Numerical study on thermal performance of packed-bed latent heat thermal energy storage system with bionic-calabash-shaped capsule

Abstract:

Following the background of "dual carbon" energy with peak carbon and carbon neutrality, conventional heat storage capsule with phase change materials (PCM) and latent heat thermal storage system (LHTES) with packed bed cannot meet the current heat storage demand. The application of bionics in the field of heat storage offers a new approach to improve the heat storage efficiency of the capsule and LHTES. This paper introduces a novel bionic-calabash-shaped capsule for thermal energy storage units to increase heat transfer surface area and improve the thermal performance of LHTES systems. Firstly, the influence of optimized dimensional parameters of the biomimetic gourd unit on its melting characteristics is analyzed to determine the optimal dimensions for achieving desirable melting characteristics. Secondly, the analysis of temperature distribution, liquid fraction, heat storage capacity, and other performance indicators is conducted for LHTES of conventional sphere and biomimetic calabash. The results reveal that the bionic-calabash capsule can increase the heat transfer area by 14.5%. Compared to the traditional model, the liquid phase fraction and heat storage completion rate of biomimetic model increase by 12.67% and 6.2%, respectively. On this basis, the influence of inlet temperature and flow rate on system performance is analyzed, and the results show that the inlet temperature significantly impacts the system′s thermal storage performance. A 15 K increase in the import temperature leads to a 59.6% reduction in the thermal storage time for the stacked bed system. This study provides valuable insights for optimizing stacked bed LHTES systems and enhancing their thermal performance under real-world conditions.