Enhancing thermal energy storage system efficiency: Geometric analysis of phase change material integrated wedge-shaped heat exchangers
Houssam Eddine Abdellatif, Ahmed Belaadi, Adeel Arshad, Boon Xian Chai, Djamel Ghernaout
Abstract
• Ten TES configurations with varied tube, shell, and fin geometries were analysed. • Melting time reduced by up to 56.75%, significantly boosting system efficiency. • Energy storage capacity improved, enhancing overall thermal performance. • Enhanced convection increases heat transfer across optimized geometries. • Design modifications improve economic feasibility with a cost-performance peak. This study presents a comprehensive investigation into thermal energy storage (TES) utilizing phase change material (PCM), involving modifications in inner tube geometry, shell geometry, and the addition of fins across ten distinct cases. While previous research has explored the influence of PCM on melting performance and heat transfer, limited attention has been given to non-circular geometries, such as wedge shapes with fins, and their effects on melting time, behaviour, and overall TES efficiency. This investigation focuses on key performance metrics: temperature and liquid fraction contours, melting time ( t m ), energy storage capacity ( Q ) , enhancement ratio ( ER ), Nusselt number ( N u ), and economic performance ( P c ) by changing the tube, shell, and fins configurations. Starting with a circular shell and tube in the original case, subsequent cases introduce alterations such as horizontal and vertical wedge-shaped inner tubes, shells parallel to the inner tubes, and the incorporation of fins. Results show incremental improvements in t m , decreasing from 5920 s in the original case to 2560 s in the case with three wedges and a shell parallel to the wedges with fins, indicating enhanced efficiency with a time saving of 56.75%. Similarly, Q improves from 3050 kJ in the original case to 3070 kJ in the case with three wedges and a shell parallel to the wedges with fins, with the highest value observed at 3076 kJ in the case where the inner tube consisted of two horizontal wedges, while the shell was parallel to these wedges. Notably, the case with three wedges and a shell parallel to the wedges with fins also achieves the highest ER , with peaks occurring between 1000 s and 3500 s. Enhanced convection currents are evident in these cases. Economic feasibility, assessed through P c values ranging from 6.03 J s . $ to 10.6 J s . $ , showing that the case with three wedges and a shell parallel to the wedges with fins is the most cost-effective, achieving the shortest melting time and high performance. This study underscores the importance of strategic geometric modifications in enhancing TES efficiency and economic feasibility, offering valuable insights for future system design.