Inhibition Effect of Solid Products and DC Breakdown Characteristics of the HFO1234Ze(E)–N₂–O₂ Ternary Gas Mixture

Abstract

HFO1234ze(E) is an environmentally friendly SF 6 substitute gas with prominent application potential. To suppress the generation of the HFO1234ze(E) solid decomposition products, which may cause great hazards to the gas–solid insulation strength, a gas mixing scheme screening method based on the reactive force field (ReaxFF) molecular dynamics (MD) simulation was innovatively proposed. The simulation results show that the inhibitory effect of O 2 on the formation of HFO1234ze(E) solid products is better than those of CO 2 and CF 4 . Further study shows that when O 2 accounts for 3.33% of the gas mixture, the solid precipitate content is reduced by 48%. The experimental study shows that an O 2 content of 3.33% can inhibit the generation of solid products by more than 50%. Besides, compared with HFO1234ze(E)-N 2 , the DC breakdown voltage of HFO1234ze(E)-N 2 -O 2 is slightly increased, and the breakdown voltage dispersion degree and continuous breakdown voltage drop rate are decreased. This work gives a feasible solution for the suppression of HFO1234ze(E) solid decomposition products and provides an efficient method for solving similar problems of environmentally friendly insulating gas in C/F/O/N systems.

Partial discharge induced decomposition and by-products generation properties of HFO-1234ze(E)/CO2: a new eco-friendly gas insulating medium

“…Normally, the generation of solid by-products will cause dielectric strength deterioration, operational reliability and service life decreases of GIE, which is common in fluorocarbon eco-friendly gases [34][35][36]. As reported by Liu et al, there exists a relatively large voltage drop between the first and second DC breakdown voltage of HFO-1234ze(E)/N 2 gas mixture owing to the generation of solid by-products that increased the surface roughness of electrode under quasiuniform electric field [26]. Soulie et al also found that under the slightly non-uniform electric field, the presence of solid precipitates greatly reduced the DC breakdown voltage of HFO-1234ze(E) [30].…”

“…Some of these particles will re-combine to HFO-1234ze(E), and the others will undergo compound reaction to form stable gaseous decomposition by-products such as CF 4 , CHF 3 , C 2 F 6 , C 3 HF 7 (as shown in figure 11(a)). For the gas decomposition mechanism of HFO-1234ze(E) gas mixture, density functional theory or ReaxFF-MD calculations have been conducted by Wang et al [25], Lin et al [24], Liu et al [26]. Relevant results show that HFO-1234ze(E) initially undergoes bond-cleavage reactions to generate CF 3 , F and H radicals, leading to abstraction reaction to form CF 4 , CHF 3 , and C 2 F 6 which is consistent with our experimental results.…”

“…and cis-C 3 H 2 F. Some black solid by-products also appeared on the electrode and a breakdown voltage drop of 6.2% existed [25]. Liu et al pointed out that the generation of solid by-products in HFO-1234ze(E)/N 2 can be inhibited by adding 3.33% O 2 owing to its oxidative effect [26].…”

Reactive molecular dynamics simulations on the pyrolysis of SF6

“…ReaxFF can simulate chemical reactions at the mesoscopic scale, as well as related thermodynamic and kinetic properties, etc., and has been widely used in pyrolysis [19], combustion [20], new materials development [21] and other fields. Recently, it has also been used to study the chemical properties of insulating gases with satisfactory results [22,23]. Liu et al used the ReaxFF method to investigate the impact of an O 2 environment on the decomposition of SF 6 .…”