Novel Low-Cost Anorthite Porous Ceramic-Based Binary Chlorate High-Temperature Thermal Energy Storage Material: Preparation and Characterization

Abstract

This work creatively proposed novel, low-cost, anorthite porous ceramic (APC)-based eutectic NaCl-KCl salt composite phase-change materials (C-PCMs) by using industrial solid waste blast furnace slag (BFS) and fly ash (FA) as the main materials. The spontaneous infiltration method was applied in this study, and the prepared composites have a promising prospect in the field of high-temperature heat storage because of good thermal stability, high thermal conductivity, and low cost. It was found that stable anorthite ceramic phase, high porosity, and good mechanical properties could be obtained at the sintering temperature of 1150 °C. Good chemical compatibility between APC and NaCl-KCl even under high temperature was proved by X-ray diffraction (XRD) analysis. The melting temperature and enthalpy of the prepared NaCl-KCl/APC C-PCMs were measured as 655.6 °C and 79.6 J/g, respectively, by differential scanning calorimetry (DSC). The supercooling of the NaCl-KCl/APC C-PCMs was only 4.2 °C comparing to 9.6 °C for pure NaCl-KCl, which was beneficial to improve the stability and prolong the service life. The thermal conductivity of NaCl-KCl was significantly enhanced from 0.57 to 2.69 W/(m·K) at 700 °C after penetration into APC. The microstructure observed by a scanning electron microscope (SEM) showed that NaCl-KCl eutectics successfully filled the irregular holes of APC. The good wettability between NaCl-KCl and APC was conducive to the infiltration of NaCl-KCl, improving the stability of the composites and preventing leakage of the molten salt. The prepared NaCl-KCl/APC C-PCMs could retain 97% of latent heat, and no significant cracks or new phases formed even after 100 melting–freezing thermal cycle tests. In all, these findings demonstrate that the prepared NaCl-KCl/APC C-PCMs have considerable potential in concentrated solar power plant, industrial waste heat recovery, and other high-temperature thermal energy storage fields.

Research on NaCl-KCl High-Temperature Thermal Storage Composite Phase Change Material Based on Modified Blast Furnace Slag

“…Hence, effective modification of the two solid wastes becomes imperative in order to address their instability with eutectic chloride salt materials. The solid waste modification method in this study is based on reference [35], which successfully achieved the production of stable calcium feldspar ceramic phase skeleton materials through high-temperature sintering of mixed solid wastes. Therefore, in this paper, BFS was utilized as the primary material to obtain stable calcium feldspar-like ceramic phase skeleton materials.…”