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Simultaneous experimental investigation of nucleate boiling heat transfer and power output in ORC using R245fa and R1233zd(E)

Title data

Welzl, Matthias ; Heberle, Florian ; Brüggemann, Dieter:
Simultaneous experimental investigation of nucleate boiling heat transfer and power output in ORC using R245fa and R1233zd(E).
In: Energy Procedia. Vol. 129 (September 2017) . - pp. 435-442.
ISSN 1876-6102
DOI: https://doi.org/10.1016/j.egypro.2017.09.113

Project information

Project financing: Bayerisches Staatsministerium für Wissenschaft, Forschung und Kunst

Abstract in another language

In binary geothermal power plants based on the Organic Rankine Cycle (ORC) typically shell-and-tube heat exchangers are used as evaporators. In the shell-side, nucleate boiling of the working fluid takes place on the outer surface of the tubes. For the replacement of fluids with high global warming potential (GWP) or selection of efficient working fluids, a comprehensive evaluation has to be performed. Therefore, the knowledge about the nucleate boiling heat transfer coefficient (HTC) in combination with the electrical power output is necessary. In this study, the focus is led on the investigation of the replacement of R245fa by the low GWP fluid R1233zd(E) in geothermal applications. The nucleate boiling HTC on a horizontal tube and the electrical power of a 1 kW scroll expander are simultaneously measured with an ORC test rig for both fluids. The thermal input is provided by an electrically heated preheater and evaporator. Nucleate boiling takes place on a plain copper tube with an outer diameter of 32 mm and a heated length of 822 mm. The surface temperature of the copper tube is determined by thermocouples within the tube in consideration of thermal conduction. The obtained results, regarding power output as well as heat transfer characteristics, show that the working fluid R245fa performs better at equal saturation temperatures due to the higher density and pressure, and the lower viscosity. The HTC of R245fa is exemplarily up to 43.2 % increased in comparison to R1233zd(E).

Further data

Item Type: Article in a journal
Refereed: Yes
Keywords: Organic Rankine Cycle; geothermal; scroll expander; nucleate boiling; R245fa; R1233zd(E); low GWP working fluid
Institutions of the University: Faculties > Faculty of Engineering Science > Chair Engineering Thermodynamics and Transport Processes
Faculties > Faculty of Engineering Science > Chair Engineering Thermodynamics and Transport Processes > Chair Engineering Thermodynamics and Transport Processes - Univ.-Prof. Dr.-Ing. Dieter Brüggemann
Profile Fields > Emerging Fields > Energy Research and Energy Technology
Research Institutions > Research Units > ZET - Zentrum für Energietechnik
Faculties
Faculties > Faculty of Engineering Science
Profile Fields
Profile Fields > Emerging Fields
Research Institutions
Research Institutions > Research Units
Result of work at the UBT: Yes
DDC Subjects: 600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited: 15 Mar 2019 09:15
Last Modified: 18 Mar 2019 07:54
URI: https://eref.uni-bayreuth.de/id/eprint/47319