Enhanced thermal performance of finned latent heat thermal energy storage system: fin parameters optimization

Abstract

Integration of thermal energy storage (TES) systems in concentrated solar power (CSP) plants plays an important role, followingly, the mismatch between energy production and demand can be adjusted. Generally, latent heat thermal energy storage (LHTES) can ensure important amounts of energy compared to sensible heat thermal energy storage systems (SHTES), which has oriented researchers, engineers, and decision makers toward using this technology because of its high energy density. Otherwise, using phase change materials (PCMs) in LHTES systems can considerably reduce their performance as PCMs have relatively low thermal conductivity values, which makes it very necessary to take measures for enhancing the thermal conductivity or heat transfer inside of these LHTES units. This study simulated, modeled and optimized a proposed system for heat transfer enhancement, which is a shell-and-tube storage units with annular fins, by using the finite element method during the charging and discharging processes. In addition, NaNO3–NaNO2 was used as PCM while the Delco Term Solar E 15 was used as heat transfer fluid (HTF). The main objective of this work is to provide the optimal geometry parameters of the studied system in terms of length, number, step, and fin thickness by comparing many fin geometries. According to the results, an increase around 65.04% in the charging (melting) time and 58.36% in the discharging (solidification) period was achieved by the integration of optimal fins. The recommended fin parameters corresponding to the highest thermal performance were; length = 14 mm, thickness = 1 mm, step = 3.45 mm, and number = 66.