An experimental study is conducted in order to investigate melting and solidification processes of paraffin RT35 as phase change materials in a finned-tube. Therefore the effect of using fins in this study as well as some operational parameters is considered. The motivation of this study is to design and construct a novel storage unit and to compare it with a finless heat exchanger. A series of experiments are conducted to investigate the effect of increasing the inlet temperature and flow rate on the charging and discharging processes of the phase change material. It is shown that, using fins in phase change process enhances melting and solidification procedures. The trend of this variation is different for the heat exchangers; increasing the inlet temperature for the bare tube heat exchanger more effectively lowers melting time. Similarly, flow rate variation varies the solidification time more intensely for the bare tube heat exchanger. 1. Introduction In light of the availability of considerable latent heat of fusion upon melting and solidification (freezing), phase change materials (PCM) have long been used for thermal energy storage applications including waste heat recovery, thermal management of electronics, and solar thermal energy utilization. The main advantage of these systems is their ability to store a large amount of energy in a relatively small volume at a constant phase change temperature. Thus, many authors have reported the results of researches on PCM thermal storage during melting and solidification processes in energy storage systems. In thermal storage systems low conductivity of different PCMs is a disadvantage, since the adequate amount of energy capacity may be available but the system may not be able to use it at the desired rate. Regarding the defect of low thermal PCMs conductivity, several ideas and innovations have been proposed in the literature to enhance heat transfer for which the effects and consequences are studied both numerically and experimentally. Employing finned-tubes with different configurations [1–9] and adding particles with higher thermal conductivity than the PCM [1, 10–19] enhance the effective thermal conductivity of PCM used in PCM-based thermal systems. Hosseini et al. [20] experimentally and numerically studied the effects of natural convection during melting of a paraffin wax in a shell and tube heat exchanger. They found that the melting front appeared at different times at positions close to the HTF (heat transfer fluid) tube and progressed at different rates outwards, toward the shell. They
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