Melting and Thermal Behavior of Phase Change Materials Around an Asymmetrically Confined Circular Cylinder

Abstract

Due to increasing energy demand caused by growing civilization and human comfort on one hand, and the limited presence of conventional energy resources such as fossil fuels on the other hand, the use of phase change materials (PCM) in thermal energy storage (TES) systems has significantly increased. Typical applications are in building walls, glass windows, heat and cold storage units, textiles, cooling helmets, batteries, solar water heating system, HVAC units, etc. These materials store and release a bulk amount of latent heat during phase change process. Moreover, such materials are more economical and eco-friendly in use. However, the design and optimization of a system utilizing PCM is challenging. The objective of this work is to design and investigate a system yielding high rate of heat transfer to ensure lesser melting time required to achieve thermostat condition. In this work, the effect of asymmetric positioning of a heated circular cylinder on melt fraction, energy storage and temperature profiles is studied numerically for the Lauric acid as PCM (melting temp ~ 319K, Rayleigh number ~ 20,000, Prandtl number ~ 140) confined in a square duct. The simulations have been carried out using ANSYS Fluent 19.2. We considered five different positions/locations of the cylindrical object. It is found that a simple modulation in the location of the heated object, it is possible to tune the rate of heat transfer and thus the performance of TES devices.