Enhancement of the extended corresponding states techniques for thermodynamic modeling. II. Mixtures

Moving from a former work for pure fluids a new modeling technique has been developed for obtaining a fundamental mixture equation of state in the Helmholtz energy form. This model can be considered an evolution of the extended corresponding states method, which is modified from the conventional analytical mode to a heuristic one through the integration of a general function approximator for the representation of the scale factor functions of a target mixture. The assumed approximator is a multilayer feedforward neural network (MLFN) with two outputs, one for each scale factor. A reference pure fluid, conformal with the components of the studied mixture, is chosen and the independent variables of its dedicated equation of state (DEoS) are distorted by the scale factors, which are individual functions of temperature, density, and composition. The MLFN scale factor functions can be obtained from regression on any kind of thermodynamic data of the target mixture. The model capability to accurately represent the thermodynamic surfaces of five binary and two ternary haloalkane mixtures is studied assuming data generated from the corresponding DEoSs. The obtained prediction accuracies for the mixture thermodynamic properties are competitive with those of the available conventional DEoSs. The proposed modeling technique is then robust and straightforward for the effective development of a mixture DEoS from thermodynamic quantities distributed in the range of interest.