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Journal of solar energy engineering |
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Ajouter le résultat dans votre panierMethane decarbonization in indirect heating solar reactors of 20 and 50 kW for a CO2-free production of hydrogen and carbon black / Sylvain Rodat in Transactions of the ASME. Journal of solar energy engineering, Vol. 133 N° 3 (N° Spécial) (Août 2011)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : Methane decarbonization in indirect heating solar reactors of 20 and 50 kW for a CO2-free production of hydrogen and carbon black Type de document : texte imprimé Auteurs : Sylvain Rodat, Auteur ; Stéphane Abanades, Auteur ; Flamant, Gilles, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Chemical reactors Heating Hydrogen production Index. décimale : 621.47 Résumé : Solar methane decarbonization is an attractive pathway for a transition toward an hydrogen-based economy. In the frame of the European SOLHYCARB project, it was proposed to investigate this solar process extensively. At CNRS-PROMES, two indirect heating solar reactors (20 and 50 kW) were designed, built, and tested for methane decarbonization. They consist of graphite cavity-type receivers approaching the blackbody behavior. The CH4 dissociation reaction was carried out in tubular sections inserted in the solar absorber receiving concentrated solar irradiation. The 20 kW solar reactor (SR20) was especially suitable to study the chemical reaction and methane conversion performances depending on the experimental conditions (mainly temperature and residence time). The 50 kW solar reactor (SR50) was operated to produce significant amounts of carbon black for determining its properties and quality in the various possible commercial applications. The main encountered problem was the particle evacuation. Solutions were proposed for large-scale industrial applications. A process analysis was achieved for a 14.6 MW solar chemical plant on the basis of a process flow-sheet. A production of 436 kg/h of hydrogen and 1300 kg/h of carbon black could be obtained for 1737 kg/h of methane consumed, with an hydrogen cost competitive to conventional methane reforming. This paper summarizes the main results and conclusions of the project. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Methane decarbonization in indirect heating solar reactors of 20 and 50 kW for a CO2-free production of hydrogen and carbon black [texte imprimé] / Sylvain Rodat, Auteur ; Stéphane Abanades, Auteur ; Flamant, Gilles, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Chemical reactors Heating Hydrogen production Index. décimale : 621.47 Résumé : Solar methane decarbonization is an attractive pathway for a transition toward an hydrogen-based economy. In the frame of the European SOLHYCARB project, it was proposed to investigate this solar process extensively. At CNRS-PROMES, two indirect heating solar reactors (20 and 50 kW) were designed, built, and tested for methane decarbonization. They consist of graphite cavity-type receivers approaching the blackbody behavior. The CH4 dissociation reaction was carried out in tubular sections inserted in the solar absorber receiving concentrated solar irradiation. The 20 kW solar reactor (SR20) was especially suitable to study the chemical reaction and methane conversion performances depending on the experimental conditions (mainly temperature and residence time). The 50 kW solar reactor (SR50) was operated to produce significant amounts of carbon black for determining its properties and quality in the various possible commercial applications. The main encountered problem was the particle evacuation. Solutions were proposed for large-scale industrial applications. A process analysis was achieved for a 14.6 MW solar chemical plant on the basis of a process flow-sheet. A production of 436 kg/h of hydrogen and 1300 kg/h of carbon black could be obtained for 1737 kg/h of methane consumed, with an hydrogen cost competitive to conventional methane reforming. This paper summarizes the main results and conclusions of the project. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Titre : A model for solar photocatalytic mineralization Type de document : texte imprimé Auteurs : Franck Correia, Auteur ; Vincent Goetz, Auteur ; Gaël Plantard, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Catalysis Photochemistry Index. décimale : 621.47 Résumé : Modeling the mineralization of an organic pollutant was studied using a slurry of TiO2 powder. 2-4 dichlorophenol was chosen as the target molecule. In a first stage, a study was carried out, on the basis of a semi-empirical approach in order to define the optimal concentration of the catalyst. In a second stage, a series of photocatalytic mineralization was performed with a laboratory set-up using an artificial UV source. The parameters involved in the kinetics of mineralization were identified by a comparison of results obtained by simulations and experiments at constant but different levels of irradiation. In a third stage, the robustness and suitability of the model were tested with experiments carried out with an experimental solar set-up with different dimensions. No supplementary adjustment of parameters was needed to simulate the experiments performed under unsteady irradiation. Finally, the model is used to illustrate the great variation in treatment capability of a solar photocatalytic process depending on the weather conditions and, more particularly, the seasonal variations in UV irradiation. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] A model for solar photocatalytic mineralization [texte imprimé] / Franck Correia, Auteur ; Vincent Goetz, Auteur ; Gaël Plantard, Auteur . - 2012 . - 05 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Mots-clés : Catalysis Photochemistry Index. décimale : 621.47 Résumé : Modeling the mineralization of an organic pollutant was studied using a slurry of TiO2 powder. 2-4 dichlorophenol was chosen as the target molecule. In a first stage, a study was carried out, on the basis of a semi-empirical approach in order to define the optimal concentration of the catalyst. In a second stage, a series of photocatalytic mineralization was performed with a laboratory set-up using an artificial UV source. The parameters involved in the kinetics of mineralization were identified by a comparison of results obtained by simulations and experiments at constant but different levels of irradiation. In a third stage, the robustness and suitability of the model were tested with experiments carried out with an experimental solar set-up with different dimensions. No supplementary adjustment of parameters was needed to simulate the experiments performed under unsteady irradiation. Finally, the model is used to illustrate the great variation in treatment capability of a solar photocatalytic process depending on the weather conditions and, more particularly, the seasonal variations in UV irradiation. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Titre : Optimized bands : a new design concept for concentrating solar parabolic mirrors Type de document : texte imprimé Auteurs : Lifang Li, Auteur ; Andres Kecskemethy, Auteur ; A. F. M. Arif, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Cost reduction Finite element analysis Mirrors Power generation economics Sheet materials Solar absorber-convertors Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : Parabolic concentrator mirrors are an important component of many solar energy systems, particularly solar mirror collectors. Precision parabolic mirrors are expensive to fabricate and to transport. Here, a new concept for designing and fabricating precision parabolic mirrors is presented. The mirror is formed from a thin flat very flexible metal sheet with a highly reflective surface. Attached to the rear surface of the mirror sheet is a backbone band whose figure is optimized to form the reflective sheet into a precision parabola when its two ends are pulled toward each other. An analytical model to optimize the shape and thickness of the band is presented. The validity of the concept is demonstrated using Finite Element Analysis (FEA) and laboratory experiments. The concept would permit flat mirror elements to be easily fabricated and efficiently packaged and shipped to field sites and assembled into the parabolic trough concentrators with potentially substantial costs reductions compared with the conventional methods. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Optimized bands : a new design concept for concentrating solar parabolic mirrors [texte imprimé] / Lifang Li, Auteur ; Andres Kecskemethy, Auteur ; A. F. M. Arif, Auteur . - 2012 . - 09 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Mots-clés : Cost reduction Finite element analysis Mirrors Power generation economics Sheet materials Solar absorber-convertors Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : Parabolic concentrator mirrors are an important component of many solar energy systems, particularly solar mirror collectors. Precision parabolic mirrors are expensive to fabricate and to transport. Here, a new concept for designing and fabricating precision parabolic mirrors is presented. The mirror is formed from a thin flat very flexible metal sheet with a highly reflective surface. Attached to the rear surface of the mirror sheet is a backbone band whose figure is optimized to form the reflective sheet into a precision parabola when its two ends are pulled toward each other. An analytical model to optimize the shape and thickness of the band is presented. The validity of the concept is demonstrated using Finite Element Analysis (FEA) and laboratory experiments. The concept would permit flat mirror elements to be easily fabricated and efficiently packaged and shipped to field sites and assembled into the parabolic trough concentrators with potentially substantial costs reductions compared with the conventional methods. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 11 p.
Titre : Thermal performances of a high temperature air solar absorber based on compact heat exchange technology Type de document : texte imprimé Auteurs : B. Grange, Auteur ; A. Ferrière, Auteur ; D. Bellard, Auteur Année de publication : 2012 Article en page(s) : 11 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Energy conservation Gas turbines Heat exchangers Heat transfer High-temperature techniques Hybrid power systems Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : In the framework of the French PEGASE project (Production of Electricity by GAs turbine and Solar Energy), CNRS/PROMES laboratory is developing a 4 MWth pressurized air solar receiver with a surface absorber based on a compact heat exchanger technology. The first step of this development consists in designing and testing a pilot scale (1/10 scale, e.g., 360 kWth) solar receiver based on a metallic surface absorber. This paper briefly presents the hydraulic and thermal performances of the innovative pressurized air solar absorber developed in a previous work. The goal is to be capable of preheating pressurized air from 350 °C at the inlet to 750 °C at the outlet, with a maximum pressure drop of 300 mbar. The receiver is a cavity of square aperture 120 cm × 120 cm and 1 m deepness with an average concentration in the aperture of more than 300. The square shaped aperture is chosen due to the small scale of the receiver; indeed, the performances are not enhanced that much with a round aperture, while the manufacturability is much more complicated. However in the perspective of PEGASE, a round aperture is likely to be used. The back of the cavity is covered by modules arranged in two series making the modular and multistage absorber. The thermal performances of one module are considered to simulate the thermal exchange within the receiver and to estimate the energy efficiency of this receiver. The results of the simulation show that the basic design yields an air outlet temperature of 739 °C under design operation conditions (1000 W/m2 solar irradiation, 0.8 kg/s air flow rate). Using the cavity walls as air preheating elements allows increasing the air outlet temperature above 750 °C as well as the energy efficiency up to 81% but at the cost of a critical absorber wall temperature. However, this wall temperature can be controlled by applying an aiming point strategy with the heliostat field. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Thermal performances of a high temperature air solar absorber based on compact heat exchange technology [texte imprimé] / B. Grange, Auteur ; A. Ferrière, Auteur ; D. Bellard, Auteur . - 2012 . - 11 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 11 p.
Mots-clés : Energy conservation Gas turbines Heat exchangers Heat transfer High-temperature techniques Hybrid power systems Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : In the framework of the French PEGASE project (Production of Electricity by GAs turbine and Solar Energy), CNRS/PROMES laboratory is developing a 4 MWth pressurized air solar receiver with a surface absorber based on a compact heat exchanger technology. The first step of this development consists in designing and testing a pilot scale (1/10 scale, e.g., 360 kWth) solar receiver based on a metallic surface absorber. This paper briefly presents the hydraulic and thermal performances of the innovative pressurized air solar absorber developed in a previous work. The goal is to be capable of preheating pressurized air from 350 °C at the inlet to 750 °C at the outlet, with a maximum pressure drop of 300 mbar. The receiver is a cavity of square aperture 120 cm × 120 cm and 1 m deepness with an average concentration in the aperture of more than 300. The square shaped aperture is chosen due to the small scale of the receiver; indeed, the performances are not enhanced that much with a round aperture, while the manufacturability is much more complicated. However in the perspective of PEGASE, a round aperture is likely to be used. The back of the cavity is covered by modules arranged in two series making the modular and multistage absorber. The thermal performances of one module are considered to simulate the thermal exchange within the receiver and to estimate the energy efficiency of this receiver. The results of the simulation show that the basic design yields an air outlet temperature of 739 °C under design operation conditions (1000 W/m2 solar irradiation, 0.8 kg/s air flow rate). Using the cavity walls as air preheating elements allows increasing the air outlet temperature above 750 °C as well as the energy efficiency up to 81% but at the cost of a critical absorber wall temperature. However, this wall temperature can be controlled by applying an aiming point strategy with the heliostat field. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : Concentrated solar energy to study high temperature materials for space and energy Type de document : texte imprimé Auteurs : Ludovic Charpentier, Auteur ; Kamel Dawi, Auteur ; Julien Eck, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : In this paper, the concentrated solar energy is used as a source of high temperatures to study the physical and chemical behaviors and intrinsic properties of refractory materials. The atmospheres surrounding the materials have to be simulated in experimental reactors to characterize the materials in real environments. Several application fields are concerned such as the aerospace and the energy fields: examples of results will be given for the heat shield of the Solar Probe Plus mission (NASA) for the SiC/SiC material that can be used as cladding materials for next nuclear reactor (gas-cooled fast reactor—GFR, Generation IV) and for new advanced materials for solar absorbers in concentration solar power (CSP) plant. Two different facilities—REHPTS and MEDIASE—implemented at the focus of two different solar furnaces of the PROMES-CNRS laboratory—5 kW and 1 MW—are presented together with some experimental results on the behavior of high temperature materials. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Concentrated solar energy to study high temperature materials for space and energy [texte imprimé] / Ludovic Charpentier, Auteur ; Kamel Dawi, Auteur ; Julien Eck, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : In this paper, the concentrated solar energy is used as a source of high temperatures to study the physical and chemical behaviors and intrinsic properties of refractory materials. The atmospheres surrounding the materials have to be simulated in experimental reactors to characterize the materials in real environments. Several application fields are concerned such as the aerospace and the energy fields: examples of results will be given for the heat shield of the Solar Probe Plus mission (NASA) for the SiC/SiC material that can be used as cladding materials for next nuclear reactor (gas-cooled fast reactor—GFR, Generation IV) and for new advanced materials for solar absorbers in concentration solar power (CSP) plant. Two different facilities—REHPTS and MEDIASE—implemented at the focus of two different solar furnaces of the PROMES-CNRS laboratory—5 kW and 1 MW—are presented together with some experimental results on the behavior of high temperature materials. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : High temperature thermochemical heat storage for concentrated solar power using gas–solid reactions Type de document : texte imprimé Auteurs : Franziska Schaube, Auteur ; Antje Wörner, Auteur ; Rainer Tamme, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Chemical energy conversion Finite element analysis Heat transfer Reaction kinetics Solar power stations Thermal conductivity Index. décimale : 621.47 Résumé : High temperature thermal storage technologies that can be easily integrated into future concentrated solar power plants are a key factor for increasing the market potential of solar power production. Storing thermal energy by reversible gas–solid reactions has the potential of achieving high storage densities while being adjustable to various plant configurations. In this paper the Ca(OH)2/CaO reaction system is investigated theoretically. It can achieve storage densities above 300 kWh/m3 while operating in a temperature range between 400 and 600°C. Reactor concepts with indirect and direct heat transfer are being evaluated. The low thermal conductivity of the fixed bed of solid reactants turned out to considerably limit the performance of a storage tank with indirect heat input through the reactor walls. A one-dimensional model for the storage reactor is established and solved with the Finite Element Method. The reactor concept with direct heat transfer by flowing the gaseous reactant plus additional inert gas through the solid reactants did not show any limitation due to heat transfer. If reaction kinetics are fast enough, the reactor performance in case of the Ca(OH)2/CaO reaction system is limited by the thermal capacity of the gaseous stream to take-up heat of reaction. However, to limit pressure drop and the according losses for compression of the gas stream, the size of the storage system is restricted in a fixed bed configuration. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] High temperature thermochemical heat storage for concentrated solar power using gas–solid reactions [texte imprimé] / Franziska Schaube, Auteur ; Antje Wörner, Auteur ; Rainer Tamme, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Chemical energy conversion Finite element analysis Heat transfer Reaction kinetics Solar power stations Thermal conductivity Index. décimale : 621.47 Résumé : High temperature thermal storage technologies that can be easily integrated into future concentrated solar power plants are a key factor for increasing the market potential of solar power production. Storing thermal energy by reversible gas–solid reactions has the potential of achieving high storage densities while being adjustable to various plant configurations. In this paper the Ca(OH)2/CaO reaction system is investigated theoretically. It can achieve storage densities above 300 kWh/m3 while operating in a temperature range between 400 and 600°C. Reactor concepts with indirect and direct heat transfer are being evaluated. The low thermal conductivity of the fixed bed of solid reactants turned out to considerably limit the performance of a storage tank with indirect heat input through the reactor walls. A one-dimensional model for the storage reactor is established and solved with the Finite Element Method. The reactor concept with direct heat transfer by flowing the gaseous reactant plus additional inert gas through the solid reactants did not show any limitation due to heat transfer. If reaction kinetics are fast enough, the reactor performance in case of the Ca(OH)2/CaO reaction system is limited by the thermal capacity of the gaseous stream to take-up heat of reaction. However, to limit pressure drop and the according losses for compression of the gas stream, the size of the storage system is restricted in a fixed bed configuration. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : Analysis of solar-thermal power plants with thermal energy storage and solar-hybrid operation strategy Type de document : texte imprimé Auteurs : Stefano Giuliano, Auteur ; Reiner Buck, Auteur ; Santiago Eguiguren, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Combined cycle power stations Fossil fuels Hybrid power systems Power generation dispatch Solar power stations Steam turbines Index. décimale : 621.47 Résumé : Selected solar-hybrid power plants for operation in base-load as well as midload were analyzed regarding supply security (dispatchable power due to hybridization with fossil fuel) and low CO2 emissions (due to integration of thermal energy storage). The power plants were modeled with different sizes of solar fields and different storage capacities and analyzed on an annual basis. The results were compared to each other and to a conventional fossil-fired combined cycle in terms of technical, economical, and ecological figures. The results of this study show that in comparison to a conventional fossil-fired combined cycle, the potential to reduce the CO2 emissions is high for solar-thermal power plants operated in base-load, especially with large solar fields and high storage capacities. However, for dispatchable power generation and supply security it is obvious that in any case a certain amount of additional fossil fuel is required. No analyzed solar-hybrid power plant shows at the same time advantages in terms of low CO2 emissions and low levelized electricity cost (LEC). While power plants with solar-hybrid combined cycle (SHCC®, Particle-Tower) show interesting LEC, the power plants with steam turbine (Salt-Tower, Parabolic Trough, CO2-Tower) have low CO2 emissions. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Analysis of solar-thermal power plants with thermal energy storage and solar-hybrid operation strategy [texte imprimé] / Stefano Giuliano, Auteur ; Reiner Buck, Auteur ; Santiago Eguiguren, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Combined cycle power stations Fossil fuels Hybrid power systems Power generation dispatch Solar power stations Steam turbines Index. décimale : 621.47 Résumé : Selected solar-hybrid power plants for operation in base-load as well as midload were analyzed regarding supply security (dispatchable power due to hybridization with fossil fuel) and low CO2 emissions (due to integration of thermal energy storage). The power plants were modeled with different sizes of solar fields and different storage capacities and analyzed on an annual basis. The results were compared to each other and to a conventional fossil-fired combined cycle in terms of technical, economical, and ecological figures. The results of this study show that in comparison to a conventional fossil-fired combined cycle, the potential to reduce the CO2 emissions is high for solar-thermal power plants operated in base-load, especially with large solar fields and high storage capacities. However, for dispatchable power generation and supply security it is obvious that in any case a certain amount of additional fossil fuel is required. No analyzed solar-hybrid power plant shows at the same time advantages in terms of low CO2 emissions and low levelized electricity cost (LEC). While power plants with solar-hybrid combined cycle (SHCC®, Particle-Tower) show interesting LEC, the power plants with steam turbine (Salt-Tower, Parabolic Trough, CO2-Tower) have low CO2 emissions. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : Recycled material for sensible heat based thermal energy storage to be used in concentrated solar thermal power plants Type de document : texte imprimé Auteurs : Xavier Py, Auteur ; Nicolas Calvet, Auteur ; Régis Olives, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Asbestos Ceramics Recycling Solar power stations Thermal energy storage Thermal power stations Vitrification Index. décimale : 621.47 Résumé : Current technologies of concentrated solar power plants (CSP) are under extensive industrial development but still suffer from lack of adapted thermal energy storage (TES) materials and systems. In the case of extended storage (some hours), thousands of tonnes of materials are concerned leading to high investment cost, high energy and GHG contents and major conflicts of use. In this paper, recycled industrial ceramics made by vitrification of asbestos containing wastes (ACW) are studied as candidates to be used as sensible TES material. The material presents no hazard, no environmental impact, good thermophysical properties (lambda= 1.4 W m−1 K−1; Cp = 1025 J kg−1 K−1; rho= 3100 kg m−3) and at very low investment cost. Thanks to the vitrification process of the wastes, the obtained ceramics is very stable up to 1200 °C and can be directly manufactured with the desired shape. The vitrified ACW can be used as TES material for all kinds of the CSP processes (from medium up to high concentration levels) with properties in the same range than other available materials but with lower cost and without conflict of use. The proposed approach leads also to sustainable TES allowing a pay back of the energy needed for the initial waste treatment. Furthermore, this new use of the matter can enhance the waste treatment industry instead of land fill disposal. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Recycled material for sensible heat based thermal energy storage to be used in concentrated solar thermal power plants [texte imprimé] / Xavier Py, Auteur ; Nicolas Calvet, Auteur ; Régis Olives, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Asbestos Ceramics Recycling Solar power stations Thermal energy storage Thermal power stations Vitrification Index. décimale : 621.47 Résumé : Current technologies of concentrated solar power plants (CSP) are under extensive industrial development but still suffer from lack of adapted thermal energy storage (TES) materials and systems. In the case of extended storage (some hours), thousands of tonnes of materials are concerned leading to high investment cost, high energy and GHG contents and major conflicts of use. In this paper, recycled industrial ceramics made by vitrification of asbestos containing wastes (ACW) are studied as candidates to be used as sensible TES material. The material presents no hazard, no environmental impact, good thermophysical properties (lambda= 1.4 W m−1 K−1; Cp = 1025 J kg−1 K−1; rho= 3100 kg m−3) and at very low investment cost. Thanks to the vitrification process of the wastes, the obtained ceramics is very stable up to 1200 °C and can be directly manufactured with the desired shape. The vitrified ACW can be used as TES material for all kinds of the CSP processes (from medium up to high concentration levels) with properties in the same range than other available materials but with lower cost and without conflict of use. The proposed approach leads also to sustainable TES allowing a pay back of the energy needed for the initial waste treatment. Furthermore, this new use of the matter can enhance the waste treatment industry instead of land fill disposal. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : Face-down solid particle receiver using recirculation Type de document : texte imprimé Auteurs : Marc Röger, Auteur ; Lars Amsbeck, Auteur ; Birgit Gobereit, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Steam turbines Thermal energy storage Turbines Index. décimale : 621.47 Résumé : Solar thermal energy generation needs receiver technologies which can drive highly efficient turbines and decouple the collection of energy from its use by an economic storage technology. High-temperature solid particle receivers for solar tower systems with particle storage are one option. Important issues regarding high-temperature particle receivers are minimization of convective losses, no particle loss due to susceptibility to wind, and high efficiency also in part-load operation. A design approach facing these challenges is the face-down receiver using recirculation of particles. A screening performance analysis studying different recirculation patterns is presented. Using smart recirculation schemes, high receiver efficiencies can be maintained also at part-load operation (100% load ~90%; 50% load ~86%; 20% load ~67%). Simulations of the face-down geometry yield total annual solar-to-electric efficiencies of 24% using a surround field. From the analyses, it can be concluded that solid particle receivers using smart recirculation patterns are a viable receiver option for storage and high-temperature high-efficiency turbine processes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Face-down solid particle receiver using recirculation [texte imprimé] / Marc Röger, Auteur ; Lars Amsbeck, Auteur ; Birgit Gobereit, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Steam turbines Thermal energy storage Turbines Index. décimale : 621.47 Résumé : Solar thermal energy generation needs receiver technologies which can drive highly efficient turbines and decouple the collection of energy from its use by an economic storage technology. High-temperature solid particle receivers for solar tower systems with particle storage are one option. Important issues regarding high-temperature particle receivers are minimization of convective losses, no particle loss due to susceptibility to wind, and high efficiency also in part-load operation. A design approach facing these challenges is the face-down receiver using recirculation of particles. A screening performance analysis studying different recirculation patterns is presented. Using smart recirculation schemes, high receiver efficiencies can be maintained also at part-load operation (100% load ~90%; 50% load ~86%; 20% load ~67%). Simulations of the face-down geometry yield total annual solar-to-electric efficiencies of 24% using a surround field. From the analyses, it can be concluded that solid particle receivers using smart recirculation patterns are a viable receiver option for storage and high-temperature high-efficiency turbine processes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : Feasibility study of an innovative dry-cooling system with phase-change material storage for concentrated solar power multi-MW size power plant Type de document : texte imprimé Auteurs : Lorenzo Pistocchini, Auteur ; Mario Motta, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Condensers (steam plant) Cooling Phase change materials Phase change memories Solar power stations Steam power stations Turbines Index. décimale : 621.47 Résumé : This work concerns the economic potential assessment of an innovative hybrid-cooling system for steam condensation in concentrated solar power plants. The system consists of an air-cooled condenser (ACC) working in parallel to a latent heat storage with phase-change material (PCM). The purpose of the hybrid system is to store some of the latent heat of steam condensation during the turbine operation and reject it at night, in order to shift a share of the cooling work and exploit the high diurnal temperature range of desert areas. System's energy and economic performances are assessed by the parametric analysis of a theoretical case study, referred to an existing solar power plant and based on historical meteorological data. The analysis considers an ideal “perfect” PCM storage system, namely with no technological barriers, and different cost scenarios. The simulation campaign outcome indicates how the innovative solution can provide just a slight improvement of the plant performance, which is anyway significant in qualitative terms since the risk of breakdowns of turbine operation during the hottest summer days is avoided. It is remarkable that the introduction of the heat storage allows for a reduction of the ACC installed power. The economic feasibility of the proposed solution follows on mainly from the comparison between the investment cost increase —due to the PCM storage—and savings—due to reduction of the installed ACC modules. The hybrid-cooling system would be an attractive alternative to standard systems if the PCM storage cost could be contained by increasing the conductivity of the PCM material. As an alternative, a cheaper heat storage technology (e.g., a water thermocline) could be coupled to an indirect-cooling system. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Feasibility study of an innovative dry-cooling system with phase-change material storage for concentrated solar power multi-MW size power plant [texte imprimé] / Lorenzo Pistocchini, Auteur ; Mario Motta, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Condensers (steam plant) Cooling Phase change materials Phase change memories Solar power stations Steam power stations Turbines Index. décimale : 621.47 Résumé : This work concerns the economic potential assessment of an innovative hybrid-cooling system for steam condensation in concentrated solar power plants. The system consists of an air-cooled condenser (ACC) working in parallel to a latent heat storage with phase-change material (PCM). The purpose of the hybrid system is to store some of the latent heat of steam condensation during the turbine operation and reject it at night, in order to shift a share of the cooling work and exploit the high diurnal temperature range of desert areas. System's energy and economic performances are assessed by the parametric analysis of a theoretical case study, referred to an existing solar power plant and based on historical meteorological data. The analysis considers an ideal “perfect” PCM storage system, namely with no technological barriers, and different cost scenarios. The simulation campaign outcome indicates how the innovative solution can provide just a slight improvement of the plant performance, which is anyway significant in qualitative terms since the risk of breakdowns of turbine operation during the hottest summer days is avoided. It is remarkable that the introduction of the heat storage allows for a reduction of the ACC installed power. The economic feasibility of the proposed solution follows on mainly from the comparison between the investment cost increase —due to the PCM storage—and savings—due to reduction of the installed ACC modules. The hybrid-cooling system would be an attractive alternative to standard systems if the PCM storage cost could be contained by increasing the conductivity of the PCM material. As an alternative, a cheaper heat storage technology (e.g., a water thermocline) could be coupled to an indirect-cooling system. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Titre : Optimization model for solar thermochemical reactor: efficiency increase by a nonuniform heat sink distribution Type de document : texte imprimé Auteurs : S. Tescari, Auteur ; N. Mazet, Auteur ; P. Neveu, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Chemical energy conversion Chemical reactions Chemical reactors Computational fluid dynamics Heat sinks Optimisation Power consumption Solar energy concentrators Solar power Temperature distribution Index. décimale : 621.47 Résumé : This study focuses on thermochemical cavity-type reactor, with a reactive material directly irradiated by concentrated solar energy. General tendencies of reactor performance are analyzed as a function of the reactor geometry. The objective is to define a simplified model that can be adapted easily to different reactor designs or different operating conditions. For this reason, the chemical reaction is not precisely fixed but rather characterized by a reaction temperature and a useful power consumed by the endothermic reaction, inside the reactive material. In order to increase the efficiency, two new reactor designs are proposed. These designs allow obtaining a nonuniform distribution of the useful power consumed by the reaction with the depth in a circular cylindrical cavity (z-axis). This is done in two ways: by varying the reactive material thickness along the axis or by varying its density at a constant thickness. The results show that these reactor concepts lead to a more uniform temperature distribution along the z-axis and a diminution of the heat losses. Thus, the reactor efficiency can increase significantly. The results of the simplified model can be used as a system predesign. A more accurate CFD model could be used afterward to refine the optimal shape. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Optimization model for solar thermochemical reactor: efficiency increase by a nonuniform heat sink distribution [texte imprimé] / S. Tescari, Auteur ; N. Mazet, Auteur ; P. Neveu, Auteur . - 2012 . - 06 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Mots-clés : Chemical energy conversion Chemical reactions Chemical reactors Computational fluid dynamics Heat sinks Optimisation Power consumption Solar energy concentrators Solar power Temperature distribution Index. décimale : 621.47 Résumé : This study focuses on thermochemical cavity-type reactor, with a reactive material directly irradiated by concentrated solar energy. General tendencies of reactor performance are analyzed as a function of the reactor geometry. The objective is to define a simplified model that can be adapted easily to different reactor designs or different operating conditions. For this reason, the chemical reaction is not precisely fixed but rather characterized by a reaction temperature and a useful power consumed by the endothermic reaction, inside the reactive material. In order to increase the efficiency, two new reactor designs are proposed. These designs allow obtaining a nonuniform distribution of the useful power consumed by the reaction with the depth in a circular cylindrical cavity (z-axis). This is done in two ways: by varying the reactive material thickness along the axis or by varying its density at a constant thickness. The results show that these reactor concepts lead to a more uniform temperature distribution along the z-axis and a diminution of the heat losses. Thus, the reactor efficiency can increase significantly. The results of the simplified model can be used as a system predesign. A more accurate CFD model could be used afterward to refine the optimal shape. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : The MED-CSD project : potential for concentrating solar power desalination development in mediterranean countries Type de document : texte imprimé Auteurs : Massimo Moser, Auteur ; Franz Trieb, Auteur ; Jürgen Kern, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Desalination Distillation Seawater Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : Within the MED-CSD project, feasibility studies of integrated hybrid concentrating solar power (CSP) and seawater desalination (DES) plants were carried out in selected locations in Morocco, Italy, Cyprus, Egypt and Gaza/West Bank. After a review on CSP and desalination technologies, ten typical sites within the five partner countries have been selected. For each location, a CSP-DES plant was modeled. The model bases on hourly time series of solar irradiance, ambient temperature, as well as wind speed and includes local seasonal and hourly load curves for power and water. Surplus thermal energy from the solar field is fed into the energy storage, so that operation is possible at night and during cloud transients; gaps between demand and solar power production are covered by cofiring with fossil fuel. Different plant components (solar field collectors and desalination technologies) have been compared. A techno-economic model is applied in order to analyze the economic feasibility and the required financial framework conditions of the projects. Furthermore, an analysis of the market potential of concentrating solar power for sea water desalination in the Mediterranean Region and socio-economic and environmental impact analyses were implemented. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] The MED-CSD project : potential for concentrating solar power desalination development in mediterranean countries [texte imprimé] / Massimo Moser, Auteur ; Franz Trieb, Auteur ; Jürgen Kern, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Desalination Distillation Seawater Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : Within the MED-CSD project, feasibility studies of integrated hybrid concentrating solar power (CSP) and seawater desalination (DES) plants were carried out in selected locations in Morocco, Italy, Cyprus, Egypt and Gaza/West Bank. After a review on CSP and desalination technologies, ten typical sites within the five partner countries have been selected. For each location, a CSP-DES plant was modeled. The model bases on hourly time series of solar irradiance, ambient temperature, as well as wind speed and includes local seasonal and hourly load curves for power and water. Surplus thermal energy from the solar field is fed into the energy storage, so that operation is possible at night and during cloud transients; gaps between demand and solar power production are covered by cofiring with fossil fuel. Different plant components (solar field collectors and desalination technologies) have been compared. A techno-economic model is applied in order to analyze the economic feasibility and the required financial framework conditions of the projects. Furthermore, an analysis of the market potential of concentrating solar power for sea water desalination in the Mediterranean Region and socio-economic and environmental impact analyses were implemented. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Titre : Development of molten salt heat transfer fluid with low melting point and high thermal stability Type de document : texte imprimé Auteurs : Justin W. Raade, Auteur ; David Padowitz, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Heat transfer Melting point Solar energy concentrators Solar power stations Thermal stability Index. décimale : 621.47 Résumé : This paper describes an advanced heat transfer fluid (HTF) consisting of a novel mixture of inorganic salts with a low melting point and high thermal stability. These properties produce a broad operating range molten salt and enable effective thermal storage for parabolic trough concentrating solar power plants. Previous commercially available molten salt heat transfer fluids have a high melting point, typically 140 °C or higher, which limits their commercial use due to the risk of freezing. The advanced HTF embodies a novel composition of materials, consisting of a mixture of nitrate salts of lithium, sodium, potassium, cesium, and calcium. This unique mixture exploits eutectic behavior resulting in a low melting point of 65 °C and a thermal stability limit over 500 °C. The advanced HTF described in this work was developed using advanced experiment design and data analysis methods combined with a powerful high throughput experimental workflow. Over 5000 unique mixtures of inorganic salt were tested during the development process. Additional work is ongoing to fully characterize the relevant thermophysical properties of the HTF and to assess its long term performance in realistic operating conditions for concentrating solar power applications or other high temperature processes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Development of molten salt heat transfer fluid with low melting point and high thermal stability [texte imprimé] / Justin W. Raade, Auteur ; David Padowitz, Auteur . - 2012 . - 06 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Mots-clés : Heat transfer Melting point Solar energy concentrators Solar power stations Thermal stability Index. décimale : 621.47 Résumé : This paper describes an advanced heat transfer fluid (HTF) consisting of a novel mixture of inorganic salts with a low melting point and high thermal stability. These properties produce a broad operating range molten salt and enable effective thermal storage for parabolic trough concentrating solar power plants. Previous commercially available molten salt heat transfer fluids have a high melting point, typically 140 °C or higher, which limits their commercial use due to the risk of freezing. The advanced HTF embodies a novel composition of materials, consisting of a mixture of nitrate salts of lithium, sodium, potassium, cesium, and calcium. This unique mixture exploits eutectic behavior resulting in a low melting point of 65 °C and a thermal stability limit over 500 °C. The advanced HTF described in this work was developed using advanced experiment design and data analysis methods combined with a powerful high throughput experimental workflow. Over 5000 unique mixtures of inorganic salt were tested during the development process. Additional work is ongoing to fully characterize the relevant thermophysical properties of the HTF and to assess its long term performance in realistic operating conditions for concentrating solar power applications or other high temperature processes. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Titre : Thermodynamic cycles for a small particle heat exchange receiver used in concentrating solar power plants Type de document : texte imprimé Auteurs : Kyle Kitzmiller, Auteur ; Fletcher Miller, Auteur Année de publication : 2012 Article en page(s) : 08 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Brayton cycle Convection Fossil fuels Heat exchangers Hybrid power systems Solar energy concentrators Solar power Solar power stations Index. décimale : 621.47 Résumé : Gas-cooled solar receivers for concentrating solar power plants are capable of providing high temperature, pressurized gas for electrical power generation via a Brayton cycle. This can be accomplished by expanding hot, pressurized gas directly through a turbine, or through using a heat exchanger to indirectly heat pressurized air. Gas-cooled receivers can be divided into two basic technologies. In tube based solar receivers, thermal energy is transferred to air through convection with the heated tube wall. This limits receiver efficiency since the tube wall needs to be substantially hotter than the gas inside due to the relatively poor gas heat transfer coefficient. In volumetric receivers, solar energy is absorbed within a volume, rather than on a surface. The absorption volume can be filled with ceramic foam, wires, or particles to act as the absorbing medium. In a small particle heat exchange receiver, for example, submicron sized particles absorb solar radiation and transfer this energy as heat to a surrounding fluid. This effectively eliminates any thermal resistance, allowing for higher receiver efficiencies. However, mechanical considerations limit the size of volumetric, pressurized gas-cooled receivers.In order to solve this problem, several thermodynamic cycles have been investigated, each of which is motivated by key physical considerations in volumetric receivers. The cyclic efficiencies are determined by a new MATLAB code based on previous Brayton cycle modeling conducted by Sandia National Laboratories. The modeling accounts for pressure drops and temperature losses in various components, and parameters such as the turbine inlet temperature and pressure ratio are easily modified to run parametric cases.The performance of a gas-cooled solar receiver is largely a function of its ability to provide process gas at a consistent temperature or pressure, regardless of variations in solar flux, which can vary due to cloud transients or apparent sun motion throughout the day. Consistent output can be ensured by combusting fuel within the cycle, effectively making a solar/fossil fuel hybrid system. Several schemes for hybridization with natural gas are considered here, including externally fired concepts and combined receiver/combustor units. Because the efficiency of hybridized cycles is a function of the solar thermal input, the part load behavior of the recuperated cycle is examined. However, off-design models are simplistic in this research, as the goal of the work is an introductory evaluation of different potential cycles. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Thermodynamic cycles for a small particle heat exchange receiver used in concentrating solar power plants [texte imprimé] / Kyle Kitzmiller, Auteur ; Fletcher Miller, Auteur . - 2012 . - 08 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 08 p.
Mots-clés : Brayton cycle Convection Fossil fuels Heat exchangers Hybrid power systems Solar energy concentrators Solar power Solar power stations Index. décimale : 621.47 Résumé : Gas-cooled solar receivers for concentrating solar power plants are capable of providing high temperature, pressurized gas for electrical power generation via a Brayton cycle. This can be accomplished by expanding hot, pressurized gas directly through a turbine, or through using a heat exchanger to indirectly heat pressurized air. Gas-cooled receivers can be divided into two basic technologies. In tube based solar receivers, thermal energy is transferred to air through convection with the heated tube wall. This limits receiver efficiency since the tube wall needs to be substantially hotter than the gas inside due to the relatively poor gas heat transfer coefficient. In volumetric receivers, solar energy is absorbed within a volume, rather than on a surface. The absorption volume can be filled with ceramic foam, wires, or particles to act as the absorbing medium. In a small particle heat exchange receiver, for example, submicron sized particles absorb solar radiation and transfer this energy as heat to a surrounding fluid. This effectively eliminates any thermal resistance, allowing for higher receiver efficiencies. However, mechanical considerations limit the size of volumetric, pressurized gas-cooled receivers.In order to solve this problem, several thermodynamic cycles have been investigated, each of which is motivated by key physical considerations in volumetric receivers. The cyclic efficiencies are determined by a new MATLAB code based on previous Brayton cycle modeling conducted by Sandia National Laboratories. The modeling accounts for pressure drops and temperature losses in various components, and parameters such as the turbine inlet temperature and pressure ratio are easily modified to run parametric cases.The performance of a gas-cooled solar receiver is largely a function of its ability to provide process gas at a consistent temperature or pressure, regardless of variations in solar flux, which can vary due to cloud transients or apparent sun motion throughout the day. Consistent output can be ensured by combusting fuel within the cycle, effectively making a solar/fossil fuel hybrid system. Several schemes for hybridization with natural gas are considered here, including externally fired concepts and combined receiver/combustor units. Because the efficiency of hybridized cycles is a function of the solar thermal input, the part load behavior of the recuperated cycle is examined. However, off-design models are simplistic in this research, as the goal of the work is an introductory evaluation of different potential cycles. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Titre : Numerical analysis of heat loss from a parabolic trough absorber tube with active vacuum system Type de document : texte imprimé Auteurs : Matthew Roesle, Auteur ; Volkan Coskun, Auteur ; Aldo Steinfeld, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Computational fluid dynamics Convection Design engineering Flow simulation Heat conduction Heat losses Heat radiation Monte Carlo methods Pipe flow Radiative transfer Rarefied fluid dynamics Solar absorber-convertors Solar power stations Vacuum pumps Index. décimale : 621.47 Résumé : In current designs of parabolic trough collectors for concentrating solar power plants, the absorber tube is manufactured in segments that are individually insulated with glass vacuum jackets. During the lifetime of a power plant, some segments lose vacuum and thereafter suffer from significant convective heat loss. An alternative to this design is to use a vacuum pump to actively maintain low pressure in a long section of absorber with a continuous vacuum jacket. A detailed thermal model of such a configuration is needed to inform design efforts for such a receiver. This paper describes a combined conduction, convection, and radiation heat transfer model for a receiver that includes the effects of nonuniform solar flux on the absorber tube and vacuum jacket as well as detailed analysis of conduction through the rarefied gas in the annular gap inside the vacuum jacket. The model is implemented in commercial CFD software coupled to a Monte Carlo ray-tracing code. The results of simulations performed for a two-dimensional cross-section of a receiver are reported for various conditions. The parameters for the model are chosen to match the current generation of parabolic trough receivers, and the simulation results correspond well with experimental measurements. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Numerical analysis of heat loss from a parabolic trough absorber tube with active vacuum system [texte imprimé] / Matthew Roesle, Auteur ; Volkan Coskun, Auteur ; Aldo Steinfeld, Auteur . - 2012 . - 05 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Mots-clés : Computational fluid dynamics Convection Design engineering Flow simulation Heat conduction Heat losses Heat radiation Monte Carlo methods Pipe flow Radiative transfer Rarefied fluid dynamics Solar absorber-convertors Solar power stations Vacuum pumps Index. décimale : 621.47 Résumé : In current designs of parabolic trough collectors for concentrating solar power plants, the absorber tube is manufactured in segments that are individually insulated with glass vacuum jackets. During the lifetime of a power plant, some segments lose vacuum and thereafter suffer from significant convective heat loss. An alternative to this design is to use a vacuum pump to actively maintain low pressure in a long section of absorber with a continuous vacuum jacket. A detailed thermal model of such a configuration is needed to inform design efforts for such a receiver. This paper describes a combined conduction, convection, and radiation heat transfer model for a receiver that includes the effects of nonuniform solar flux on the absorber tube and vacuum jacket as well as detailed analysis of conduction through the rarefied gas in the annular gap inside the vacuum jacket. The model is implemented in commercial CFD software coupled to a Monte Carlo ray-tracing code. The results of simulations performed for a two-dimensional cross-section of a receiver are reported for various conditions. The parameters for the model are chosen to match the current generation of parabolic trough receivers, and the simulation results correspond well with experimental measurements. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 12 p.
Titre : A 9-m-aperture solar parabolic trough concentrator based on a multilayer polymer mirror membrane mounted on a concrete structure Type de document : texte imprimé Auteurs : Roman Bader, Auteur ; Andrea Pedretti, Auteur ; Steinfeld, Aldo, Auteur Année de publication : 2012 Article en page(s) : 12 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Design engineering Membranes Monte Carlo methods Ray tracing Solar energy concentrators Index. décimale : 621.47 Résumé : A large-span solar parabolic trough concentrator is designed based on a multilayer polymer mirror membrane mounted on a rotatable concrete structure. The multilayer membrane is contained in a transparent protective air tube and generates a multicircular profile that approaches the trough parabolic shape. An analytical model of the mechanical behavior of the membrane mirror construction coupled to a Monte Carlo ray-tracing simulation is formulated and applied for design and optimization and for elucidating the influence of manufacturing and operational parameter variations on the radiative flux distribution. It is found that the parabolic shape can be well approximated with four stacked membranes that generate an arc-spline of four tangentially adjacent circular arcs. A 45-m-long 9-m-aperture full-scale prototype concentrator was fabricated and experimentation was carried out to validate the simulation model. Highest measured peak solar radiative flux concentration was 18.9, corresponding to 39% of the theoretical maximum value for an ideal parabolic trough concentrator. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] A 9-m-aperture solar parabolic trough concentrator based on a multilayer polymer mirror membrane mounted on a concrete structure [texte imprimé] / Roman Bader, Auteur ; Andrea Pedretti, Auteur ; Steinfeld, Aldo, Auteur . - 2012 . - 12 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 12 p.
Mots-clés : Design engineering Membranes Monte Carlo methods Ray tracing Solar energy concentrators Index. décimale : 621.47 Résumé : A large-span solar parabolic trough concentrator is designed based on a multilayer polymer mirror membrane mounted on a rotatable concrete structure. The multilayer membrane is contained in a transparent protective air tube and generates a multicircular profile that approaches the trough parabolic shape. An analytical model of the mechanical behavior of the membrane mirror construction coupled to a Monte Carlo ray-tracing simulation is formulated and applied for design and optimization and for elucidating the influence of manufacturing and operational parameter variations on the radiative flux distribution. It is found that the parabolic shape can be well approximated with four stacked membranes that generate an arc-spline of four tangentially adjacent circular arcs. A 45-m-long 9-m-aperture full-scale prototype concentrator was fabricated and experimentation was carried out to validate the simulation model. Highest measured peak solar radiative flux concentration was 18.9, corresponding to 39% of the theoretical maximum value for an ideal parabolic trough concentrator. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Titre : Annual yield analysis of solar tower power plants with GREENIUS Type de document : texte imprimé Auteurs : Jürgen Dersch, Auteur ; Peter Schwarzbözl, Auteur ; Timo Richert, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Mirrors Power system simulation Solar absorber-convertors Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : An existing software tool for annual performance calculation of concentrating solar power and other renewable energy plants has been extended to enable the simulation of solar tower power plants. The methodology used is shown and a demonstrative example of a 50 MWe tower plant in southern Spain is given. The influence of design power and latitude on solar field layout is discussed. Furthermore, a comparison of the tower plant with a 50 MWe parabolic trough and a Linear Fresnel plant at the same site is given. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Annual yield analysis of solar tower power plants with GREENIUS [texte imprimé] / Jürgen Dersch, Auteur ; Peter Schwarzbözl, Auteur ; Timo Richert, Auteur . - 2012 . - 09 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Mots-clés : Mirrors Power system simulation Solar absorber-convertors Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : An existing software tool for annual performance calculation of concentrating solar power and other renewable energy plants has been extended to enable the simulation of solar tower power plants. The methodology used is shown and a demonstrative example of a 50 MWe tower plant in southern Spain is given. The influence of design power and latitude on solar field layout is discussed. Furthermore, a comparison of the tower plant with a 50 MWe parabolic trough and a Linear Fresnel plant at the same site is given. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Titre : AIMFAST : an alignment tool based on fringe reflection methods applied to dish concentrators Type de document : texte imprimé Auteurs : Charles E. Andraka, Auteur ; Julius Yellowhair, Auteur ; Kirill Trapeznikov, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Solar absorber-convertors Solar energy concentrators Solar power Stirling engines Index. décimale : 621.47 Résumé : The proper alignment of facets on a dish engine concentrated solar power system is critical to the performance of the system. These systems are generally highly concentrating to produce high temperatures for maximum thermal efficiency so there is little tolerance for poor optical alignment. Improper alignment can lead to poor performance and shortened life through excessively high flux on the receiver surfaces, imbalanced power on multicylinder engines, and intercept losses at the aperture. Alignment approaches used in the past are time consuming field operations, typically taking 4–6 h per dish with 40–80 facets on the dish. Production systems of faceted dishes will need rapid, accurate alignment implemented in a fraction of an hour. In this paper, we present an extension to our Sandia Optical Fringe Analysis Slope Technique mirror characterization system that will automatically acquire data, implement an alignment strategy, and provide real-time mirror angle corrections to actuators or labor beneath the dish. The Alignment Implementation for Manufacturing using Fringe Analysis Slope Technique (AIMFAST) has been implemented and tested at the prototype level. In this paper we present the approach used in AIMFAST to rapidly characterize the dish system and provide near-real-time adjustment updates for each facet. The implemented approach can provide adjustment updates every 5 s, suitable for manual or automated adjustment of facets on a dish assembly line. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] AIMFAST : an alignment tool based on fringe reflection methods applied to dish concentrators [texte imprimé] / Charles E. Andraka, Auteur ; Julius Yellowhair, Auteur ; Kirill Trapeznikov, Auteur . - 2012 . - 06 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Mots-clés : Solar absorber-convertors Solar energy concentrators Solar power Stirling engines Index. décimale : 621.47 Résumé : The proper alignment of facets on a dish engine concentrated solar power system is critical to the performance of the system. These systems are generally highly concentrating to produce high temperatures for maximum thermal efficiency so there is little tolerance for poor optical alignment. Improper alignment can lead to poor performance and shortened life through excessively high flux on the receiver surfaces, imbalanced power on multicylinder engines, and intercept losses at the aperture. Alignment approaches used in the past are time consuming field operations, typically taking 4–6 h per dish with 40–80 facets on the dish. Production systems of faceted dishes will need rapid, accurate alignment implemented in a fraction of an hour. In this paper, we present an extension to our Sandia Optical Fringe Analysis Slope Technique mirror characterization system that will automatically acquire data, implement an alignment strategy, and provide real-time mirror angle corrections to actuators or labor beneath the dish. The Alignment Implementation for Manufacturing using Fringe Analysis Slope Technique (AIMFAST) has been implemented and tested at the prototype level. In this paper we present the approach used in AIMFAST to rapidly characterize the dish system and provide near-real-time adjustment updates for each facet. The implemented approach can provide adjustment updates every 5 s, suitable for manual or automated adjustment of facets on a dish assembly line. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Titre : Jülich solar power tower : experimental evaluation of the storage subsystem and performance calculation Type de document : texte imprimé Auteurs : Stefan Zunft, Auteur ; Matthias Hänel, Auteur ; Michael Krüger, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Heat losses Solar power stations Thermal energy storage Index. décimale : 621.47 Résumé : Storage technology based on solid media heated in direct contact—so-called regenerators—is well suited to promote the market introduction of solar central receiver plants with air receivers. However, starting from existing technologies, several design issues need to be addressed. A test campaign was performed at the Solar Power Tower Jülich, an experimental central receiver plant, to experimentally verify the functionality and to quantify the performance of the plant's storage subsystem. To this end, a gas burner used during commissioning of the plant, was reactivated and used to run a series of operation sequences. Computer simulations have been set up and applied to retrace the storage behavior to confirm the validity of the underlying models and to gain further insight into the relevant phenomena. The test results confirm the full functionality of the storage subsystem, the ability to perform cycling at high discharge heat rates and relatively low heat losses, supporting the view that the technology represents a promising basis for up-scaled implementations. Measurement data and simulation results are in good agreement, confirming the maturity of existing design tools. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Jülich solar power tower : experimental evaluation of the storage subsystem and performance calculation [texte imprimé] / Stefan Zunft, Auteur ; Matthias Hänel, Auteur ; Michael Krüger, Auteur . - 2012 . - 05 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Mots-clés : Heat losses Solar power stations Thermal energy storage Index. décimale : 621.47 Résumé : Storage technology based on solid media heated in direct contact—so-called regenerators—is well suited to promote the market introduction of solar central receiver plants with air receivers. However, starting from existing technologies, several design issues need to be addressed. A test campaign was performed at the Solar Power Tower Jülich, an experimental central receiver plant, to experimentally verify the functionality and to quantify the performance of the plant's storage subsystem. To this end, a gas burner used during commissioning of the plant, was reactivated and used to run a series of operation sequences. Computer simulations have been set up and applied to retrace the storage behavior to confirm the validity of the underlying models and to gain further insight into the relevant phenomena. The test results confirm the full functionality of the storage subsystem, the ability to perform cycling at high discharge heat rates and relatively low heat losses, supporting the view that the technology represents a promising basis for up-scaled implementations. Measurement data and simulation results are in good agreement, confirming the maturity of existing design tools. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Titre : Radiation boundary conditions for computational fluid dynamics models of high-temperature cavity receivers Type de document : texte imprimé Auteurs : Siri Sahib S. Khalsa, Auteur ; Clifford K. Ho, Auteur Année de publication : 2012 Article en page(s) : 06 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Boundary layers Computational fluid dynamics Confined flow Convection Flow simulation Ray tracing Solar absorber-convertors Solar radiation Testing Index. décimale : 621.47 Résumé : Rigorous computational fluid dynamics (CFD) codes can accurately simulate complex coupled processes within an arbitrary geometry. CFD can thus be a cost-effective and time-efficient method of guiding receiver design and testing for concentrating solar power technologies. However, it can be computationally prohibitive to include a large multifaceted dish concentrator or a field of hundreds or thousands of heliostats in the model domain. This paper presents a method to allow the CFD code to focus on a cavity receiver domain alone, by rigorously transforming radiance distributions calculated on the receiver aperture into radiance boundary conditions for the CFD simulations. This method allows the incoming radiation to interact with participating media such as falling solid particles in a high-temperature cavity receiver. The radiance boundary conditions of the CFD model can take into consideration complex beam features caused by sun shape, limb darkening, slope errors, heliostat facet shape, multiple heliostats, off-axis aberrations, atmospheric effects, blocking, shading, and multiple focal points. This paper also details implementation examples in ansys fluent for a heliostat field and a dish concentrator, which are validated by comparison to results from delsol and the ray-tracing code asap, respectively. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Radiation boundary conditions for computational fluid dynamics models of high-temperature cavity receivers [texte imprimé] / Siri Sahib S. Khalsa, Auteur ; Clifford K. Ho, Auteur . - 2012 . - 06 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 06 p.
Mots-clés : Boundary layers Computational fluid dynamics Confined flow Convection Flow simulation Ray tracing Solar absorber-convertors Solar radiation Testing Index. décimale : 621.47 Résumé : Rigorous computational fluid dynamics (CFD) codes can accurately simulate complex coupled processes within an arbitrary geometry. CFD can thus be a cost-effective and time-efficient method of guiding receiver design and testing for concentrating solar power technologies. However, it can be computationally prohibitive to include a large multifaceted dish concentrator or a field of hundreds or thousands of heliostats in the model domain. This paper presents a method to allow the CFD code to focus on a cavity receiver domain alone, by rigorously transforming radiance distributions calculated on the receiver aperture into radiance boundary conditions for the CFD simulations. This method allows the incoming radiation to interact with participating media such as falling solid particles in a high-temperature cavity receiver. The radiance boundary conditions of the CFD model can take into consideration complex beam features caused by sun shape, limb darkening, slope errors, heliostat facet shape, multiple heliostats, off-axis aberrations, atmospheric effects, blocking, shading, and multiple focal points. This paper also details implementation examples in ansys fluent for a heliostat field and a dish concentrator, which are validated by comparison to results from delsol and the ray-tracing code asap, respectively. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Titre : Methodology to assess potential glint and glare hazards from concentrating solar power plants : analytical models and experimental validation Type de document : texte imprimé Auteurs : Clifford K. Ho, Auteur ; Cheryl M. Ghanbari, Auteur ; Richard B. Diver, Auteur Année de publication : 2012 Article en page(s) : 09 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Eye protection Health hazards Optical elements Solar absorber-convertors Solar energy concentrators Solar power stations Sunlight Index. décimale : 621.47 Résumé : With a growing number of concentrating solar power systems being designed and developed, the potential impact of glint and glare from concentrating solar collectors and receivers is receiving increased attention as a potential hazard or as a distraction for motorists, pilots, and pedestrians. This paper provides analytical methods to evaluate the irradiance originating from specularly and diffusely reflecting sources as a function of distance and characteristics of the source. Sample problems are provided for both specular and diffuse sources, and validation of the models is performed via testing. In addition, a summary of safety metrics is compiled from the literature to evaluate the potential hazards of calculated irradiances from glint and glare for short-term exposures. Previous safety metrics have focused on prevention of permanent eye damage (e.g., retinal burn). New metrics used in this paper account for temporary after-image, which can occur at irradiance values several orders of magnitude lower than the irradiance values required for irreversible eye damage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Methodology to assess potential glint and glare hazards from concentrating solar power plants : analytical models and experimental validation [texte imprimé] / Clifford K. Ho, Auteur ; Cheryl M. Ghanbari, Auteur ; Richard B. Diver, Auteur . - 2012 . - 09 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 09 p.
Mots-clés : Eye protection Health hazards Optical elements Solar absorber-convertors Solar energy concentrators Solar power stations Sunlight Index. décimale : 621.47 Résumé : With a growing number of concentrating solar power systems being designed and developed, the potential impact of glint and glare from concentrating solar collectors and receivers is receiving increased attention as a potential hazard or as a distraction for motorists, pilots, and pedestrians. This paper provides analytical methods to evaluate the irradiance originating from specularly and diffusely reflecting sources as a function of distance and characteristics of the source. Sample problems are provided for both specular and diffuse sources, and validation of the models is performed via testing. In addition, a summary of safety metrics is compiled from the literature to evaluate the potential hazards of calculated irradiances from glint and glare for short-term exposures. Previous safety metrics have focused on prevention of permanent eye damage (e.g., retinal burn). New metrics used in this paper account for temporary after-image, which can occur at irradiance values several orders of magnitude lower than the irradiance values required for irreversible eye damage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : Validation of two optical measurement methods for the qualification of the shape accuracy of mirror panels for concentrating solar systems Type de document : texte imprimé Auteurs : Tobias März, Auteur ; Christoph Prahl, Auteur ; Steffen Ulmer, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Error analysis Hybrid power systems Mirrors Photogrammetry Solar energy concentrators Solar power stations Spatial variables measurement Thermal power stations Index. décimale : 621.47 Résumé : The solar field is the major cost component of a solar thermal power plant and the optical quality of the concentrators has a significant impact on the field efficiency and thus on the performance of the power plant. Measuring slope deviations in the parabolic shape of the mirror panels in the accuracy and resolution required for these applications is a challenge as it is not required with the same characteristics in other industries. Photogrammetry and deflectometry are the two optical measurement methods that are typically used to measure this shape accuracy of mirror panels used in CSP applications. They have been compared and validated by measuring a typical mirror panel under optimal conditions. Additionally, a flat water surface has been measured as an absolute reference object using deflectometry. The remaining deviations between the results of both methods and to the reference object are discussed and possible sources of errors during the measurement are identified. A detailed error analysis is conducted for both methods and compared to the experimental findings. The results show that both methods allow for surface slope measurement with the necessary accuracy for present CSP applications and that among the two, deflectometry exhibits advantages in speed, measurement accuracy, and spatial resolution. However, for obtaining correct results several sources of errors have to be addressed appropriately during measurement and postprocessing. DEWEY : 621.47 ISSN : 0199-6231 En ligne : asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO0001330000030310220 [...] [article] Validation of two optical measurement methods for the qualification of the shape accuracy of mirror panels for concentrating solar systems [texte imprimé] / Tobias März, Auteur ; Christoph Prahl, Auteur ; Steffen Ulmer, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Error analysis Hybrid power systems Mirrors Photogrammetry Solar energy concentrators Solar power stations Spatial variables measurement Thermal power stations Index. décimale : 621.47 Résumé : The solar field is the major cost component of a solar thermal power plant and the optical quality of the concentrators has a significant impact on the field efficiency and thus on the performance of the power plant. Measuring slope deviations in the parabolic shape of the mirror panels in the accuracy and resolution required for these applications is a challenge as it is not required with the same characteristics in other industries. Photogrammetry and deflectometry are the two optical measurement methods that are typically used to measure this shape accuracy of mirror panels used in CSP applications. They have been compared and validated by measuring a typical mirror panel under optimal conditions. Additionally, a flat water surface has been measured as an absolute reference object using deflectometry. The remaining deviations between the results of both methods and to the reference object are discussed and possible sources of errors during the measurement are identified. A detailed error analysis is conducted for both methods and compared to the experimental findings. The results show that both methods allow for surface slope measurement with the necessary accuracy for present CSP applications and that among the two, deflectometry exhibits advantages in speed, measurement accuracy, and spatial resolution. However, for obtaining correct results several sources of errors have to be addressed appropriately during measurement and postprocessing. DEWEY : 621.47 ISSN : 0199-6231 En ligne : asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO0001330000030310220 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Titre : Evaluation of annual performance of 2-tank and thermocline thermal storage systems for trough plants Type de document : texte imprimé Auteurs : Gregory J. Kolb, Auteur Année de publication : 2012 Article en page(s) : 05 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Energy storage Power plants Temperature distribution Index. décimale : 621.47 Résumé : A study was performed to compare the annual performance of 50 MWe Andasol-like trough plants that employ either a 2-tank or a thermocline-type molten-salt thermal storage system. trnsys software was used to create the plant models and to perform the annual simulations. The annual performance of each plant was found to be nearly identical in the base-case comparison. The reason that the thermocline exhibited nearly the same performance is primarily due to the ability of many trough power blocks to operate at a temperature that is significantly below the design point. However, if temperatures close to the design point are required, the performance of the 2-tank plant would be significantly better than the thermocline. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Evaluation of annual performance of 2-tank and thermocline thermal storage systems for trough plants [texte imprimé] / Gregory J. Kolb, Auteur . - 2012 . - 05 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 05 p.
Mots-clés : Energy storage Power plants Temperature distribution Index. décimale : 621.47 Résumé : A study was performed to compare the annual performance of 50 MWe Andasol-like trough plants that employ either a 2-tank or a thermocline-type molten-salt thermal storage system. trnsys software was used to create the plant models and to perform the annual simulations. The annual performance of each plant was found to be nearly identical in the base-case comparison. The reason that the thermocline exhibited nearly the same performance is primarily due to the ability of many trough power blocks to operate at a temperature that is significantly below the design point. However, if temperatures close to the design point are required, the performance of the 2-tank plant would be significantly better than the thermocline. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 13 p.
Titre : Uncertainties in modeled direct irradiance around the Sahara as affected by aerosols : are current datasets of bankable quality? Type de document : texte imprimé Auteurs : Christian A. Gueymard, Auteur Année de publication : 2012 Article en page(s) : 13 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Aerosols Photovoltaic power systems Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : The design, energy output, and cost effectiveness of solar projects using concentrators critically depend on the resource in direct normal irradiance (DNI). Many modeled DNI datasets now exist, and a recent preliminary study has shown some areas of serious disagreement in Europe. So far, no rigorous performance assessment has been undertaken for other parts of the world. The present contribution focuses on North Africa and bordering regions, which have great solar potential for power plants based on thermal or photovoltaic concentration systems. The mean monthly and annual performance of eight different modeled datasets providing DNI is analyzed here, with respect to measured radiation data at 14 sites, which are used as “ground-truth”. Relatively good results are generally obtained for sites in southern Europe. Serious problems, however, are found at various sites in North Africa or the Middle East. Most of these problems appear linked to inadequate aerosol optical depth data used by the models, and to the dust storms from the Sahara that regularly, and strongly, modify the aerosol regime. A method that can potentially correct these problems, or allow for model benchmarking based on a reference aerosol database, is proposed. The bankability of current datasets is questioned. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Uncertainties in modeled direct irradiance around the Sahara as affected by aerosols : are current datasets of bankable quality? [texte imprimé] / Christian A. Gueymard, Auteur . - 2012 . - 13 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 13 p.
Mots-clés : Aerosols Photovoltaic power systems Solar absorber-convertors Solar power stations Index. décimale : 621.47 Résumé : The design, energy output, and cost effectiveness of solar projects using concentrators critically depend on the resource in direct normal irradiance (DNI). Many modeled DNI datasets now exist, and a recent preliminary study has shown some areas of serious disagreement in Europe. So far, no rigorous performance assessment has been undertaken for other parts of the world. The present contribution focuses on North Africa and bordering regions, which have great solar potential for power plants based on thermal or photovoltaic concentration systems. The mean monthly and annual performance of eight different modeled datasets providing DNI is analyzed here, with respect to measured radiation data at 14 sites, which are used as “ground-truth”. Relatively good results are generally obtained for sites in southern Europe. Serious problems, however, are found at various sites in North Africa or the Middle East. Most of these problems appear linked to inadequate aerosol optical depth data used by the models, and to the dust storms from the Sahara that regularly, and strongly, modify the aerosol regime. A method that can potentially correct these problems, or allow for model benchmarking based on a reference aerosol database, is proposed. The bankability of current datasets is questioned. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : On the development of a low cost pyrheliometer Type de document : texte imprimé Auteurs : Michael Gnos, Auteur ; Brenton Greska, Auteur ; Anjaneyulu Krothapalli, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Atmospheric measuring apparatus Electric sensing devices Solar radiation Star trackers Temperature sensors Thermoelectric devices Index. décimale : 621.47 Résumé : A low cost pyrheliometer, based on a thermoelectric sensor, was developed at the Energy and Sustainability Center at the Florida State University. In addition, an inexpensive double-axis tracking device, capable of autonomous operation, enables the pyrheliometer to operate as a stand-alone system. Widely available off-the-shelf components were used and compromises in accuracy and time responsiveness were made in order to keep the cost low. The obtained data was compared with an Eppley Normal Incidence Pyrheliometer (NIP) using model ST-1 solar tracker. Steady state values of irradiance were measured with an accuracy better than ±2%. Transient measurements are time delayed by a thermal lag of about 2 min, which leads to a high error for instantaneous measured values. However, the integrated irradiance over the course of any given day yields irradiation values with accuracy better than ±2%, even on days when the sun and clouds quickly alternate. Based on a manufacturing cost analysis, the prototype pyrheliometer system is anticipated to cost an order of magnitude less than commercially available products if mass-produced. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] On the development of a low cost pyrheliometer [texte imprimé] / Michael Gnos, Auteur ; Brenton Greska, Auteur ; Anjaneyulu Krothapalli, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Atmospheric measuring apparatus Electric sensing devices Solar radiation Star trackers Temperature sensors Thermoelectric devices Index. décimale : 621.47 Résumé : A low cost pyrheliometer, based on a thermoelectric sensor, was developed at the Energy and Sustainability Center at the Florida State University. In addition, an inexpensive double-axis tracking device, capable of autonomous operation, enables the pyrheliometer to operate as a stand-alone system. Widely available off-the-shelf components were used and compromises in accuracy and time responsiveness were made in order to keep the cost low. The obtained data was compared with an Eppley Normal Incidence Pyrheliometer (NIP) using model ST-1 solar tracker. Steady state values of irradiance were measured with an accuracy better than ±2%. Transient measurements are time delayed by a thermal lag of about 2 min, which leads to a high error for instantaneous measured values. However, the integrated irradiance over the course of any given day yields irradiation values with accuracy better than ±2%, even on days when the sun and clouds quickly alternate. Based on a manufacturing cost analysis, the prototype pyrheliometer system is anticipated to cost an order of magnitude less than commercially available products if mass-produced. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Titre : Concentrated solar power harvesting using self-powered, wireless, thin-profile, lightweight solar tiles Type de document : texte imprimé Auteurs : Serhan M. Ardanuç, Auteur ; Amit Lal, Auteur ; Samuel C. Jones, Auteur Année de publication : 2012 Article en page(s) : 07 p. Note générale : Solar energy Langues : Anglais (eng) Mots-clés : Energy harvesting Maintenance engineering Mirrors Photovoltaic power systems Solar absorber-convertors Solar cells Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : This paper presents a modular and scalable approach to concentrated solar power (CSP) harvesting by using low-profile, light-weight, sun-tracking, millimeter-to-centimeter-scale mirror arrays that can be wirelessly controlled to reflect the incident solar energy to a central receiver. Conventional, utility-scale CSP plants use large-area heliostats, parabolic troughs, or dish collectors that are not only heavy and bulky, but also require significant labor for installation and maintenance infrastructure. Furthermore, form-factors of current heliostats are not compatible with low-profile roof-mountable systems, as seen by the dominance of the conventional Photovoltaic systems for roof-top installations. Solar TILE (STILE) technology to be presented in this work enables concentrated solar power harvesting on a given surface with form factor and weight per unit area comparable to those of ceramic tiles used on walls/floors or that of Photovoltaic modules. Self-powered operation by integrated solar cells, elimination of wiring for power transfer, wireless control, and weather-proof enclosure of moving parts help STILE technology promise lower installation and maintenance costs than PV approaches, while enabling novel beam-redirection applications over large surfaces. As the STILEs are made of mostly plastic, which costs at least an order of magnitude less than solar grade silicon, associated material costs could potentially be much cheaper than silicon PV cells. After a description of the STILE technology and a discussion of mirror scaling, we present a prototype tile with dimensions 33 × 33 × 6.4 cm3 and detail its wireless operation. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...] [article] Concentrated solar power harvesting using self-powered, wireless, thin-profile, lightweight solar tiles [texte imprimé] / Serhan M. Ardanuç, Auteur ; Amit Lal, Auteur ; Samuel C. Jones, Auteur . - 2012 . - 07 p.
Solar energy
Langues : Anglais (eng)
in Transactions of the ASME. Journal of solar energy engineering > Vol. 133 N° 3 (N° Spécial) (Août 2011) . - 07 p.
Mots-clés : Energy harvesting Maintenance engineering Mirrors Photovoltaic power systems Solar absorber-convertors Solar cells Solar energy concentrators Solar power stations Index. décimale : 621.47 Résumé : This paper presents a modular and scalable approach to concentrated solar power (CSP) harvesting by using low-profile, light-weight, sun-tracking, millimeter-to-centimeter-scale mirror arrays that can be wirelessly controlled to reflect the incident solar energy to a central receiver. Conventional, utility-scale CSP plants use large-area heliostats, parabolic troughs, or dish collectors that are not only heavy and bulky, but also require significant labor for installation and maintenance infrastructure. Furthermore, form-factors of current heliostats are not compatible with low-profile roof-mountable systems, as seen by the dominance of the conventional Photovoltaic systems for roof-top installations. Solar TILE (STILE) technology to be presented in this work enables concentrated solar power harvesting on a given surface with form factor and weight per unit area comparable to those of ceramic tiles used on walls/floors or that of Photovoltaic modules. Self-powered operation by integrated solar cells, elimination of wiring for power transfer, wireless control, and weather-proof enclosure of moving parts help STILE technology promise lower installation and maintenance costs than PV approaches, while enabling novel beam-redirection applications over large surfaces. As the STILEs are made of mostly plastic, which costs at least an order of magnitude less than solar grade silicon, associated material costs could potentially be much cheaper than silicon PV cells. After a description of the STILE technology and a discussion of mirror scaling, we present a prototype tile with dimensions 33 × 33 × 6.4 cm3 and detail its wireless operation. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO000133000003 [...]
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