Aerosol Formation by Condensation

A chemical method for the production of aerosol involves the direct condensation of drops or particles in the air or other gaseous environment. In order 

TABLE 13.1. A Snimnary of Some Basic Rotary Atomizer and Feed Liquid Characteristics and Their Expected Effects on Average Drop Size of the Aerosol Produced 

Characteristic Expected Effect of Increase on Drop Size 

It will be remembered that the formation of a new phase by homogeneous nucleation involves first the formation of small clusters of molecules, which then may disperse or grow in size by accretion until some critical size is reached, at which point the cluster becomes recognizable as a liquid drop. The drop may then continue to grow by accretion or by coalescence with other drops to produce the final aerosol. Normally, extensive drop formation is not observed unless the vapor pressure of the incipient liquid is considerably higher than its saturation value that is, unless the vapor is supersaturated. 

The barrier to the condensation of the liquid drop is related to the high surface energy possessed by a small drop relative to its total free energy. Thermodynamically, a simple argument can be given to illustrate the process. If one considers the condensation process as being 

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