Pulsed Townsend measurement of electron swarm parameters in C4F7N–CO2 and C4F7N–N2 mixtures as eco-friendly insulation gas

Abstract

Recently, C4F7N mixtures have attracted attention as a promising SF6 alternative due to their low global warming potential and excellent electrical performance. In this study, we introduce a newly built experimental setup for pulsed Townsend measurements as well as the physical model for the acquisition of electron swarm parameters. The effective ionization rate coefficients, electron drift velocity, and density-normalized longitudinal diffusion coefficients in C4F7N and its mixtures with CO2 and N2 were obtained. The reduced critical electric field for pure C4F7N at 100 Pa is determined to be 1002 Td, while it decreases with increasing pressure because of the effect of ion kinetics during the discharge process. C4F7N shows good synergism with CO2 and N2. To have a dielectric strength equivalent to that of SF6, the mixing ratio of C4F7N in its mixtures with CO2 and N2 should be 18% and 12%, respectively. The results provide fundamental data for modeling discharges in C4F7N and its mixtures.

Determination and assessment of a complete and self-consistent electron-neutral collision cross-section set for the C4F7N molecule

“…In the E/N < 950 Td range, the [14], Nechmi et al [16], Qin et al [47], Yi et al [18] and our previous work [15]. [14], Qin et al [47] and our previous work [15]. calculated k i and k a are in good agreement with the experimental measurements of Chachereau et al For a higher E/N range, the calculated k i and k a are slightly smaller than the experimental measurements.…”

“…The calculated results are generally consistent with measurements, even if there are still some imperfections. In the E/N < 950 Td range, the [14], Nechmi et al [16], Qin et al [47], Yi et al [18] and our previous work [15]. [14], Qin et al [47] and our previous work [15].…”

“…The inert gas Ar is often selected in such electron swarm methods to avoid non-unique cross-sections [31,33]. The electron swarm parameters for pure C 4 F 7 N and C 4 F 7 N/N 2 mixtures were obtained from our previous work [15]. The electron swarm parameters for C 4 F 7 N/Ar mixtures of different C 4 F 7 N abundances (1.02%, 4.93%, 9.74%, 20.08%, 48.32%) were newly measured by our PT setup and are presented here for the first time.…”

“…Indeed, electron swarm parameters in pure C 4 F 7 N and mixtures with N 2 , CO 2 , air were already measured independently by Chachereau et al in 2018 [14] and Zhang et al in 2022 [15] using pulsed Townsend (PT) experiments. Others have used steady-state Townsend (SST) experiments to obtain ionization and attachment coefficients of C 4 F 7 N [16][17][18].…”

Kinetic and Experimental Investigations on the Unimolecular Thermal Decomposition of an Eco-friendly Insulating Gas HFO-1336mzz(E)

“…In recent years, fluorinated ketones (such as C 5 F 10 O , ) and fluorinated nitriles (such as C 4 F 7 N − ) have received widespread attention from researchers in the power industry. However, these gases are not perfect SF 6 substitutes.…”