Novel value-add recycling route of industry solid waste for acting as supporting skeleton of NaNO3 phase change materials (PCMs)

Abstract

This study provided a value-added utilization route for industrial solid waste by converting them into porous ceramics to act as supporting skeleton for PCMs. Steel slag (SS), ferronickel-slag (FNS) and Fly ash (FA) was used as main raw material to prepared anorthite-cordierite (AC) porous ceramics. Five groups of formula with different phase content were designed by adjusting the amount of SS and FNS addition. FactSage 8.0 software was applied to calculate the equilibrium phase composition of AC at high temperature, which provided guidance for the actual high temperature synthesis process. The prepared AC porous ceramics were found to have good mechanical strength and high porosity. Good chemical compatibility between AC and NaNO3 was demonstrated and the infiltration ratio was varied from 42% to 45%. In addition to high thermal storage capacity, AC has been found to help reduce the supercooling of NaNO3 and helps to improve the thermal storage performance. After 100 thermal cycles of melting and freezing, NaNO3/AC C-PCMs could maintained high than 97% of latent heat. Thermal transfer properties of AC were significantly enhanced after molten NaNO3 infiltrated. The thermal conductivity of NaNO3/AC40 C-PCMs at 25 °C reached 1.60 W·(m·K)−1, which is more than three times that of pure NaNO3. The good thermal storage performance of NaNO3/AC C-PCMs makes it potential candidate in high-temperature thermal storage fields like industrial waste heat recovery and solar energy storage. In a word, the application potential of metallurgical slag in the field of energy saving was well demonstrated by this study.