Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Hybrid integral transforms for analysis of combined laminar forced convection and thermal radiation
Submission Author:
Dhiego Veloso , PB , Brazil
Co-Authors:
Dhiego Veloso, Carlos Antonio Cabral Santos, Fábio Lima, Gustavo Assad, Igor Silveira, Ryan R de Azevedo
Presenter: Dhiego Veloso
doi://10.26678/ABCM.COBEM2023.COB2023-0437
Abstract
Many engineering applications are capable of producing high temperature exhaust gases, making analysis of the flow of participating fluids relevant and necessary in different situations, such as: fire-tubes boilers, propulsion systems, turbocharged engines, among others. At high temperature levels, thermal radiation plays a key role in the fluid's internal heat transfer process, as well as in the heat exchange between the fluid and surrounding surfaces; the omission of the radiative effect gives an appreciable error in computing the heat transfer rate. The present work aims to analyze the heat transfer in laminar flow of participating fluids inside circular and rectangular ducts. Its about a problem of simultaneous heat transfer by convection and radiation, hydrodynamically developed and thermally developing. The fluid is treated as gray, purely absorber and emitter of thermal radiation. The duct wall is considered gray and perfectly diffused, being maintained at constant temperature. In the present study, a differential approximation is used to model radiative transference, based on the method of moments, in accordance with some works found in the specialized literature. A hybrid method, numerical-analytical, called Generalized Integral Transformation Technique (GITT), is applied to simultaneously solve the energy equation and the radiative transfer equation. Three different strategies are used to solve the problem, all of them through integral transformations, which are compared with each other and demonstrate the versatility of GITT. The results, presented in the form of tables and graphs, allow to analyze the influence that the parameters conduction-radiation, optical thickness and contour surface emissivity exert in the temperature field and in the Convective, Radiative and Total Nusselt numbers. The significance of the thermal radiation and the behavior of the convective process with and without the inclusion of the radiation is investigated. The results obtained in the present work were confronted with existing ones in the open literature, in order to validate the presented model.
Keywords
Participating fluids, GITT, temperature field, Nusselt numbers
