Air at 1 bar and 158C enters the compressor of an ideal cold air-standard regenerative Brayton cycle. The pressure at the compressor exit is 10 bar and the maximum cycle temperature is 11008C. For k 5 1.4, determine (a) the net work developed, in kJ per kg of air flowing. (b) the energy added by heat transfer, in kJ per kg of air flowing. (c) the thermal efficiency. (d) Using Eq. (b) of Problem 9.65, check the value obtained in (c) for thermal efficiency.

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.