The final step of a manufacturing process in which a protective coating is applied to the inner surface of a circular tube involves passage of dry, atmosphere air through the tube to remove a residual liquid associated with the process. Consider a coated 5-m-long tube with an inner diameter of 50 mm. The tube is main- tained at a temperature of 300 K, and the residual liquid exists as a thin film whose corresponding vapor pres- sure is 15 mm Hg. The molecular weight and diffusion coefficient of the vapor are MA = 70 kg/kmol and DAB  = 10-5  m2/s, respectively. Air enters the tube at a normal body temperature of 37°C and may  be assumed to be saturated with water.

(a) Assuming steady, fully developed flow in the trachea, estimate the mass transfer convection coefficient.

(b) Estimate the daily water loss (liter/day) associated with evaporation in the trachea.