Air enters the compressor of a cold air-standard brayton cycle at 100 kpa, 300 k, with a mass flow rate of 6 kg/s. the compressor pressure ratio is 10, and the turbine inlet temperature is 1400 k. the turbine and compressor each have isentropic efficiencies of 80%. for k=1.4, calculate: a) the thermal efficiency of the cycle. b) the back work ratio. c) the net power developed, in kw. d) the rates of exergy destruction in the compressor and turbine, respectively, each in kw, for t0=300 k.

Steam in a heating system flows through tubes whose outer radius is 2.5 cm and whose walls are maintained at a temperature of 180 °c . circular aluminum alloy 2024-t6 fins ( k= 186 wm. k) of outer radius 3 cm and constant thickness 1 mm are attached to the tube. the space between the fins is 3 mm and thus there are 250 fins per meter of tube length. heat is transferred to the surrounding air at too-25 °c, with a heat transfer coefficient of 40 w/m2. k. manufacturer a claims that this system is rated at 3.5 kw per meter of tube length. if the fins are an integral part of the steam tube, find the heat transfer rate in kw for a 1-m length of tube. is manufacturer a's claim valid? compare the heat transfer rate from 1 meter of tube length if there are no fins.