A. Nowarski et Dg. Friend, Application of the extended corresponding states method to the calculationof the ammonia-water mixture thermodynamic surface, INT J THERM, 19(4), 1998, pp. 1133-1142
The paper presents an application of the one-fluid extended corresponding s
tates method to the calculation of the thermodynamic surface of the ammonia
-water mixture. Each pure component of the mixture is considered as a refer
ence fluid, and to lest the behavior of the model in wide ranges of tempera
ture and pressure, the Haar-Gallagher and the Pruss-Wagner equations of sta
te were chosen for pure ammonia and water, respectively. To avoid numerical
problems during the calculation of the pure-component equivalent substance
reducing ratios (or scaling factors), a method based on the mapping define
d by the extended corresponding states algorithm and two-dimensional interp
olation is proposed. The estimation of the binary interaction parameters wa
s performed using the general case of the Least squares method, i.e., the c
ase when all measurements (observations) and unknowns are subject to uncert
ainty and are adjusted simultaneously with the constraint equations. The re
sults show a strong temperature and composition dependence of both interact
ion parameters for the liquid, as well as for the vapor phase. A formulatio
n for the binary interaction parameters as continuous functions of these va
riables was also derived and optimized using the structural optimization an
d regression analysis. The final statistical quality of the approach presen
ted in the paper was assessed using the available data on thermophysical pr
operties of the mixture.