Thermal Conductivity of Supercritical CO2-Saturated Coal

Abstract

The present study reports the effective thermal conductivity (ETC) of supercritical (SC) CO2-saturated black coal sample at temperatures from (304.15 to 323.15) K and pressures up to 20 MPa using a steady-state guarded parallel-plate method. The expanded uncertainty of thermal conductivity, pressure, and temperature measurements at the 95 % confidence level with a coverage factor of k = 2 was estimated to be 4 % (in the range of regular behavior of the thermal conductivity) and 5–6 % (in the critical region of the saturated CO2), 0.1 %, and 30 mK, respectively. This uncertainty in ETC measurement does not include the uncertainty due to contact thermal resistance and radiative conductivity inherent in this method. The effect of critical anomaly of thermal conductivity and other thermodynamic properties of pure CO2 near- and supercritical conditions on the total measured values of the ETC of SC CO2-saturated coal was studied. The thermal conductivity behavior of pure SC CO2 in coal pores was interpreted based on finite-size scaling theory of critical phenomena.