University of Tehran Journal of Solar Energy Research 2588-3097 11 2 2026 04 01 Implementation Investigation of Solar Energy Storage System Enhancement by Spiral-Finned Tube Heat Exchanger 2992 3009 106914 10.22059/jser.2026.411357.1724 EN Kadhim Suffer Mechanical Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq Hiba Hasan Mechanical Engineering Department, University of Technology, Baghdad, Iraq Vinous M Hameed Chemical Engineering Department, College of Engineering, Al-Nahrain University, Baghdad, Iraq Malek Khalaf Department of Industrial Systems Engineering, Mutah University, Mutah, Alkarak 61710, Jordan Journal Article 2026 02 19 This study verified paraffin wax as a phase change material (PCM), enhancing the performance of latent thermal energy storage. Computational Fluid Dynamics (CFD) software was used and validated by an experimental investigation to evaluate three vertical configurations of shell-and-tube heat exchangers: conventional (STHX), pin-finned (SFTHX), and a novel spiral wire-wound on pin fins (SSTHX). Water at 20°C was fed through the tube to initiate PCM solidification. The CFD models' results showed significant outperformance of SSWTHX compared to other models. It showed a complete solidification process in 3193 seconds, while SFTHX  exhibited 4317 seconds and STHX 5710 seconds. These results show a significant improvement in PCM thermal energy storage efficiency of 44% and 25% over STHX and STHX models compared to the SSWTHX model.  Under 3000 seconds of the solidification process, 98% of paraffinic wax solidified in the SSWTHX-model compared to 90% in SFTHX. The increment in the SSWTHX surface area and the presence of the spiral wire in the heat exchanger resulted in the performance enhancement. The CFD temperature distribution showed strong agreement with the experimental work, which validated the three CFD models. These results supported the SSWTHX configuration with a higher thermal solar storage efficiency system. https://jser.ut.ac.ir/article_106914_c267d312304433cae37befe9263b6115.pdf