A Cubic Equation of State with Group Contributions for the Calculation of Vapor−Liquid Equilibria of Mixtures of Hydrofluorocarbons and Lubricant Oils

Elvassore, Nicola; Bertucco, Alberto; Wahlström, Åsa

doi:10.1021/ie980570w

Cited by 22 publications

(19 citation statements)

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“…The thermophysical properties (thermodynamic and transport) that are needed include density, vapor pressure, heat capacity, sound speed, viscosity, and thermal conductivity. Some property measurements have already been performed on polyol ester base oils and lubricants, − in addition to mixtures for refrigeration applications . Additional measurements are being performed at NIST to expand the temperature and pressure regimes and provide updated thermophysical property models. − …”

Section: Introductionmentioning

confidence: 99%

“…Some property measurements have already been performed on polyol ester base oils and lubricants, 5−8 in addition to mixtures for refrigeration applications. 9 Additional measurements are being performed at NIST to expand the temperature and pressure regimes and provide updated thermophysical property models. 10−12 Although neopentyl polyol esters are considered to be more thermally stable than other esters, which is attributed to the absence of a labile hydrogen on the β-carbon (central carbon atom in Figure 1), they are not immune to thermal degradation.…”

Section: ■ Introductionmentioning

confidence: 99%

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Thermal Decomposition Kinetics of Polyol Ester Lubricants

et al. 2016

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Synthetic lubricants are widely used for applications that require high thermal and oxidative stability. In order to facilitate new designs and applications for these fluids, we are measuring a suite of thermophysical and transport properties for lubricant base fluids and mixtures. As part of the property measurements, here, we report the global thermal decomposition kinetics of four polyol ester lubricant base oils, in addition to a fully qualified (MIL-PRF-23699) formulation. The fluids were heated in stainless steel ampule reactors and the extent of decomposition was measured by gas chromatography coupled with flame ionization detection (GC-FID), from which pseudo-first-order rate constants were derived. The rate constants for decomposition ranged from 1 × 10–8 s–1 at 500 K to 2 × 10–4 s–1 at 675 K. Arrhenius parameters across this temperature regime are also reported. Other techniques for chemical characterization applied in this work include gas chromatography with mass spectrometry (GC-MS), nuclear magnetic resonance (NMR) spectroscopy, and Karl Fischer titration.

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Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Thermal Decomposition Kinetics of Polyol Ester Lubricants

et al. 2016

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“…Some works aiming at modeling the thermodynamic properties of the refrigerant + lubricant mixtures were published in the literature,15–22 but they mainly addressed the representation of the vapor–liquid equilibrium. These works are based either on the modified Flory–Huggins model, on cubic equations of state (including or not a modified UNIFAC model), or on perturbed‐hard‐sphere‐chain equations of state.…”

Section: Introductionmentioning

confidence: 99%

A fundamental equation of state for the (R134a + triethylene glycol dimethyl ether) mixture

Marchi

Scalabrin

Ihmels³

et al. 2007

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).The thermodynamic properties of the mixture of 1,1,1,2-tetrafluoroethane (R134a) and triethylene glycol dimethyl ether (TriEGDME) have been modeled with equations of state in an extended corresponding states format. A recent equation of state for pure R134a was assumed as the reference while the scale factors have been obtained in neural network form by regression of experimental data for the mixture. The modeling was focused on the liquid phase, considering the possible application of such a mixture in a refrigeration plant; since the vapor pressure of pure TriEGDME is negligible over the considered temperature range, the vapor phase of the mixture at vapor-liquid equilibrium condition is almost pure R134a. Two fundamental equations are proposed herein. The first one, developed from a limited amount of experimental data is valid for R134a mole fractions greater than 0.94. The second equation was obtained from a wider data base; it has a larger number of free parameters to regress and covers the R134a mole fractions greater than 0.59. 2007 American Institute of Chemical Engineers AIChE J, 53: [1349][1350][1351][1352][1353][1354][1355][1356][1357][1358][1359][1360][1361] 2007 Keywords: extended corresponding states, neural networks, R134a, refrigerant þ lubricant mixtures, thermodynamic properties, TriEGDME IntroductionThe environmental problems connected with the use of chlorofluorocarbon (CFC) refrigerants, in particular the depletion of the stratospheric layer of ozone, have imposed the phase-out of such substances and their replacement with less harmful fluids. Consequently, the study of alternative refrigerants and of their properties has become a fundamental task for scientific and technical research.Nowadays, the fluids mainly used in the refrigeration and air-conditioning plants are hydrofluorocarbons (HFC) that show better environmental behavior, thanks to the absence of chlorine atoms in their molecules. Among the substances of this family, 1,1,1,2-tetrafluoroethane (R134a) is widely used, because of its favorable thermodynamic performances in compression cycles and its compatibility with the existing refrigeration plants designed for CFC refrigerants.The identification of a suitable alternative refrigerant does not completely solve the technical problem: in fact, in the compression plants, the working fluid is not a pure refrigerant (or a mixture of refrigerants), but a certain amount of lubricant, compatible and soluble with the refrigerant, must be added. Because the mineral oils that were used with CFCs for years show low solubility in HFC refrigerants, it is necessary to propose alternative lubricants. The problems posed by the selection of the lubricant have been widely studied in recent years; a partial review is given by Marsh and Kandil.1 Guidance for the choice of the most efficient lubricant for specific technical applications, as for instance the design of a refrigeration plant, requires the knowledge of the thermophysical properties of t...

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“…53-63, see 64 for a review] need different sets of parameter for different isomers with the same sum formula. (See, for example, Elvassore and Bertucco [139] for a list of pure component parameter of branched and linear alkanes.) LCT-EOS, however, can incorporate the structure of molecules and thereby only has one set of parameters.…”

Section: Predictive Capabilities Of Lct-eosmentioning

confidence: 99%