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, AIM 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 AIM nanoparticles and CMC were measured. The results show that AIM 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 degrees 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. (C) 2011 Elsevier B.V. All rights reserved.