CONDENSATION STUDIES
Abstract
Condensation processes are important in the thermal dissemination of CW agents. Heterogeneous and homogeneous nucleation was studied to determine the important factors controlling condensing systems. Effects of salt nuclei on the particle size distribution of the disseminated aerosol were studied and special pyrotechnic systems which were salt nuclei-free were investigated. Aerosols composed of two- to five-micron-diameter particles with a high degree of particle size homogeneity make the optimum aerosol for lung retention and maximum transparency. The production of such an aerosol was shown to be feasible by the technique of incorporating nonvolatile giant nuclei material in the pyrotechnic mix. These giant nuclei when disseminated with the agent vapor acted as preferential condensation sites and as small particle scavengers by coagulation. The secondary process of coagulation was shown to be important in removing the highly visible submicron particles. A pyrotechnic dissemination system was suggested to produce uniform, low visibility aerosols which included coagulation of the small particles to be disseminated on giant nuclei at elevated temperature and high concentrations. Homogeneous nucleation always occurs in condensing systems of high vapor concentrations even in the presence of foreign nuclei. Critical supersaturation ratios of a number of compounds were measured by a newly developed experimental method. It was demonstrated that the classical Becker-Doering theory is inadequate for the preparation of nucleation models. A modified model is presented showing the interrelationships among physical properties, chemical structure, and temperature.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1967
- Accession Number
- AD0819480
Entities
People
- C. Naar
- R. C. Robbins
Organizations
- SRI International