Computational comparison of approaches based on geometrical orientation and gravity components in analysing the melting behaviour of thermal energy storage system

Phase change materials (PCMs) are efficient means of storing latent thermal energy content owing to their excellent storage capacities at constant temperature conditions. Despite the limitations such as low thermal conductivity and inadequate performance characteristics; the PCMs are often employed in connection with structurally modified configurations of heat exchangers to secure enhanced thermal outputs. In order to ascertain the thermal performance for different structural modifications; a 2D Numerical Model of Thermal energy storage (TES) was instituted to unearth the melting rates of PCM; so as to understand the impacts of conventional position of latent heat storage and gravity component effect for fixed angular positions. The study employed the Enthalpy-Porosity technique to simulate the phase transition phenomena occurring within the thermal energy storage TES system. In continuation to the same exercise; in all, 14 mathematical models having variation of angular inclination from 0° to 90°; were numerical simulated and examined for the TES. In this work two different approach to consider gravity effect is incorporated and compared with conventional approach of geometry orientation for angular positioning initially, with the help of conventional approach the geometry was given angular orientation from 0° to 90° and the performance was adjudged numerically in terms of melting fraction and energy storage. Later on the orientation of the TES was fixed i.e. horizontal based on the angular orientation value the gravity components in x and y direction were given as input into the software. Both the approaches produced similar results and a significant reduction of 75% in melting time of 90° orientation in comparison to 0° orientation. The maximum energy achieved, according to observations, is 307.70 kJ/kg at an orientation angle of 75°.