A Shock Tube Study on Condensation Kinetics

Abstract

Refrigerant vapors were filled in the high pressure side of a shock tube, and measurements were made as the vapors condensed spontane usly through adiabatic expansion in the rarefaction wave. The experimental observations were analyzed on the basis of the classical nucleation theory, and for each of the test vapors, the surface energy density (or the surface tension) of critical-sized droplets, which corresponds to the activation energy in chemical reactions, was evaluated utilizing the condensation point locus on the P-T plane. It turned out that the estimated surface tension was consistently smaller than the macroscopic value for three kinds of refrigerants studied. In the case of methyl alcohol vapor, for which the expansion rate was varied over a wide range, the condensation locus was found to shift accordingly in agreement with the theoretical prediction. It was also shown that the droplet growth history could be inferred from the temporal change of the light transmission.