Dielectric properties of alternative refrigerants

Santos, F.J.V.; Pai-Panandiker, R. S.; Castro, C. A. Nieto de; Mardolcar, U. V.

doi:10.1109/tdei.2006.1657961

Cited by 8 publications

(14 citation statements)

References 17 publications

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“…Table presents the values of the coefficients A and B of the Vedam equation for each isotherm of the three refrigerants. The behavior found for these refrigerants is similar to all studied before . The intercept values are nearly zero for all isotherms, B ≅ 0, and the slope of the linear variation of Δ with Σ is negative for all temperatures, decreasing linearly with the increase with temperature, as expected from the theory.…”

Section: Resultssupporting

confidence: 82%

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Relative Permittivities of 1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-Hexafluoropropane (HFC-236ea), and 1,1,1,3,3-Pentafluorobutane (HFC-365mfc) in the Liquid Phase

et al. 2007

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Relative permittivity measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), and 1,1,1,3,3-pentafluorobutane (HFC-365mfc) in the liquid phase are reported. Measurements were performed by using a direct capacitance method at temperatures from 223 K to 303 K and pressures up to 16 MPa for HFC-227ea and HFC-236ea and at temperatures from 263 K to 303 K up to 16 MPa for HFC-365mfc. The uncertainty of the relative permittivity measurements is estimated to be better than ±1.1·10-2. The theory developed by Vedam et al., and adapted by Diguet, and the Kirkwood modification of the Onsager were applied to obtain the apparent dipole moment of HFC-227ea, HFC-236ea, and HFC-365mfc in the liquid state, found to be 2.356 D for HFC-227ea, 2.624 D for HFC-236ea, and 4.917 D for HFC-365mfc. The effective dipole in the liquid state of HFC-236ea predicted by the Kirkwood−Frölich theory is 2.065 D. Density functional and density functional self-consistent calculations (SCIPCM) of the electronic distribution and of the dipole moment are reported for HFC-227ea.

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Section: Resultssupporting

confidence: 82%

“…Additionally, the data are fundamental for the design of machinery used in the air-conditioning and refrigeration industry. Relative permittivity provides information about the behavior of the molecules under an electrical field, controlled by their chemical structure and molecular interactions …”

Section: Introductionmentioning

confidence: 99%

Relative Permittivities of 1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-Hexafluoropropane (HFC-236ea), and 1,1,1,3,3-Pentafluorobutane (HFC-365mfc) in the Liquid Phase

et al. 2007

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“…45,46 The atmospheric concentration of HFCs is rapidly increasing and causing great environmental concern due to their greenhouse potential. 45,47 Due to their technological and environmental relevance, HFCs have been the focus of a number of experimental [48][49][50][51] and simulation stud-4 Figure 1: Molecular structure of CF 3 H (A), CF 2 H 2 (B), and CFH 3 (C). The molecular frame of reference used for spatial distribution functions is also shown.…”

Section: Introductionmentioning

confidence: 99%

“…The aim of the present work is to assess the accuracy of KS-DFT by using different models that can account for dispersion interactions (PBE-D3, BLYP-D3, and rVV10) for predicting the vapor liquid coexistence curves (VLCC) of hydrofluoromethanes via FPMC simulations. We selected hydrofluoromethanes as hydrofluorocarbons (HFCs) are extensively used as a refrigerant in refrigerators and air conditioning units, fire suppression agents, propellant in the metered dose inhalers, etching agents, and blowing agent purposes. , The atmospheric concentration of HFCs is rapidly increasing and causing great environmental concern due to their greenhouse potential. , Due to their technological and environmental relevance, HFCs have been the focus of a number of experimental − and simulation studies. − Furthermore, previous systems considered for FPMC had hydrogen bonding (water and methanol) and dispersion interactions (methane) as the dominant interactions. , HFCs selected here belong to a different class as these molecules, in addition to dispersion interactions, will have significant permanent dipole–dipole interactions, where upon thermal averaging, the leading order term goes as r –6…”

Section: Introductionmentioning

confidence: 99%

Vapor Liquid Equilibria of Hydrofluorocarbons Using Dispersion-Corrected and Nonlocal Density Functionals

Goel

Butler

Windom

et al. 2016

J. Chem. Theory Comput.

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Recent developments in dispersion corrected and nonlocal density functionals are aimed at accurately capturing dispersion interactions, a key shortcoming of local and semilocal approximations of density functional theory. These functionals have shown significant promise for dimers and small clusters of molecules as well as crystalline materials. However, their efficacy for predicting vapor liquid equilibria is largely unexplored. In this work, we examine the accuracy of dispersion-corrected and nonlocal van der Waals functionals by computing the vapor liquid coexistence curves (VLCCs) of hydrofluoromethanes. Our results indicate that the PBE-D3 functional performs significantly better in predicting saturated liquid densities than the rVV10 functional. With the PBE-D3 functional, we also find that as the number of fluorine atoms increase in the molecule, the accuracy of saturated liquid density prediction improves as well. All the functionals significantly underpredict the saturated vapor densities, which also result in an underprediction of saturated vapor pressure of all compounds. Despite the differences in the bulk liquid densities, the local microstructures of the liquid CFH3 and CF2H2 are relatively insensitive to the density functional employed. For CF3H, however, rVV10 predicts slightly more structured liquid than the PBE-D3 functional.

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“…Hence, investigating the dielectric properties of HFE and FK is both relevant and timely. Specifically, relative permittivity [11, 12], AC dissipation factor [11], DC conductivity [13] and breakdown strength [14–16] are the four key parameters that are used to evaluate coolant dielectric properties. A previous study has reported the temperature effect on AC spectroscopy and DC conductivity [17].…”

Section: Introductionmentioning

confidence: 99%

Effect of temperature on the dielectric properties of hydrofluoroethers and fluorinated ketone

Chippendale

Lewin

et al. 2019

IET Science, Measurement & Technology

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Dielectric properties of alternative refrigerants

Cited by 8 publications

References 17 publications

Relative Permittivities of 1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-Hexafluoropropane (HFC-236ea), and 1,1,1,3,3-Pentafluorobutane (HFC-365mfc) in the Liquid Phase

Relative Permittivities of 1,1,1,2,3,3,3-Heptafluoropropane (HFC-227ea), 1,1,1,2,3,3-Hexafluoropropane (HFC-236ea), and 1,1,1,3,3-Pentafluorobutane (HFC-365mfc) in the Liquid Phase

Vapor Liquid Equilibria of Hydrofluorocarbons Using Dispersion-Corrected and Nonlocal Density Functionals

Effect of temperature on the dielectric properties of hydrofluoroethers and fluorinated ketone

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