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Park, J.-Y.; Lim, Jong Sung; Lee, B.-G.; Lee, Y.-W.

doi:10.1023/a:1010735318011

Cited by 36 publications

(11 citation statements)

References 6 publications

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“…Nowadays, SF 6 gas is being replaced by alternative protection gases with a low global warming potential such as HFC134a or SF 6 /HFC134a mixture for magnesium melt protection . Because HFC134a costs only about a third of SF 6 and its global warming potential is 18 times lower, , it can serve as a suitable guest molecule because of its lower hydrate equilibrium compared to other gases ,− and its relative low solubility (0.11% at 27 °C) . Therefore, a hydrate-based desalination process using SF 6 /HFC134a mixture as the hydrate-forming agent is a more promising option in terms of energy consumption and capital cost.…”

Section: Introductionmentioning

confidence: 99%

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture

et al. 2021

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In this study, the effects of salinity on the equilibrium and kinetics of sulfur hexafluoride (SF6), 1,1,1,2-tetrafluoroethane (HFC134a), and their mixture were evaluated to analyze their potential applications to hydrate-based desalination. The equilibrium pressure of the mixture gas (SF6/HFC134a) was lower than that of pure SF6 gas but higher than that of pure HFC134a gas. The thermodynamic effects of various concentrations (0, 3.5, 5, and 8 wt %) of NaCl on the gas hydrates were evaluated. Experiments were performed on the formation kinetics in the presence of NaCl solution at the same experimental temperature and pressure (274.15 K and 0.70 MPa). The hydrate growth rates decreased with increasing NaCl concentration. The rates also declined with time, associated with the inhibition of mass transfer between the gas and the liquid. During hydrate formation, the vapor compositions of the mixture gas were analyzed by in situ Raman spectroscopy and the results were consistent with those obtained by gas chromatography. Furthermore, an in situ Raman spectroscopic analysis demonstrated that the SF6 and HFC134a molecules occupy only the large cage (51264) of the structure II (sII) hydrate during SF6/HFC134a formation and the addition of salt did not change the structure of the SF6 and HFC134a hydrates. The hydrate phase behavior and kinetic results of this study can serve as foundational data for hydrate-based desalination technology and fluorinated gases separation and recovery processes.

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Section: Introductionmentioning

confidence: 99%

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture

et al. 2021

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“…Both HFC-227ea and HFC-227ca have been used as the replacement refrigerant for CFC-114 (CF 2 ClCF 2 Cl) in centrifugal chillers. Moreover, CF 3 CHFCF 3 (HFC227ea) are considered as a Halon replacement in firefighting applications [7][8][9]. Owing to their importance, some experimental and theoretical studies [10,11] have been performed on the reactions CF 3 CHFCF 3 with OH radical and oxygen atom.…”

Section: Introductionmentioning

confidence: 99%

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Wang

Zhao

Zhang

2011

Journal of Fluorine Chemistry

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“…Between 94 and 140 min, the hydrates continued to form and settle toward the bottom and took on a completely formed morphology at 140 min. Meanwhile, the P – T – t outline shows a temperature peak that corresponds to a steep pressure descent from 88 to 140 min, indicating that R134a hydrates had formed in a certain quantity that was accompanied by gas consumption, which gave off much heat due to the large phase change heat of hydrates (358 kJ/kg 13 ).…”

Section: Results and Discussionmentioning

confidence: 99%

“…Gas hydrates are ice-like crystals that host water molecules to form lattices via hydrogen bonding to engage gas molecules at a certain temperature and pressure. − According to the selection principle of the cold storage medium, it is also very important to choose suitable hydrates as the cold storage medium . Among hydrates, 1,1,1,2-tetrafluoroethane (R134a) hydrates match well with the cold storage system due to the lower phase equilibrium pressure (0.05–0.41 MPa), higher phase equilibrium temperature (1–10 °C), and larger phase change latent heat (358 kJ/kg). Nevertheless, R134a hydrates in cold storage applications are limited by the large stochastic nature of hydrate nucleation, the instability of cyclic hydrate formation (including first hydrate formation and several repeated hydrate reformations), and the low hydrate dissociation rate.…”

Section: Introductionmentioning

confidence: 99%

Cyclic Formation Stability of 1,1,1,2-Tetrafluoroethane Hydrate in Different SDS Solution Systems and Dissociation Characteristics Using Thermal Stimulation Combined with Depressurization

et al. 2019

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Cold storage using hydrates for cooling is a high-efficiency technology. However, this technology suffers from problems such as the stochastic nature of hydrate nucleation, cyclic hydrate formation instability, and a low cold discharge rate. To solve these problems, it is necessary to further clarify the characteristics of hydrate formation and dissociation in different systems. First, a comparative experimental study in pure water and sodium dodecyl sulfate (SDS) solution systems was conducted to explore the influence of SDS on the morphology of the hydrate and the time needed for its formation under visualization conditions. Subsequently, the cyclic hydrate formation stability was investigated at different test temperatures with two types of SDS solution systems—with or without a porous medium. The induction time, full time, and energy consumption time ratio of the first hydrate formation process and the cyclic hydrate reformation process were analyzed. Finally, thermal stimulation combined with depressurization was used to intensify hydrate dissociation compared with single thermal stimulation. The results showed that the growth morphology of hydrate and the time required for its formation in the SDS solution system were obviously different than those in pure water. In addition, the calculation and comparison results revealed that the induction time and full time of cyclic hydrate reformation were shorter and the energy consumption time ratio was smaller in the porous medium. The results indicated that a porous medium could improve the cyclic hydrate formation process by making it more stable and by decreasing time and energy costs. Thermal stimulation combined with depressurization at different backpressures (0.1, 0.2, 0.3, and 0.4 MPa) effectively promoted the decomposition of hydrates, and with the decrease in backpressure, the dissociation time decreased gradually. At a backpressure of 0.1 MPa, the dissociation time was reduced by 150 min. The experimental results presented the formation and dissociation characteristics of 1,1,1,2-tetrafluoroethane hydrates in different systems, which could accelerate the application of gas hydrates in cold storage.

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Cited by 36 publications

References 6 publications

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Cyclic Formation Stability of 1,1,1,2-Tetrafluoroethane Hydrate in Different SDS Solution Systems and Dissociation Characteristics Using Thermal Stimulation Combined with Depressurization

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Untitled

Cited by 36 publications

References 6 publications

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF6, HFC134a, and Their Mixture

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF6, HFC134a, and Their Mixture

Direct dynamics studies for the reactions of CF3CHFCF3 and CF3CF2CHF2 with H atoms

Cyclic Formation Stability of 1,1,1,2-Tetrafluoroethane Hydrate in Different SDS Solution Systems and Dissociation Characteristics Using Thermal Stimulation Combined with Depressurization

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Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture

Effects of Salinity on Hydrate Phase Equilibrium and Kinetics of SF₆, HFC134a, and Their Mixture