Determine the concentration of naphthalene in the air as

Question

Several thin sheets of naphthalene, 0.25 cm thick and 10 cm square, are arranged parallel to each other with their centers at 1-cm intervals. Air at 273 K and 1:013 × 10⁵ Pa enters this sandwich arrangement with a bulk velocity of 15 m/s. At 273 K, the mass diffusivity for naphthalene in air is 5:14 × 10^-6 m²/s, the Schmidt number is 2.57, and the vapor pressure of naphthalene is 1.0 Pa. Determine the concentration of naphthalene in the air as it leaves the arrangement, evaluating the mass-transfer coefficient using the

(a) Reynolds analogy;

(b) von Ka´rma´n analogy;

(c) Chilton-Colburn analogy.

Determine the length of time the sheets must be exposed until half of their mass will be sublimed under these conditions.