Thermodynamic stability conditions of clathrate hydrates for refrigerant (R134a or R410a or R507) with MgCl₂ aqueous solution

Clathrate hydrate dissociation data were measured for systems comprising of refrigerants (R134a, R410a and R507) + water + MgCl₂ at varying salt concentrations. The ternary system for R134a + water + MgCl₂ 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 + MgCl₂ 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 CaCl₂ 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 MgCl₂ aqueous solutions compared to CaCl₂ 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.