This paper aims to evaluate the effects of fin arrangement in a vertical finned double-pipe latent heat storage system based on the locations, thickness and diameter of the fins in melting and solidification mechanisms. The PCM is placed in the outer tube while water is passed through the inner tube. The fins are circularly placed around the inner pipe in the PCM zone considering a constant fins number. The results show significant advantages of fins addition in reducing the melting time along with a lower advantage on the solidification time. For the uniform fin array compared with the non-fined case, the melting and solidification times reduces by 41.4% and 9.7%, respectively. For the best fin array compared with the uniform case, the melting time reduces by 23.9%. For the solidification process, the best case is the uniform distribution of the fins when the rate of heat recovery increases by 11.4% compared with the non-finned case. Furthermore, the melting time reduces by decreasing the thickness of the fins. The evaluation of fins’ diameter shows that after a certain diameter, increasing the diameter of the fins shows an adverse effect due to suppressing the natural convection effect.
