Simulation of Thermal Radiation and Turbulent Free Convection in an Enclosure with a Glass Wall and a Local Heater

Abstract

In this study, a numerical modelling of thermal radiation and turbulent thermogravitational convection in a large-scale chamber containing a thermally-generating element is conducted. The lower border of the cabinet is maintained under adiabatic conditions, while on the other walls the convective boundary conditions (Robin boundary condition) are used. The managing equations with corresponding restrictions are transformed using the stream function–vorticity formulation and then solved by employing a finite difference method. The influence of both the height and wall emissivity of the heated source on fluid motion and the heat transmission in a large-scale chamber is investigated. Our results of the calculations on non-uniform grids with algebraic transformation are in excellent agreement with other available experimental and numerical outcomes for turbulent thermal convection in enclosures. The computations indicate that the average total Nusselt number is enhanced up to 2 times with an increase in the heater height. The results show that the surface emissivity of the heat source has a great influence on the total thermal transference coefficient. Furthermore, a growth of the heater surface emissivity has no significant effect on the flow structure.

Keywords

• fluid flow
• natural convection
• radiation
• computational fluid dynamics
• heat transfer intensification
• thermophysical properties