Thermal radiation of gas/solid mixtures

Abstract

Thermal radiation of gadsolid mixtures in high-temperature heat exchangers is of considerable importance for the design of heat exchange surfaces. Therefore, an experimental plant was constructed to measure solid particle emissivities, since there is a lack of relevant data in the existing literature. A theoretical equation was derived to describe the solid particle emissivity as a function of layer thickness, specific solid surface area, solid loading and absorption and scatter coefficients. Measurements were carried out for fluidized bed ash and quartz sand. The emissivities of these particle fractions increase with increasing layer thickness, solid loading, specific solid surface area and temperature. The description of these data by the derived model equation is very satisfactory. No dependence on wavelength was observed. The ash components do exert some influence which, for the present, cannot be described exactly.

Metal Dust Explosion Hazards: A Technical Review

“…Particle emissivity contributes significantly to the radiative heat flux that exists throughout the combustion zone. As described in experiments by Elsner et al, the particulate emissivity of solid organic fuels (ash and quartz sand) is complex and dependent on a variety of factors including dust cloud thickness, primary particle specific surface area, solid loading (or dust concentration), adsorption factors, and scatter coefficients …”

“…As described in experiments by Elsner et al, the particulate emissivity of solid organic fuels (ash and quartz sand) is complex and dependent on a variety of factors including dust cloud thickness, primary particle specific surface area, solid loading (or dust concentration), adsorption factors, and scatter coefficients. 37 As demonstrated in eq E3, the Stefan−Boltzmann law describes the flux of energy (j) radiated across all wavelengths per unit surface area of a blackbody per unit time:…”