Energy storage and exergy efficiency analysis of a shell and tube latent thermal energy storage unit with non-uniform length and distributed fins

Abstract

This work proposes a novel type of shell and tube latent thermal energy storage unit (LTESU). Effects of the thermal conductivity of PCM, the inlet temperature of heat transfer fluid (HTF), the inlet velocity of HTF and fin layout (fin length and distribution) on the thermal performance and exergy efficiency of the LTESU are numerically investigated. The transient numerical computation of the PCM phase transition process incorporates iterative by the finite volume method based on enthalpy-porosity technique. The results showed that the role of fin layout for enhancing the energy storage performance of LTESU is more predominant than that by the PCM thermal conductivity. The LTESU with fins has better heat storage intensity compared with the case of no-fins, where the heat storage intensity increased by 104.33% with non-uniform fin length and distribution and 61.06% with uniform fin length and distribution. In addition, the exergy efficiency of LTESU with reduced fin length and uniform distribution along the HTF flow direction (Case 1) has the greatest improvement, which is increased by 8.53% for Case 1 relative to the no-fins case. The findings reveal that adopting non-uniform length and distributed fins is an effective solution to attain higher thermal performance in LTESU.