Thermodynamic properties of THF + CO₂ hydrates in relation with refrigeration applications

Clathrate hydrate slurries are promising systems in the field of cold distribution. In this work, the L_w-H-V equilibrium conditions, the dissociation enthalpy, and the CO₂ hydration number of a clathrate hydrate formed from THF/CO₂/water mixtures were studied, using a DSC method. For equilibrium condition determination, THF concentration was varied from 1.0 to 16.0 wt % and CO₂ partial pressure range was 0.2 to 2.0 MPa. For enthalpy measurements, THF concentration was fixed at 19 wt % and CO₂ partial pressure investigated from 0.2 to 2.0 MPa. Experimental equilibrium temperatures and enthalpy values were in good agreement with the results of a model combining the van der Waals and Platteeuw approach with the RKS equation of state associated to a MHV2 mixing rule and UNIFAC model. Equilibrium conditions and dissociation enthalpy show that THF + CO₂ hydrate slurries are promising mixtures for refrigeration application.