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Author: search.filters.author.Authayanun, SuthidaSubject: search.filters.subject.Biogas

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    Performance and environmental study of a biogas-fuelled solid oxide fuel cell with different reforming approaches
    (2018-03-01)
    Chatrattanawet, Narissara
    ;
    Saebea, Dang
    ;
    Authayanun, Suthida
    ;
    Arpornwichanop, Amornchai
    ;
    Patcharavorachot, Yaneeporn
    In this work, solid oxide fuel cells (SOFCs) using biogas as the fuel with two different reforming approaches, i.e., external and internal reforming, were studied to determine the optimal operation conditions for each approach. Thermodynamic analysis was performed using a flowsheet simulator. The equilibrium gas composition was calculated by minimizing the Gibbs free energy. An electrochemical model that includes three voltage losses (i.e., activation, ohmic, and concentration losses) was used to predict the performance of the SOFCs. The simulation results showed that the reformer in the external reforming SOFC should be operated at a temperature of 973 K, a pressure of 1 atm, and a steam-to-carbon molar ratio of 0.5. In performance analysis, the simulation results indicated that both approaches have the same optimal operating conditions, i.e. a temperature of 1173 K, a pressure of 3 atm, and a current density of 5000 A/m<sup>2</sup>. Under the same operating conditions, the internal reforming SOFC exhibited better electrical efficiency than that of the external reforming SOFC. Considering the CO<inf>2</inf> and CO emissions, the exhaust gas obtained from the anode side of the internal reforming SOFC contained 7.4% CO<inf>2</inf> and 37.9% CO, which are higher values than those for the external reforming SOFC (1.9% CO<inf>2</inf> and 32.5% CO).
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    Theoretical analysis of a biogas-fed PEMFC system with different hydrogen purifications: Conventional and membrane-based water gas shift processes
    (2014-01-01)
    Authayanun, Suthida
    ;
    Aunsup, Pounyaporn
    ;
    Patcharavorachot, Yaneeporn
    ;
    Arpornwichanop, Amornchai
    This study presents a thermodynamic analysis of biogas reforming and proton electrolyte membrane fuel cell (PEMFC) integrated process with different hydrogen purifications: conventional and membrane-based water gas shift processes. The aim is to determine the optimal reforming process for hydrogen production from biogas in the PEMFC system. The formation of carbon is concerned in the hydrogen production. The simulation results show that increases in the steam-to-methane ratio and reformer temperature can improve the hydrogen yield and reduce the carbon formation. From the performance analysis, it is found that when the PEMFC is operated at high temperature and fuel utilization, the overall system efficiency enhances. The performance of the PEMFC system with the installation of a water gas shift membrane unit in the hydrogen purification step is slightly increased, compared with a conventional process. © 2014 Elsevier Ltd. All rights reserved.
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    Thermodynamic analysis of hydrogen production from the adsorption-enhanced steam reforming of biogas
    (2014-01-01)
    Saebea, Dang
    ;
    Authayanun, Suthida
    ;
    Patcharavorachot, Yaneeporn
    ;
    Arpornwichanop, Amornchai
    Biogas is considered a potential, renewable fuel to be used as a hydrogen source. At present, a steam reforming is widely used process in hydrogen production, but it needs to be operated at high temperature to achieve high hydrogen yield. Because biogas consists of mostly CO<inf>2</inf>, the hydrogen purification of a reformate gas obtained is another important issue, especially for fuel cell applications. In this study, an enhanced-adsorption steam reforming process in which steam reforming reaction and CO<inf>2</inf> adsorption are occurred in a single unit is investigated. A thermodynamic analysis is performed to study effects of important operating parameters on hydrogen yield and product distribution. It is found that a biogas processor should be operated at high temperatures and inlet steam-T o-methane ratio. The content of CO in the reformate gas increases with increased operating temperature. The steam reforming of biogas coupled with a CO<inf>2</inf> adsorption gives a higher hydrogen product with considerable low CO content, compared to the conventional steam reforming of biogas.