ICHMT DIGITAL LIBRARY ONLINE

ISSN 961-91393-0-5

Year 1997

• 1Radiative Transfer II Proceedings of the Second International Symposium on Radiation Transfer - Kusadasi, Turkey, July, 1997

632 pages

Volume price - $192.00

Hans-Gerd Brummel
Siemens AG, Power Generation KWU Department: 'Total Plant Thermodynamics, Steam Generators' D-91050 Erlangen, Germany

Dieter Vortmeyer
Thermodynamics Division, Technical University of Munich, 8000 Munich 2, Germany

An available engineering model for the estimation of radiative heat transfer between gas-solid-dispersions and the surrounding walls at optically thin conditions (optical thickness < 0.3) was extended for the treatment of higher particle concentrations where the influence of backscattering cannot be ignored anymore. For this purpose the Mie-theory was applied in two different ways. First it was used to determine iteratively representative mean optical properties for fly-ashes from emission measurements, which were available for numerous ashes from European coals. In a subsequent step the mean efficiencies for absorption and backscattering for a wide range of particle sizes were calculated based on these representative fly-ash properties. Good correlation exists with comparable data obtained from published spectral optical properties measured for selected ash compositions. With the resulting mean efficiencies, inserted in the above mentioned two-flux model, the radiation of the dispersed solid phase at higher particle concentrations can be treated now with greater accuracy. For the coupling of the gas and particle radiation in the transition region between optically thin and thick conditions an empirical approach was developed, based on the determination of the maximum effective layer thickness for the radiative heat exchange between the gas-solid-dispersion and the surrounding walls.

Download article

Article price - $35.00

<< Previous article   Next article >>