Investigation of different topology-optimized fin structures in a cylindrical latent heat thermal energy storage unit

Abstract

Latent heat thermal energy storage (LHTES) has received great attention from many researchers due to the high energy density of phase change materials (PCM), which helps to store more energy while allowing for a compact storage volume. However, most of these PCMs have low thermal conductivity, which requires enhancement techniques to efficiently distribute and store heat inside the LHTES unit. Therefore, different structures of finned heat exchangers have been investigated in the literature. Still, most of these structures are intuitive designs, which makes the literature very lacking in terms of non-intuitive heat exchanger designs for LHTES units. In this paper, we will use topology optimization to efficiently distribute the fins in the PCM domain. Afterwards, we will examine numerically the performance of different topology optimized fin designs, that were obtained through radial topology optimization and a novel axial topology optimization approach. The PCM used in this study is paraffin RT35 with water used as heat transfer fluid (HTF). The results presented in this study show a significant increase in performance by the topology-optimized designs with a maximum increase in performance of 86.3%. Additionally, the radially finned structure has proved to be a better enhancement in this specific case with a fin distribution that’s occupying 20% of the initial PCM volume for large-scale applications.