Performance enhancement of nano PCM solidification in a hexagonal storage unit with innovative fin shapes dealing with time-dependent boundary conditions

Abstract

The effect of innovative branching fins and nanoparticles as direct and indirect heat transfer augmentation methods on the solidification of a PCM within a hexagonal storage unit was numerically investigated in this research. A time-dependent boundary condition of the third kind is applied to the cold walls which let us investigate the influences of the amplitude and periodicity of the ambient temperature variation on the phase-change process during the time-dependent boundary conditions. Also, the exergy efficiency of the system is analyzed by conducting an exergy analysis. In the indirect method, nano-enhanced PCM is made by dispersing CuO nanoparticles to it. Furthermore, the finite element method was employed to simulate the procedure. The results of the current parametric study depicted that the addition of innovative fins, with a 30% decrement in the full solidification time, was a more effective method than making nano-enhanced phase change material, which at best (ϕ=0.04) had a 14.5% reduction in the full solidification time. Moreover, a reduction of about 3% in release exergy efficiency is obtained by raising the HTF from 240 K to 260 K. Additionally, it was found that augmenting the amplitude and duration of the cold wall would speed up the solidification process.