A numerical study of the effects of coil pipes arrangement on the thermal storage capacity of phase change energy storage tanks

Against the backdrop of global energy transition and sustainable development, the pursuit of disruptive technological breakthroughs has emerged as a pivotal research objective in the energy storage field. Helical tube storage systems have attracted attention due to their high thermal efficiency, compact design, and broad applicability. The thermal distribution on the helical tube wall and winding characteristics are the primary factors influencing the charging and discharging efficiency of these systems. To gain an in-depth understanding of the effects of wall-surface heat distribution and coiling characteristics of spiral tubes on the thermal performance of the heat exchange system. Therefore, this study employs computational fluid dynamics (CFD) to investigate the effects of helical tube wall temperature, winding number, and tube arrangement on thermal storage performance. An increase in wall temperature from 363.7 K to 383.7 K results in a 24 % increase in the melting rate of the PCM. By comparing five helical copper tube winding configurations, the 8 × 14 coil exhibited the best performance, shortening melting time by 52.38 % and enhancing heat storage capacity by 6558 kJ. Comparison of four helical tube arrangements shows that the top-bottom dense arrangement improved heat transfer efficiency by 11.1 % and heat storage capacity by 17,320 kJ; the left-right dense arrangement improved efficiency by 33.3 % and capacity by 22,989 kJ, with negligible difference between the two. These findings provide a theoretical basis for the design and optimization of compact, high-performance helical tube energy storage systems.