Optical Properties of Single Particles for Solar Heated Fluidized Beds.

Abstract

Experimental investigations on the optical absorption properties of solid-gas solar receivers by Sandia National Labortories in 1986 have shown some particles as good candidates for falling curtain receivers or fluidized beds. Their experiments have shown the necessity for detailed investigations of single particles and ensembles since the optical properties play a vital role for effective absorption the solar spectrum and as well as low heat losses in the infrared. At the DLR in Stuttgart an optical laboratory has been installed with the aim to develop further instrumentation and measurement techniques for determining optical scattering and absorption properties of particulates of interest in fluidized beds. An electrodynamic levitator used to "electrically suspend" single charged particles in order to measure light scattering is presented. This technique allows the determination of optical constants from a spherical, chemically inert particle of unknown chemical composition.