Air enters the compressor of an air-standard brayton cycle with regeneration at 100 kpa and 300 k, with a mass flow rate of 6 kg/s. the compressor pressure ratio is 10 while the turbine inlet temperature is 1400 k. the turbine and compressor each have an isentropic efficiency of 80%, while the regenerator effectiveness is 80%. assuming constant properties evaluated at 300 k determine:

a) the thermal efficiency of the cycle

b) the back-work ratio

c) the net power produced, in kw

d) the rate of entropy generation in the regenerator, in kw/k.

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.