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Prediction of relative vapor ratios for binary mixtures applicable to industrial hygiene.
NIOSH 1980 Jan; :1-148
A theoretical model for predicting relative vapor ratios for solvent mixtures was tested. The model was based on the evaporation process. It combined a thermodynamic model for vapor liquid equilibrium with a mass transfer model for diffusion across a thin gas film. The difference in chemical potentials of the components in gas and liquid phases was the evaporation force used by the model. The simulation model involved the evaporation of a liquid of constant composition into a moving air stream at atmospheric pressure. Equations were derived for gas and liquid evaporation and relative vapor ratios. The model enabled determination of the constant composition mixture of the liquid by predicting operational and equilibrium relative volatility, it was not sensitive to velocity and geometry, but was dependent on diffusion. It yielded an average absolute percent error of 6.2. Vapor ratios were predicted with reasonable accuracy, but the error limits could not be determined due to the varying effect of the liquid film resistance. The author concludes that the unique features of the model are the method of predicting the activity coefficient and the elimination of geometry specific mass transfer parameters. The model is applicable to mixtures.
NIOSH-Grant; Chemical-analysis; Chemical-properties; Physical-properties; Analytical-methods; Laboratory-testing; Fumes; Quantitative-analysis
Final Grant Report
National Institute for Occupational Safety and Health
University of California, Berkeley
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division