Kinetic Study of Gas Hydrate Formation in an R410a+CaCl2 Aqueous Solution System in the Presence or Absence of Cyclopentane: Application to Hydrate-Based Desalination

Hydrate-based desalination is a cost-effective novel technique to produce fresh water. However, the main bottleneck of such a process is the relatively low kinetics of hydrate formation in the presence of multiple salts in the saline water stream. In this work, kinetics of an R410a refrigerant (0.5 mass fraction difluoromethane + 0.5 mass fraction 1,1,1,2,2pentafluoroethane) hydrate in the presence of various concentrations of CaCl2 are investigated. Furthermore, the effect of cyclopentane addition to the system on the corresponding hydrate formation kinetics is studied. The experimental results show that lower concentrations of CaCl2 (1 and 2 wt %) had no significant effect on hydrate formation induction time and its semicompletion time; meanwhile, a higher CaCl2 concentration of 4 wt % leads to a decline in the corresponding kinetic parameters. Moreover, gas consumption is also reduced in the presence of a higher concentration of CaCl2. It is further demonstrated that the presence of cyclopentane at 0.5 mol % could increase water to hydrate conversion required to improve the kinetics of hydrate formation for the system of interest.