| In recent years,the study of the thermodynamic properties of metal vapors has received more and more attention.Alkali metals has been widely used in industrial applications since it has lower melting point.It is very important to study the thermodynamic properties of alkali metal vapors.Compressibility factors and Second virial coefficients can be used to express deviations between the actual state of the vapors and ideal conditions.It is a bridge for other thermodynamic properties.At present,it is still difficult to obtain the properties through experiments.The theoretical calculations of the compressibility factors and the second virial coefficients are great significance.In this study,the Sove-Redlich-Kwong(S-R-K)equation and the Peng-Robinson(P-R)equation were checked by PVT data(Na,K,Rb,Cs)in the temperature range of 600-1700K.An improved form of?-function is proposed,the parameters of the new?-function were obtained through non-linear fitting,and the general formula of the improved?-function was obtained according to the?-parameters of Na,K,Rb,and Cs associated with the alkali metal acentric factors and performed Consistency test,comparing the improved?function with the calculation result of the original?function,the result is accurate.The correlation between the cubic equation,the compressibility factor,and the second virial coefficient was established.The compressibility factors of alkali metal vapors in the temperature range of 700~3000 K under the pressure of 1000~50×10~5 Pa were calculated.Compared with the literature values,the average absolute deviation is less than 4.4%.The second virial coefficient of the alkali metal vapors in the temperature range of 600~3000 K were calculated using the improved cubic equations of state,and the results are in good agreement with the literature data.The Boyle temperatures of the alkali metal vapors were calculated which indicate that the Boyle temperature and the critical temperature are linear.The results provide a theoretical methods for the calculation of the thermodynamic properties of metal vapors and the thermodynamic properties of other metal vapors by cubic equations. |
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