A Modified Exponential Wide Band Model for Gas Emissivity Prediction in Pressurized Combustion and Gasification Processes

2018 ◽  
Vol 32 (2) ◽  
pp. 1634-1643 ◽  
Author(s):  
Linbo Yan ◽  
Yang Cao ◽  
Xuezheng Li ◽  
Boshu He
Keyword(s):  
Wide Band ◽  
Band Model ◽  
Pressurized Combustion ◽  
Wide Band Model

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.

Radiation Modeling in Oxy-Fuel Combustion Scenarios

2009 ◽  
Author(s):  
Gautham Krishnamoorthy ◽  
Muhammad Sami ◽  
Stefano Orsino ◽  
Anura Perera ◽  
Mehrdad Shahnam ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Wide Band ◽  
Full Scale ◽  
Radiative Properties ◽  
Band Model ◽  
Particle Radiation ◽  
Gas Radiation ◽  
Gaseous Media ◽  
Wide Band Model ◽  
Radiation Modeling

Three gray models for the radiative properties of gases were examined for their usage in oxy-combustion simulations of a full scale boiler with flue gas recycle. Fully coupled computational fluid dynamic (CFD) simulations of a full scale boiler were carried out employing the weighted-sum-of-gray-gases model (WSGGM) at air burn, dry-recycle and wet-recycle conditions. The resulting thermal and composition fields were then frozen and the radiative properties of the gaseous media recomputed employing the Exponential Wide Band Model (EWBM) and correlations for total emissivities of gas mixtures. It is shown that when high CO2/H2O ratios were encountered within the boiler such as in dry-recycle scenarios, employing emissivity correlations developed for purely CO2 media within the models can result in incorrect gas properties. The errors associated with this can be significant when there are large pockets within the furnace where the gas radiation dominates the particle radiation.

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