Effect of porosity of conducting matrix on a phase change energy storage device

Phase Change Material (PCM) has been widely used in recent years for thermal storage devices, and PCM-filled metal matrix has become one of the common configurations that provide both a high thermal capacity and a faster heating/cooling cycle. A thermal storage device having a shell and tube arrangement was investigated in this paper. The shell contains paraffin wax saturated in aluminum foam. Effect of the porosity of aluminum foams on the thermal behavior of the system was investigated by comparing two foams with different porosity (95% and 77%). Both experimental measurements and numerical simulation were performed in this study. In addition, direct observation of the melting/solidification process of the paraffin wax was also made through visualization method. Measurement results were presented and compared with the model predicted solution fields, and good agreements were found. Results showed that the use of conducting matrix with PCM material significantly reduced the time needed for an operating cycle, and that the metal foam with less porosity further shortened the cycle due to higher overall thermal conductivity.