Spectrally correlated radiation and laminar forced convection in the entrance region of a circular duct

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• 作者：Sediki ; EzEddine ; Soufiani ; Anouar ; Sifaoui ; Mohamed Salah
• 刊名：International Journal of Heat and Mass Transfer
• 出版年：2002
• 出版时间：December, 2002
• 年：2002
• 卷：45
• 期：25
• 页码：5069-5081
• 全文大小：640 K

文摘

The two-dimensional combined radiative and convective transfer in emitting and absorbing real gases in the entrance region of a duct with a jump of wall temperature is studied. The axial propagation of radiation is taken into account in the analysis. The flow field and the energy equations are solved simultaneously and the radiative properties of the flowing gases, CO₂ or H₂O, are modeled by using either the narrow-band correlated-k model or the global absorption distribution function (ADF) model. The results are presented in terms of temperature and radiative power fields, and of the evolution of bulk temperatures and of heat transfer coefficients. Due to the axial component of the radiative flux, the gas is preheated or precooled before the change in wall temperature and this induces a persistent difference between the results of 1-D and 2-D radiation analyses. Some differences between CO₂ and H₂O temperature and radiative power profiles, due to the different structures of their spectra, are put in evidence. The ADF model, only suitable for gray walls, is shown to be less accurate when the gas is heated than when it is cooled.