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The SnO2/Sn carbothermic cycle for splitting water and production of hydrogen / Michael Epstein 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. [031007/1-7] Titre : The SnO2/Sn carbothermic cycle for splitting water and production of hydrogen Type de document : texte imprimé Auteurs : Michael Epstein, Auteur ; Irina Vishnevetsky, Auteur ; Alexander Berman, Auteur Année de publication : 2011 Article en page(s) : pp. [031007/1-7] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Carboreduction  of  metal  oxide  Metal  hydrolysis  Tin  dioxide  thermochemical  cycle Index. décimale : 621.47 Résumé : The carboreduction in SnO2 to produce Sn and its hydrolysis with steam to generate hydrogen were studied. The SnO2/C/Sn system has several advantages compared with the most advanced cycle considered so far, which is the ZnO/C/Zn system. The most significant one is the lower reduction temperatures (850–900°C for the SnO2 versus 1100–1150°C for the ZnO). The rate of carbothermal reduction was studied experimentally. SnO2 powder (300 mesh, 99.9% purity) was reduced with beech charcoal and graphite using a thermogravimetric analysis apparatus and fixed bed flow reactor at a temperature range of 800–1000°C. Optimal temperature range for the reduction with beech charcoal is 875–900°C. The reaction time needed to reach conversion of SnO2 close to 100% is 5–10 min in this temperature range. The transmission electron microscopy results show that after cooling, the product of carboreduction contains mainly metallic Sn with a particle size of 1–3 µm. The hydrolysis step is crucial to the success of the entire cycle. Reactions between the steam and solid tin having as powder structure similar to the reduced one were performed at a temperature range of 350–600°C. Results of both the reduction and hydrolysis reactions are presented in addition to thermodynamic analysis of this cycle. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] The SnO2/Sn carbothermic cycle for splitting water and production of hydrogen [texte imprimé] / Michael Epstein, Auteur ; Irina Vishnevetsky, Auteur ; Alexander Berman, Auteur . - 2011 . - pp. [031007/1-7]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031007/1-7] Mots-clés : Carboreduction  of  metal  oxide  Metal  hydrolysis  Tin  dioxide  thermochemical  cycle Index. décimale : 621.47 Résumé : The carboreduction in SnO2 to produce Sn and its hydrolysis with steam to generate hydrogen were studied. The SnO2/C/Sn system has several advantages compared with the most advanced cycle considered so far, which is the ZnO/C/Zn system. The most significant one is the lower reduction temperatures (850–900°C for the SnO2 versus 1100–1150°C for the ZnO). The rate of carbothermal reduction was studied experimentally. SnO2 powder (300 mesh, 99.9% purity) was reduced with beech charcoal and graphite using a thermogravimetric analysis apparatus and fixed bed flow reactor at a temperature range of 800–1000°C. Optimal temperature range for the reduction with beech charcoal is 875–900°C. The reaction time needed to reach conversion of SnO2 close to 100% is 5–10 min in this temperature range. The transmission electron microscopy results show that after cooling, the product of carboreduction contains mainly metallic Sn with a particle size of 1–3 µm. The hydrolysis step is crucial to the success of the entire cycle. Reactions between the steam and solid tin having as powder structure similar to the reduced one were performed at a temperature range of 350–600°C. Results of both the reduction and hydrolysis reactions are presented in addition to thermodynamic analysis of this cycle. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Truncation of the secondary concentrator (CPC) as means to cost effective beam-down system / Akiba Segal 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. [031004/1-4] Titre : Truncation of the secondary concentrator (CPC) as means to cost effective beam-down system Type de document : texte imprimé Auteurs : Akiba Segal, Auteur ; Michael Epstein, Auteur Année de publication : 2011 Article en page(s) : pp. [031004/1-4] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Optics  Solar  energy  concentrators  Solar  power  stations Index. décimale : 621.47 Résumé : A central solar plant based on beam-down optics is composed of a field of heliostats, a tower reflector (hyperboloid mirror), and a ground receiver interfaced at its aperture with one or a cluster of secondary concentrators (compound parabolic concentrator). In previous publications, a method was presented, illustrating the correlation between the tower reflector position and its size on one hand and the geometry, dimensions, and reflective area of the secondary concentrator on the other hand, both related to the heliostat field reflective area. Obviously, when one wishes to reduce the size of a tower reflector by locating it closer to the upper focal point, the image created at the lower focus will be broader, resulting in a larger secondary ground concentrator. The present paper describes a method for substantial decrease in the dimensions of the ground secondary concentrator cluster (and, implicitly, the concentrator's area) via truncation and some geometrical corrections without significant sacrifice of the optical performance. This offers a method for cost effective design of future central solar plants, utilizing the beam-down optics. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Truncation of the secondary concentrator (CPC) as means to cost effective beam-down system [texte imprimé] / Akiba Segal, Auteur ; Michael Epstein, Auteur . - 2011 . - pp. [031004/1-4]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031004/1-4] Mots-clés : Optics  Solar  energy  concentrators  Solar  power  stations Index. décimale : 621.47 Résumé : A central solar plant based on beam-down optics is composed of a field of heliostats, a tower reflector (hyperboloid mirror), and a ground receiver interfaced at its aperture with one or a cluster of secondary concentrators (compound parabolic concentrator). In previous publications, a method was presented, illustrating the correlation between the tower reflector position and its size on one hand and the geometry, dimensions, and reflective area of the secondary concentrator on the other hand, both related to the heliostat field reflective area. Obviously, when one wishes to reduce the size of a tower reflector by locating it closer to the upper focal point, the image created at the lower focus will be broader, resulting in a larger secondary ground concentrator. The present paper describes a method for substantial decrease in the dimensions of the ground secondary concentrator cluster (and, implicitly, the concentrator's area) via truncation and some geometrical corrections without significant sacrifice of the optical performance. This offers a method for cost effective design of future central solar plants, utilizing the beam-down optics. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]