Radiative Transfer in Packed Fluidized Beds: Dependent Versus Independent Scattering

Abstract

Experimental measurements are compared with theoretical predictions for radiative transfer in suspensions of 11.0 μ dia Dow latex particles using 0.6328 μ He-Ne laser light. Both absorbing and nonabsorbing particles are studied with particle volume fraction ranging from 0.01 to 0.7 (close-packed). Predictions based on the classical assumptions that particles act as independent point scatterers are shown to give close agreement with experimental data even for close-packed conditions, as long as the interparticle clearance is greater than about 0.3 wavelengths. Evidence is presented indicating that interparticle spacing measured in wavelengths is the most critical parameter to gauge the importance of dependent scattering and that high particle concentration alone is no indication that scattering is dependent. The results have direct application to the design of packed/fluidized bed systems wherein thermal radiation is a significant heat transfer mode.