas pressure shows that under the catalysis of ethanol, the average cooling rate of coal gradually accelerates with the increased amount of ethanol (from 0 to 600 mL) in the early stage. Additionally when charging gas into the coal canister, the cooling rate of coal at each subzero temperature accelerates with the increased adsorption pressure of gas, and the low temperature preservation time (<0 °C) of coal is also prolonged. There is a good linear relationship between gas pressure and coal temperature, which indicates that the CH₄ adsorption and desorption in coal are basically reversible; but the desorption hysteresis is extensively observed, associated with the occurrence of numerous ink-bottle type micropores.

To investigate the adsorption properties of methane in coal under low temperatures, the isothermal adsorption tests of the three coal samples with different metamorphic degrees were conducted at the ambient temperatures of 253.15−293.15 K, and the low‐temperature nitrogen adsorption (LNA) tests of coal were also performed. Then a relational expression of equilibrium pressure, temperature, and methane adsorption capacity (T−Pmodel) was deduced to predict the adsorption isotherm at any other temperature based on the Polanyi adsorption theory. The results show that the gas adsorption capacity of coal can be significantly increased at low temperatures (below 273.15 K), and the adsorbed methane in anthracite is obviously more than that in lean coal and coking coal by the virtue of possessing a larger micropore/transition pore volume and specific surface area. The relations between adsorption potential (ε) and adsorption volume (ω) at different temperatures can be drawn on one single logarithmic curve, and a suitable pseudo‐saturation pressure can be obtained by the improved Amankwah's method. The predicted adsorbed capacities via theT−Pmodel are in line with the measured results at other equilibrium conditions, indicating that the model can contribute to the deep coalbed methane resources estimation and the gas disaster prevention and control in coal mines.