Combined measurement and calibration method for the thermal conductivity of phase change materials

Abstract

A combined method for determining the thermal conductivity of phase-change materials (PCMs) is proposed in this paper. A primary concern for this method is mitigating the effect of factors that exist in real experiments but are excluded in the measurement model. Thus, a measurement model was proposed to establish the mathematical relationship between the thermal conductivity and liquid fraction during the melting process. An experimental system was developed, and two different PCMs were used for the experiment. The thermal conductivity obtained via the experiments depicted an increasing trend during the entire melting process; these measurements were treated as the effective thermal conductivity of the PCM. The enhanced heat transfer rate prompted by natural convection was identified as the factor that affected the thermal conductivity measurement; a numerical calibration approach was presented to mitigate this influence. The numerical model considered all factors influencing the errors, and thermal conductivities were obtained via repeated iterations. Deviations between the calibrated thermal conductivity and reference data were less than 8%, meeting the practical requirements of engineering applications.