Natural Convection in Concentric Enclosed Cavities
Laís Ferreira Oton1; Francisco Marcondes1; Rebeca Pereira Marcondes1
1 Federal University of Ceará
doi:10.20906/CPS/CILAMCE2017-0439
Resumo
Due to the large spectrum of application in engineering, natural convection in enclosed cavities has been widely investigated that include cooling of fluids, ventilation of buildings, food processing and storing, solar collectors, refrigeration of heated surfaces. The study of natural convection in elliptical and cylindrical concentric cavities has received a lot of attention by the scientific community. However, square concentric cavities in which the internal cavity is heat by Joule's effect and it is cooled by natural convection by fluid confined in the concentric cavity has not been investigated yet. This configuration can be viewed as a first approximation of the complex heat transfer phenomenon that take place in electrical transformers. This research consists in the study of the heat transfer in a square concentric cavity with incompressible two-dimensional flow, whose core is heated through the Joule's effect and is cooled by natural convection by the fluid that resides in the concentric cavity. Basically there are two domains: The nucleus that is governed by the diffusion of heat with internal source from the dissipation of energy by the Joule's dissipation and the concentric cavity that filled with a fluid and is characterized by natural convection. For the concentric cavity, we assumed a turbulent natural convection that is model with the k-ε and k-ω models. The governing equations in both domains are solved using the ANSYS CFX software. We assume that the external walls of the cavity are isothermal, and we force the energy balance for the internal wall of the concentric cavity. As the internal temperature of the cavity is one unknown of the problem, we have an iterative procedure to obtain the steady-steady solution in both domains. The results are presented in terms of isotherms, streamlines and local and average heat flux for several Prandtl numbers.
Palavras-chave: Turbulent flow; Natural convection; Concentric enclosed cavities; Element based Finite-Volume Method