Convective heat transference of non-Newtonian functional phase variation nano-encapsulated liquids

Abstract

Convective flowing and heat transference of non-Newtonian liquid comprising nano-encapsulated phase-changing material (NEPCM) suspensions, filled in a square cavity, is numerically investigated. The molecules of NEPCM are cored with n-octadecane, shelled by polymethyl-methacrylate, and suspended in non-Newtonian fluid. The enclosure is insulated horizontally and heated vertically. Finite element method (FEM) is implemented for the numerical solution under different variables such as nanoparticles volume fraction (0<<0.05), Stefan number (Ste=0.2,0.313,0.5), the heat capacity ratio (λ) of about (0.4), the temperature of fusion of the NEPCM (0<θf<1) and the density ratio (ρPρf) (0.7<ρPρf≤0.9). The results show that the Nusselt quantity is related to the fusion temperature. An improvement in heat transference is observed when the fusion temperature deviates from the wall temperature, which is in the range of 0.25<θf<0.75. For all power law index values (n), a linear increase of the Nusselt number with the solid volume fraction is detected. The shear-thinning nanofluid (n=0.6) demonstrates higher Nusselt number values than those of n=1 and 1.4