Feasibility Studies of Encapsulated Particles With Heat Absorbing Medium at 800–1300°C for Concentrating Solar Power Technology

The feasibility of using liquid Al or B₂O₃ encapsulated in SiC particles was studied by using thermodynamic analysis and fluid-solid analysis at temperatures ranging from 800 to 1300°C. Alloy melts of the Al-Si and Fe-Al-Si systems were considered for absorbing and desorbing energy for a high temperature energy storage (TES) unit incorporated in a concentrating solar power scheme. Boria was also evaluated instead of metallic melts and compared with the traditional NaNO₃-KNO₃ molten salt as a TES medium. In addition to determining the enthalpies for sensible heat and phase transformations, the phase equilibrium was determined for possible reactions at the liquid Al/SiC and B₂O₃/SiC interfaces by calculating their thermodynamic stability. The transport of encapsulated SiC particles within a fluid and their effect on the thermal conductivity is discussed toward the efficacy of the thermal energy storage.