A vertical multi-tube latent thermal energy system with tube inserts and radial fins: Experimental and CFD modeling study

Enhancing heat transfer in latent thermal energy storage (LTES) is a pivotal endeavor. A shell and multi-tube LTES unit is a compact and promising heat storage technology, which has a larger heat transfer capacity and higher practical engineering application value compared with a single shell and tube LTES unit. However, both experimental and three-dimensional numerical studies of vertical shell and multi-tube LTES units are scarce. In this study, a three-dimensional computational fluid dynamic model of a vertical shell and multi-tube LTES unit was developed and validated against experiments. Details of the melting and solidification processes were explored. Results showed that there was inconsistent melting/solidification of the phase change material (PCM) near the central and peripheral tubes, and the charging process of the unit took longer in comparison to the discharging process. Besides, the region with radial fins significantly enhanced the melting/solidification rate compared to the pure PCM region, and the tube insert had a thermal storage effect. Moreover, increasing the flow rate from 50 kg/h to 360 kg/h significantly reduced charging and discharging times (by 69 % and 65 % respectively).