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Considerations for the design of solar-thermal chemical processes / Janna Martinek in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031013/1-6] Titre : Considerations for the design of solar-thermal chemical processes Type de document : texte imprimé Auteurs : Janna Martinek, Auteur ; Melinda Channel, Auteur ; Allan Lewandowski, Auteur Année de publication : 2011 Article en page(s) : pp. [031013/1-6] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Carnot  cycle  Enthalpy  Nickel  compounds  Ray  tracing  Solar  energy  conversion  Zinc  compounds Index. décimale : 621.47 Résumé : A methodology is presented for the design of solar thermal chemical processes. The solar receiver efficiency for the high temperature step, defined herein as the ratio of the enthalpy change resulting from the process occurring in the receiver to the solar energy input, is limited by the solar energy absorption efficiency. When using this definition of receiver efficiency, both the optimal reactor temperature for a given solar concentration ratio and the solar concentration required to achieve a given temperature and efficiency shift to lower values than those dictated by the Carnot limitation on the system efficiency for the conversion of heat to work. Process and solar field design considerations were investigated for ZnO and NiFe2O4 “ferrite” spinel water splitting cycles with concentration ratios of roughly 2000, 4000, and 8000 suns to assess the implications of using reduced solar concentration. Solar field design and determination of field efficiency were accomplished using ray trace modeling of the optical components. Annual solar efficiency increased while heliostat area decreased with increasing concentration due to shading and blocking effects. The heliostat fields designed using system efficiency for the conversion of heat to work were found to be overdesigned by up to 21% compared with those designed using the receiver efficiency alone. Overall efficiencies of 13–20% were determined for a “ferrite” based water splitting process with thermal reduction conversions in the range of 35–100%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Considerations for the design of solar-thermal chemical processes [texte imprimé] / Janna Martinek, Auteur ; Melinda Channel, Auteur ; Allan Lewandowski, Auteur . - 2011 . - pp. [031013/1-6]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031013/1-6] Mots-clés : Carnot  cycle  Enthalpy  Nickel  compounds  Ray  tracing  Solar  energy  conversion  Zinc  compounds Index. décimale : 621.47 Résumé : A methodology is presented for the design of solar thermal chemical processes. The solar receiver efficiency for the high temperature step, defined herein as the ratio of the enthalpy change resulting from the process occurring in the receiver to the solar energy input, is limited by the solar energy absorption efficiency. When using this definition of receiver efficiency, both the optimal reactor temperature for a given solar concentration ratio and the solar concentration required to achieve a given temperature and efficiency shift to lower values than those dictated by the Carnot limitation on the system efficiency for the conversion of heat to work. Process and solar field design considerations were investigated for ZnO and NiFe2O4 “ferrite” spinel water splitting cycles with concentration ratios of roughly 2000, 4000, and 8000 suns to assess the implications of using reduced solar concentration. Solar field design and determination of field efficiency were accomplished using ray trace modeling of the optical components. Annual solar efficiency increased while heliostat area decreased with increasing concentration due to shading and blocking effects. The heliostat fields designed using system efficiency for the conversion of heat to work were found to be overdesigned by up to 21% compared with those designed using the receiver efficiency alone. Overall efficiencies of 13–20% were determined for a “ferrite” based water splitting process with thermal reduction conversions in the range of 35–100%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]