J. Rainwater and R. Tillner-Roth
Accepted for the Proceedings of the 13th International Conference on the Properties of Water and Steam
Two distinct thermodynamic models, the modified Leung-Griffiths (MLG) model and a Helmholtz multiparameter equation of state, are used to correlate high-pressure vapor-liquid equilibrium (VLE) of ammonia-water. In view of the absence of experimental coexisting density data in this region, results from the equation of state are used as input for an optimized MLG correlation. Then the MLG phase boundary is used as input for a revised equation of state optimization, and so on iteratively. After three iterations, the two correlations are in basic agreement except for a small region close to the critical locus, where they must disagree due to differing critical exponents. The final MLG model agrees well with most high-pressure VLE data, except for some data shown to be suspect for separate reasons.