(20 pts) air enters a convergent-divergent nozzle at 20 × 105 n/m2 and 40 ◦c. the receiver pressure is 2 × 105 n/m2 and the nozzle throat area is 10 cm2 . (a) what should the exit area be for the design conditions above(i. e.,to operate at third critical? ) (b) with the nozzle area fixed at the value determined in part (a) and the inlet pressure held at 20 × 105 n/m2 , what receiver pressure would cause a shock to stand at the exit? (c) what receiver pressure would place the shock at the throa

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.