Exergoeconomic analysis and optimization of a flash-binary geothermal power system

In the present study, a flash-binary geothermal power system using organic Rankine cycle (ORC) as subsystem was modeled under a steady state. An exergoeconomic performance indicator, namely the average levelized cost per unit of exergy products for the overall system (csystem), was newly developed to analyze and optimize the system. Parametric analysis was performed to examine the effects of key thermodynamic parameters including flash pressure, ORC turbine inlet pressure and ORC turbine inlet temperature on the system performance. Exergoeconomic optimization for minimum csystem was carried out on the system. As comparison, thermodynamic optimization for maximum exergy efficiency was also conducted. Optimization results implied that the most exergoeconomically effective system couldn't obtain the best system thermodynamic performance and vice versa. It was shown that in exergoeconomics the significant improvement in system's economy is at the expense of the slight diminishment in system's thermodynamic performance. Therefore, the exergoeconomic models developed in the current study provide comprehensive understanding of geothermal power systems as well as useful guidelines for designers.