Carbon dioxide mean free path

Knudsen Diffusion Only Is Occurring. For a very fine pore material in which the effective pore diameter is less than the mean free path of the molecules, bulk diffusion and Poiseuille flow do not occur. For this case, the change in volume given when C + CO2 —> 2CO has no influence on the rate of diffusion of carbon dioxide into the rod, and is not dependent on the total pressure in the pores. Considering a wedge of carbon (Fig. Al),... 

Figure 10.10 Mean-free-path X of helium, air and carbon dioxide as a function of the pressure p and at the temperature T = 293 K. From [Ard64].

An alternative application of the Thome-Enskog equations is that en loyed by Veso-vic Wakeham (1989,1991). The procedure has been described in detail in Section 5.5, so that it is necessary here to describe only the sources of information employed. First the correlation of the viscosity of pure carbon dioxide has been taken from the work of Vesovic etal. (1990) and that of ethane from the workofHendl etal. (1994). For each temperature at which it was desired to evaluate the mixture viscosity these correlations were used in equation (5.53) to evaluate the pseudo-radial distribution functions g,- for each pure component, while equation (5.56) was used to determine a consistent value of the mean free-path shortening parameter a,-, for i-i interactions. Figure 15.3 contains a plot of the pseudo-radial distribution function determined in this way for the two pure gases at one temperature. 

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