Question

Cucumbers are preserved by storage in a salt brine with a
concentration of 20% NaCl. The initial NaCl concentration
in the cucumber is 0.6% and the moisture content is 96.1%
(wb). The convective mass transfer coeffi cient at the surface of
the cucumbers is suffi ciently high to cause the mass transfer
Biot number to be greater than 100. The mass diffusivity for
NaCl in water is 1.5 10 9 m 2 /s. Estimate the time required
for the center of a 2 cm cucumber to reach 15%. Note that the
concentration percentages in the cucumber are kg NaCl per kg
of cucumber, whereas the brine concentration is kg NaCl per
kg water.

Answer 1

using given data and equation for semi infinite medium diffusion we can find the required time

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