Design and performance of a rapid piston expansion tube for the investigation of droplet condensation

Abstract

 A piston expansion tube (pex-tube) is described which has been developed for the investigation of homogeneous nucleation in a supersaturated vapor and subsequent droplet growth. The design of the tube with periphery is discussed as well as the underlying gasdynamics. Examples for the measurement of nucleation and growth rates in a binary mixture of n-propanol/water carried in nitrogen demonstrate performance and range. The focus of the paper is on the determination of the nucleation state. It is shown that this state may not be based on an adiabatic expansion when helium is used as carrier gas instead of argon or nitrogen.