Study on the change of active groups and heat transfer characteristics of coal samples with different degrees of metamorphism

In order to investigate the changes and relationship of reactive groups and heat transfer properties in coal samples with different degrees of metamorphism, the changes of active groups and thermal properties of 4 kinds of coal samples with different degrees of metamorphism were investigated by infrared spectroscopy and laser thermal conductivity. The results show that with the increase of coal metamorphism, the percentage of aromatic compounds and aliphatic compounds in coal increases gradually, and the percentage of oxygen-containing functional groups decreases gradually. The oxygen-containing functional groups in coal are mainly alcohols, phenols and ethers. With the increase of temperature, the thermal diffusion coefficient of coal decreases first and then increases, while the specific heat capacity and thermal conductivity increase continuously. The thermal properties of coal are related to the degree of coal metamorphism and industrial analysis data. The results of Pearson correlation coefficients show that —C＝C—, —CH₃, —CH₂— and aliphatic —CH have a large negative correlation with thermal diffusion coefficient and thermal conductivity, while —C＝O has a large positive correlation with the thermal diffusivity and thermal conductivity while —OH has a good negative correlation with specific heat capacity.