Abstract
Monochromatic radiative properties of anisotropically scattering fly-ash polydispersions in combustion gas, such as an extinction coefficient, a scattering coefficient, a scattering albedo and Legendre expansion coefficients for a phase function, are calculated by the Mie scattering computer code with the monochromatic complex refractive index measured and arranged in a wavelength region of 0.7∼13μm and with a measured or an estimated bimodal particle distribution of fly-ash. Extinction and absorption coefficients calculated for fly-ash polydispersions closely agree with the results obtained by a small-particle (x«1) approximation when the Sauter diameter D32 for polydispersions is much smaller than the incident wavelength (x32<0.1). They also agree with the approximations of the complex refractive index near 1(|m-1|«1) when D32 is much larger than the wavelength (x32>10) ; in the intermediate region (0.1<x32<10), however, exact Mie scattering calculations are required.
