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Example: calculation of viscosity and thermal conductivity for a dissociated CO2 gas mixture

Transport coefficients were calculated for the case of LTE reacting CO2 mixture (CO2, CO, O2, O, C) at pressure P=1 atm in the temperature range 300≤T≤4000 K. The following parameters for Lennard-Jones potential were used:

CO2-CO2:       e/k= 216 K,  d= 3.87 Angstrom;    O2-O2:    e/k= 107 K,  d= 3.47 Angstrom;

CO-CO:          e/k= 100 K,  d= 3.71 Angstrom;    O-O:        e/k= 107 K,  d= 3.05 Angstrom;

C-C:                e/k=  31 K,  d= 3.39 Angstrom.

The necessary non-diagonal values eij and dij were calculated using the conventional combination rules. Transport coefficients were calculated using the accurate formulae of the Chapman-Enskog method with account for higher approximations, e.g. x=2 for viscosity, x=4 for translational thermal conductivity.

In figures (a) and (b) the calculated (a) viscosity and (b) total thermal conductivity l=ltr+lint of CO2 are compared with the experimental and theoretical data. This comparison indicates that the results of calculations are accurate to within about 1.4% for T≤2000 K, the uncertainty is of 7% at T=3000 K and 17% at T=4000 K because of the use of the Lennard-Jones potential for all pairs of particles.

Calculated and experimental data for transport coefficients - viscosity and thermal conductivity for a dissociated CO2 gas mixture
The calculated transport coefficients are shown by blue line: (a) viscosity and (b) thermal conductivity. The experimental data are shown by red circles (Vargaftic N.B. et al. Tables on the thermophysical properties of liquids and gases. N.Y., Halsted Press, 1975; Vargaftic N.B. et al. Handbook of thermal conductivity of liquids and gases, CRC Press, 1994). Theoretical data are shown by black squares (Carbon dioxide. Transport and thermodynamic properties. Andriatis A.V., Sokolova I.A. Mathematical modeling, Vol.7, N.2, 1995. In Russian).

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