Thermodynamic properties and transport coefficients of high-temperature CO₂thermal plasmas mixed with C₂F₄

Abstract

This paper is devoted to the calculation of fundamental properties of CO 2 mixed with C 2 F 4 . The species composition and thermodynamic properties (mass density, entropy, enthalpy and specific heat at constant pressure) are based on Gibbs free energy minimization. The transport properties (electrical conductivity, viscosity and thermal conductivity) are calculated by the well-known Chapman-Enskog method. The Lennard-Jones like phenomenological potential and some recently updated transport cross sections are adopted to obtain collision integrals. The calculation is developed in the temperature range between 300 and 30 000 K, for a pressure between 1 to 16 bar and for several C 2 F 4 proportions. Transport coefficients for CO 2 are also compared with previous published values, and the reasons for discrepancies are analyzed. The results obtained for CO 2 -C 2 F 4 mixtures provide reliable reference data for the simulation of switching arcs in CO 2 circuit breakers with the ablation of PTFE.

State of Art and Challenges for the Calculation of Radiative and Transport Properties of Thermal Plasmas in HVCB

“…The thermodynamic properties (mass density, enthalpy, and specific heat at constant pressure) are directly deduced from the plasma compositions. Some results are given in [2][3][4][5][6][7][8][9] and behaviors are explained versus temperature, mixtures and pressure. The transport coefficients (viscosity, thermal and electrical conductivities) are obtained according to the Chapman-Enskog method and a previous calculation of collision integrals depending on the interaction potentials chosen to characterize the different collisions between particles (neutral-neutral, ion-neutral, electron-neutral and charged-charged collisions).…”

“…The transport coefficients (viscosity, thermal and electrical conductivities) are obtained according to the Chapman-Enskog method and a previous calculation of collision integrals depending on the interaction potentials chosen to characterize the different collisions between particles (neutral-neutral, ion-neutral, electron-neutral and charged-charged collisions). The study of the collision integrals constitutes the most important part of the calculation of the transport coefficients and are often responsible for the differences observed between the authors [2][3][4][5][6][7][8][9][10][11][12][13].…”

“…Figure5. Specific heat at constant pressure of heavy particles C P h versus electronic temperature Te for pure SF6, for θ = 5 and pressure of 1 bar.…”

Effects of Ultrasonic Vibration on the Transport Coefficients in Plasma Arc Welding

“…Therefore, if we know the influence law of ultrasound on the velocity distribution function of gas, we can analyze the influence of ultrasound on the gas transport coefficients through theoretical analysis and numerical calculation. The general theory and calculation method of gas transport coefficients have been systematically studied [14][15][16], and many researchers have also calculated the transport coefficients of various gases such as argon and helium, including the calculation of transport coefficients of two-temperature plasma [17,18] and mixed plasma [19,20]. The roles of shielding gas and metal vapour in affecting the plasma arc [21][22][23][24] and the coupling mechanism of plasma arc-keyhole-weld pool [25][26][27] have been numerically simulated.…”

Ablation-Dominated Arcs in CO2 Atmosphere—Part II: Molecule Emission and Absorption

“…It is well-known from composition calculations of thermal plasmas that the dissociation of filling gases like SF 6 and CO 2 , reactions with the ablation product C 2 F 4 and metal vapor from electrode erosion can produce a number of molecular species in an intermediate temperature range before an almost complete dissociation of atoms occurs at higher temperatures (see e.g., [10]). Mixtures of CO 2 with higher amount of C 2 F 4 are expected to contain considerable amounts of molecules at temperatures above 3000 K, namely CF 4 , CF 3 , CF 2 , C 2 F, C 3 , C 2 , CF, and CO (in order of dissociation with increasing temperatures) [11]. Hence, the study of molecule radiation can help to analyze the interesting ranges of lower temperatures near the nozzle boundaries and in the arc quenching phases.…”