Water is the working fluid in a cogeneration cycle that generates electricity and provides heat for campus buildings. Steam at 2.5 MPa, 320oC and a mass flow rate (m⋅) of 1 kg/s, expands through a two-stage turbine. Steam at 0.2 MPa with a mass flow rate (m⋅) of 0.3 kg/s is extracted between the two stages and provided for heating. The remaining steam expands through the second stage to the condenser at a pressure of 6 kPa. The condensate returns from the campus buildings at 0.1 MPa, 60oC and passes through a trap into the condenser. Each turbine stage has an isentropic efficiency of 80%. Heat addition to the boiler takes place from a source at 1200oC, the building is maintained at 50oC, and the atmospheric conditions are 100 kPa, 20oC.
(a) Perform an energy analysis and draw an energy flow diagram for the system.
(b) Define and evaluate the energetic efficiency of the system.