Dry air, flowing at a velocity of 1.5m/s, enters a 10m - long, 0.15 -m-diameter tube at 310K and 1.013105Pa. The inner surface of the tube is lined with a felt material (diameter-to- roughness ratio, D/, of 10,000 ) that is continuously saturated with water at 290K. Assuming constant temperature of the air and the pipe wall, determine the exit concentration of water in the exit gas stream. Diffusivity of water in air at 300K=2.6105m2/s Kinematic viscosity of air at 300K=1.569105m2/s The vapor pressure of water at 290K=17.5mmHg The gas constant =0.08206Latm/molK The Fanning friction factor is given by: f=0.00791Re0.12