Abstract
Gas mixtures containing fluoro-nitriles C<sub>4</sub>F<sub>7</sub>N or fluoro-ketones C<sub>5</sub>F<sub>10</sub>O as minority components (<20%) have been identified as promising alternatives to SF<sub>6</sub> in medium voltage gas-insulated switchgear (GIS) applications, because of their low Global Warming Potential together with their dielectric strength values being comparable to SF<sub>6</sub>. The buffer gases in such fluoro-nitrile or fluoro-ketone based gas mixtures are usually N<sub>2</sub>, O<sub>2</sub>, CO<sub>2</sub>, or air. In this contribution, we provide calculation results of transport properties, assuming local thermodynamic equilibrium (LTE), of thermal plasma containing following gas mixtures: C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> and C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub>-O<sub>2</sub>. The modifications in the thermodynamic and transport properties upon the addition of oxygen to the C<sub>4</sub>F<sub>7</sub>N-CO<sub>2</sub> mixtures in the temperature range 300&thinsp;K-30&thinsp;kK at 1&thinsp;bar are provided and discussed. These properties have been utilized to calculate the plasma temperature profile for a free-burning arc in a companion paper.
Highlights
In the decades following the Kyoto Protocol (1997), there has been an active industry-wide interest in analyzing possible replacements to SF6 in high voltage gas-insulated switchgear applications with voltage ratings greater than 52 kV [1]
Gas mixtures containing fluoro-nitriles C4F7N or fluoro-ketones C5F10O as minority components (
We provide calculation results of transport properties, assuming local thermodynamic equilibrium (LTE), of thermal plasma containing following gas mixtures: C4F7N − CO2 and C4F7N − CO2 − O2
Summary
In the decades following the Kyoto Protocol (1997), there has been an active industry-wide interest in analyzing possible replacements to SF6 in high voltage gas-insulated switchgear applications with voltage ratings greater than 52 kV [1]. Owing to the high boiling points (at 1 bar) of the promising main alternatives – fluoro-ketones (C5F10O, 27◦C) and fluoro-nitriles (C4F7N, −4.7◦C), suitable buffer gases like air or CO2 for example, are added to prevent liquefaction at temperatures lower than −30◦C. We calculate the relevant properties for the fluoro-nitrile-based C4F7N − CO2 − O2 mixtures for the temperature range 300 K–30 kK and pressure of 1 bar, with maximum mole fractions of C4F7N and O2 being 20%. These validation results are not provided here since the properties results at high pressures (>1 atm) are beyond the scope of current work
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