Thermal characterization of NaNO.sub.3/KNO.sub.3 with different concentrations of Al.sub.2O.sub.3 and TiO.sub.2 nanoparticles

• Published in: Journal of thermal analysis and calorimetry 2019-04, Vol.136 (1), p.235
• Main Authors: Raja Jeyaseelan, T, Azhagesan, N, Pethurajan, Vignesh
• Format: Article
• Language: English
• Subjects: Calorimetry; Electric properties; Force and energy; Heat storage; Nanoparticles; Physical instruments; Thermal properties
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-018-7980-6

The thermo-physical properties of NaNO.sub.3/KNO.sub.3 (solar salt) added with Al.sub.2O.sub.3 and TiO.sub.2 nanoparticles as phase change material in thermal energy storage system were investigated. Initially the Al.sub.2O.sub.3 and TiO.sub.2 nanoparticles were added to NaNO.sub.3/KNO.sub.3 (60:40) with a concentration of 1%, 3% and 5 mass% using low-energy ball mill. The differential scanning calorimetry instrument is used to measure the thermal properties of the prepared PCM composites. It is found that the phase change temperature and latent heat capacity vary with Al.sub.2O.sub.3 and TiO.sub.2 nanoparticles loading levels. When the loading is not over 3 mass% of Al.sub.2O.sub.3, the phase change temperature drops, and the latent heat capacity increases up to 23.3%. When the loading is over 3 mass% of Al.sub.2O.sub.3, the phase change temperature increases, and the latent heat capacity drops to 14.23%. A significant increase in latent heat capacity is found around 3 mass% of Al.sub.2O.sub.3 loading. When the TiO.sub.2 nanoparticle concentration increases, the phase change temperature decreases, and the latent heat capacity increases up to 32.2%. When the TiO.sub.2 nanoparticle's concentration decreases, the phase change temperature increases, and the latent heat capacity decreases. The thermal conductivity of the composites was found to increase with the increase in the loading of nanoparticles. After adding 3% by mass of Al.sub.2O.sub.3 and TiO.sub.2 nanoparticles, the thermal conductivity was found to increase by 8.30 and 8.10%, respectively. From the characterization studies, we found that TiO.sub.2 helps to achieve the improved thermo-physical properties and heat storage characteristics for NaNO.sub.3/KNO.sub.3 which suggests their potential candidate of usage in the thermal energy storage system.