Problem

i. Steam at 5.0 MPa, 500 degrees C enters an insulated turbine operating at steady state with a mass flow rate of 7kg/s and exits at 0.3 MPa. potential and Kinetic energy effects are negligible.  Evaluate the maximum theoretical power that can be developed by the turbine, in kW, and the corresponding exit temperature. If the steam exits the turbine at 250 degrees C, and 0.5 MPa, evaluate the isentropic efficiency.

ii. The Novel Air Conditioning Company claims to have developed a new air conditioner, which will maintain a room at 22 degrees C while rejecting 105kJ of heat at 42 degrees C.  The unit needs 10kJ or work.  Is this device believable? Why?

iii. A reversed Carnot engine as a heat pump consumes 6 kW and has a COP of 3.0.  A house, containing 1800 kg of air, is initially at 12 degrees C and the heat raises the air temperature to 21 degrees C.  How long will this take?