Transient flow of a binary gas mixture through a long capillary at arbitrary rarefaction parameters

Area of Science:

• Fluid Dynamics
• Statistical Mechanics
• Chemical Engineering

Background:

• Simulating transient gas mixture flow in capillaries is crucial for processes like gas filling.
• Existing models may struggle with arbitrary rarefaction parameters and complex gas mixtures.
• Understanding flow behavior is key to preventing operational issues such as clogging.

Purpose of the Study:

• To develop a robust model for simulating transient gas mixture flow in long capillaries.
• To investigate the clogging phenomenon during gas filling processes.
• To establish criteria for predicting and analyzing clogging.

Main Methods:

• Developed a transient flow model based on linear relationships between thermodynamic fluxes and forces.
• Solved the linearized, steady Boltzmann equation using the finite-difference method to obtain kinetic coefficients.
• Employed the Chebyshev polynomial approximation to optimize computational efficiency.

Main Results:

• The model accurately predicts transient gas flow for various rarefaction parameters and molar fractions.
• A critical pressure ratio criterion for clogging was proposed and investigated.
• Identified correlations between critical pressure ratio and rarefaction parameter, molar fraction, and molecular mass ratio.

Conclusions:

• The proposed model enables efficient and accurate simulation of transient gas flow in capillaries.
• The critical pressure ratio provides a useful criterion for assessing clogging risk.
• Rarefaction parameter and molar fraction significantly influence clogging, while molecular mass ratio's effect is limited to specific conditions.