Reconsider Prob. 18-91. Now, it is proposed that the liquid water coming out of the separator be used as the heat source in a binary cycle with isobutane as the working fluid (Fig. P18-93). Geothermal liquid water leaves the heat exchanger at 90oC while isobutane enters the turbine at 3.25 MPa and 145oC and leaves at 80oC and 400 kPa. Isobutane is condensed in an air-cooled condenser and then pumped to the heat exchanger pressure. Assuming an isentropic efficiency of 90 percent for the pump, determine
(a) The mass flow rate of isobutane in the binary cycle
(b) The net power outputs of both the flashing and the binary sections of the plant
(c) The thermal efficiencies of the binary cycle and the combined plant. The properties of isobutane may be obtained from EES.

Transcribed Image Text:

Steam turbine Separator Condenser S Isobutane turbine Air-cooled condenser Binary cycle Flash chamber Heat Pump #0) exchanger Production Reinjection well well FIGURE P18-93