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Parametric optimization and comparative study of an organic Rankine cycle power plant for two-phase geothermal sources

For two-phase geothermal resource, Organic Rankine Cycle (ORC) based binary plant is often applied for power production. In this work, a network topology was built with the Thermal Engineering Systems in Python (TESPy) software to simulate the stationary operation of the ORC plant. With this topology, the performance of nine different working fluids are compared. From the thermodynamic perspective, the gross and net power output is optimized respectively. Results show that R600 has the highest gross power output of 17.55MW, while R245fa has the highest net power output of 12.93MW. However, the turbine inlet temperatures for these two working fluids need to be designed at the upper limit of 131℃. It is also found that R245ca and R601a (Isopentane) require the heat exchange rates of IHE to be larger than 1.51MW and 0.99MW to satisfy the re-injection temperature limit, which are smaller than the R600 (6.7MW) and R245fa (6.0MW) cases. Besides, in order to establish a stable ORC plant, the lower geo-steam fraction, the working fluid with lower critical state is preferred. The workflow for the ORC design and optimization in this work is generic, and can be further applied to thermo-economic investigation.


Chaofan Chen1,2, Francesco Witte3, Ilja Tuschy3, Olaf Kolditz1,2, Haibing Shao1
1Helmholtz Centre for Environmental Research GmbH – UFZ, Germany; 2Applied Environmental Systems Analysis, Dresden University of Technology; 3Flensburg University of Applied Sciences
GeoKarlsruhe 2021