Thermo-economic optimization of Organic Rankine Cycle (ORC) systems for geothermal power generation: A comparative study of system configurations
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Author(s)
Song, Jian
Loo, Ping
Teo, Jaime
Markides, Christos N
Type
Journal Article
Abstract
The suitability of organic Rankine cycle (ORC) technology for the conversion of low- and medium-grade heat sources to useful power has established this as a promising option in geothermal power-generation applications. Despite extensive research in this field, most of which has focused on parametric analyses and thermodynamic performance evaluations, there is still a lack of understanding concerning the comparative performance of different plant configurations from both thermodynamic and economic perspectives. This study seeks to investigate the thermo-economic performance of subcritical and transcritical geothermal ORC power-plants, while considering a range of working fluids and the use of superheating and/or recuperation. A specific case study based on the exploitation of a medium-temperature geothermal heat source (180 °C, 40 kg/s) is conducted. Multi-objective optimization is performed to maximize the power/exergy efficiency (i.e., resource use) and to minimize the payback period. Different optimized configurations are compared and the influence on system performance of superheating, recuperation, and subcritical vs. transcritical operation are evaluated. The results reveal that superheating is preferable for working fluids with low critical temperatures, but hinders the performance of fluids whose critical temperature is higher. Recuperation is not attractive under most operating conditions, since the thermodynamic performance improvement and cooling water saving cannot compensate the cost associated with the installation of the additional heat exchanger. Finally, transcritical ORC systems are favored thanks to the better thermal match between the heat source and the working fluid in these configurations. A more generalized geothermal heat source is then considered to explore the optimal configuration over a range of heat sources, which indicates that non-recuperated transcritical-cycle systems with working fluids whose critical temperature is close to the heat-source temperature are generally favorable.
Date Issued
2020-02-07
Date Acceptance
2020-01-10
Citation
Frontiers in Energy Research, 2020, 8
ISSN
2296-598X
Publisher
Frontiers Media
Journal / Book Title
Frontiers in Energy Research
Volume
8
Copyright Statement
© 2020 Song, Loo, Teo and Markides. This is an open-access article
distributed under the terms of the Creative Commons Attribution License (CC BY) https://creativecommons.org/licenses/by/4.0/.
The use, distribution or reproduction in other forums is permitted, provided the
original author(s) and the copyright owner(s) are credited and that the original
publication in this journal is cited, in accordance with accepted academic practice.
No use, distribution or reproduction is permitted which does not comply with these
terms.
distributed under the terms of the Creative Commons Attribution License (CC BY) https://creativecommons.org/licenses/by/4.0/.
The use, distribution or reproduction in other forums is permitted, provided the
original author(s) and the copyright owner(s) are credited and that the original
publication in this journal is cited, in accordance with accepted academic practice.
No use, distribution or reproduction is permitted which does not comply with these
terms.
License URL
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000517215800001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Technology
Energy & Fuels
geothermal
optimization
ORC
power generation
thermo-economic
configuration
EXERGOECONOMIC ANALYSIS
WORKING FLUID
COMBINED HEAT
KALINA CYCLE
PERFORMANCE
SELECTION
PLANTS
EXPLOITATION
TECHNOLOGY
WATER
Publication Status
Published
Article Number
6
Date Publish Online
2020-02-07