Effects of Measuring Method on the Effective Thermal Diffusivity of Packed Coal Column during Carbonization

Abstract

The effective thermal diffusivity(κ_eff) of pulverized coal is measured by two different methods;one is "continuous heating method", and the other is "modified periodic heating method" in which the continuous heating is overlaid with periodic heating. Results with each method are similar in the temperature lower than about 750K. Above 750K, the temperature dependency on κ_eff is different at each method. The estimation is made on the measurement errors based on the temperature dependency of thermal properties, the heating rate and the endothermic reaction by numerical calculation. It is found that κ_eff is measured with high accuracy by modified periodic heating method. κ_eff is characterized in three temperature regions between 400 and 1 100K; in the first region, κ_eff is constant, in the second, κ_eff increases rapidly with temperature and in the third, κ_eff increases slowly.