Abstract: To explore the variation law of thermal conductivity of loose coal with its influencing factors, based on parallel hot line method and cross hot line method, thermal conductivity values of loose coal samples with different particle sizes, temperature and water content were measured by using a self-made test device. Curves of thermal conductivity with temperature and water content were fitted. By introducing the secondary response surface method, a Box-Behnken test design was made for the particle size, temperature and water content to obtain to list them in order of importance. The results show that the test device can be used to accurately measure the thermal conductivity of loose coal with a measurement error within 3.0%, and the thermal diffusivity and specific heat capacity can be obtained at the same time, that the thermal conductivity of loose coal decreases with the increase of particle size, decreases with the increase of temperature, and increases with the increase of water content, that for the importance to the first-order term of the thermal conductivity formula, there is an order of water content > particle size > temperature, and for the importance to the second-order term of the formula, there is two orders of particle size and temperature > particle size and water content > water content and temperature, and that there is interaction between particle size and temperature merely.

Key words: loose coal, response surface methodology, thermal conductivity, particle size, temperature, water content