Thermodynamic modeling of phase equilibrium for gas hydrate in single and mixed refrigerants by using sPC-SAFT equation of state

• Three-phase equilibrium data, (VLWH)(VLWH), were determined in the presence of several refrigerants.
• The pressures were evaluated by sPC-SAFT EOS and temperature dependant mixing rule.
• The Kihara potential parameters of refrigerants were generated by optimizing scheme.

This paper demonstrates the ability of simplified PC-SAFT equation of state for prediction of hydrate dissociation pressure of refrigerants namely (CFC13, HCFC22, HFC23, HFC32, HFC125, HCFC141b, HFC134a, HFC152a, HFC143a and R744) and their mixtures at different temperatures and concentrations. The presented model is based on water chemical potential difference in the liquid and hydrate phases. The Van der Waals and Platteeuw model was also applied to illustrate the chemical potential of water in hydrate phase. The simplified Perturbed-Chain Statistical Associating Fluid Theory (sPC-SAFT) equation of state was used to determine the fugacity of each component in vapor and liquid phases. Moreover, the temperature dependent binary interaction parameters (kij) were adjusted, taking advantage of the well-described phase equilibria. The Kihara potential parameters were generated based on the dissociation conditions of single refrigerants hydrate to use for prediction of mixture gas hydrate dissociation conditions. The agreement between the experimental and predicted pressure is acceptable in the presented model; the average absolute deviation of model is between (0.06–3.80) for single systems and (1.90–4.99) for mixed systems.