MASS TRANSFER FROM A SINGLE MICRO-DROPLET TO A GAS FLOWING AT LOW REYNOLDS NUMBER

Abstract

Using an electrodynamic balance to suspend stably a charged micro-droplet in a laminar jet flow of either nitrogen or helium, droplet evaporation rates were measured for various flow rates and temperatures. Droplets diameters in the range 1-100 μm were measured precisely during the evaporation process by means of light scattering. For low Peclet numbers (Pe <1.5) the theoretical results of Kronig and Bmijsten (1951) and Acrivos and Taylor (1962) are in good agreement with the data. Levich's (1962) interpolation formula based on asymptotic solutions is in poor agreement with data at intermediate Peclet numbers [Pe = 0(1)]. A correlating equation was developed based on the asymptotic solutions of Kronig and Bniijsten and Levich, and it is shown to be in very good agreement with the data over the whole range of Peclet numbers studied. Gas phase diffusivities determined from the diffusion-controlled evaporation data at low flow rates are somewhat lower than the diffusivities calculated from empirical correlation developed from data for lower molecular weight nonpolar molecules

KEYWORDS:

• Aerosol mass transfer
• Diffusion
• Droplet evaporation
• Electrodynamic balance
• Light scattering