Radiative properties of char, fly-ash, and soot particles in coal flames. Technical progress report, 2nd year, September 15, 1993--September 15, 1994
A detailed understanding of pulverized-coal combustion process is crucial to developing more efficient and cost-effective combustion chambers and furnaces that use coal as the primary source of energy. Several complicated phenomena occur simultaneously in pulverized-coal flames, and radiation heat transfer is only one of them. However, the contribution of radiation to total heat transfer can be as high as 90% at large-scale pulverized-coal fired furnaces. Because of this, modeling of radiation heat transfer requires special consideration. In predicting the radiative heat flux distribution in combustion systems, three important problems must be considered simultaneously: (i) mathematical formulation and solution of the radiative transfer equation (RTE), (ii) modeling of spectrally banded radiation from the combustion gases, and (iii) modeling of continuum radiation from the particles such as pulverized coal, char, fly-ash, and soot in the combustion products. The accuracy of the solution to the RTE depends on the accuracy of the radiative properties of the medium used in the analysis. Mathematical models for the radiative properties of combustion gases, such as water vapor and carbon dioxide, are well established. Particle radiative properties, i.e. for pulverized coal, fly-ash, and soot, are more critical than those of combustion gases, because particles absorb, emit and scatter radiation within the entire wavelength spectrum, while gases contribute only in certain spectral bands. State-of-the-art reviews of the radiative property data of particles have been given by Viskanta and Menguec (1987), Sarofim (1988), Blokh (1988), and Menguec and Webb (1993). It is sufficient to say that there is no agreement between different researchers on the complex index of refraction of coal/char and soot particles; although, for fly-ash particles the available data are quite reliable (Goodwin, 1986).
- Research Organization:
- Kentucky Univ., Lexington, KY (United States). Dept. of Mechanical Engineering
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG22-92PC92533
- OSTI ID:
- 10196009
- Report Number(s):
- DOE/PC/92533--9; ON: DE95003532
- Country of Publication:
- United States
- Language:
- English
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