Abstract:
Phase Change Materials (PCMs) are widely used in Latent Heat Thermal Energy Storage Systems (LHTES). This work aims to study the melting behavior of low-temperature phase change materials in cylindrical containers placed at different angular positions. Simulations were performed using ANSYS FLUENT by applying the enthalpy porosity model to analyze melting of beeswax in a cylindrical glass tube subject to an isothermal wall condition. The tube was placed at angular positions of 0°, 30°, 60° and 90° to the horizontal in order to study the effect of angular position on melting behavior. The simulation results were then validated by performing experiments and capturing images at regular intervals of time to track the solid-liquid interface. Image processing using MATLAB was performed on the captured images to study the variation of melt fraction as a function of time. It is observed that the experimental results were in good agreement with the simulations. From these studies, it was observed that the total melting time increases with the angle of tilt from 0° to 90° Initially, the melting progressed similar to the analytical solutions of one-dimensional phase-change heat transfer. As the melting continued, the experimental and numerical results deviated from the analytical solutions and the rate of melting increased due to convection effects. The results obtained in this study can be used to predict the melting behavior of PCMs in a solar flat plate collector kept at different angular inclinations. This result can be kept in mind while designing a thermal energy storage system to set an appropriate angle to match the cycle time of the system.