Experimental study on the properties of millimeter-sized NaCl-KCl/MgO ceramic particles for high-temperature solar-thermal phase change applications

The development of molten salt composite phase change materials (CPCMs), which can store both sensible and latent heat, is a promising strategy to enhance the thermal energy storage capacity in solar thermal systems. Currently, bulk CPCMs are primarily prepared using the mixed sintering method, but their application is limited by issues such as easy collapse, leakage, and the fact that they can only be stacked for use. To address these issues, this study proposes a novel method that combines extrusion-spheronization with mixed sintering to produce composite phase change particles with high fluidity, excellent leakage resistance, and high energy storage density. An MgO skeleton is incorporated into the NaCl-KCl phase change material to provide structural support, prevent leakage and deformation, and enhance the thermal conductivity. The enthalpy value of the CPCM reaches 146 kJ/kg, and its thermal conductivity is as high as 4.57 W/(m⋅K). With 15% MnFe2O4, the solar spectral absorbance reaches 86.62%.