### Abstract

Dielectric permittivities (epsilon(r)) have been measured using a microwave re-entrant resonator at temperatures from (248 to 365) K and pressures up to 11 MPa for the alternative refrigerants 1,3,3,3-tetrafluoropropene (R1234ze(E)) and 2,3,3,3-tetrafluoropropene (R1234yf) in the liquid and vapour phases. Values of epsilon(r) were also measured for liquid CO2 at temperatures below 274 K, extending the data available for this fluid. Molecular polarizability, dipole moment, and the dielectric virial coefficients of each hydrofluoroolefin (HFO) refrigerant were determined by applying the dielectric virial expansion and Kirkwood equation to the measured permittivity data. The experimental results for the vapour phase lead to dipole moments with relative standard uncertainties around 5% that are in reasonable agreement with values from molecular modelling. The measured dipole moment for R1234ze(E) of 1.13 D is about 12% smaller than predicted, while the measured dipole moment for R1234yf of 2.24 D is about 11% smaller than predicted. In the compressed liquid region, the two refrigerants exhibited quite different dependencies on temperature and density. The polarizability of liquid R1234ze(E) could be predicted within 4.2% using the gas phase parameters (measured dipole moment and molecular polarizability). In contrast, the temperature dependence of the polarizability of R1234yf was twice as large in the liquid phase as in the gas phase. The density dependence of the polarizability for liquid R1234yf is at least 10 times that of liquid R1234ze(E). Liquid phase data were also used to estimate effective Kirkwood correlation factors, g, by assuming them to be temperature independent over the range of measurements. The results indicate g approximate to 2.4 for R1234yf and g approximate to 1.2 for R1234ze(E). (C) 2018 Elsevier Ltd.

Original language | English |
---|---|

Pages (from-to) | 148-158 |

Number of pages | 11 |

Journal | Journal of Chemical Thermodynamics |

Volume | 128 |

DOIs | |

Publication status | Published - Jan 2019 |

### Cite this

*Journal of Chemical Thermodynamics*,

*128*, 148-158. https://doi.org/10.1016/j.jct.2018.07.011

}

*Journal of Chemical Thermodynamics*, vol. 128, pp. 148-158. https://doi.org/10.1016/j.jct.2018.07.011

**Dielectric permittivity, polarizability and dipole moment of refrigerants R1234ze(E) and R1234yf determined using a microwave re-entrant cavity resonator.** / Sampson, Catherine C.; Kamson, Mobolaji; Hopkins, Matthew G.; Stanwix, Paul L.; May, Eric F.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Dielectric permittivity, polarizability and dipole moment of refrigerants R1234ze(E) and R1234yf determined using a microwave re-entrant cavity resonator

AU - Sampson, Catherine C.

AU - Kamson, Mobolaji

AU - Hopkins, Matthew G.

AU - Stanwix, Paul L.

AU - May, Eric F.

PY - 2019/1

Y1 - 2019/1

N2 - Dielectric permittivities (epsilon(r)) have been measured using a microwave re-entrant resonator at temperatures from (248 to 365) K and pressures up to 11 MPa for the alternative refrigerants 1,3,3,3-tetrafluoropropene (R1234ze(E)) and 2,3,3,3-tetrafluoropropene (R1234yf) in the liquid and vapour phases. Values of epsilon(r) were also measured for liquid CO2 at temperatures below 274 K, extending the data available for this fluid. Molecular polarizability, dipole moment, and the dielectric virial coefficients of each hydrofluoroolefin (HFO) refrigerant were determined by applying the dielectric virial expansion and Kirkwood equation to the measured permittivity data. The experimental results for the vapour phase lead to dipole moments with relative standard uncertainties around 5% that are in reasonable agreement with values from molecular modelling. The measured dipole moment for R1234ze(E) of 1.13 D is about 12% smaller than predicted, while the measured dipole moment for R1234yf of 2.24 D is about 11% smaller than predicted. In the compressed liquid region, the two refrigerants exhibited quite different dependencies on temperature and density. The polarizability of liquid R1234ze(E) could be predicted within 4.2% using the gas phase parameters (measured dipole moment and molecular polarizability). In contrast, the temperature dependence of the polarizability of R1234yf was twice as large in the liquid phase as in the gas phase. The density dependence of the polarizability for liquid R1234yf is at least 10 times that of liquid R1234ze(E). Liquid phase data were also used to estimate effective Kirkwood correlation factors, g, by assuming them to be temperature independent over the range of measurements. The results indicate g approximate to 2.4 for R1234yf and g approximate to 1.2 for R1234ze(E). (C) 2018 Elsevier Ltd.

AB - Dielectric permittivities (epsilon(r)) have been measured using a microwave re-entrant resonator at temperatures from (248 to 365) K and pressures up to 11 MPa for the alternative refrigerants 1,3,3,3-tetrafluoropropene (R1234ze(E)) and 2,3,3,3-tetrafluoropropene (R1234yf) in the liquid and vapour phases. Values of epsilon(r) were also measured for liquid CO2 at temperatures below 274 K, extending the data available for this fluid. Molecular polarizability, dipole moment, and the dielectric virial coefficients of each hydrofluoroolefin (HFO) refrigerant were determined by applying the dielectric virial expansion and Kirkwood equation to the measured permittivity data. The experimental results for the vapour phase lead to dipole moments with relative standard uncertainties around 5% that are in reasonable agreement with values from molecular modelling. The measured dipole moment for R1234ze(E) of 1.13 D is about 12% smaller than predicted, while the measured dipole moment for R1234yf of 2.24 D is about 11% smaller than predicted. In the compressed liquid region, the two refrigerants exhibited quite different dependencies on temperature and density. The polarizability of liquid R1234ze(E) could be predicted within 4.2% using the gas phase parameters (measured dipole moment and molecular polarizability). In contrast, the temperature dependence of the polarizability of R1234yf was twice as large in the liquid phase as in the gas phase. The density dependence of the polarizability for liquid R1234yf is at least 10 times that of liquid R1234ze(E). Liquid phase data were also used to estimate effective Kirkwood correlation factors, g, by assuming them to be temperature independent over the range of measurements. The results indicate g approximate to 2.4 for R1234yf and g approximate to 1.2 for R1234ze(E). (C) 2018 Elsevier Ltd.

KW - EQUATION-OF-STATE

KW - CARBON-DIOXIDE

KW - RELATIVE PERMITTIVITY

KW - FLUID REGION

KW - DEW POINTS

KW - MIXTURES

KW - PRESSURES

KW - CONSTANT

KW - GAS

KW - MPA

U2 - 10.1016/j.jct.2018.07.011

DO - 10.1016/j.jct.2018.07.011

M3 - Article

VL - 128

SP - 148

EP - 158

JO - J. Chem. Thermodynamics

JF - J. Chem. Thermodynamics

SN - 0021-9614

ER -