Preparation and thermal properties of palmitic acid/copper foam phase change materials

Phase change materials (PCMs) are promising options of thermal energy storage mediums. However, their low thermal conductivity and leakage issues remain the setback and limits the practical applications. In this work, Palmitic acid (PA)/copper foam (CF) composite PCMs have been prepared using the melting-vacuum impregnation method, with PA serving as the phase change material (PCM) and CF as the supporting material. The surface of CF with pore sizes of 15, 20, 25, 30 and 35 PPI (pores per inch) has been chemically modified with hydrochloric acid to increase the surface roughness of CF, strengthening the adsorption capacity of CF skeleton structure for PCM. The melting temperature and the latent heat of PA/CF composite PCMs were measured by differential scanning calorimeter (DSC) to evaluate the heat storage performance. The charging/discharging properties of the PA/CF composite PCMs have been experimentally investigated. At the same time, the solidification process of PA/CF composite PCMs was tested and analysed using infrared imaging technology. The introduction of CF to form composite PCM not only improves greatly the thermal conductivity of PCM but also prevents the leakage. The thermal conductivities of PA/CF composites have obtained a significant enhancement. The composite PCM based on 15 PPI CF has the highest thermal conductivity of 5.112 W/(m∙K), which is more than 31 times higher than that of pure PA. The 15 PPI sample melts at 61.4 °C with a latent heat of 174.788 kJ/kg and possesses the fastest charging/discharging rate. Besides, the prepared samples behave uniform temperature distribution and perfect shape-stabilization when cooled. The prepared samples have the high thermal conductivity and fast thermal response rate, and could play a crucial role in the field of heat storage and thermal management of electronic devices.