Thermodynamic Modeling of Refrigerants Using the Statistical Associating Fluid Theory with Variable Range. 2. Applications to Binary Mixtures

Abstract

An ever increasing concern on the stratospheric ozone depletion has led to a worldwide ban on fully halogenated chlorofluorocarbons (CFCs) and prompted a rigorous search for alternative refrigerants with a zero ozone-depletion potential (ODP) and a low global warming potential (GWP). Accurate thermodynamic information is required to develop an optimum alternative to replace an existing CFC pure fluid or mixture. In this work, statistical associating fluid theory with variable range (SAFT-VR) is used to correlate the vapor liquid equilibria (VLE) and the vapor-liquid-liquid equilibria (VLLE) for various refrigerant mixtures. An analysis on the pure component parameters for pentane was performed due to the existence of multiple parameter sets using SAFT-VR. The effects of the pure component parameters in mixture phase predictions were investigated. An optimized binary interaction parameter (k ij ) value was used to correlate the experimental data. It was found that the mixture phase predictions were sensitive to the adjusted k ij value in such a way that fundamental changes in the phase diagram can occur with a small change in the k ij value. Hence, an attempt was made to model new refrigerant mixture blends by transferring the k ij value to similar mixtures. The good agreement of the predictions made using the transferred k ij value and the experimental data aids in suggesting new alternative refrigerant blends.

Implementation of CP-PC-SAFT and CS-SAFT-VR-Mie for Predicting Thermodynamic Properties of C1–C3 Halocarbon Systems. I. Pure Compounds and Mixtures with Nonassociating Compounds

“…As discussed elsewhere, many halocarbons exhibit association or/and polar interactions. Thus, both or one of these interactions have been incorporated by several approaches applied for modeling their pure compound and mixture properties. − Although this practice is suitable from the molecular viewpoint, it enhances the complexity of models and increases the number of their substance-specific adjustable parameters. At the same time, other studies − have demonstrated accurate modeling of halocarbon systems using various Cubic and SAFT-type EoSs while neglecting such interactions.…”

Modeling Hydrofluoroolefins with the Cubic Plus Association and Perturbed-Chain Statistical Associating Fluid Theory Equations of State

“…Thus, we have also used method 2 with a two-site (2B) association scheme. This is in analogy to the extensive study of refrigerants using the SAFT method by Swaminathan and Visco 50,51 . They developed the SAFT-VR model with a two-site association scheme for 49 pure refrigerants that have non-zero dipole moment, irrespective of their molecular structure.…”

“…Our 24 models for HFOs do not include an explicit contribution for the polar interactions, thus we have assumed a two-site (2B) association scheme in method 2. This is inspired by other researchers who modeled strong polarity via association 50,51 . The %AAD all of CPA and PC-SAFT with method 2 are 3.6% and 2.7%, indicating that CPA performs better than method 1 but PC-SAFT performs worse.…”

Integrated Working Fluids and Process Optimization for Refrigeration Systems Using Polar PC-SAFT

“…Therefore, the polar PC-SAFT could still be safely used. Many efforts have been devoted to the evaluation of thermodynamic properties of refrigerant mixtures by applying different SAFT models, e.g., SAFT-VR, − PC-SAFT, CS–SAFT-VR-Mie, and Polar PC-SAFT . In general, the SAFT models allow a relatively satisfactory prediction over symmetric mixtures but require additional binary parameters for correction in the case of asymmetric mixtures.…”