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Thermodynamics of CeO2 Thermochemical Fuel Production

Bulfin, Brendan and Call, Friedemann and Lange, Matthias and Lübben, O. and Sattler, Christian and Pitz-Paal, Robert and Shvets, Igor (2015) Thermodynamics of CeO2 Thermochemical Fuel Production. Energy and Fuels, 29, pp. 1001-1009. ACS Publications. DOI: 10.1021/ef5019912 ISSN 0887-0624

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Official URL: http://pubs.acs.org/journal/enfuem

Abstract

In this work the thermodynamics of thermochemical fuel production using a CeO2 redox cycle are studied. The need to reduce the oxygen partial pressure in order to improve efficiency is investigated, with both sweep gas and vacuum pumping considered as methods of achieving this. At ambient pressure the cycles can be maximized with respect to the temperature swing, the minimum oxygen partial pressure, and the extent of the oxidation reaction. For reduction at 1500 °C the maximum efficiency was found to be 4.5%, which is significantly lower than the values found in previous studies. In Addition isothermal operation had very low efficiency (less than 2%) under all of the conditions considered. If the system is operated at lower than ambient pressure, the pumping efficiency will depend on the pressure. From an investigation of commercially available pumps the pressure dependence was given an analytical expression. The results showed the cycles have an optimal operating pressure and that using sweep gas, as well as pumping, only reduced the overall efficiency. The efficiency was maximized with respect to the temperature swing, the reduction pressure, and the extent of oxidation, giving a peak efficiency of 7.5% for a reduction temperature of 1500 °C. Reducing the pressure during reduction could also be beneficial due to improved reaction kinetics at lower pressure and an increased yield due to lower oxygen partial pressures. Recovering heat from both the high temperature ceria and the oxidation reaction, and using it as process heat, was also considered. With 60% of this heat being recovered, the peak efficiency for the 1500 °C pumped cycle increased to 11%. Finally the practicality of the cycles, in terms of the quantity of ceria required to maintain continuous operation, are considered, and some suggestions for improving the cycle are given.

Item URL in elib:https://elib.dlr.de/95535/
Document Type:Article
Title:Thermodynamics of CeO2 Thermochemical Fuel Production
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Bulfin, Brendanbulfinb (at) tcd.ieUNSPECIFIED
Call, Friedemannfriedemann.call (at) dlr.deUNSPECIFIED
Lange, Matthiasmatthias.lange (at) dlr.deUNSPECIFIED
Lübben, O.Trinity College DublinUNSPECIFIED
Sattler, Christianchristian.sattler (at) dlr.deUNSPECIFIED
Pitz-Paal, Robertrobert.pitz-paal (at) dlr.deUNSPECIFIED
Shvets, Igorivchvets (at) tcd.ieUNSPECIFIED
Date:7 January 2015
Journal or Publication Title:Energy and Fuels
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:29
DOI :10.1021/ef5019912
Page Range:pp. 1001-1009
Editors:
EditorsEmail
Klein, Michael T.mtklein@efuels.acs.org
Publisher:ACS Publications
ISSN:0887-0624
Status:Published
Keywords:thermochemical cycles, CeO2, ceria, fuel production, solar
HGF - Research field:Energy
HGF - Program:Renewable Energies
HGF - Program Themes:Concentrating Solar Systems (old)
DLR - Research area:Energy
DLR - Program:E SF - Solar research
DLR - Research theme (Project):E - Solar Process Technology (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Solar Research > Solare Verfahrenstechnik
Deposited By: Sattler, Prof. Dr. Christian
Deposited On:24 Mar 2015 14:07
Last Modified:08 Mar 2018 18:37

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