Numerical Solution of the Kinetic Equation for the Size Distribution Function of Particles with Regard for Their Coagulation

As an alternative to the known sorption methods used for the cleaning of gases from impurities, the volume condensation of carbon dioxide from its mixture with air in the divergent part of a Laval nozzle is considered. This process is defined by the kinetic equation for the size (mass) distribution function of particles, in which the Brownian coagulation of particles is estimated in the two-temperature approximation and which, in the one-dimensional form, is solved by the direct numerical method and, in the three-dimensional form, with the use of the special computational module "Volume Condensation" integrated into the computational CFD package. The distributions of parameters of condensing aerosol along the central axis of the nozzle with and without coagulation of its particles have been obtained. It is shown that, as a result of the coagulation of particles in this aerosol, their number in it decreases. In this case, the size of the particles increases, but their mass remains unchanged. It was established that the contribution of the coagulation of particles in a vapor–gas mixture into their growth exceeds 10% and increases with a rate of expansion of a mixture flow. The results obtained agree qualitatively with the results of the corresponding experiments.