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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. [ABSTRACT FROM AUTHOR]

This paper presents an experimental numerical study on melting behavior of a phase change material in a shell and tube heat exchanger. Thus the effects of parameters including adding Nano-Enhanced Phase Change Material (NEPCM) and inclination angle are considered and investigated. Experimental studies are designed to characterize PCM/NEPCM properties. The details of the process progression are presented via temperature contours, streamlines and phase front displacement. Enthalpy porosity method is used for modeling of the phase change process in which pure conduction and natural convection are considered in the simulation. Results reveal that thermal conduction mechanism is dominated at initial and final steps of melting that slows down the process. As the process advances, the buoyancy effect becomes dominant in the melting process. By increasing mass fractions of nanoparticle, thermal conductivity coefficient increases that leads to faster melting rate at the bottom of the heat exchanger. Also results indicate that increasing inclination angle leads to faster pace of melting at higher attitudes that results in shorter total melting time. Contemporaneous adding nanoparticle and increasing inclination angle reveals that both natural convection and thermal conductivity improves that leads to better melting of NEPCM. [ABSTRACT FROM AUTHOR]

In this paper, melting of a phase change material (PCM) in a multi-tube heat exchanger (MTHX) is investigated. Water, as the heat transfer fluid (HTF), flows through the inner tube/tubes and the outer one while RT35 as the PCM fills the middle. The aim of this study is to investigate the effect of number of inner tubes as a geometrical parameter during charging process. Also consequences of increasing operational parameters including the HTF mass flow rate and inlet temperature are studied. In order to understand the effects of the proposed configurations, a comparison between double pipe and simple MTHX is carried out. Results show that as the inlet temperature increases melting process accelerates and complete melting time reduces, whereas, similar mass flow rate increase doesn't reduce the melting time to such an extent. By increasing the number of inner tubes from 1 to 4 in the shell side of the MTHX, melt region enlarges and its including vortices strengthens which leads to a dominated convective heat transfer and thus a higher melting rate. This increase in number of tubes leads to 29% reduction in melting time. [ABSTRACT FROM AUTHOR]