During the combustion of pulverized coal, ash particles (formed from inorganic species) can deposit on heat-transfer surfaces, resulting in a decrease in heat transfer rates and system efficiency. In addition to the knowledge of the thermal conductivity of the deposits it is necessary to obtain information on the thermal radiation characteristics of the furnace walls to predict the influence of ash sedimentation on heat transfer. At the Department of Energy Plant Technology investigations on the spectral emissivity of different coal ashes and slags were performed applying a spectral radiometer. The samples were electrically heated. Temperatures were varied between 600 and 1400 °C. Emissivities in the range of wavelengths from 1 to 15 μm have been determined. An essential result is that coal ashes show selective thermal radiation characteristics. The main factor of influence on the emissivity is the chemical composition. Therefore, measurements on the single phases SiO2, Al2O3 and MgO were carried out and compared with the emissivity of typical coal ashes and slags. Furthermore, the emissivity depends on temperature, mainly in the wavelength range from 1 to 6 μm.
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ASME 2003 Heat Transfer Summer Conference
July 21–23, 2003
Las Vegas, Nevada, USA
Conference Sponsors:
- Heat Transfer Division
ISBN:
0-7918-3693-2
PROCEEDINGS PAPER
Spectral Thermal Radiation Characteristics of Coal Ashes and Slags: Influence of Chemical Composition and Temperature Available to Purchase
V. Scherer
V. Scherer
University of Bochum, Bochum, Germany
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S. Linka
University of Bochum, Bochum, Germany
S. Wirtz
University of Bochum, Bochum, Germany
V. Scherer
University of Bochum, Bochum, Germany
Paper No:
HT2003-47187, pp. 33-39; 7 pages
Published Online:
December 17, 2008
Citation
Linka, S, Wirtz, S, & Scherer, V. "Spectral Thermal Radiation Characteristics of Coal Ashes and Slags: Influence of Chemical Composition and Temperature." Proceedings of the ASME 2003 Heat Transfer Summer Conference. Heat Transfer: Volume 1. Las Vegas, Nevada, USA. July 21–23, 2003. pp. 33-39. ASME. https://doi.org/10.1115/HT2003-47187
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