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Multicomponent gas transport coefficients: alternate formulations.
1Department of Chemistry, University of British Columbia, Vancouver, Canada V6T 1Z1.
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|January 15, 2011
Summary
This study revises gas transport calculations by proposing new gradients for the Boltzmann equation, impacting thermal diffusion coefficients and binary diffusion constants under varying densities. It highlights a disparity in standard thermodynamic variable usage.
Area of Science:
- Thermodynamics
- Statistical Mechanics
- Fluid Dynamics
Background:
- The phase rule dictates local fluid properties using c+1 variables for c components.
- Standard Boltzmann equation solutions for gas transport use only c gradients, excluding convective motion.
- A disparity exists between the phase rule and standard Boltzmann equation methodologies.
Purpose of the Study:
- To address the disparity in independent variables used in the Boltzmann equation for gas transport.
- To propose an alternative set of gradients for solving the Boltzmann equation.
- To re-evaluate expressions for thermal diffusion and binary diffusion coefficients.
Main Methods:
- Solving the Boltzmann equation with an alternative set of gradients.
- Utilizing irreversible thermodynamics as a reference framework.
- Analyzing the impact on thermal diffusion and binary diffusion coefficients.
Main Results:
- Added terms are introduced in the expressions for thermal diffusion coefficients.
- The standard binary diffusion constant is found to be valid only at constant total density.
- An alternative formulation for gas transport properties is presented.
Conclusions:
- The proposed alternative gradients offer a more consistent approach with the phase rule.
- The findings necessitate a re-evaluation of standard gas transport coefficient calculations.
- This work provides a refined theoretical basis for understanding gas transport phenomena.
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