Numerical study of natural convection and radiation exchange in an asymmetrically heated inclined channel

Abstract

Introduction: In this paper, numerical study is carried out to investigate natural convection and radiation heat transfer in an asymmetrical heated inclined air channel with open ends. The Reynolds-averaged Navier–Stokes equations are solved using a commercial computational fluid dynamics solver ANSYS-FLUENT© in conjunction with the discrete ordinate radiation model. Simulations were run considering the channel with inclination angle to horizontal in the range 18° to 45° and a wall surface emissivity of 0.27–0.95. The channel length to channel space ratio was selected in the range 44–220. A uniform heat flux in the range 100–500 W/m2 was applied along the upper wall of the channel while the lower wall and side walls were assumed thermally insulated. Results: Temperature profiles along the upper and lower walls of the channel were obtained with variations in the channel length to space ratios, angles of inclination, radiation emissivity, and input Ohmic heat flux. The effect of various parameters on the maximum wall temperature and heat transfer was investigated. The numerical predictions are validated by comparison with the experimental data available in literature. Conclusion: The numerical results obtained are found in good agreement with the experimental measurements. From the numerical results, a correlation of local and average Nusselt number with modified channel Rayleigh number in the range of 101–105 is developed at asymmetric heat flux boundary conditions. Nu = 0.6851Ra” 0.2612