Thermodynamic analysis and compatibility improvement of latent heat stores: Insights from experimental and numerical studies

It is vital to achieve an integrated design of latent heat stores with high-performance heat transfer and long service life. Increased operating temperatures facilitate the efficiency of the system, but impose more stringent requirements on the compatibility of the energy storage devices. Molten carbonates are among the promising candidate materials for high-temperature thermal energy storage, however, severe corrosion attack at elevated temperatures poses a critical threat to their large-scale application. Herein, we developed a two-dimensional transient model for shell-and-tube energy storage devices and carried out the thermodynamic analysis including thermal front evolution, energy and exergy analysis. On this basis, we elaborated on the compatibility of structural alloys SS310 of the device with Li2CO3-K2CO3 (28–72 wt%) eutectic salt. The effectiveness of sprayed aluminium in mitigating corrosion was also examined in detail, with the corrosion mechanisms elucidated through SEM & EDS and density functional theory calculations. It revealed that the tested coupon could form a high-adherence protective LiAlO2 passivation scale using affordable thermal-sprayed aluminide coatings to enhance the corrosion resistance. Besides, the properties of the post-corrosion PCM and the mechanical properties of the alloy coupons were comprehensively evaluated. It provides guidance for the future design of high-performance and long-life latent heat stores.