Proposal and thermoeconomic analysis of geothermal flash binary power plants utilizing different types of organic flash cycle

In this work, an enhanced organic flash cycle (EOFC) employing an internal heat exchanger is proposed to be used to further recover the thermal energy of geofluid from a flash cycle for geothermal resources. The proposed flash-binary system is improved by applying two methods One method is usage of two separate flash evaporating steps instead of only one in EOFC (double flash). Another method is replacement of the throttling valve with a two- phase expander. A comprehensive thermoeconomic evaluation is carried out to investigate the effects of four key thermodynamic parameters on system performance. The results show that under the given condition, the net power output increases by 36.7% when two-phase expanders are employed in flash-binary geothermal cycle with single flash EOFC (TBSEOFC). Net power output increases by 1.2% for TBSEOFC by utilization of two separate flash steps in EOFC subsystem. In this case, unit cost of product insignificantly decreases. Moreover, a parametric optimization is conducted to obtain the optimum system performance.