Heat transfer enhancement for combined convection flow of nanofluids in a vertical rectangular duct considering radiation effects

Abstract

In this paper, combined convective heat transfer and nanofluids flow characteristics in a vertical rectangular duct are numerically investigated. This investigation covers Rayleigh numbers in the range of 2 × 10 6 ≤ Ra ≤ 2 × 10 7 and Reynolds numbers in the range of 200 ≤ Re ≤ 1000. Pure water and five different types of nanofluids such as Ag, Au, CuO, diamond, and SiO 2 with a volume fraction range of 0.5% ≤ ϕ ≤ 3% are used. The three-dimensional steady, laminar flow, and heat transfer governing equations are solved using finite volume method (FVM). The effects of Rayleigh number, Reynolds number, nanofluids type, nanoparticle volume fraction of nanofluids, and effect of radiation on the thermal and flow fields are examined. It is found that the heat transfer is enhanced using nanofluids by 47% when compared with water. The Nusselt number increases as the Reynolds number and Rayleigh number increase and aspect ratio decreases. A SiO 2 nanofluid has the highest Nusselt number and highest wall shear stress while the Au nanofluid has the lowest Nusselt number and lowest wall shear stress. The results also revealed that the wall shear stress increases as Reynolds number increases, aspect ratio decreases, and nanoparticle volume fraction increases.

Numerical Investigations on the Advantage of Nanofluids under DDMC in a Lid‐Driven Cavity

“…A comprehensive study on nanofluid heat transfer characteristics and their applications can be found in Chitra and Sendhilnathan [1], Godson and colleagues [2], and Sarkar [3]. Many investigations [4][5][6][7] explained that nanofluids clearly exhibit enhanced thermal conductivity, which augments with an increase in the volumetric fraction of nanoparticles. Hwang and colleagues [8] from their research observed that heat transfer coefficient of a nanofluid decreases with an increase in the size of nanoparticles, in a natural convection case in a rectangular cavity using Al 2 0 3 nanoparticles.…”