Working-fluid selection and thermoeconomic optimisation of a combined cycle cogeneration dual-loop organic Rankine cycle (ORC) system for solid-oxide fuel cell (SOFC) waste heat recovery
File(s)Emadietal_APEN2019_R1_Clean.pdf (1.48 MB)
Accepted version
Author(s)
Emadi, Mohammad Ali
Chitgar, Nazanin
Oyewunmi, Oyeniyi
Markides, Christos
Type
Journal Article
Abstract
A novel combined-cycle system is proposed for the cogeneration ofelectricityand cooling, in which a dual-loop organic Rankine cycle (ORC)engine is used for waste-heat recovery from a solidoxide fuel cellsystem equipped witha gas turbine(SOFC-GT). Electricity is generated by the SOFC, its associated gas turbine, the two ORC turbines and a liquefied natural gas (LNG)turbine; the LNGsupply tothe fuel cell is also used as the heat sink to the ORC enginesandas a cooling medium for domestic applications. The performance of the system with 20 different combinationsof ORC working fluids isinvestigated by multi-objective optimisationof its capitalcostrateand exergy efficiency, using an integrationof a genetic algorithm and a neural network. The combination of R601(top cycle) and Ethane(bottom cycle)isproposed for the dual-loop ORC system, due to the satisfaction of the optimisationgoals, i.e., an optimal trade-off between efficiency and cost.With theseworking fluids, the overall system achieves an exergy efficiency of51.6%, a total electrical powergeneration of1040kW, with the ORC waste-heat recovery system supplying 20.7% of thispower,and a cooling capacityof 567kW. In addition, an economic analysisof theproposed SOFC-GT-ORCsystemshowsthat the cost of production of an electrical unit amounts to$33.2perMWh, which is 12.9%and 73.9%lowerthan the levelized cost of electricityofseparateSOFC-GT and SOFC systems,respectively. Exergy flow diagrams are usedto determine the flow rate of the exergy andthe value of exergy destructionin each component. In the waste heat recovery system,exergy destruction mainly occurs within theheat exchangers, the highestof which isin the LNG cooling unit followedby the LNG vaporiser and the evaporator ofthe bottom-cycleORCsystem, highlightingthe importance of these components’designin maximising the performance of the overall system.
Date Issued
2020-03-01
Date Acceptance
2019-12-14
Citation
Applied Energy, 2020, 261, pp.1-20
ISSN
0306-2619
Publisher
Elsevier
Start Page
1
End Page
20
Journal / Book Title
Applied Energy
Volume
261
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Engineering & Physical Science Research Council (EPSRC)
Engineering & Physical Science Research Council (EPSRC)
Identifier
https://www.sciencedirect.com/science/article/pii/S0306261919320719?via%3Dihub
Grant Number
EP/P004709/1
EP/R045518/1
Subjects
Science & Technology
Technology
Energy & Fuels
Engineering, Chemical
Engineering
Solid oxide fuel cell (SOFC)
Organic Rankine cycle (ORC)
Liquefied natural gas (LNG)
Thermoeconomic analysis
Working-fluid selection
Multi-objective optimisation
LOW-GRADE HEAT
2-PHASE THERMOFLUIDIC OSCILLATOR
INTEGRATED POWER-SYSTEM
LIQUEFIED NATURAL-GAS
SAFT-VR MIE
THERMODYNAMIC ANALYSIS
MULTIOBJECTIVE OPTIMIZATION
MULTIGENERATION SYSTEM
BIOMASS GASIFICATION
TRIGENERATION SYSTEM
Energy
09 Engineering
14 Economics
Publication Status
Published
Date Publish Online
2020-02-08