Energy and Exergy Analyses of Geothermal Organic Rankine Cycles Considering the Effect of Brine Reinjection Temperature

Yuan Zhao, Chenghao Gao, Chengjun Li, Jie Sun, Chunyan Wang, Qiang Liu () and Jun Zhao
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Yuan Zhao: Powerchina Huadong Engineering Corporation Limited, Hangzhou 311122, China
Chenghao Gao: Powerchina Huadong Engineering Corporation Limited, Hangzhou 311122, China
Chengjun Li: Powerchina Huadong Engineering Corporation Limited, Hangzhou 311122, China
Jie Sun: State Key Laboratory of Petroleum Resources and Prospecting, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China
Chunyan Wang: State Key Laboratory of Petroleum Resources and Prospecting, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China
Qiang Liu: State Key Laboratory of Petroleum Resources and Prospecting, College of Mechanical and Transportation Engineering, China University of Petroleum, Beijing 102249, China
Jun Zhao: Key Laboratory of Efficient Utilization of Low and Medium Grade Energy, Ministry of Education, Tianjin University, Tianjin 300350, China

Energies, 2022, vol. 15, issue 17, 1-20

Abstract: The organic Rankine cycles (ORCs) have been used to convert low-enthalpy geothermal brine into power. Parameter optimization and working fluid selection are the main approaches to enhance geothermal ORC performance. This work uses environmentally friendly fluids, including R1224yd(Z), R1233zd(E), R1336mzz(Z), R601 and R601a, as the geothermal ORC working fluids. The evaporation temperatures of the selected fluids were optimized to maximize the cycle net power outputs. The thermodynamic characteristics are investigated with the consideration of the influence of the allowed reinjection temperature (ARIT). Among the selected fluids, R1224yd(Z) has the highest optimal evaporation temperature with the maximum turbine power output for a brine inlet temperature (BIT) higher than 120 °C, especially at a lower allowed reinjection temperature. However, the parasitic power consumption by the pumps in an ORC with R1224yd(Z) is also higher than with the other four fluids. The net power output for ORC with R1336mzz(Z) is slightly more than that with R1224yd(Z). Although the optimal evaporation temperature for a RORC is lower than that for an ORC, the higher preheater inlet temperature leads to a higher geothermal heating exergy efficiency and more power output for a BIT less than 120 °C. The RORC with R1336mzz(Z) produces 2.6% more net power than an ORC for a brine inlet temperature of 100 °C. As the ARIT increases from 70 °C to 75 °C, the plant exergy efficiencies of ORCs are decreased by 6–8% for a geothermal brine inlet temperature of 100 °C.

Keywords: geothermal power generation; organic Rankine cycle; exergy analysis; working fluid; optimization (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (3)

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