Phase change performance of sodium acetate trihydrate with AlN nanoparticles and CMC

Sodium acetate trihydrate (SAT), which has high energy storage density and high thermal conductivity, is an important phase change material (PCM) for thermal storage. But it suffers from serious supercooling and phase segregation during the solidification process, and therefore its application requires the use of effective nucleating and thickening agents. In this study, AlN nanoparticles were proposed as the nucleating agent and carboxyl methyl cellulose (CMC) was selected as the thickener for SAT. The phase change temperature and the latent heat of SAT with the addition of AlN nanoparticles and CMC were measured. The results show that AlN nanoparticles can prevent supercooling of SAT significantly. For SAT with 5 wt% AlN nanoparticles and 4 wt% CMC, no supercooling phenomenon occurs, and its phase change temperature and latent heat are 52.5 °C and 227.54 kJ/kg, respectively. AlN nanoparticles and CMC additives also can improve the dehydration temperature according to the results of TG–DTA. Size distribution of AlN nanoparticles was measured by means of light scattering method. The size range is 95–300 nm, which is confirmed by environmental scanning electron microscope. The radial needle-like crystals growth process was also observed and recorded by an optical microscope.

Graphical abstractFreezing curve and crystal of pure Sodium Acetate Trihydrate (left). Freezing curve and crystal of Sodium Acetate Trihydrate with 5 wt% AlN and 4 wt% CMC (right).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► AlN nanoparticles are proposed as the nucleating agent for sodium acetate trihydrate (SAT). ► For SAT with 5 wt% AlN nanoparticles and 4 wt% CMC, no supercooling phenomenon occurs. ► Size distribution of AlN nanoparticles in SAT is in the range of 95–300 nm. ► Phase change temperature and latent heat are 52.5 °C and 227.54 kJ/kg for SAT+5 wt% AlN+4 wt% CMC.