This project involves two components: (1) a new theoretical approach to multiphase equilibria predictions and (2) a new experimental technique for their measurement. The first portion uses collinearity constraints and optimum tuning at extreme loci to increase the physical reality of equation of state (EOS)/mixture combining rules (MCR) prediction models. The second part of the proposal uses the microwave cavity method for accurate dew and bubble point curve location (to plus or minus 0.1 degree Celsius and plus or minus 0.1 atm), plus the more traditional Burnett-Isochoric density measurements. The improvement of the tangent plane method via new algorithms for minimization of the Gibbs energy for multicomponent systems is an important related objective of this project. Both the theoretical and experimental work in this project are significantly different from anything studied before. The collinearity constraints have not been used previously to determine which EOS/MCR combinations are thermodynamically consistent. To date, EOS/MCR computer programs, the backbone of industrial vapor-liquid equilibria predictions, have been based largely on empiricism; this project is the first attempt in the past thirty years to interject physical constraints into this field. While it is difficult to forecast the results, they are likely to change the face of how multiphase predictions at elevated pressure are made by oil/gas/chemical companies. One of the strengths of the project is its ability to eliminate particular EOS and MCR as thermodynamically inconsistent and thereby discard proposed research initiatives. More positively, the collinearity constraints can act as an overseer to guide one along prediction paths, which while partly empirical, are, at least, thermodynamically consistent.
