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Clathrate hydrate dissociation data were measured for systems comprising of refrigerants (R134a, R410a and R507) + water + MgCl 2 at varying salt concentrations. The ternary system for R134a + water + MgCl 2 was measured at salt concentrations of (0.259, 0.546, and 0.868) mol.kg −1 in the temperature range of (277.1–283) K and a pressure range of (0.114–0.428) MPa. Hydrate measurements for the {R410a or R507} + water + MgCl 2 systems were measured at salt concentrations of (0.259 and 0.546) mol.kg −1 in the temperature range of (274.3–293) K and a pressure range of (0.154–1.421) MPa. The isochoric pressure-search method was used to measure the hydrate dissociation data. This study is a continuation of previous investigations which focused on obtaining hydrate dissociation data for R134a, R410a and R507 refrigerants in NaCl and CaCl 2 aqueous solutions. The measured hydrate dissociation data can be used to design industrial wastewater treatment and desalination processes. The results show that the effect of salt concentration on hydrate formation is smaller for MgCl 2 aqueous solutions compared to CaCl 2 and NaCl as salt concentration increases. Modelling of the measured data is performed using a combination of the solid solution theory of van der Waals and Platteeuw, the Aasberg–Petersen et al. model, and the Peng–Robinson equation of state with classical mixing rules. The model is in good agreement with the measured hydrate dissociation data. [ABSTRACT FROM AUTHOR]

Hydrate dissociation data are presented for systems of refrigerants (R134a, R410a, and R507) + water + CaCl2 at varying salt concentrations. The R134a + water + CaCl2 system was measured at salt concentrations of (0, 0.358, 0.591, and 0.756) mol·kg-1 in the temperature range of (276.2 to 283) K and a pressure range of (0.125 to 0.428) MPa. The systems composed of {R410a or R507} + water + CaCl2 were measured at salt concentrations of (0, 0.358 and 0.756) mol·kg-1 in the temperature range of (274.7 to 293) K and a pressure range of (0.179 to 1.421) MPa. The isochoric pressure-search method was used for all the hydrate measurements. The data generated can be used in the design and optimization of industrial wastewater treatment and desalination processes. The presence of CaCl2 in the aqueous solutions shifts the hydrate-liquid water-vapor (H-Lw-V) equilibrium phase boundary toward lower temperatures as salt concentration increases. The experimental data were modeled using a combination of the solid solution theory of van der Waals and Platteeuw, the Aasberg-Petersen et al. model, and the Peng-Robinson equation of state with classical mixing rules. The model provides a good correlation of the experimental hydrate dissociation data. [ABSTRACT FROM AUTHOR]

Hydrate dissociation data are presented for systems of refrigerants (R134a, R410a, and R507) + water + CaCl2 at varying salt concentrations. The R134a + water + CaCl2 system was measured at salt concentrations of (0, 0.358, 0.591, and 0.756) mol•kg-1 in the temperature range of (276.2 to 283) K and a pressure range of (0.125 to 0.428) MPa. The systems composed of {R410a or R507} + water + CaCl2 were measured at salt concentrations of (0, 0.358 and 0.756) mol•kg-1 in the temperature range of (274.7 to 293) K and a pressure range of (0.179 to 1.421) MPa. The isochoric pressure-search method was used for all the hydrate measurements. The data generated can be used in the design and optimization of industrial wastewater treatment and desalination processes. The presence of CaCl2 in the aqueous solutions shifts the hydrate-liquid water-vapor (H-Lw-V) equilibrium phase boundary toward lower temperatures as salt concentration increases. The experimental data were modeled using a combination of the solid solution theory of van der Waals and Platteeuw, the Aasberg-Petersen et al. model, and the Peng-Robinson equation of state with classical mixing rules. The model provides a good correlation of the experimental hydrate dissociation data. [ABSTRACT FROM AUTHOR]

Experimental gas hydrate dissociationdata for the refrigerantsR134a, R410a, and R507 in the absence and presence of NaCl aqueoussolutions at various molalities were measured. The binary systems,in this study, which consisted of {chloro(difluoro)methane (R22),1,1,1,2-tetrafluoroethane (R134a), (0.5 mass fraction difluoromethane+ 0.5 mass fraction 1,1,1,2,2-pentafluoroethane) (R410a), or (0.5mass fraction 1,1,1-trifluoroethane + 0.5 mass fraction 1,1,1,2,2-pentafluoroethane)(R507)} + water were measured in the temperature range between (276.4to 291.8) K and pressures ranging from (0.114 to 1.421) MPa. The ternarysystem R134a + water + NaCl, at three salt molalities of (0.900, 1.901,and 3.020) mol·kg–1, was measured in the temperaturerange between (268.1 to 280.6) K and pressures ranging from (0.086to 0.383) MPa. For the ternary systems comprising of {R410a or R507}+ water + NaCl, at two salt molalities of (0.900 and 1.901) mol·kg–1, measurements were undertaken in the temperaturerange between (273.9 to 290.9) K and pressures ranging from (0.226to 1.345) MPa. The isochoric pressure-search method was used to undertakethe measurements. The purpose of this study is to generate accuratehydrate phase equilibrium data which will be used to design wastewatertreatment and desalination processes using gas hydrate technology.The results show that the presence of NaCl in the aqueous solutionshas a thermodynamic inhibition effect on refrigerant gas hydrates.Modeling of the data measured was undertaken using a combination ofthe solid solution theory of van der Waals and Platteeuw for the hydratephase, the Aasberg–Petersen et al. model for the electrolyteaqueous system, and the Peng–Robinson equation of state withclassical mixing rules for the liquid and vapor phases. The correlatedmodel results show good agreement with the experimental dissociationdata. [ABSTRACT FROM AUTHOR]