Which of the following boundary layer conditions cause Stefan's flow correction factor ($p_{BM}/P$) to significantly enhance mass transfer flux in unidirectional diffusion compared to equimolar counter-diffusion?
Options:
(A) High solute vapor pressure at the evaporating food surface
(B) Presence of a completely non-diffusing (stagnant) inert gas component
(C) Net convective bulk drift velocity normal to the interface induced by the diffusing species
(D) Strict absence of concentration gradients across the gas film
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
In evaporation through stagnant air, non-diffusing air creates a bulk convective flux (Stefan's flow, C) to balance air back-diffusion (B). At high vapor pressures (A), $p_{BM} < P$, substantially magnifying mass flux ($N_A = \frac{P}{p_{BM}} N_{A,\text{EMD}}$).