The Effect of Molecular Gas Absorption on Radiative Heat Transfer With Scattering

1982 ◽  
Vol 104 (4) ◽  
pp. 580-586 ◽  
Author(s):  
R. O. Buckius
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Wide Band ◽  
Gas Absorption ◽  
Molecular Gas ◽  
Absorption Properties ◽  
Pressure Limit ◽  
Band Absorption ◽  
Planar Medium

Radiative heat transfer in an isotropically scattering and nongray absorbing planar medium is investigated. General wide-band absorption quantities, including the effects of gray absorption and scattering by the scattering components and nongray absorption by the gaseous components, are considered. Analysis for the reflection, transmission, and emission from isothermal layers is presented. Numerical calculations are presented for the wide-band absorption quantities in the high-pressure limit. The effects of the scattering and absorption properties on the wide band absorption quantities are discussed.

Prediction of Radiative Heat Transfer in Industrial Equipment Using the Radiation Element Method

2001 ◽  
Vol 123 (4) ◽  
pp. 530-536 ◽  
Author(s):  
Zhixiong Guo ◽  
Shigenao Maruyama
Keyword(s):  
Heat Transfer ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Narrow Band ◽  
Particle Density ◽  
Three Dimensional ◽  
Wide Band ◽  
Band Model ◽  
Participating Media ◽  
Carbon Particles

The radiation element method by ray emission method, REM2, has been formulated to predict radiative heat transfer in three-dimensional arbitrary participating media with nongray and anisotropically scattering properties surrounded by opaque surfaces. To validate the method, benchmark comparisons were conducted against the existing several radiation methods in a rectangular three-dimensional media composed of a gas mixture of carbon dioxide and nitrogen and suspended carbon particles. Good agreements between the present method and the Monte Carlo method were found with several particle density variations, in which participating media of optical thin, medium, and thick were included. As a numerical example, the present method is applied to predict radiative heat transfer in a boiler model with nonisothermal combustion gas and carbon particles and diffuse surface wall. Elsasser narrow-band model as well as exponential wide-band model is adopted to consider the spectral character of CO2 and H2O gases. The distributions of heat flux and heat flux divergence in the boiler furnace are obtained. The difference of results between narrow-band and wide-band models is discussed. The effects of gas model, particle density, and anisotropic scattering are scrutinized.

The Use of the Milne-Eddington Absorption Coefficient for Radiative Heat Transfer in Combustion Systems

1977 ◽  
Vol 99 (3) ◽  
pp. 458-465 ◽  
Author(s):  
J. D. Felske ◽  
C. L. Tien
Keyword(s):  
Heat Transfer ◽  
Absorption Coefficient ◽  
Closed Form ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Wide Band ◽  
One Dimensional ◽  
Soot Particles ◽  
Closed Form Solutions ◽  
Combustion Systems

The applicability of the Milne-Eddington absorption coefficient approximation is discussed in relation to the calculation of radiative transport involving the two distinct types of species produced in combustion systems—gases and soot particles. The approximation is found to apply well to hydrocarbon soot particles and as a result analytical closed-form solutions are derived for the radiative heat transfer inside one-dimensional slab shaped soot clouds. (The applicability of the gray approximation to soot is also discussed.) For the calculation of total band radiation from gases, however, the Milne-Eddington approximation is found to be questionable. The meaning of its assumption is discussed in light of an established Curtis-Godson wide band scaling approximation. Its usefulness for real gases is then assessed through the calculation and comparison of slab radiation by both techniques.

Computation of Radiative Heat Transfer in a Cylindrical Enclosure

1996 ◽  
Author(s):  
Huiyu Fu ◽  
Ali Veshagh
Keyword(s):  
Heat Transfer ◽  
Absorption Coefficient ◽  
Combustion Chamber ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Gas Absorption ◽  
Combustion Model ◽  
Integration Scheme ◽  
Transfer Model ◽  
Zone Method

Abstract A radiative heat transfer model for cylindrical enclosure in which the gas and temperature are axi-symmetrically distributed was developed using the zone method of analysis. A rigorous numerical integration scheme was devised to calculate various types of direct exchange areas between different zones. The radiative heat transfer between gas zones and that between gas zones and surface zones could therefore be computed accurately based upon distributions of gas temperature and absorption coefficient. This radiation model was used to compute the radiative heat transfer in a diesel engine combustion chamber. Extensive soot data obtained via a sampling valve were used to calculate the gas absorption coefficient. An attempt was also made to allow for the radiation from the non-luminous gases, i.e. carbon dioxide and water vapour. Temperature distribution was obtained from a multi-zone combustion model. Results showed that the radiative heat transfer to the combustion chamber walls was negligible during the early stage of combustion, but represented a significant part of the total heat transfer when it reached its peak value. The results also showed the importance of radiative heat transfer between the various gas zones in the combustion chamber.

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