Thermal characteristics on melting/solidification of low temperature PCM balls packed bed with air charging/discharging

Melting and solidification phenomena of low-temperature phase change material (PCM) balls packed bed with air flowing during charging and discharging were tested and modeled by numerical enthalpy method. In this study, a commercial paraffin RT-42 (melting point 38 degrees C-43 degrees C) contained in a set of celluloid balls each having 0.04 m diameter. The experiments were performed with various bed thicknesses, air mass flow rates, and inlet air temperatures. It could be found that the simulated results on the PCM temperature and the outlet air temperature of the PCM bed agreed well with those of the experimental data. With these data, correlations were developed in dimensionless terms which could be used to estimate the air temperature leaving the bed at any operating period and any PCM bed thickness for both melting and solidification processes.