Non linear vibrations of stretched strings

Abstract

The viscosity of pure Freon-12 and Freon-22 vapours and their mixtures has been determined by an oscillating disc viscometer at room temperature and pressure. The results agree well with the published data for the pure Freons. The viscosity of mixtures calculated from Hirschfelder, Curtiss and Bird's equation, Wilke's equation and Herning and Zipperer's equation are in good agreement with the present experimental values for mixtures. However, the predictions by Dean and Stiel's equation for Freons and their mixtures do not compare well with the present experimental results. A novel method that enables determination of the masses of the components of gas mixtures accurately and, hence, their mixture composition has been devised. This method enables accurate determination of mixture composition by the direct weighing of the masses of the components, as it obviates the need to resort to the equations of state. The force constants and second virial coefficients for pure Freon-12 and Freon-22 vapours have been determined using Lennard-Jones potential to enable prediction of viscosity of these pure vapours and their mixtures by theoretical equations developed from statistical mechanics. The agreement between theoretical and experimental viscosity is good. The excess viscosity concept has been extended to Freon-12 and Freon-22 vapours and their mixtures. It is established that the excess viscosity is a unique function of density for pure components and mixtures. The viscosity of Freon-12 and Freon-22 vapours and their mixtures may be predicted from the excess viscosity data obtained in this investigation.