Condensed species in products of the reaction of SF₆with Cu up to 4000 K

Abstract

This paper is concerned with condensed species in the equilibrium composition of a system of products of the reaction of sulphur hexafluoride with copper. It is assumed that SF6 is an insulation medium in the circuit breaker and reacts with the Cu contained in the circuit breaker contacts or in other parts of the circuit breaker. The system of products of the reaction of SF6 with Cu is assumed to be in local thermodynamic equilibrium for temperatures ranging from ambient temperature to 4000 K, with the pressure in the system being within an interval from 0.1 MPa to 2 MPa. The occurrence of condensed species and their phase transformations significantly affect the composition and thus also the system properties in a range of temperatures at which arc ignition or arc extinction take place. Data on the condensed species considered are analysed and the effects of the phase rule and the selected theoretical model on the occurrence of condensed species in the equilibrium composition are examined.

Calculation of two-temperature plasma composition: II. Consideration of condensed phases

“…For instance, in the arc plasmas in circuit breakers, the metallic vapours, e.g. copper vapour resulting from elec trode erosion, are likely to condense in the form of metals or metallic compounds when the arc temperature has decreased sufficiently during arc extinction [1,2]. These condensed particles will modify the plasma composition, affecting the plasma properties such as thermodynamic properties, trans port coefficients and radiation coefficients.…”

“…Rochette et al [3] calculated the compositions of Ag-SiO 2 plasmas mixed with various proportions of air con sidering the vaporization of liquid silver and silica. Rong et al [1] and Coufal and Toman [2] investigated the composition of SF 6 arcs in highvoltage circuit breakers considering the pos sible existence of condensed CuF, CuF 2 , CuS, Cu 2 S as well as copper and sulphur. Wang et al [4] revealed the effect of copper impurities on the dielectric breakdown properties of SF 6 arc by studying the composition with consideration of condensed species.…”

Graphite production in two‐temperature non‐LTE plasmas of C4F7N and C5F10O mixed with CO2, N2, and O2 as eco‐friendly SF6 replacements: A numerical study

“…[ 30 ] In such algorithms, the Lagrange multipliers are usually used to construct a nonlinear equation system representing Gibbs free energy minimization, chemical equilibrium, electrical neutrality, and Dalton's law. [ 28 ] As there have been a certain amount of previous works on the optimization algorithms for obtaining plasma compositions, [ 30–33 ] this study does not introduce the implementation of the algorithms in detail. Instead, we focus on how to calculate the Gibbs free energy of a plasma system with various mixtures using the parameters we can obtain from literature or by computation.…”

Calculation of two-temperature plasma composition: I. Mass action law methods and extremum searching methods

“…Instead of obtaining plasma composition by solving the equations of mass action laws simultaneously for all the reactions in plasmas, another kind of method is to obtain plasma composition by searching for an extremum in which the whole plasma system reaches the minimum Gibbs free energy or maximum entropy. The former is well known as the method of the Gibbs free energy minimization, which is widely used in the calculation of LTE plasma composition [3,[18][19][20][21] as well as 2T plasma composition [14,15]. However, it seems that researchers preferred to use the methods based on the law of mass action rather than the minimization of the Gibbs free energy.…”