The Segregation of Aerosols by Cloud-Nucleating Activity. Part I: Design, Construction, and Testing of A High-Flux Thermal Diffusion Cloud Chamber for Mass Separation

Abstract

We describe a thermal diffusion cloud chamber operated in series with an aerodynamic dichotomous separator that can segregate aerosol particles by their abilities to nucleate cloud droplets. The apparatus takes advantage of compensating gradients in flow velocities and supersaturations to operate with an effective aperture of 70 cm2 and high flow rates (up to 50 L min?1) to produce narrow distributions of 4?5 ?m diameter droplets grown from those particles which would nucleate clouds at a range of supersaturations from 0 to 1%. Subsequent aerodynamic separation of these large droplets from unactivated smaller aerosol particles is achieved with efficiencies exceeding 90%, by mass, at a supersaturation of 0.64% (+0, ?0.3%).