Consider water in a 25-mm diameter test tube evaporating into dry air at 1 atm. The distance from the water-air interface to the top of the tube is L = 15 cm. The mass fraction of the water vapour at the water-air interface is 0.0235, and the binary diffusivity for water vapour in air is 2.6x10-5 m 2 /s.

a) Determine the mass evaporation rate of the water

b) Determine the water vapour mass fraction at x =L/2

c) Determine the fraction of the water mass flow that is contributed by the bulk flow and the fraction contributed by diffusion at x =L/2