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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Molecular weight of solvent B
Absolute temperature		° K
Viscosity of solvent B		cP
Molal volume of solute A		cm3/g-mol
Association factor of solvent B

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OUTPUT   VARIABLES   &   GRAPHS

Variables	Values	Units
♦  Diffusion coefficient of liquid phase		cm2/s	Graphs:  Diffusion coeff. Vs Molal volume

Liquid-Phase Diffusion

Diffusion is the spontaneous migration of substances from regions where their concentration is high to regions where their concentration is low. The knowledge of the degree of diffusion is important in several chemical engineering mass transfer process design - eg. gas adsorption, distillation and liquid-liquid extraction. A number of correlations have been proposed for predicting the diffusion coefficient for a binary mixture of solute A in solvent B (e.g. propane in chlorobenzene). The Wilke-Chang method estimates this coefficient for dilute solutions via the equation:

where
     D⁰_AB = diffusion coefficient of solute A in solvent B, cm²/s
     M_wB = molecular weight of solvent B
     T = absolute temperature, °K
     v_A = molal volume of solute A at its normal boiling point temperature, cm³/g-mol
     μ_A = viscosity of solvent B, cP
     φ = association factor of solvent B, e.g. = 1 for unassociated solvents, =2.6 for water

In the implementation here, the infinite series is approximated by summation from m=0 => 250, with insignificant loss of accuracy.

Tips

    ◊ Use link EXAMPLE Of Input/Output  to demo data entry expectations and results; you may edit & use it as starting point

BIBLIOGRAPHY

• Coker, AK; Fortran Programs For Chemical Process Design, Analysis & Simulation; Gulf Publ. Co, Houston, 1995.
• Chopey, NP; Handbook of Chemical Engineering Calculations; McGraw Hill, New York, 2003.