A Second Law analysis has been developed for a vapor-liquid contacting device as in the sieve tray of a distillation column. Using a discrete bubble dynamics model, an equation for entropy balance has been formulated to numerically evaluate the entropy generation rate associated with heat, mass and momentum transfer for bubble movement through a moving liquid pool; The entropy generation rates per unit bubble mass have been evaluated for variations in sieve tray parameters like orifice diameter and weir height for fixed separation characteristics of components constituting the two phases. It has been found that among the tray parameters, weir height plays a dominant role compared to sieve hole diameter on entropy generation.