Performance analysis and structural optimization of shell and tube phase change thermal storage devices based on industrial flue gas waste heat recovery

Abstract

Efficient recovery of high-temperature flue gas waste heat is critical for industrial energy sustainability, yet remains challenging due to the poor thermal conductivity of phase change materials (PCMs) in conventional thermal storage systems. This study introduces a novel shell-and-tube phase change thermal storage device, with a focus on analyzing the effects of different eccentric distances and flue gas pipeline spiral fin configurations on the thermal performance of the thermal storage device. The performance of the smooth pipe, the channel pipe, and the finned pipe in recovering waste heat from high-temperature flue gas is compared and their thermal storage capacities are explored. Additionally, a performance indicator called STESR is introduced to assess the impact of various design parameters on the thermal storage capacities of the thermal storage devices. Research results indicate that increasing the eccentric distance of the flue gas pipeline can significantly speed up the melting and solidification processes of phase change materials. Optimizing the design of flue gas pipeline fins can further enhance the melting process of PCM. However, excessively increasing the number or height of fins can lead to performance improvement bottlenecks. The channel pipe is more effective than smooth pipe in accelerating the melting process and is easier to work with, making them better suited for practical engineering applications. The STESR value offers an intuitive and effective means of evaluating performance. Case 6 shows the best performance in terms of STESR value, achieving a 65.2 % increase compared to the smooth pipe. Ultimately, case 1 emerges as the optimal design solution, with a 66.8 % increase in melting time and a 47.2 % increase in STESR value compared to the smooth pipe. This makes it well-suited for efficient thermal energy storage and flue gas waste heat recovery applications. This study provides a theoretical basis and reference for optimizing the design and practical application of phase change thermal storage devices.