Energizing organic phase change materials using silver nanoparticles for thermal energy storage

Medium temperature phase change materials (PCMs) are of great interest for thermal devices due to their energy storage capability. In the current study, organic PCMs with silver nanoparticles are experimentally investigated and energized to improve the energy storage ability. Organic PCM composites with silver metal nanoparticles of 20–40 nm in size at different concentrations of 0.2 %, 0.4 %, 0.6 %, 0.8 % and 1.0 % were prepared and characterized to explore the thermophysical properties. Scanning electron microscopy observations provides a higher magnification level to ensure the presence of Ag nanoparticles in the PCM matrix. Optical investigation confirms that the permeability of PCM with Ag nanoparticle decreases from 22.7 % to 15.9 % at a concentration of 0.8 %, which increases the absorptivity; this phenomenon is due to the dark colour of the silver nanoparticle. Thermal conductivity of Ag dispersed composite improved the thermal conductivity of the base material PCM from 0.218 W/mK to 0.44 W/mK with a mass fraction of 0.8 % of nanoparticles, resulting in an improvement of 101 %, which can be attributed to the well-developed thermal networks with the PCM matrix. The latent heat of the composite PCM differs by 1 % from the base PCM, which is important for effective energy storage due to better intermolecular attraction. The Ag dispersed composites were also thermally stable up to a temperature of 220 °C and their thermal stability was slightly improved by the nanoparticles. Composite PCM samples with better thermal conductivity were tested for 500 thermal cycles and its chemical stability and thermal properties were equated with PCM. In addition, a numerical heat transfer analysis is performed under varied heat sources (60 °C, 70 °C & 80 °C) to compare the thermal performance between PCM and the synthesized nano PCM. In correspondence to the experimental characterization and numerical investigation the silver nanoparticle dispersed PCM exhibits outstanding energy storage & release routine, ensuring the beneficial usage of developed composite PCM in TES applications like battery thermal management and solar photovoltaic thermal systems.