Investigation of hydrofluoroolefins as potential working fluids in organic Rankine cycle for geothermal power generation
Document type:
Zeitschriftenaufsatz
Author(s):
Liu, W.; Meinel, D.; Wieland, C.; Spliethoff, H.
Abstract:
Recently, HFOs (hydrofluoroolefins) are presented as a group of the fourth generation refrigerants with
zero ODP (Ozone Depletion Potential) and a very low GWP (Global Warming Potential). This paper
presents a study on eight different HFOs and their potential applications in ORC (Organic Rankine Cycle)
for geothermal power generation. The thermodynamic properties are calculated based on PengeRobinson
equation of state, and are used for simulating a standard ORC for geothermal heat sources with
different temperatures. System efficiency, which involves both heat transfer efficiency and thermal efficiency,
is considered to be the main criterion to evaluate the ORC system performance. An innovative
term, i.e. the optimal heat source temperature is proposed for the determination of thermodynamic
performances of each investigated working fluid in combination with the pinch point analysis. Based on
the system efficiencies of all HFOs, some of them are selected in a series of case studies for comparison
with other relevant ORC fluids. As a conclusion, some of the presented HFOs show promising performances
in terms of system efficiency especially for low-to medium temperature geothermal ORC power
generation (120°C < ths < 150 °C).
Keywords:
Hydrofluoroolefins Geothermal ORC power generation System efficiency Optimal heat source temperature Global warming potential