Numerical Analysis of Energy Storage Systems Using Two Phase-Change Materials with Nanoparticles

In the present work, a numerical analysis of phase-change processes was conducted using a finite element analysis. A rectangular capsule containing a phase-change material was modeled; then, the obtained results were validated using previous experimental results. After, a capsule containing two different phase-change materials with different melting points was modeled; the obtained results were validated using previous numerical results. Because of the low thermal conductivity of phase-change materials, copper and alumina nanoparticles were added to improve the system's efficiency, and the effect of adding these nanoparticles to the melting time of the phase-change materials was investigated numerically. It was observed that, when alumina nanoparticles with a volumetric fraction of 0.2 were added to the phase-change materials, the melting time was reduced by 12.5%. It was also observed that the relationship between the reduction in the melting time and the volumetric fraction of the nanoparticles added to the phase-change materials is linear. Special control systems could be manufactured using linear equations and by choosing the proper volumetric fraction of nanoparticles to control the melting time within the capsules. It was also observed that, when copper nanoparticles with a volumetric fraction of 0.2 were added to the phase-change materials, the solidification time reduced by 18.8%.