The moisture in hot, humid, stagnant air surrounding a cold water pipeline continually diffuses to the cold surface where it condenses. The condensed water forms a liquid film around the pipe, and then continuously drips off the pipe to the ground below. At a distance of 10 cm from the surface of the pipe, the moisture content of the air is constant. Close to the pipe, the moisture content approaches the vapor pressure of water evaluated at the temperature of the pipe.

a) Draw a picture of the physical system and state at least five reasonable assumptions for the mass transfer aspects of the process.

b) What coordinate system should be used? b) What is the simplified differential form of Fick's equation for water vapor (spech

c) What is the simplified form of the general differential equation for mass transfer in terms of flux NA? What term is constant over the diffusion path?

d) What is the general differential equation for mass transfer in terms of concentr Propose two boundary conditions that may be used to solve the resulting differential equation.