The influence of friction factor on the combined convective and radiative heat transfer in a rectangular duct with interior circular core

Abstract EN

The effect of friction factor on the steady state natural convective – radiative heat transfer in an inclined rectangular channel with concentric circular core is investigated from continuity, momentum and energy equations.

These equations are normalized and solved using the Vorticity-Stream function and the Body Fitted Coordinates (B.F.C) methods.

The finite difference approach with the Line Successive Over-Relaxation (LSOR) method is used to obtain all the computational results.

The (B.F.C) method is used to generate the grid of the problem.

A computer program (Fortran 90) is built to calculate the Nusselt number (Nu) and friction factor f in steady state flow for thermal boundary condition of constant wall temperature and for aspect ratio AR (0.55-1) and geometry ratio GR (0.1-0.9).

The fluid Prandtl number is Pr = 0.7, Rayleigh number (0 ≤ Ra ≤ 104), Reynolds number (1 ≤ Re ≤ 2000), Optical Thickness (0 ≤ t ≤ 10), Conduction- Radiation parameter (0 ≤ N ≤ 100) and Inclination angle (0° ≤ λ ≤ 90°).

The results show reasonable representation to the relation between Nusselt number and friction factor with other parameters (AR, GR, and Re, Ra, λ, t and N).

Generally, Nu will be increased with increasing Ra, t, N, λ, and Re.

In the same time, fRe will be increased when Re and GR increase and AR decrease.

The effect of radiation on the bulk temperature is concluded by correlation equations.