Calculation of Thermal Plasma Thermodynamic Properties for Arbitrary Gas Mixtures

Askari, O. (2017). Calculation of Thermal Plasma Thermodynamic Properties for Arbitrary Gas Mixtures. International Mechanical Engineering Congress and Exposition. Tampa, FL.

Chemical composition and thermodynamics properties of different thermal plasmas are calculated in a wide range of temperatures (300 - 100,000 K) and pressures (10-6 -100 atm). The calculation is performed in dissociation and ionization temperature ranges using statistical thermodynamic modeling. The thermodynamic properties are being considered in this study are enthalpy, entropy, Gibbs free energy, specific heat at constant pressure, specific heat ratio, speed of sound, mean molar mass, and degree of ionization. The calculations have been done for seven pure plasmas such as hydrogen, helium, carbon, nitrogen, oxygen, neon and argon. In this study, the Debye-Hukel cutoff criterion in conjunction with the Griem\'s self-consistent model are applied for terminating the electronic partition function series and to calculate the reduction of the ionization potential. The Rydberg and Ritz extrapolation laws have been used for energy levels which are not observed in tabulated data. Two different methods called complete chemical equilibrium and progressive methods are presented to find the composition of available species. The calculated pure plasma properties are then presented as functions of temperature and pressure, in terms of a new set of thermodynamically self-consistent correlations for efficient use in CFD simulations. The results have been shown excellent agreement with literature. The results from pure plasmas are then used as a reliable reference source to calculate the thermodynamic properties of any arbitrary plasma mixtures having elemental atoms of H, He, C, N, O, Ne and Ar in their chemical structure. This alternative method is only valid for high temperature thermal plasmas.