Solidification around axial finned tube submersed in PCM: Modeling and experiments

The low thermal conductivity of PCM is a discouraging factor for its wide application. A variety of techniques are investigated to improve the thermal conductivity of PCM including dispersing metallic powders, wires, meshes and fins into PCM. Fins are most preferred because of their simplicity and efficiency. This paper reports the results of a numerical and experimental study on axially finned tubes for cold applications using water as PCM. A model for an axial finned tube submersed in liquid PCM is developed based on transient two dimensional heat conduction equation, the enthalpy approach and the Alternating Direction Implicit formulation. The code is developed, tested, optimized and validated against available experimental and numerical results showing relatively good agreement. The code is further used to investigate the enhancement of solidification around finned tubes caused by the operational and geometrical parameters such as tube wall temperature, number of fins and fin width. The results showed that the increase of the number of fins and width and the reduction of the tube wall temperature enhance the interface position and velocity and reduce the total solidification time. The study also revealed the existence of optimum number of fins and optimum width of fin after which no significant gain in stored final energy or decrease in the time of complete phase change. The home built numerical code thoroughly validated with available results can be extended to treat the case of heat flux and variable tube wall temperature.