Metal Oxide Nanoparticle Dispersed-Polyethylene Glycol: Thermal Conductivity and Thermal Energy Storage Properties

Polyethylene glycols as phase change materials (PCMs) have good latent heat storage (LHS) characteristics, but the low thermal conductivity property significantly hinders their usage potential in thermal energy storage (TES) applications. Within this framework, four different metal oxide nanoparticles (Al2O3, CuO, TiO2, and ZnO) dispersed-PEG as thermal conductivity enhanced PCMs were developed for TES purposes. Sediment photographs and scanning electron microscopy/energy dispersive spectroscopy (SEM/EDX) analysis results showed excellent stability of the composites. The Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD) diffractograms proved that no chemical interaction happened between the MONPs and PEG. Thermal conductivity of PEG was enhanced by 1.27–1.34 times after loading of 2 wt % MONPs as well as significantly reduced their heat charging/discharging periods. The differential scanning calorimeter (DSC) measurements indicated that the phase change temperatures of the composites shifted between −1.1 and +5.6 °C, while the reduction in the TES capacity was varied in the range of 1.0–5.1% relative to the PEG. The composites demonstrated good cycling chemical stability and TES reliability. Thermal enhanced properties make the developed composites useful PCMs for TES implantations.