Numerical investigation on the melting of circular finned PCM system using CFD & full factorial design

Heat energy storage equipment has the advantages of highly efficient energy storage performance and constant temperature owing to its adoption of Phase change material (PCM); however, its shortcoming is that it takes longer to complete thermal energy storage due to its low thermal conductivity. New technologies are being developed to overcome such shortcomings, including technology that would improve the heat transfer. This study is aimed at analyzing the impact on the energy storage time of the PCM via the Design of experiments (DOE) method and with changes to the following variables: The number of installed fins; the employed material (thermal conductivity); and the temperature of the supplied warm water, all by relying on Computational fluid dynamics (CFD). The PCM system is in the shape of a long vertical cylinder, with circular fins. The number of installed circular fins was one or five, the material used in the pipe and circular fins was changed from iron to copper, and the temperature of the warm water was 309.15 or 313.15 K. The thermal conductivity of each material employed for the CFD was 80.2 or 401.0 W/m-K. The DOE analysis was also performed to check for any curvature effect by adding a center point. The PCM used in this study is n-Octadecane 99% (CH3(CH2)16CH3) with its melting temperature being roughly 300.85 K. To sum up the conclusions of this study, the change in the number of installed circular fins and the temperature of supplied warm water have a substantial influence on the melting of the PCM. The change in the thermal conductivity of the pipe and circular fins has only a meager influence on the melting of the PCM. To reduce the melting time of the PCM most effectively, it is recommended to install as many circular fins as possible and to raise the temperature of the supplied warm water. This may be related to the fact that the melting of the PCM is influenced more by convection inside the PCM system rather than conduction.