Cascaded latent thermal energy storage using a charging control method

Abstract

Several studies have used thermal energy storage systems to store renewable heat energy. Nevertheless, few studies have addressed the charging of renewable heat sources with unsteady temperatures. In this study, a cascaded latent thermal energy storage (CLTES) system utilizing a charging control method (CCM) is proposed for the efficient charging of renewable energy under unsteady temperature conditions. The CCM was used to control the inlet positions of CLTES tanks depending on the inlet temperatures. A CLTES system with a total volume of 834 L (3 x 278 L) was manufactured for the experiment using three tanks and phase change materials (PCM) with three different melting points. To verify the performance of the CCM system, three system types were considered: Single-PCM latent thermal energy storage, CLTES, and CLTES with CCM. The results show that the CCM increased the charged and discharged thermal energy by 33% and 44%, respectively, compared with the reference case under unsteady inlet heat transfer fluid temperature conditions. The results confirm that a multi-tank cascade system utilizing CCM can be used to efficiently charge unsteady renewable thermal energy sources. (c) 2020 Elsevier Ltd. All rights reserved.