Melting characteristics of concentric and eccentric inner elliptic tube in double tube latent heat energy storage unit

Abstract

Thermal energy storage is critically necessary for most solar energy applications. The phase change energy storage systems are the most promising; however, the poor thermal conductivity of the material is a major disadvantage. This work aims to simulate the melting process and investigate the optimum design parameters for a stable and high melting rate of phase-change energy storage systems. A 2-D axisymmetric numerical model has been developed using ANSYS 17. The model was validated by published experimental data. A new elliptical design of the inner tube was investigated; and the main parameters considered were eccentricity (0, 0.1, 0.2, 0.3, 0.4, and 0.5), aspect ratio (1, 0.9, 0.8, 0.7, 0.6, and angle of 0.5), and inclination (0°, 30°, 60°, and 90°) of the inner tube. The outcome of this investigation revealed that the maximum enhancement of the average melting rate was 19.14%, 42.65%, 71.3%, 105.51%, and 150.1%, for eccentricity of 0.1,0.2,0.3,0.4, and 0.5, respectively, for an aspect ratio of 1. The maximum and minimum average melting rate were 0.00516 and 0.00417 kg/min for the vertical inner elliptical tube (θ = 90°) and the horizontal inner elliptic (θ = 0°) respectively for an aspect ratio of 0.5.