Nucleation rates of droplets in supersaturated steam and water vapour–carrier gas mixtures between 200 and 450 K

Abstract

We compare experimental nucleation rates for water vapour in various carrier gases, estimated nucleation rates for steam, and nucleation rates obtained from molecular simulations. The data for steam are deduced from empirical adjustments of the classical nucleation theory developed by various authors to reproduce pressure and optical data for condensing steam flows in converging-diverging nozzles and turbine stages. By combining the data for nucleation in carrier gases and the data for steam nucleation, an unprecedented temperature range of 250 K is available to study the temperature dependence of nucleation rate. Original results of molecular dynamic simulations for TIP4P/2005 force field in the NVE (system constrained by number of particles, volume and energy) conditions are provided. Correction of classical nucleation theory for non-isothermal nucleation conditions is applied to experimental and simulated data. The nucleation rate data for steam follow a similar temperature trend as the nucleation rate data for water vapour in carrier gases at lower temperatures. The ratio of observed nucleation rates to classical nucleation theory predictions decreases more steeply with temperature than the empirical correlation by Wö lk et al. (J Chem Phys 2002; 117: 4954-4960). On the contrary to experimental data, the ratios of nucleation rates computed from molecular simulations to classical nucleation theory predictions do not show a significant temperature trend.

Multiplicative Noise Effects in an Optically Trapped Aerosol

“…While in most cases these filtration processes are carried out in the fixed-bed mode, they may also be conducted in fluidized-bed mode (Knettig and Beeckmans, 1974). More recent efforts in aerosol research in chemical engineering involve the nucleation of supersaturated droplets, the dispersion of particles as clouds, and gas cleaning (Lu et al, 2005;Hrubý et al, 2018). Also, understanding the process of creation of aerosols can help to design techniques for removal of aerosol after combustion; for example, the removal of particulate non-combusted material in coal fired power stations by electrostatic precipitators (Slama et al, 2000).…”