An experimental study on the effect of annular and radial fins on thermal performance of a latent heat thermal energy storage unit

Abstract

Latent heat thermal energy storage (LHTES) has been used to deal with the cyclical nature of energy production through solar means. One problem with LHTES systems is the PCM having a low thermal conductivity. This results in low heat transfer rate prolonging the charging and discharging cycles. In the current study, the thermal characteristics of a latent heat thermal energy storage system enhanced with annular and radial fins are investigated experimentally. Rubitherm RT-55 is used as the phase change material (PCM) and is enclosed within a vertical cylindrical container. Water is used as the heat transfer fluid (HTF) which is circulated in a copper pipe that passes through the center of the container. Different numbers of annular and radial fins attached to the central pipe, all containing the same volume of copper are studied. The effects of these configurations on the thermal performance of the latent heat thermal energy storage system during the charging and discharging processes is monitored. The no-fin benchmark case took 47.87 h to charge the LHTES unit and 42.5 h to discharge. The ten-annular fins charged the system 84.1% faster and discharged the system 68.21% faster. The twenty-annular fin case reduced the charging time by 85.8% and the discharging by 68.58%. The four-fin radial case was found to decrease the charging time by 81.9% and 70.0%; whereas the eight-fin radial case was found to have the greatest decrease the charging and discharging times, being 86.6% and 80.1%, respectively.