Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Comparison of the performances of the wide-band based weighted-sum-of-gray-gases and box models in the calculation of non-gray boundaries at high pressures
Submission Author:
Roberta Juliana Collet da Fonseca , RS
Co-Authors:
Roberta Juliana Collet da Fonseca, Guilherme Crivelli Fraga, Francis França
Presenter: Roberta Juliana Collet da Fonseca
doi://10.26678/ABCM.COBEM2023.COB2023-2129
Abstract
Thermal radiation is a mechanism of heat transfer that generally dominates the heat exchange in flames, furnaces and fires at high temperatures. In combustion problems, a difficulty is that typical products of the burning process (water vapor, carbon dioxide and soot) participate in the thermal exchange, absorbing, emitting or scattering radiation. In most applications, the boundaries are treated as black, which allows the decoupling of the spectral integration of the medium in relation to the surface, so that the gas models can be developed independently of the conditions at the boundary. Alternatively to the spectral integration of the radiative transfer equation (RTE) through the line-by-line (LBL) method, the spectral models reduce the computational cost, keeping the accuracy of the solution. In this paper, the wide-band based weighted-sum-of-gray-gases (WBW) model solves the radiative transfer of a participating medium with a H2O-CO2 mixture confined by non-gray walls. In this model, the spectrum is divided into bands, and the standard weighted-sum-of-gray-gases (WSGG) model is used to solve each segment. The total pressure of the system assumes values between 1 atm and 20 atm. Results show that the WBW model has a higher accuracy than conventional box models, with maximum errors of 4%.
Keywords
thermal radiation, wide-band models, box models, non-gray surfaces, high pressures
