THERMODYNAMICS MODELING OF REFRIGERANT GASES HYDRATES BY USING PSRV2 EQUATION OF STATE

In this study, a thermodynamic model is presented for the study of the phase equilibria of clathrate hydrates of refrigerants namely Chlorodifluoromethane (R22), Trifluoromethane (R23), difluoromethane) R32), Pentafluoroethane (R125), 1,1,1,2-tetrafluoroethane (R134a), 1,1-difluoroethane  (R152a), and carbon dioxide  (R744). For the modeling of the vapor and liquid phases, the Peng-Robinson equation of state modified by Stryjek and Vera (PRSV2) and the Margules-type mixing rule were employed. To achieve more accurate results, binary interaction parameters are adjusted as a function of temperature. The model is based on equality of water fugacity in the liquid water and hydrate phases. Equation of Du and Guo has been used for the calculation of the Langmuir constant. Also, the parameters was fitted by Nedler–Mead non-linear regression method. The experimental and predicted values show good agreement. The average absolute deviation values of models for R22, R23, R32, R125, R134a, R152a, and R744 refrigerants hydrates are about 1.33%, 0.24%, 0.71%, 1.34%, 0.84%, 0.99%, and 0.97% respectively.