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Author
Jung, D. S. | Didion, D. A.
Title
Mixing Rule for Liquid Viscosities of Refrigerant Mixtures.
Coporate
National Institute of Standards and Technology, Gaithersburg, MD
Journal
Rev. Int. Froid, Vol. 13, 243-248, 1990
Keywords
refrigerants | mixing rule | liquid viscosities | refrigerant mixtures | mixing | azeotropes
Abstract
An investigation of mixing rules for liquid viscosities of refrigerant mixtures is reported. Measured liquid viscosities of seven azeotropes and their corresponding pure components are compared with available mixing rules and Hildebrand's correlation. The results indicate that the viscosities of pure refrigerants are a strong function of volume, supporting Hildebrand's theory. The mixing rules popular in the refrigeration industry are not universally valid for all the mixtures considered. The volume change due to mixing is responsible for almost all of the deviations of the liquid viscosities of mixtures from ideal values. A simple relationship between excess viscosity and excess volume is developed, which results in deviations of less than 2% when used with Grunberg and Nissan's correlation. Based on this study, it is recommended that density measurements are accompanied by viscosity measurements for refrigerant mixtures.