Experimental investigation of binary nucleation rates of water–n-propanol and water–n-butanol vapors by means of a pex-tube

Measurements of homogeneous nucleation rates of two binary vapor mixtures of water and alcohol carried in nitrogen have been performed with a new instrument for nucleation and droplet growth studies, the piston expansion tube (pex-tube). The pex-tube subjects the vapors to short supersaturation pulses generating a limited number of nuclei which grow into monodisperse droplets. The droplets are detected in number and size by Mie light scattering. The results provide nucleation rates between 105 and 109 cm−3 s−1 at constant temperature as a function of the vapor phase activities a1 and a2 of water and alcohol, respectively. Comparison with published experimental data exhibits good agreement.