Beschreibung:
Molten salts have been widely used as energy storage materials in medium- and high-temperature thermal energy storage. However, pure salt commonly suffers from low thermal conductivity and many conventional methods for heat transfer enhancement do not apply due to the serious corrosion and the extremely high temperature. In the present study, a porous SiC ceramic foam with open-cell structure was integrated with medium-temperature solar salt, forming ceramic/salt composite phase change material (CPCM), to enhance heat transfer and avoid severe corrosion issues. A visualised experiment was for the first time conducted to investigate the melting phase change and heat transfer in the ceramic foam/salt CPCM, addressing the solid-liquid interface, temperature field, melting rate, etc. A representative elementary volume (REV)-scale simulation was simultaneously performed and the results from computational modelling were compared with experimental data. It is found that the heat conduction friendly ceramic skeleton can remarkably enhance the heat transfer in molten salt, especially in the energy storage region far away from the heat source. The spatial temperature difference across the composite is decreased in both horizontal and vertical directions and the local superheating is mitigated. Due to the configuration of open cells and large pores of the ceramic foam, natural convection is not suppressed seriously while the heat conduction is boosted greatly; as a result, the melting of the CPCM is accelerated by 42.9%. This study provides crucial benchmark data of phase change heat transfer for medium-temperature thermal energy storage and paves the way for system design and optimization