Inner pipe downward movement effect on melting of PCM in a double pipe heat exchanger

This study is aimed to investigate the melting of phase change material (PCM) in a horizontal double pipe heat exchanger. The area between the pipes is filled with RT50 as PCM and water is used as a heat transfer fluid (HTF) which flows through inner pipe. The downward movement of inner pipe, inlet temperature and mass flow rate of HTF are considered and compared with the base system. The results show that inner pipe downward movement increases the convection-dominant zone which reduces melting time considerably (up to 64%). Results also indicate that by increasing the HTF inlet temperature thermal potential of the system increases which accelerates the melting process. However increasing the mass flow rate of HTF does not have significant role in melting rate.