Thermodynamic and Transport Properties of CO₂, CO₂-O₂ and CO₂-H₂ Mixtures at Temperatures of 300-30,000K and at Pressures of 0.1-10MPa

Abstract

This paper provides the theoretical calculation results of thermodynamic and transport properties of CO₂, CO₂-O₂ mixture, CO₂-H₂ mixture under thermal equilibrium condition at temperatures of 300-30,000K and at pressures of 0.1-10MPa. The gas CO₂ is one of the candidates for the environmentally-benign arc-quenching medium in a circuit breaker. Furthermore, effect of addtional gases O₂ and H₂ on the thermodynamic and transport properties of CO₂ was also invesitigated in this paper. The hydrogen atom included CO₂ is similar to the polymer ablated vapor in a switching devices. First, equilibrium compositions of CO₂, CO₂-O₂ mixture, CO₂-H₂ mixture were calculated through Gibbs' free energy minimization method. Secondly, thermodynamic properties were computed using the calculated composition. Finally, transport properties were calculated by the first order approximation of Chapman-Enskog method using the collision integrals between species. Inclusion of H₂ increases the electrical conductivity of CO₂ in range 3,000-6,000K because CHO molecules produced in this temperature range emit more electron due to the lower ionization potential of CHO. It also increases the thermal conductivity of CO₂ especially due to dissociation reactions of H₂ around 3,900K and ionization of H around 15,000K. These properties data provided here can be used for CO₂ thermal plasma simulation.