Thermal behavior of Composite Material (nanoPCM/aluminum foam) used for thermal energy storage (TES) applications

Abstract

Thermal energy storage systems (TESS) using phase change materials (PCM) have attracted interest in various fields of science and technology. However, the interest of these systems is limited by the relatively low thermal conductivity of PCMs and their leakage in the melted state. To overcome these drawbacks, the present paper suggests a new alternative for the enhancement of the PCMs by incorporating highly conductive materials, such as metal foam and/or nanoparticles. A Direct Numerical Simulation (DNS) was carried out to investigate the melting process of paraffin wax as PCM enhanced with alumina nanoparticles (i.e. nanoPCM) embedded in aluminum foam under constant temperature. A three-dimensional (3D) foam regular structure was designed. The effects of aluminum foam porosity and nanoparticles’ volume fraction on the thermal behavior of composite PCMs were investigated. The two-temperature model based on the assumption of local thermal non equilibrium was applied due to the great difference of thermal conductivity between nanoPCM and aluminum foam.The results showed that both aluminum foam and alumina nanoparticles (Al$_{{2}}$O$_{{3}}$) significantly accelerate the melting process. Furthermore, the effective thermal conductivity of composite PCM (nanoPCM/aluminum foam) drastically increased. The DNS results showed important temperature difference between PCM and metallic ligament, assuring the viability of local thermal non-equilibrium.

Keywords

• Alumina nanoparticles
• Aluminum foam
• Phase change material
• Thermal energy storage
• Direct numerical simulation