HW 2 - p 3.30 - Dissolution of a Napthalene Tube in Laminar Flow- 7 pts
Air at 1 atm and 100oC flows through a straight, 5-cm-diameter circular tube, cast from naphthalene, at a Reynolds number of 1,500. Air entering the tube has an established laminar-flow velocity profile. Properties are given in Example 3.14. If pressure drop through the tube is negligible, calculate the length of a tube needed for the average mole fraction of naphthalene in the exiting air to be 0.005.
posted by Dr. B at 2:23 PM
2 Comments:
Hi Dr.B,
Since outlet mole frac should be 0.005 for naphtalene, can you also calculate for concentration of napthalene at the outlet? In other word, how to calculate for Cax in the log mean driving force formula.
Thanks,
blogger 7:38 PM:
The key is that it is a gas phase and we can assume it is an ideal gas.
Ca = ya Ctot, where Ctot = n/V = P/RT
Similarly,
Cai = yai Ctot and yai = Pa* / Ptot
I hope this is helpful.
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