Heat transfer and fluid flow analysis using nanofluids in diamond-shaped cavities with novel obstacles

Abstract

This work computationally explores the two-phase flow of nanofluids and their thermal energy transport coefficients in 3D diamond-shaped cavities with square-shaped barriers having reducing dimensions. Materials with two emissivity values, ε = 0.3 and 0.9, have been considered to investigate the effect of the radiation thermal energy transport coefficient while the hot side is maintained at 400 or 500 K. Two values of the Rayleigh number, Ra = 10 6 and 10 8 , are used for the study. Cu nanoparticles (NPs) with an average size of 25 nm have been used at a concentration of 0.01-0.05% in the base fluid. The temperature gradients and thermal energy transport coefficient characteristics are enhanced by raising the volume concentration of nanoparticles, but the streamlines do not alter substantially. By increasing Ra, the thermal energy transport coefficient rate is further augmented. It is also found that increasing the Ra and volume concentration of NPs results in enhanced heat transfer inside a cavity, while a change in the emissivity coefficient has no significant impact on the thermal and flow characteristics of the nanofluid. For each case, there is an optimum NP volume fraction for each model that leads to the highest Nusselt number.

Obstacle's effects and their location inside the square cavity on the thermal performance of Cu–Al2O3/H2O hybrid nanofluid

“…Aghaei et al 10 examined the two‐phase flow and heat energy transmission coefficients of nanofluids in diamond‐shaped cavities with square‐shaped barriers in three dimensions. They examined the influence of the radiation thermal energy transit coefficient using two values of Ra = 10 6 and 10 8 .…”

“…ave L 0 1 (10) 49 to our numerical results for the isothermal in the cavity with central obstruction placement for Ra = 10 6 .…”