Transient Charging Characteristics of Shell and Tube Latent Heat Storage System—A Novel Two-Dimensional Analytical Approach

Abstract

Energy storage using latent heat of solid–liquid phase change material (PCM) is an efficient option due to high energy density and low volume variation during phase change. Such type of storage is suitable to exploit untapped solar energy and waste heat energy. The present work explores the analytical approach to study the unsteady charging behavior of PCM inside latent heat thermal energy storage (LHTES) system. The radial, axial as well as temporal effects on the melting of PCM are investigated analytically. Relation between time, temperature, radius, and axial distance of storage system is developed using energy equation in cylindrical coordinates. The 49% reduction in melting time of PCM was noted with an increase in heat transfer fluid inlet temperature from 185 °C to 200 °C. It was also observed that melt front moves 1.28 times faster when axial position changes from 100 mm to 200 mm. Convection heat transfer plays a vital role during the charging process, and it is found that the melt front moves radially outward and axially upward during the melting of PCM. It can also be concluded that analytical tools like the one presented in this study can be instrumental in analyzing the thermal performance of storage units.