Transport Coefficients for Water–Air Mixture Gases with Dissociation Reactions

Transport coefficients of water-air mixture gases with dissociation reactions, consisting of diffusion coefficients, viscosity, and thermal conductivity, were calculated using the Chapman-Enskog method. To validate the accuracy of the calculation, the transport coefficients for pure water vapor and air were computed and compared with values reported in Aubreton et al. (2009) and Boulos et al. (1994). The calculated viscosity and thermal conductivity showed good agreements with the values reported in the previous studies. Furthermore, the calculated transport coefficients of water-air mixture gases were compared with the estimated values obtained using conventional mixing rules. The error in viscosity calculated using the mixing rule proposed by Wilke (1950) ranged from -6.0% to 2.4%, indicating that it provides a relatively accurate estimation of the viscosity in mixture systems. In contrast, the errors in thermal conductivity obtained using the mixing rules proposed by Lindsay and Bromley (1950), Mason and Saxena (1958), and Tondon and Saxena (1968) were significantly large, ranging from -29.0% to 14.8%, -36.3% to 2.5%, and -27.6% to 12.6%, respectively. These results suggest that the conventional mixing rules are not suitable for estimating the thermal conductivity of water-air mixture gases, where dissociation reactions play a significant role.