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

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.