Dry air at 1-atm pressure and a velocity of 15 m/s is to be humidified by passing it in cross flow over a porous cylinder of diameter D = 40 mm, which is saturated with water. Assuming the water and air to be at 305 K, calculate the mass rate of water evaporated, in kg/s-m, under steady-state conditions from the cylindrical medium per unit length. Evaluate the binary diffusion coefficient, DAB, for the water vapor-air at 305 K. 0.00023 n" kg/s.m