1. Consider gas flow of mass density p and rate m· through a tube whose inner surface is coated with a liquid or a sublimable solid of uniform vapor density pA,s. Derive Equation 8.86 for variation of the mean vapor density, pA,m, with distance x from the tube entrance and Equation 8.83 for the total rate of vapor transfer from a tube of length L.
2. Atmospheric air at 25°C and 3 X 10-4 kg/s flows through a 10-mm-diameter, 1-m-long circular tube whose inner surface is wetted with a water film. Deter- mine the water vapor density at the tube outlet, assum- ing the inlet air to be dry. What is the rate at which vapor is added to the air?