Enhancing Thermal Storage Performance Using Finned Tubes in PCM Units

Abstract

This research presents a comprehensive numerical investigation into the enhancement of latent heat thermal energy storage (LHTES) performance through the integration of finned tubes within phase change material (PCM) units. Given the inherent challenges in theoretically analyzing the non-linear moving solid-liquid interface during phase transitions, a robust finite volume model was developed to simulate the solidification process of PCM, specifically paraffin, around the outer surface of circular cylindrical finned tubes. The simulation utilizes an enthalpic formulation and a fully implicit scheme to accurately predict the fraction of solidified PCM and the transient evolution of the liquid-solid interface over time. Validation of the numerical model against established experimental and numerical data demonstrated excellent agreement, confirming the reliability of the proposed computational approach. A detailed parametric study was conducted to evaluate the influence of various geometric and operational factors on the energy charging rates and total discharge times. The results indicate that the thermal performance of the storage system is significantly improved by increasing the fin diameter, fin thickness, and the total number of fins, as these modifications facilitate superior heat conduction into the PCM. Furthermore, the study highlights that a higher temperature difference between the tube wall and the PCM, as well as the implementation of more compact tube arrays, leads to shorter discharge times and a greater amount of energy being recovered. The findings provide critical insights and practical design guidelines for optimizing PCM-based thermal energy storage systems, emphasizing the effectiveness of finned configurations in overcoming the low thermal conductivity of common phase change materials.