Thermal modeling of a geothermal powered organic rankine cycle integrated with parabolic trough solar collectors

In this thesis, the thermodynamic performance of a supercritical organic Rankine cycle (ORC) integrated with parabolic trough solar collectors (PTSC), which uses the energy of geothermal water and solar energy as the heat sources, is investigated. As a case study, energy and exergy analyses of an existing geothermal power plant based on a supercritical ORC, which is located in Gümüşköy, Aydın, Turkey is presented. Control volumes enclosing each component of the ORC and PTSC are taken; and detailed thermal models are developed for the heat exchanger and PTSC; whereas energy balances are applied to the remaining components (turbine, regenerator, air cooled condenser and pump). System performance is assessed using exergetic parameters (total exergy loss, total exergy destruction, productivity lack, and fuel depletion ratio) for each component of the ORC and PTSC. The set of thermal modeling equations is solved by Engineering Equations Solver (EES). Several parametric studies were performed to investigate the effect of some of the important design and operating parameters on the key output parameters. The results of the model are first compared by the actual operating data taken from the power plant for validation. Then, the effects of addition of PTSC on the system, different working fluid on the system, number of PTSCs, geothermal water entering the heat exchangers on the system, ambient temperature and solar irradiance on the output parameters of the system are examined. These output parameters include the power output of the turbine, the net power output, electrical and exergetic efficiency of the system. As a result of these parametric studies, the operating parameters and the working fluid that give the best performance for the integrated system are found.