Page 213 - Modelling in Transport Phenomena A Conceptual Approach
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7.3. CONSERVATION OF TOTAL MASS 193
2. Ideal gas behavior.
Analysis
System: Naphthalene sphere
The terms appearing in the conservation of species A, Eq. (7.2-2), are
Therefore, Eq. (7.2-2) reduces to
Taking CA, = 0 and rearrangement gives
where Do is the initial diameter of the naphthalene sphere.
The average mass transfer coeficient, (ICC), can be related to the diameter of the
sphere, Dp, by using one of the mass transfer correlations given in Section 4.3.3.
The use of the Ranz-Marshall correlation, Eq. (4.3-33), gives
Sh = 2 + 0.6 Reg2 SC”~ (3)
a) When air is stagnant, i.e., Rep = 0, Eq. (3) reduces to
Substitution of Eq. (4) into Eq. (2) and integration gives
The saturation concentration of naphthalene, CA, , is
psot
A
CAW = -
RT
- 11.7/760
- = 5.17 x lo-* kmol/ m3
(0.08205)(90 + 273)
