Brokaw's formula

Input data

Temperature

Pressure

Molar mass of component A

Polarity of component A

Molar mass of component B

Polarity of component B

Output data

Diffusivity

Description

Given the molar masses and polarities of two compounds, as well as the operation temperature and pressure, calculates the diffusivity coefficient by the Brokaw's equation:

Dab=1.858.10−3.T32.(1Ma+1Mb)12P∗Ωd∗σab2; Dab = \frac{1.858.10^{-3}.T^\frac{3}{2}.{(\frac{1}{Ma}+\frac{1}{Mb})}^{\frac{1}{2}}}{P*Ωd*σab^2};

Been:

  • A: as the first chemical compound inserted, which is difusive in B;
  • B: as the second chemical compound inserted, which is the diffusive environment.

The Brokaw's equation uses the Hirschfelder's equation with alteration in the colision diameter and the colision integral:

  • Modified colision integral is given by:
ΩD=ΩD∗+0,196.SAB2T∗ Ω_D = Ω^*_D + \frac{0,196.S_{AB}^2}{T^*}
  • Modified colision diameter is given by:
σAB=σA.σB12 σ_{AB} = {σ_A.σ_B}^{\frac{1}{2}}

References

  • WELTY, James; WICKS, Charles E.; WILSON, Robert E.; RORRER, Gregory L. Fundamentals of Momentum, Heat and Mass Transfer. 5th Ed. John Wiley & Sons, 2008.