Cryoscopic Studies - Concentrated Solutions of Hydroxy Compounds"

Ross, Halkey K.

doi:10.1021/ie50531a054

Cited by 58 publications

(27 citation statements)

References 3 publications

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“…The present results for the critical parameters are also good (0.2-0.6 K, 0.02-0.08 MPa, and 2-3 kg · m −3 ), based on comparisons with data reported by other authors [17,22,32,[65][66][67][68][69][70][71][72][73]. Large differences (up to 2-3 K , for the critical temperature) were found for data reported by other authors [17,31,36,[74][75][76][77][78][79][80][81][82] and (10-45 kg · m −3 for the critical density) were found for data reported by Polikhronidi et al [37], Battelli [66], and Ramsay and Young [77].…”

Section: Critical Parameter Determinationmentioning

confidence: 67%

PVT Measurements for Pure Ethanol in the Near-Critical and Supercritical Regions

et al. 2007

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The P V T properties of pure ethanol were measured in the near-critical and supercritical regions. Measurements were made using a constant-volume piezometer immersed in a precision thermostat. The uncertainty of the density measurements was estimated to be 0.15%. The uncertainties of the temperature and pressure measurements were, respectively, 15 mK and 0.05%. Measurements were made along various near-critical isotherms between 373 and 673 K and at densities from 91.81 to 497.67 kg · m −3 . The pressure range was from 0.226 to 40.292 MPa. Using two-phase P V T results, the values of the saturated-liquid and -vapor densities and the vapor pressure for temperatures between 373.15 and 513.15 K were obtained by means of an analytical extrapolation technique. The measured P V T data and saturated properties for pure ethanol were compared with values calculated from a fundamental equation of state and correlations, and with experimental data reported by other authors. The values of the critical parameters (T C ,P C ,ρ C ) were derived from the measured values of saturated densities and vapor pressure near the critical point. The derived values of the saturated densities near the critical point for ethanol were interpreted in term of the "complete scaling" theory.

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Section: Critical Parameter Determinationmentioning

confidence: 67%

PVT Measurements for Pure Ethanol in the Near-Critical and Supercritical Regions

et al. 2007

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“…UNIQUAC parameters for the water-methanol system are of particular importance because the fugacity of water in the aqueous liquid phase is the key quantity that determines hydrate inhibition. Parameters for this binary were obtained from a fit to water-methanol freezing-point-depression data (Miller and Carpenter, 1964;Ross, 1954) and from data on methanol inhibition of methane hydrate (Ng andRobinson, 1983, 1984). Figure 3 shows a correlation for the freezing-point depression of water by methanol.…”

Section: Liquid-phase Fugacitiesmentioning

confidence: 99%

Inhibition of gas hydrates by methanol

1986

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A molecular-thermodynamic correlation has been developed for calculating the inhibition effect of methanol on the formation of hydrates in moist gas mixtures. Six phases are potentially present in these mixtuies: gas, aqueous liquid, hydrocarbon liquid, ice, and hydrate structures I and II. For a given temperature and system composition, the molecular-thermodynamic method described here allows computation of the hydrate-point pressure as well as relative amounts and compositions of all coexisting phases. Good agreement is obtained when calculated results are compared with diverse experimental data reported in the literature. The correlation given here may be useful for computeraided design for gas processing and transportation. F. E. SCOPENumerous articles are concerned with gas/ hydrate phase equilibria (e.g., Berecz and Balla-Achs, 1983). Where no inhibitor is present, correlations for hydratesystem properties are restricted to selected parts of the general, multiphase-multicomponent diagram. A number of these studies are directed at the threephase system hydrate/vapor/aqueous-liquid (or ice) (Parrish and Prausnitz, 1972;Ng and Robinson, 1976). Others have directed attention to the two-phase system hydrate/gas (Sloan et al., 1976; Ng and Robinson, 1980; Aoyagi et al., 1980;Song and Kobayashi, 1982). Limited studies of the three-phase system hydrate/ aqueous-liquid/hydrocarbon-liquid have been made (Ng and Robinson, 1976, 1977). While several proprietary correlations exist (Gas Processors Assn.), no thermodynamically consistent overall multicomponentmultiphase correlation for this hydrate inhibition problem has appeared in the literature. Previous correlations for the effects of inhibitors on hydrate formation (Menten et al., 1981) have assumed that only condensed aqueous phases coexist with the gas and hydrate phases. This work covers all of the above-mentioned equilibria in a unified framework suitable for further development for computer-aided process design. CONCLUSIONS AND SIGNIFICANCEThis work presents a method for predicting the amount of inhibitor that must be added to prevent hydrate formation in gas processing. The method, based on molecular-thermodynamic models and a computational framework, calculates hydrate-point pressures and temperatures, and coexisting-phase fractions and compositions for gas/water/methanol mixtures in the region from 220 to 320 K and pressures to 500 bar (50 MPa). Consideration is given to the possible existence of all of the six potential phases: gas, aqueous liquid, hydrocarbon liquid, ice, and hydrate structures I and II; these phases may occur in various combinations. The calculation procedure includes nitrogen, methane, ethane, propane, n-butane, isobutane, n-pentane, carbon dioxide, and hydrogen sulfide along with methanol and water.Fugacities of all components in the gas phase are calculated using a modification of the Redlich-Kwong (1949) equation of state similar t o that of de Santis et al. (1974). Fugacities for all condensible components are calculated using activ...

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“…In this work, the initial freezing temperature at atmospheric pressure was obtained from literature. For glycerol solutions, data were from Refs 28–32…”

Section: Resultsmentioning

confidence: 99%

Prediction of ice content in biological model solutions when frozen under high pressure

Guignon

Aparicio

Otero

et al. 2009

Biotechnology Progress

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High pressure is, at least, as effective as cryoprotective agents (CPAs) and are used for decreasing both homogenous nucleation and freezing temperatures. This fact gives rise to a great variety of possible cryopreservation processes under high pressure. They have not been optimized yet, since they are relatively recent and are mainly based on the pressure-temperature phase diagram of pure water. Very few phase diagrams of biological material are available under pressure. This is owing to the lack of suitable equipment and to the difficulties encountered in carrying out the measurements. Different aqueous solutions of salt and CPAs as biological models are studied in the range of 0 degrees C down to -35 degrees C, 0.1 up to 250 MPa, and 0-20% w/w total solute concentration. The phase transition curves of glycerol and of sodium chloride with either glycerol or sucrose in aqueous solutions are determined in a high hydrostatic pressure vessel. The experimental phase diagrams of binary solutions were well described by a third-degree polynomial equation. It was also shown that Robinson and Stokes' equation at high pressure succeeds in predicting the phase diagrams of both binary and ternary solutions. The solute cryoconcentration and the ice content were calculated as a function of temperature and pressure conditions during the freezing of a binary solution. This information should provide a basis upon which high-pressure cryopreservation processes may be performed and the damages derived from ice formation evaluated.

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Cryoscopic Studies - Concentrated Solutions of Hydroxy Compounds"

Cited by 58 publications

References 3 publications

PVT Measurements for Pure Ethanol in the Near-Critical and Supercritical Regions

PVT Measurements for Pure Ethanol in the Near-Critical and Supercritical Regions

Inhibition of gas hydrates by methanol

Prediction of ice content in biological model solutions when frozen under high pressure

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