Describe three examples of mass transfer that relate to your daily life. For each example give the following: (a) A sketch of the physical situation in which mass transfer is involved
(b) A sketch of the concentration profile and the values at the two boundaries.
(c) An estimate of the time constant for mass transfer and the basis on which it is determined.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.