Preparation and thermophysical property analysis of nanocomposite phase change materials for energy storage

摘要

Paraffin wax and various nanoparticles (CuO, Al2O3 and Fe3O4) were used as matrix and heat conduction enhancer of phase change materials (PCMs), respectively. The dispersant Span 80 was added into the nanocomposite to provide stable PCMs. Based on analyses of melting and freezing curves and infrared thermal imaging tests, the phase change latent heat, viscosity, and thermal conductivity of the nanocomposite PCMs were measured. This article also analyzes the effects of heating power and fan power on heat transfer characteristics of the heat pipe with PCMs as the cooling system. Temperature of evaporator is investigated by applying PCMs energy storage. It is found that temperature fluctuations in the evaporator is alleviated by filling an adiabatic section covered with PCMs for energy storage in the cooling system. The results show that compared to pure paraffin wax, the thermal conductivity of 1.2 wt% CuO/paraffin composite PCMs increases by 24.9 % at 25 degrees C, whereas the thermal conductivity at 70 degrees C increases by 20.6 %. Compared to pure paraffin wax, the latent heat of the nanocomposite PCMs decreases by 1.5 %, the viscosity increases by 10.1 % at the melting temperature 70 degrees C. With an integrated cooling scheme, the temperature of the evaporator with 1.2 wt% nano-CuO/paraffin composites at a 2 V fan voltage is 22.0 % less than that without PCMs at a 0 V fan voltage.