Zeotropic mixtures as working fluids in Organic Rankine Cycles for low-enthalpy geothermal resources

Title data

Heberle, Florian ; Preißinger, Markus ; Brüggemann, Dieter:
Zeotropic mixtures as working fluids in Organic Rankine Cycles for low-enthalpy geothermal resources.
In: Renewable Energy. Vol. 37 (2012) Issue 1 . - pp. 364-370.
ISSN 1879-0682
DOI: https://doi.org/10.1016/j.renene.2011.06.044

Official URL:

Abstract in another language

This work presents detailed simulations of Organic Rankine Cycle processes for energy conversion of low-enthalpy geothermal resources. The working fluids considered in this analysis are zeotropic mixtures. Second law efficiency of subcritical cycles is calculated for isobutane/isopentane and R227ea/R245fa depending on mixture composition, heat source temperature and temperature difference of cooling water. The use of mixtures as working fluids leads to an efficiency increase compared to pure fluids, due to a glide match of temperature profiles in the condenser and evaporator. For heat source temperatures below 120 °C the raise is up to 15%. In case of pure fluids a significant efficiency increase occurs, when the maximum pressure is reached and the pinch point shifts to the inlet of the preheater. This effect appears for R227ea at 120 °C and for isobutane at 170 °C. Using mixtures this behavior can be adjusted to higher temperatures by adding a less volatile component.

Further data

Item Type:	Article in a journal
Refereed:	Yes
Keywords:	Organic Rankine Cycle; Low-temperature geothermal sources; Zeotropic mixtures
Institutions of the University:	Faculties Faculties > Faculty of Engineering Science 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 Profile Fields > Emerging Fields Profile Fields > Emerging Fields > Energy Research and Energy Technology Research Institutions > Research Units > ZET - Zentrum für Energietechnik Research Institutions Research Institutions > Research Units
Result of work at the UBT:	Yes
DDC Subjects:	600 Technology, medicine, applied sciences > 620 Engineering
Date Deposited:	27 Nov 2015 07:52
Last Modified:	26 Oct 2022 11:26
URI:	https://eref.uni-bayreuth.de/id/eprint/23024