Experimental Investigation and Computer Analysis of Sontaneous Condensation in Stationary Nozzle Flow of CO₂-Air Mixtures

Summary

The influence of an admixture of air on the onset and the progress of spontaneous condensation of carbon dioxide in a stationary supersonic nozzle flow has been studied for mixtures with CO₂-mole fractions ranging from 5 to 75 per cent. For mole fractious of 75 and 50 per cent, the supersaturation of the carbon dioxide at the Wilson point is scarcely influenced by the addition of air. In the range of lower CO₂-concentrations, the condensation of carbon dioxide is promoted by the presence of the non-condensing component, as was to be expected from various results reported in the literature.

The thermodynamic state in the Wilson point and the progress of condensation in the flow were calculated with a model of the condensation process based on the classical nucleation model and a formulation of droplet growth proposed by Gyarmathy. It is remarkable that the results of the calculation, obtained with a uniform choice of the free parameters of this condensation model, agree well with the experimental results, both for pure CO₂ and for CO₂/air-mixtures.