Natural convection improvement of PCM melting in partition latent heat energy storage: Numerical study with experimental validation

摘要

This study examines an innovative design to enhance the natural convection in a rectangular latent heat energy storage unit (LHSU). The new design divides the rectangular plane into different small partitions (1, 2, 4, 8, 16 and 32) to trap the melted phase change material (PCM) and create several melting fronts which accelerate the melting process than with a normal 1-partition LHSU. The number of these partitions was varied by changing the PCM cavity aspect ratio with values 2, 1, 0.5, 0.25, 0.125 and 0.0625 taken. To validate the numerical model developed herein, LHSUs with one and two partitions were tested experimentally. The numerical model using the ANSYS FLUENT, extended the analysis to other partition numbers. Results showed that the natural convection was significantly strengthened by partitioning the LHSU, which shortens the time required for PCM melting. However, an optimal number of partitions were obtained after which improvement ratio was declined. An LHSU with 8 partitions (0.25 aspect ratio partitions) was found as an optimum. In addition, the comparison with a normal 1-partition LHSU found that the PCM melting process was enhanced by 31.2%, 53.6%, 65% and 68% for the LHSUs with 2, 4, 8, and 16 partitions, respectively.