Page 334 - Modelling in Transport Phenomena A Conceptual Approach

314 CHAPTER 8. STEADY MICROSCOPIC BALANCES WITHOUT GEN.

Rearrangement of Eq. (8.541) results in

(8.542)

Integration of Ekl. (8.542) leads to

(8.543)

The use of the identity from Eq. (8.535), Le.,
-
I
1 - VACA = VBCB (8.544)
simplifies Eq. (8.543) to
(8.545)

which is identical with Eq. (8.538).

Example 8.17 Cyclohexane (A) is di&sing through a 1.5mm thick stagnant
benzene (B) film at 25OC. If XA, = 0.15 and XA,, = 0.05, determine the molar
flux of cyclohexane under steady conditions.
Solution

Physical properties
pA = 0.779 g/ cm3
For cyclohexane (d)
:
M~=84
For benzene (a) pB = 0.879 g/ cm3
Mg=78

Analysis

The molar volumes of species A and t3 are

- 84 - 107.8 cm3/ mol
---
0.779

- 78 - 88.7 cm3/ mol
---
0.879