Enhanced heat transfer in a PCM shell-and-tube thermal energy storage system

Abstract

The dominant technology among latent heat thermal energy storage methods relies on solid–liquid phase change. Since the primary disadvantage of phase change materials is low thermal conductivity, heat transfer enhancement techniques are required for these types of systems. In this paper, we propose a new double-tube latent heat thermal energy storage units. The melting time and exergy efficiency are compared for eight different design solutions. 3D simulations of the phase change material melting process were performed using the enthalpy-porosity model, Boussinesq approximation, and select temperature-dependent phase change material properties. This study shows that the proposed latent heat thermal energy storage unit (M06) significantly reduces PCM melting time compared with vertical (76%), horizontal (66%), and helical-coiled (53%) systems. The helical-coiled unit with spiral fins (M05) has the highest exergy efficiency (0.77) at the end of melting time. The M05, M06 and M08 units have the highest exergy efficiency at times t = 1200 s and t = 3307 s, which is essential for climates with time constraints on latent heat thermal energy storage. • Proposition of a new helical-coiled tube enhanced with spiral fins and conical shell. • 60% PCM melting time reduction, compared with horizontal LHTES unit. • The helical-coiled unit with spiral fins has the highest exergy efficiency (0.77). • Analysis of the effect of fins and conical shell design on melting process.