Experimental Study on a Novel Form-Stable Phase Change Material Based on Solid Waste Iron Tailings as Supporting Material for Thermal Energy Storage

To prevent liquid leakage during the phase transition of a phase change material (PCM), a novel form-stable PCM (FSPCM) based on LA/CIT/CNT was fabricated using a simple and facile direct impregnation method. The iron tailings (ITs) was calcinated at first. And then lauric acid (LA) was impregnated into the calcinated iron tailings (CITs) with carbon nanotubes (CNTs) as a thermal conductivity additive. Subsequently, the leakage tests and the properties of the prepared samples were investigated by diffusion-oozing testing (DOT), SEM, XRD, FTIR, DSC, TGA, and intelligent paperless recorder (IPR). DOT results showed that the impregnation ratio of LA into the CIT and CNT was up to 27.5% without leakage. SEM indicated that LA can be adsorbed into microscale pores and covered the surface of CITs and CNTs. FTIR spectra indicated that there was no chemical reaction during the preparation process. The melting and freezing temperatures of the prepared LA/CIT/CNT FSPCMs were measured as 45.24 °C and 39.61 °C, respectively. Correspondingly, the latent heat values were determined as 39.95 J/g and 35.63 J/g, respectively. The LA/CIT/CNT FSPCMs exhibited good thermal stability in the working temperature range, and its heat transfer efficiency was improved significantly by 69.23% for LA and 84.62% for LA/CIT FSPCM. In short, LA/CIT/CNT FSPCMs are a very promising material for thermal energy storage in practical low-temperature applications.