Thermodynamic and transport properties of CO2, CO2–O2, and CO2–H2 mixtures at temperatures of 300 to 30,000 K and pressures of 0.1 to 10 MPa

Abstract

AbstractThis 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 to 30,000 K and at pressures of 0.1 to 10 MPa. The gas CO2 is one of the candidates for the environmentally benign arc‐quenching medium in a circuit breaker. Furthermore, the effect of additional gases O2 and H2 on the thermodynamic and transport properties of CO2 was also investigated in this paper. The hydrogen atom included CO2 is similar to the polymer ablated vapor in switching devices. First, equilibrium compositions of CO2, CO2–O2 mixture, CO2–H2 mixture were calculated through the Gibbs free energy minimization method. Second, 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 the range 3000 to 6000 K because CHO molecules produced in this temperature range emit more electrons due to the lower ionization potential of CHO. It also increases the thermal conductivity of CO2 especially due to dissociation reactions of H2 around 3900 K and ionization of H around 15,000 K. These properties provided here can be used for CO2 thermal plasma simulation. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(4): 18–29, 2008; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20467