Diffusion coefficient nitrogen + carbon dioxide

Sato, Y. Fujiwara, K. Takikawa, T. Sumarno Takishima, S. Masuoka, H. Solubilities and diffusion coefficients of carbon dioxide and nitrogen in polypropylene, high-density polyethylene, and polystyrene under high pressures and temperatures. Fluid Phase Equilib. 1999, 162, 261-276. 

Gas transport coefficients of PVC and PVC modified with pyridine groups were studied. It was found that there is a strong time dependence of the permeability and diffusivity of oxygen, nitrogen, carbon dioxide and methane in membranes prepared by solvent casting of PVC and pyridine modified PVC. There is a two-fold reduction for PVC of the diffusion coefficients during the first two days,... 

McKay (1971) carried out experiments in a Loschmidt-type diffusion cell with a nine component system including nitrogen, carbon dioxide, and a number of paraffins. The experiments were carried out at the high temperatures and pressures typical of underground oil and gas reservoirs. McKay s paper includes a dimensioned drawing of the Loschmidt-type cell used for the experiment and the initial conditions for some of his experiments. Use the theory of Section 5.5 to predict the composition profiles in this system. State clearly any assumptions made in your calculations. You will need to estimate diffusion coefficients at high pressure. Consult Reid et al. (1987) for details of methods that can be used for this purpose. 

Fig. 5 Variation of gas diffusivity in y-irradiated PTFE. The data were taken from [84C1]. (a) diffusion coefficient (b) permeability coefficient (, O) carbon dioxide ( , ) oxygen (A, A) nitrogen ( ,0) methane.

Reasonable prediction can be made of the permeabiUties of low molecular weight gases such as oxygen, nitrogen, and carbon dioxide in many polymers. The diffusion coefficients are not compHcated by the shape of the permeant, and the solubiUty coefficients of each of these molecules do not vary much from polymer to polymer. Hence, all that is required is some correlation of the permeant size and the size of holes in the polymer matrix. Reasonable predictions of the permeabiUties of larger molecules such as flavors, aromas, and solvents are not easily made. The diffusion coefficients are complicated by the shape of the permeant, and the solubiUty coefficients for a specific permeant can vary widely from polymer to polymer. 

Let us illustrate the calculation of the effective diffusivity and the molar fluxes for the conditions existing at the start of the two bulb diffusion cell experiment of Duncan and Toor discussed in Examples 5.3.1 and 5.4.1. The components are hydrogen (1), nitrogen (2), and carbon dioxide (3) and the values of the diffusion coefficients of the three binary pairs at 35.2° C and 1-atm pressure were... 

E. B Winn, The Temperature Dependence of the Self-Diffusion Coefficients of Argon, Neon, Nitrogen, Oxygen, Carbon Dioxide, and Methane, Phys. Rev., 80 1024,1950. 

In this lecture we coiranent briefly on how molecular theory— that is statistical mechanics and kinetic theory—can describe tran port coefficients, e.g., the viscosity (n), thermal conductivity (A), and the diffusion (D), of fluids such as argon, nitrogen, oxygen, carbon dioxide, and the simple hydrocarbons. 

As hydrogen has a considerably higher diffusion coefficient than oxygen, the reaction is usually less impeded by depletion. However, the reactant concentration on the anode side decreases because of the usually smaller stochiometries. Pure (humidified) hydrogen operation results in great fractions of water vapor in the gas at the cell outlet. If the anode gas carries additional gas species (e.g., nitrogen or carbon dioxide), the problem of an impeded reaction also increases considerably at the anode. 

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