Experimental investigation on charging and discharging performance of finned shell and tube device containing pentaerythritol for low and medium temperature thermal energy storage

This work concerns the investigation of the charging and discharging performance of a finned shell and tube device that utilized for low and medium temperature thermal energy storage application. An experimental rig is built for evaluation in which a so-called solid–solid phase change material of pentaerythritol is used as energy storage substance and air is employed as heat transfer fluid. The PE has tested to have a melting temperature range of 185-205℃ and a latent heat of 290 kJ/kg. The study first examines the effect of fin number on the device thermal performance by considering configurations with 4, 6, 8, and 10 fins. Then the impact of fin height is evaluated where four different fin heights of 9 mm, 14 mm, 19 mm and 24 mm is investigated, and finally the influence of heat transfer fluid working condition is explored. The results indicate that the PE could be ideal PCM utilized in shell-tube typed thermal energy storage device. The enhancement of fin number and fin heigh can largely improve both the charging and discharging performance of the device. For a given air inlet pressure of 0.1 MPa, the device having fin number of 10 and fin height of 19 mm could be identified as the optimal configuration for heat transfer, and at such working conditions, the device achieves a charging efficiency of 91.49 % and a discharging efficiency of 86.4 %.