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.
Highlights
The study of convective–radiative heat transfer is extremely important for various fields of modern science and technology, such as mechanical engineering, microelectronics, building design, and nuclear technologies
In many works devoted to convective heat transfer in closed cavities, the influence of the radiative mechanism of energy transfer has not been taken into account due to the difficulties associated with modeling radiation or due to its insignificant influence on the circulation structure and energy transfer in some engineering applications [1,2,3,4,5]
Thecombined combined influence influence of of thermogravitational thermogravitational convection The convection and and surface surfacethermal thermalradiraation onon hydrodynamic andand energy transmission withinwithin a rectangular large-scale chamber diation hydrodynamic energy transmission a rectangular large-scale containing a local heat-generating element was studiedwas numerically this work. in Thethis obchamber containing a local heat-generating element studied in numerically tained outcomes were found to be in excellent agreement with other available experimental work
Summary
The study of convective–radiative heat transfer is extremely important for various fields of modern science and technology, such as mechanical engineering, microelectronics, building design, and nuclear technologies. The significant interest in this type of research is due, first of all, to its primary importance for understanding the physical processes taking place in modern energy and in technological structures of various kinds. In this regard, the combination of thermogravitational convection and surface radiation in chambers is the subject of many theoretical and experimental works, the number of which is rapidly increasing due to the development of methods of mathematical modeling and improvement of computing technology, along with improved visualization and methods for measuring experimental data. If the temperature of such a surface is high enough or if the fluid flow occurs at a relatively low velocity (for example, thermogravitational convection), the contribution of the radiation component can be quite significant
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