Abstract
A tool based on the mass action law was developed to calculate plasma compositions and thermodynamic properties for pure gases and mixtures, assuming a local thermodynamic equilibrium for pressures of up to 300 bar. The collection of the data that was necessary for tool calculation was automated by another tool that was written using Python, and the formats for the model were adapted directly from the NIST and JANAF websites. In order to calculate the plasma compositions for high pressures, virial correction was introduced. The influences of the parameters that were chosen to calculate the Lennard–Jones (12-6) potential were studied. The results at high pressure show the importance of virial correction for low temperatures and the dependence of the dataset used. Experimental data are necessary to determine a good dataset, and to obtain interaction potential. However, the data available in the literature were not always provided, so they are not well-adapted to a large pressure range. Due to this lack, the formulation provided by L. I. Stiel and G. Thodos (Journal of Chemical and Engineering Data, vol. 7, 1962, p. 234–236) is a good alternative when the considered pressure is not close to the critical point. The results may depend strongly on the system studied: examples using SF6 and CH4 plasma compositions are given at high pressure.
Highlights
The calculation of plasma compositions under the assumption of local thermal equilibrium (LTE)is necessary to determine the thermodynamic properties and the transport coefficients that are needed for magneto-hydrodynamic models of thermal plasma processes and systems as circuit breakers, plasma torches, or thermal engines
From the values of σ and kε obtained with the Stiel formulation, it is possible to calculate the plasma composition and the mass density at high pressure
Under the assumption of LTE, a variation of species densities with temperature can be obtained for atmospheric pressures of up to 300 bar
Summary
The calculation of plasma compositions under the assumption of local thermal equilibrium (LTE)is necessary to determine the thermodynamic properties and the transport coefficients that are needed for magneto-hydrodynamic models of thermal plasma processes and systems as circuit breakers, plasma torches, or thermal engines. Three methods are mainly used to calculate the evolution of species densities with temperature and pressure in thermal plasmas: the Gibbs free enthalpy minimization [1], the mass action law method [2,3], and the collisional radiative model Based on these methods, numerous papers have reported chemical plasma compositions for pure gases and mixtures, with or without the LTE assumption [2,4,5,6,7,8,9,10,11,12,13,14,15,16]. In the thermal plasma community, only a few authors have considered this correction at high pressures [4,6,9,14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
