Study on thermal properties of organic ester phase-change material embedded with silver nanoparticles

This study investigates the thermal properties of new silver nano-based organic ester (SNOE) phase-change material (PCM) in terms of latent heat capacity, thermal conductivity and heat storage and release capabilities experimentally. Spherical-shaped surface-functionalized crystalline silver nanoparticles (AgNP) prepared were embedded in mass proportions of 0.1 through 5.0 wt% into the pure (base) PCM. Experimental results reveal that dispersion of AgNP into PCM was effective, only physical and no chemical interaction between AgNP and PCM has been exhibited; thereby phase-change temperature of SNOE PCMs were acceptable. These are essential characteristics for SNOE PCMs which signified their thermal and chemical stability on long term. Test results suggest that while compared to pure PCM, degree of supercooling was reduced by 11.7-6.8 % for aforesaid mass proportions of AgNP, whereas latent heat capacities decreased by 7.88 % in freezing and 8.91 % in melting. The interdependencies between thermophysical properties in improving nucleation and growth rate of stable SNOE PCM crystals were signified and discussed. Thermal conductivity of SNOE PCMs were enhanced from 0.284 to 0.765 W m(-1) K-1 which was expected to be a 10-67 % increase for the above mass loading of AgNP. Furthermore, for SNOE PCMs enhancement span in freezing and melting cycles was improved by 41 and 45.6 %, respectively. Similarly, cooling and melting times were reduced by 30.8 and 11.3 %, respectively. Embedded AgNP helps to achieve improved thermophysical and heat storage characteristics for SNOE PCMs, which in turn can be considered as a potential candidate for cool thermal energy storage applications.