Generation of Fine Solid Particles by Desublimation in a Subsonic Nozzle Expansion

Abstract

The generation of fine solid particles by heterogeneous desublimation of succinic acid vapor is investigated experimentally and theoretically. In the experimental investigations, a gas mixture consisting of air and succinic acid vapor is cooled by means of subsonic nozzle expansion and is directly cooled by mixing. As a result of the cooling process, the gas mixture is supersaturated and the succinic acid vapor desublimes to fine particles. The number concentrations and particle size distribution of the powders generated are measured with an optical particle counter. The particle growth by desublimation is calculated with an Eulerian-Eulerian approach in a two-dimensional flow field. The population balance for the particle size distribution is solved and the mass and energy balance equations for each particle class are implemented in a CFD program (CFX 4.2).