Energy and Conventional and Advanced Exergy Analyses of Low-Temperature Geothermal Binary-Flashing Cycle Using Zeotropic Mixtures

Yuan Zhao, Bowen Du, Shunyi Chen, Jun Zhao, Zhipeng Guo and Lingbao Wang
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Yuan Zhao: Powerchina HuaDong Engineering Corporation Limited, Hangzhou 311122, China
Bowen Du: Powerchina HuaDong Engineering Corporation Limited, Hangzhou 311122, China
Shunyi Chen: Powerchina HuaDong Engineering Corporation Limited, Hangzhou 311122, China
Jun Zhao: Key Laboratory of Efficient Utilization of Low and Medium Grade Energy (Tianjin University), Ministry of Education of China, Tianjin 300350, China
Zhipeng Guo: School of Engineering Science, University of Science and Technology of China, Hefei 230026, China
Lingbao Wang: Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China

Energies, 2022, vol. 15, issue 10, 1-18

Abstract: Due to its deep utilization of geobrine and its high net power output, the binary-flashing cycle (BFC) is deemed to be the future geothermal energy power generation technology. The working fluids considered in present analysis are zeotropic mixtures (R245/R600a). The system thermodynamic model is built, and the energy and conventional and advanced exergy analyses are carried out to reveal the real optimization potential. It is demonstrated that the optimal ranges of R245fa mass fraction and working fluid dryness at the evaporator outlet are 0.30~0.50 and 0.40~0.60, considering the thermodynamic performance and the flammability of the zeotropic mixtures, simultaneously. Conventional exergy analysis indicates that the maximum exergy destruction occurs in the condenser, followed by the expander, evaporator, flashing tank, preheater, high-pressure pump and low-pressure pump. Meanwhile, the advanced exergy analysis reveals that the expander should be given the first priority for optimization, followed by the condenser and evaporator. The BFC has a large potential for improvement due to higher avoidable exergy destruction, about 48.6% of the total system exergy destruction can be reduced. Moreover, the interconnections among system components are not very strong, owing to small exogenous exergy destructions. It also demonstrates the effectiveness of advanced exergy analysis, and the approach can be extended to other energy conversion systems to maximize the energy and exergy savings for sustainable development.

Keywords: advanced exergy analysis; geothermal energy; binary-flashing cycle; zeotropic mixtures; inerting mass concentration (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 (1)

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