Simple Expression for the Emittance of H2O-CO2 Mixtures in Zonal Methods of Radiation Transfer Modelling

2013 ◽  
Author(s):  
German Malikov ◽  
Alexandr Titaev ◽  
Vladimir Lisienko ◽  
Raymond Viskanta
Keyword(s):  
Radiation Transfer ◽  
Wide Band ◽  
Gas Mixtures ◽  
Simple Expression ◽  
Computational Time ◽  
Band Model ◽  
Combustion Gas ◽  
Transfer Modelling ◽  
Wide Band Model ◽  
Total Emittance

A new and simple expression for the calculation of the total gas emittance of H2O-CO2 mixtures for modeling radiation transfer in combustion furnaces is presented. Its accuracy is established by comparing the predictions with those based on the well established exponential wide band model. The computational time was found to be reduced by a factor of 10–30 in comparison to other methods for computing the total emittance of combustion gas mixtures.

Simple Expression for the Emittance of H2O–CO2 Mixtures in Zonal Methods of Radiation Transfer Modeling

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Lisienko Vladimir ◽  
Malikov German ◽  
Titaev Alexander ◽  
Raymond Viskanta
Keyword(s):  
Radiation Transfer ◽  
Gas Mixtures ◽  
Simple Expression ◽  
Computational Time ◽  
Combustion Gas ◽  
Model Based ◽  
Total Emittance

A new and simple expression for the calculation of the total gas emittance of H2O–CO2 mixtures for modeling radiation transfer in combustion furnaces is presented. Its accuracy is established by comparing the predictions with those based on the well established the model based on Hitemp database. The computational time was found to be reduced by a factor of 3 in comparison to other methods for computing the total emittance of combustion gas mixtures.

Prediction of Radiative Transport in Nonhomogeneous Combustion Gas Mixtures With a Wide Band G(K) Model

2013 ◽  
Author(s):  
Liping Liu ◽  
Jing He
Keyword(s):  
Radiative Transfer ◽  
Narrow Band ◽  
Gaussian Quadrature ◽  
Wide Band ◽  
Gas Mixtures ◽  
Source Distribution ◽  
Distribution Model ◽  
Band Model ◽  
Radiative Transport ◽  
Combustion Gas

A wide band cumulative absorption coefficient distribution, g(k), model is adopted to predict radiative transport in combustion gas mixtures. Prior research has demonstrated similar accuracy of the model to the statistical narrow-band model and superiority to the exponential wideband model under isothermal and homogeneous conditions. This study aims to assess its usefulness in nonhomogeneous media. Sample calculations are performed in a 1D planar slab containing H2O/CO2 mixtures. The six-flux discrete ordinate method (S6-DOM) is employed to solve the radiative transfer equation (RTE), followed by an eight-point Gaussian quadrature of moments with zeroth-order fit. Predictions on the radiative source distribution along the slab and the net radiative flux at the walls are compared to the benchmark line-by-line calculation (LBL) and the statistical narrow-band correlated-k distribution model using the 7-point Gauss-Lobatto quadrature scheme (SNBCK-7). The differences between the g(k) model and LBL are below 5% for a large domain of the layer, with a CPU reduction by a factor of over 30 compared to SNBCK-7 and on the order of 104∼105 compared to LBL. The wide band g(k) model shows significant promise as an accurate and efficient tool to predict radiative transfer in nonhomogenerous media for combustion and fire simulations.

scholarly journals Influence of the Spectral Model of Radiation on the Calculated Characteristics of Complex Heat Exchange in Flame Furnaces of the Petrochemical Industry

2020 ◽  
Vol 6 (6) ◽  
pp. 42-47
Author(s):  
A. Abdullin
Keyword(s):  
Petrochemical Industry ◽  
Wide Band ◽  
Combustion Products ◽  
Heat Fluxes ◽  
Spectral Model ◽  
Band Model ◽  
Total Heat Transfer ◽  
Complex Heat Exchange ◽  
Tube Furnaces ◽  
Wide Band Model

The influence of the spectral model of radiation on heat fluxes and the temperature of combustion products in the radiant chambers of tube furnaces of the petrochemical industry is analyzed. A wide-band model and a Hottel gray model are considered. It is shown that the spectral model of the combustion medium radiation weakly affects the calculated characteristics of the total heat transfer.

Nongray Radiative Gas Analyses Using the S-N Discrete Ordinates Method

1991 ◽  
Vol 113 (4) ◽  
pp. 946-952 ◽  
Author(s):  
T. K. Kim ◽  
J. A. Menart ◽  
H. S. Lee
Keyword(s):  
Radiative Heat ◽  
Narrow Band ◽  
Wide Band ◽  
Heat Fluxes ◽  
Discrete Ordinates ◽  
Band Model ◽  
Spectral Correlation ◽  
Discrete Ordinates Method ◽  
Computational Speed ◽  
Wide Band Model

The S-N discrete ordinates method is applied to analyze radiative heat transfer in nongray gases. Spectral correlation between the terms in the equation of transfer is considered for black or nearly nonreflecting walls. Formulations to apply the S-N method using a narrow-band or the exponential wide-band model are presented. The net radiative wall heat fluxes and the radiative source distributions are obtained for uniform, parabolic, and boundary layer type temperature profiles, as well as for a parabolic concentration profile. The narrow- and wide-band nongray solutions are compared with gray-band approximations using the same band models. The computational speed of the gray-band approximation is obtained at the expense of accuracy in the internal fluxes and radiative source distributions. The wall radiative flux predictions by the gray-band approximation are satisfactory.

Evaluation of Coefficients for the Weighted Sum of Gray Gases Model

1982 ◽  
Vol 104 (4) ◽  
pp. 602-608 ◽  
Author(s):  
T. F. Smith ◽  
Z. F. Shen ◽  
J. N. Friedman
Keyword(s):  
Partial Pressure ◽  
Path Length ◽  
Wide Band ◽  
Band Model ◽  
Weighted Sum ◽  
Gas Temperature ◽  
Temperature Dependent ◽  
Polynomial Coefficients ◽  
Wide Band Model ◽  
Total Emissivity

The weighted sum of gray gases model postulates that total emissivity and absorptivity may be represented by the sum of a gray gas emissivity weighted with a temperature dependent factor. The gray gas emissivity is expressed in terms of a temperature-independent absorption coefficient, absorbing gas partial pressure, and path length. The weighting factors are given by polynomials in gas temperature with associated polynomial coefficients. For absorptivity, a second polynomial for the irradiation temperature is introduced. A regression scheme is employed to fit the model to total emissivity and absorptivity values obtained from the exponential wide-band model. Absorption and polynomial coefficients are reported for carbon dioxide, water vapor, and mixtures of these gases. The model with these coefficients more accurately represents the total properties over a wider range of temperatures and partial pressure-path length products than previously available coefficients.

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