Persistent Link:
http://hdl.handle.net/10150/290073
Title:
Combined carbon dioxide/water solid oxide electrolysis
Author:
Iacomini, Christine Schroeder
Issue Date:
2004
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Solid oxide electrolysis of a mixture of water and carbon dioxide has many applications in space exploration. It can be implemented in propellant production systems that use Martian resources or in closed-loop life support systems to cleanse the atmosphere of facilities in extraterrestrial bases and of cabin spacecrafts. This work endeavors to quantify the performance of combined water and carbon dioxide electrolysis, referred to as "combined electrolysis", and to understand how it works so that the technology can be best applied. First, to thoroughly motivate the research, system modeling is presented that demonstrates the competitiveness of the technology in terms of electrolysis power requirements and consequential system mass savings. Second, to demonstrate and quantify the performance of the technology, experimental results are presented. Electrolysis cells were constructed with 8% by mol yttria-stabilized zirconia electrolytes, 50/50 by weight platinum/yttria-stabilized zirconia electrodes and chromium-alloy or alumina manifolds and tubing. Performance and gas chromatograph data from electrolysis of many different gas mixtures, including water, carbon dioxide, and a combined mixture of both, are presented. Third, to explain observations made during experiments and theorize about the phenomena governing combined electrolysis, data analyses and thermodynamic modeling are applied. Conclusions are presented regarding the transient response of combined electrolysis, the relative performance of it to that of other mixtures, how its performance depends on the water to carbon dioxide ratio, its effect on cell health, and its preference to water versus carbon dioxide. Procedures are also derived for predicting the composition of combined electrolysis exhaust for a given oxygen production rate, humidity content, and inlet flow rate. The influence of the two cell materials proves to be significant. However, in both cases it is proven that combined electrolysis does not encourage carbon deposition and the makeup of its products is governed by the water gas shift reaction. It is shown that the chromium-alloy system achieves water gas shift reaction equilibrium whereas the alumina system does not. Experimental observations support the argument that chromium oxide inside the chromium alloy cell forces its water gas shift reaction to equilibrium during electrolysis, influencing combined electrolysis performance.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Engineering, Aerospace.; Engineering, Chemical.; Engineering, Mechanical.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Aerospace and Mechanical Engineering
Degree Grantor:
University of Arizona
Advisor:
Chan, Cho Lik; Sridhar, K. R.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleCombined carbon dioxide/water solid oxide electrolysisen_US
dc.creatorIacomini, Christine Schroederen_US
dc.contributor.authorIacomini, Christine Schroederen_US
dc.date.issued2004en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractSolid oxide electrolysis of a mixture of water and carbon dioxide has many applications in space exploration. It can be implemented in propellant production systems that use Martian resources or in closed-loop life support systems to cleanse the atmosphere of facilities in extraterrestrial bases and of cabin spacecrafts. This work endeavors to quantify the performance of combined water and carbon dioxide electrolysis, referred to as "combined electrolysis", and to understand how it works so that the technology can be best applied. First, to thoroughly motivate the research, system modeling is presented that demonstrates the competitiveness of the technology in terms of electrolysis power requirements and consequential system mass savings. Second, to demonstrate and quantify the performance of the technology, experimental results are presented. Electrolysis cells were constructed with 8% by mol yttria-stabilized zirconia electrolytes, 50/50 by weight platinum/yttria-stabilized zirconia electrodes and chromium-alloy or alumina manifolds and tubing. Performance and gas chromatograph data from electrolysis of many different gas mixtures, including water, carbon dioxide, and a combined mixture of both, are presented. Third, to explain observations made during experiments and theorize about the phenomena governing combined electrolysis, data analyses and thermodynamic modeling are applied. Conclusions are presented regarding the transient response of combined electrolysis, the relative performance of it to that of other mixtures, how its performance depends on the water to carbon dioxide ratio, its effect on cell health, and its preference to water versus carbon dioxide. Procedures are also derived for predicting the composition of combined electrolysis exhaust for a given oxygen production rate, humidity content, and inlet flow rate. The influence of the two cell materials proves to be significant. However, in both cases it is proven that combined electrolysis does not encourage carbon deposition and the makeup of its products is governed by the water gas shift reaction. It is shown that the chromium-alloy system achieves water gas shift reaction equilibrium whereas the alumina system does not. Experimental observations support the argument that chromium oxide inside the chromium alloy cell forces its water gas shift reaction to equilibrium during electrolysis, influencing combined electrolysis performance.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectEngineering, Aerospace.en_US
dc.subjectEngineering, Chemical.en_US
dc.subjectEngineering, Mechanical.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineAerospace and Mechanical Engineeringen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorChan, Cho Liken_US
dc.contributor.advisorSridhar, K. R.en_US
dc.identifier.proquest3132231en_US
dc.identifier.bibrecord.b46708935en_US
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