EXPERIMENTAL-STUDY OF THERMAL-CONDUCTIVITY OF SOLID AND LIQUID-PHASES AT THE PHASE-TRANSITION

An experimental method for the determination of the thermal conductivity of a pure material at its freezing/melting point has been developed. In the present investigation, this method is discussed further by studying the effective thermal conductivity of the frozen as well as the thawed state of a wet porous material, and of solid and liquid benzene at the interface. The method involves the study of the transient propagation of the freezing or melting zone through the specimen as well as the steady state of the freezing/melting process. The method makes use of the heat of transition as the heat flow, and it enables the interface to act as a heat transfer surface, thus incorporating realistic features oi the phase change process, Compared with data from the literature, the experimental results for benzene agree within 2% for the solid phase and within 3% for the liquid phase, when some precautions are made to avoid free convection. The experimental effective thermal conductivity of the packed bed is compared with data from a numerical analysis; the results agree within 4%, indicating that the method is applicable also for measurements on heterogeneous materials.