Heat transfer characteristics of PCM inside a modified design of shell and tube latent heat thermal energy storage unit

Shell and tube latent heat thermal energy storage systems are compact and effective among other types of energy storage systems. The present numerical study deals with geometry optimization of a modified design of shell and tube latent heat thermal energy storage system over melting and solidification cycles. The modified design was produced by splitting the single inner tube into three smaller inner tubes arranged in a line array with different orientations. The numerical model covered four different line array orientations: 0°, 30°, 60°, and 90°, along with a storage model consisting of a single inner tube. The surface temperature, perimeter of inner tubes, and mass of PCM in all numerical cases were assumed to be identical. The numerical model has been validated by comparing the melting fraction contours and the PCM temperature with the experimental published data. It has been found that the line array of 0° orientation has the minimum full cyclic duration with an improvement of 44.4% compared to the base case. Conversely, the line array of 90° orientation has the maximum full cyclic time; 15.83% longer compared to the base case of a single inner tube. Lastly, the orientation of the line array is more significant for melting compared to the solidification.