Accurate measurement of phase equilibria and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl for potential application in desalination

• Published in: The Korean journal of chemical engineering 2016, 33(4), 193, pp.1425-1430
• Main Authors: Lee, Dongyoung, Lee, Yohan, Lee, Seungmin, Seo, Yongwon
• Format: Article
• Language: English
• Subjects: Biotechnology; Catalysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Materials Science; Separation Technology; Thermodynamics; 화학공학
• ISSN: 0256-1115; 1975-7220
• DOI: 10.1007/s11814-015-0268-7

Phase equilibria, structure identification, and dissociation enthalpies of HFC-134a hydrates in the presence of NaCl are investigated for potential application in desalination. To verify the influence of NaCl on the thermodynamic hydrate stability of the HFC-134a hydrate, the three-phase (hydrate (H) - liquid water (L W ) - vapor (V)) equilibria of the HFC-134a+NaCl (0, 3.5, and 8.0 wt%)+water systems are measured by both a conventional isochoric (pVT) method and a stepwise differential scanning calorimeter (DSC) method. Both pVT and DSC methods demonstrate reliable and consistent hydrate phase equilibrium points of the HFC-134a hydrates in the presence of NaCl. The HFC-134a hydrate is identified as sII via powder X-ray diffraction. The dissociation enthalpies (ΔH d ) of the HFC-134a hydrates in the presence of NaCl are also measured with a high pressure micro-differential scanning calorimeter. The salinity results in significant thermodynamic inhibition of the HFC-134a hydrates, whereas it has little effect on the dissociation enthalpy of the HFC-134a hydrates. The experimental results obtained in this study can be utilized as foundational data for the hydrate-based desalination process.