System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures

Brian D. Ehrhart, Christopher Muhich, Ibraheam Al-Shankiti, Alan W. Weimer

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas–gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered.

Original languageEnglish (US)
Pages (from-to)19894-19903
Number of pages10
JournalInternational Journal of Hydrogen Energy
Volume41
Issue number44
DOIs
StatePublished - Nov 26 2016
Externally publishedYes

Fingerprint

hydrogen production
Hydrogen production
metal oxides
heat
Oxides
Inert gases
Metals
Gases
gases
rare gases
Hydrogen
Temperature
temperature
hydrogen
Optimal systems
cycles
Hot Temperature
Cerium
heat exchangers
cerium

Keywords

  • Efficiency
  • Gas separation
  • Heat recuperation
  • Hydrogen
  • Solar
  • Thermochemical

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Condensed Matter Physics
  • Energy Engineering and Power Technology

Cite this

System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2 : Impact of gas heat recuperation and separation temperatures. / Ehrhart, Brian D.; Muhich, Christopher; Al-Shankiti, Ibraheam; Weimer, Alan W.

In: International Journal of Hydrogen Energy, Vol. 41, No. 44, 26.11.2016, p. 19894-19903.

Research output: Contribution to journalArticle

@article{c1c29af1749746fdbb7e4213e8e533cb,
title = "System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2: Impact of gas heat recuperation and separation temperatures",
abstract = "The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100{\%} in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas–gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered.",
keywords = "Efficiency, Gas separation, Heat recuperation, Hydrogen, Solar, Thermochemical",
author = "Ehrhart, {Brian D.} and Christopher Muhich and Ibraheam Al-Shankiti and Weimer, {Alan W.}",
year = "2016",
month = "11",
day = "26",
doi = "10.1016/j.ijhydene.2016.07.110",
language = "English (US)",
volume = "41",
pages = "19894--19903",
journal = "International Journal of Hydrogen Energy",
issn = "0360-3199",
publisher = "Elsevier Limited",
number = "44",

}

TY - JOUR

T1 - System efficiency for two-step metal oxide solar thermochemical hydrogen production – Part 2

T2 - Impact of gas heat recuperation and separation temperatures

AU - Ehrhart, Brian D.

AU - Muhich, Christopher

AU - Al-Shankiti, Ibraheam

AU - Weimer, Alan W.

PY - 2016/11/26

Y1 - 2016/11/26

N2 - The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas–gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered.

AB - The solar-to-hydrogen (STH) efficiency is calculated for various operating conditions for a two-step metal oxide solar thermochemical hydrogen production cycle using cerium(IV) oxide. An inert sweep gas was considered as the O2 removal method. Gas and solid heat recuperation effectiveness values were varied between 0 and 100% in order to determine the limits of the effect of these parameters. The temperature at which the inert gas is separated from oxygen for an open-loop and recycled system is varied. The hydrogen and water separation temperature was also varied and the effect on STH efficiency quantified. This study shows that gas heat recuperation is critical for high efficiency cycles, especially at conditions that require high steam and inert gas flowrates. A key area for future study is identified to be the development of ceramic heat exchangers for high temperature gas–gas heat exchange. Solid heat recuperation is more important at lower oxidation temperatures that favor temperature-swing redox processing, and the relative impact of this heat recuperation is muted if the heat can be used elsewhere in the system. A high separation temperature for the recycled inert gas has been shown to be beneficial, especially for cases of lower gas heat recuperation and increased inert gas flowrates. A higher water/hydrogen separation temperature is beneficial for most gas heat recuperation effectiveness values, though the overall impact on optimal system efficiency is relatively small for the values considered.

KW - Efficiency

KW - Gas separation

KW - Heat recuperation

KW - Hydrogen

KW - Solar

KW - Thermochemical

UR - http://www.scopus.com/inward/record.url?scp=84995549473&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84995549473&partnerID=8YFLogxK

U2 - 10.1016/j.ijhydene.2016.07.110

DO - 10.1016/j.ijhydene.2016.07.110

M3 - Article

AN - SCOPUS:84995549473

VL - 41

SP - 19894

EP - 19903

JO - International Journal of Hydrogen Energy

JF - International Journal of Hydrogen Energy

SN - 0360-3199

IS - 44

ER -