Prevention of deposition and agglomeration of particles in suspensions used for direct absorption of concentrated solar radiation

Abstract

In direct absorption of solar radiation for industrial purposes, by micron-size graphite particles suspended in nitrogen gas, agglomeration and deposition of these particles are the major problems. This paper discusses two methods for limitation of agglomeration and deposition. The first is to create a thermal repulsion force between the suspension and the surface to keep the particles away. The second is the surface coating of the particles with a very thin silicon-base layer of molecular order. Theoretical calculations showed that the first method required an impracticably high temperature gradient. The second method reduced the risk of deposition by about five times while negligible change occurred in the size distribution of the particles.