Consider an airplane cruising at an altitude of 30 km where standard atmospheric conditions are (- 50°c) and 26.5 kpa at a speed of 800 km/h. each wing of the airplane can be modeled as a 25m x 3m flat plate, and the friction coefficient of the wings is 0.0016 and its surface temperature is 10°c: a) draw the schematic of the system. b) using the c-c analogy, determine the heat transfer coefficient and the rate of heat transfer for the wings at cruising conditions.

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.