The purification of hydrogen gas by diffusion through a palladium sheet was discussed in section 5.3. compute the number of kilo- grams of hydrogen that pass per hour througha 6-mm-thick sheet of palladium having an area of 0.25 m2 at 600? ? c. assume a diffusion coefficient of 1.7 ? ? 10? ? 8 m2/s, that the con- centrations at the high- and low-pressure sides of the plate are 2.0 and 0.4 kg of hy- drogen per cubic meter of palladium, and that steady-state conditions have been attained.

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.