Dépouillements

Economic potential of solar thermal power plants with direct steam generation compared with HTF plants / Jan Fabian Feldhoff in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041001/1-9] Titre : Economic potential of solar thermal power plants with direct steam generation compared with HTF plants Type de document : texte imprimé Auteurs : Jan Fabian Feldhoff, Auteur ; Daniel Benitez, Auteur ; Markus Eck, Auteur Année de publication : 2011 Article en page(s) : pp. [041001/1-9] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Power  generation  economics  Solar  power  stations  Steam  power  stations Index. décimale : 621.47 Résumé : The direct steam generation (DSG) in parabolic trough collectors is a promising option to improve the mature parabolic trough solar thermal power plant technology of the solar energy generating systems (SEGS) in California. According to previous studies [Langenkamp, 1998, “Revised LEC Projections and Discussion of Different DSG Benefits,” Technical Report No. DISS-SC-QA-02, Almeria, Spain; Price, et al., 2002, “Advances in Parabolic Trough Solar Power Technology,” ASME J. Sol. Energy Eng., 124(2), pp. 109–125; Zarza, E., 2002, “DISS Phase II Final Report,” Technical Report EU Contract No. JOR3-CT98-0277, Almeria, Spain], the cost reduction in the DSG process compared with the SEGS technology is expected to be 8–25%. All these studies were more or less preliminary since they lacked detailed information on the design of collector fields, absorber tubes required for steam temperatures higher than 400°C, and power blocks adapted to the specific needs of the direct steam generation. Power blocks and collector fields were designed for four different capacities (5 MWel, 10 MWel, 50 MWel, and 100 MWel) and different live steam parameters. The live steam temperature was varied between saturation temperature and 500°C and live steam pressures of 40 bars, 64 bars, and 100 bars were investigated. To assess the different cases, detailed yield analyses of the overall system were performed using hourly data for the direct normal irradiation and the ambient temperature for typical years. Based on these results, the levelized costs of electricity were determined for all cases and compared with a reference system using synthetic oil as heat transfer fluid. This paper focuses on two main project findings. First, the 50 MWel DSG system parameter comparisons are presented. Second, the detailed comparison between a DSG and a SEGS-like 100 MWel system is given. The main result of the investigation is that the benefit of the DSG process depends on the project site and can reach an 11% reduction in the levelized electricity cost. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Economic potential of solar thermal power plants with direct steam generation compared with HTF plants [texte imprimé] / Jan Fabian Feldhoff, Auteur ; Daniel Benitez, Auteur ; Markus Eck, Auteur . - 2011 . - pp. [041001/1-9]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041001/1-9] Mots-clés : Power  generation  economics  Solar  power  stations  Steam  power  stations Index. décimale : 621.47 Résumé : The direct steam generation (DSG) in parabolic trough collectors is a promising option to improve the mature parabolic trough solar thermal power plant technology of the solar energy generating systems (SEGS) in California. According to previous studies [Langenkamp, 1998, “Revised LEC Projections and Discussion of Different DSG Benefits,” Technical Report No. DISS-SC-QA-02, Almeria, Spain; Price, et al., 2002, “Advances in Parabolic Trough Solar Power Technology,” ASME J. Sol. Energy Eng., 124(2), pp. 109–125; Zarza, E., 2002, “DISS Phase II Final Report,” Technical Report EU Contract No. JOR3-CT98-0277, Almeria, Spain], the cost reduction in the DSG process compared with the SEGS technology is expected to be 8–25%. All these studies were more or less preliminary since they lacked detailed information on the design of collector fields, absorber tubes required for steam temperatures higher than 400°C, and power blocks adapted to the specific needs of the direct steam generation. Power blocks and collector fields were designed for four different capacities (5 MWel, 10 MWel, 50 MWel, and 100 MWel) and different live steam parameters. The live steam temperature was varied between saturation temperature and 500°C and live steam pressures of 40 bars, 64 bars, and 100 bars were investigated. To assess the different cases, detailed yield analyses of the overall system were performed using hourly data for the direct normal irradiation and the ambient temperature for typical years. Based on these results, the levelized costs of electricity were determined for all cases and compared with a reference system using synthetic oil as heat transfer fluid. This paper focuses on two main project findings. First, the 50 MWel DSG system parameter comparisons are presented. Second, the detailed comparison between a DSG and a SEGS-like 100 MWel system is given. The main result of the investigation is that the benefit of the DSG process depends on the project site and can reach an 11% reduction in the levelized electricity cost. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Geometric optimization of concentrating solar collectors using Monte Carlo simulation / A. J. Marston in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041002/1-9] Titre : Geometric optimization of concentrating solar collectors using Monte Carlo simulation Type de document : texte imprimé Auteurs : A. J. Marston, Auteur ; K. J. Daun, Auteur ; M. R. Collins, Auteur Année de publication : 2011 Article en page(s) : pp. [041002/1-9] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Monte  Carlo  methods  Regression  analysis  Solar  absorber-convertors  Stochastic  programming Index. décimale : 621.47 Résumé : This paper presents an optimization algorithm for designing linear concentrating solar collectors using stochastic programming. A Monte Carlo technique is used to quantify the performance of the collector design in terms of an objective function, which is then minimized using a modified Kiefer–Wolfowitz algorithm that uses sample size and step size controls. This process is more efficient than traditional “trial-and-error” methods and can be applied more generally than techniques based on geometric optics. The method is validated through application to the design of three different configurations of linear concentrating collector. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Geometric optimization of concentrating solar collectors using Monte Carlo simulation [texte imprimé] / A. J. Marston, Auteur ; K. J. Daun, Auteur ; M. R. Collins, Auteur . - 2011 . - pp. [041002/1-9]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041002/1-9] Mots-clés : Monte  Carlo  methods  Regression  analysis  Solar  absorber-convertors  Stochastic  programming Index. décimale : 621.47 Résumé : This paper presents an optimization algorithm for designing linear concentrating solar collectors using stochastic programming. A Monte Carlo technique is used to quantify the performance of the collector design in terms of an objective function, which is then minimized using a modified Kiefer–Wolfowitz algorithm that uses sample size and step size controls. This process is more efficient than traditional “trial-and-error” methods and can be applied more generally than techniques based on geometric optics. The method is validated through application to the design of three different configurations of linear concentrating collector. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Conceptual design of a 2× trough for use within salt and oil-based parabolic trough power plants / Gregory J. Kolb in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041003/1-6] Titre : Conceptual design of a 2× trough for use within salt and oil-based parabolic trough power plants Type de document : texte imprimé Auteurs : Gregory J. Kolb, Auteur ; Richard B. Diver, Auteur Année de publication : 2011 Article en page(s) : pp. [041003/1-6] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Parabolic  trough  Large  aperture  Molten  salt  Optics  Economics Index. décimale : 621.47 Résumé : Recent studies in the United States suggest that parabolic trough levelized energy costs (LECs) can be reduced 10–15% through integration of a large salt energy storage system coupled with the direct heating of molten salt in the solar field. While noteworthy, this relatively small predicted improvement may not justify the increased technical risks. Examples of potential issues include increased design complexity, higher maintenance costs, and salt freezing in the solar field. To make a compelling argument for development of this new system, we believe that additional technical advances beyond that previously reported will be required to achieve significant LEC reduction, greater than 25%. The new technical advances described include the development of a high-concentration trough that has double aperture and optical concentration of current technology. This trough is predicted to be more cost-effective than current technology because its cost ($/m2) and thermal losses (W/m2) are significantly lower. Recent trough optical performance improvements, such as more accurate facets and better alignment techniques, suggest a 2× trough is possible. Combining this new trough with a new low-melting point salt now under development suggests that a LEC cost reduction of ~25% is possible for a 50 MW, 2× salt plant relative to a conventional (1×) 50 MW oil plant. However, the 2× trough will also benefit plants that use synthetic oil in the field. A LEC comparison of 2× plants at sizes 200 MW shows only a 6% advantage of salt over oil. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Conceptual design of a 2× trough for use within salt and oil-based parabolic trough power plants [texte imprimé] / Gregory J. Kolb, Auteur ; Richard B. Diver, Auteur . - 2011 . - pp. [041003/1-6]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041003/1-6] Mots-clés : Parabolic  trough  Large  aperture  Molten  salt  Optics  Economics Index. décimale : 621.47 Résumé : Recent studies in the United States suggest that parabolic trough levelized energy costs (LECs) can be reduced 10–15% through integration of a large salt energy storage system coupled with the direct heating of molten salt in the solar field. While noteworthy, this relatively small predicted improvement may not justify the increased technical risks. Examples of potential issues include increased design complexity, higher maintenance costs, and salt freezing in the solar field. To make a compelling argument for development of this new system, we believe that additional technical advances beyond that previously reported will be required to achieve significant LEC reduction, greater than 25%. The new technical advances described include the development of a high-concentration trough that has double aperture and optical concentration of current technology. This trough is predicted to be more cost-effective than current technology because its cost ($/m2) and thermal losses (W/m2) are significantly lower. Recent trough optical performance improvements, such as more accurate facets and better alignment techniques, suggest a 2× trough is possible. Combining this new trough with a new low-melting point salt now under development suggests that a LEC cost reduction of ~25% is possible for a 50 MW, 2× salt plant relative to a conventional (1×) 50 MW oil plant. However, the 2× trough will also benefit plants that use synthetic oil in the field. A LEC comparison of 2× plants at sizes 200 MW shows only a 6% advantage of salt over oil. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Coal coke gasification in a windowed solar chemical reactor for beam-down optics / Tatsuya Kodama in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041004/1-6] Titre : Coal coke gasification in a windowed solar chemical reactor for beam-down optics Type de document : texte imprimé Auteurs : Tatsuya Kodama, Auteur ; Nobuyuki Gokon, Auteur ; Shu-ich Enomoto, Auteur Année de publication : 2011 Article en page(s) : pp. [041004/1-6] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : High-temperature  solar  heat  Solar  reactor  Fluidized  bed  Coal  Gasification  Solar  fuel Index. décimale : 621.47 Résumé : Solar thermochemical processes, such as solar gasification of coal, require the development of a high temperature solar reactor operating at temperatures above 1000°C. Direct solar energy absorption by reacting coal particles provides efficient heat transfer directly to the reaction site. In this work, a windowed reactor prototype designed for the beam-down optics was constructed at a laboratory scale and demonstrated for CO2 gasification of coal coke using concentrated visible light from a sun-simulator as the source of energy. Peak conversion of light energy to chemical fuel (CO) of 14% was obtained by irradiating a fluidized bed of 500–710 µm coal coke size fraction with a power input of about 1 kW and a CO2 flow-rate of 6.5 dm3 min−1 at normal conditions. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013 [...] [article] Coal coke gasification in a windowed solar chemical reactor for beam-down optics [texte imprimé] / Tatsuya Kodama, Auteur ; Nobuyuki Gokon, Auteur ; Shu-ich Enomoto, Auteur . - 2011 . - pp. [041004/1-6]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041004/1-6] Mots-clés : High-temperature  solar  heat  Solar  reactor  Fluidized  bed  Coal  Gasification  Solar  fuel Index. décimale : 621.47 Résumé : Solar thermochemical processes, such as solar gasification of coal, require the development of a high temperature solar reactor operating at temperatures above 1000°C. Direct solar energy absorption by reacting coal particles provides efficient heat transfer directly to the reaction site. In this work, a windowed reactor prototype designed for the beam-down optics was constructed at a laboratory scale and demonstrated for CO2 gasification of coal coke using concentrated visible light from a sun-simulator as the source of energy. Peak conversion of light energy to chemical fuel (CO) of 14% was obtained by irradiating a fluidized bed of 500–710 µm coal coke size fraction with a power input of about 1 kW and a CO2 flow-rate of 6.5 dm3 min−1 at normal conditions. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013 [...]

A Thermodynamic similarity framework for assessment of working fluids for solar Rankine power generation / Deborah A. Sunter in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041005/1-8] Titre : A Thermodynamic similarity framework for assessment of working fluids for solar Rankine power generation Type de document : texte imprimé Auteurs : Deborah A. Sunter, Auteur ; Van P. Carey, Auteur Année de publication : 2011 Article en page(s) : pp. [041005/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Solar  Rankine  Working  fluid  Thermodynamic  similitude Index. décimale : 621.47 Résumé : Numerous studies have compared the merits of different working fluids for use in Rankine power systems. Most often, however, these have considered a limited number of specific fluids for which the thermodynamic properties are known. In the investigation summarized here, the Redlich–Kwong fluid model was used to develop a thermodynamic similarity framework that can be used as a comparative model for evaluating the performance of Rankine cycle working fluids. This can be viewed as a reduced order model that, based on thermodynamic similarity, quantifies the characteristics of the working fluids in terms of a single dimensional coordinate space defined by the choice of critical temperature. The advantage of this framework is that it allows exploration of the performance advantages of working fluids for which full thermodynamic properties are not yet available. Predictions of the model for common fluids were examined and conclusions regarding optimal fluids for solar Rankine systems are discussed. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] A Thermodynamic similarity framework for assessment of working fluids for solar Rankine power generation [texte imprimé] / Deborah A. Sunter, Auteur ; Van P. Carey, Auteur . - 2011 . - pp. [041005/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041005/1-8] Mots-clés : Solar  Rankine  Working  fluid  Thermodynamic  similitude Index. décimale : 621.47 Résumé : Numerous studies have compared the merits of different working fluids for use in Rankine power systems. Most often, however, these have considered a limited number of specific fluids for which the thermodynamic properties are known. In the investigation summarized here, the Redlich–Kwong fluid model was used to develop a thermodynamic similarity framework that can be used as a comparative model for evaluating the performance of Rankine cycle working fluids. This can be viewed as a reduced order model that, based on thermodynamic similarity, quantifies the characteristics of the working fluids in terms of a single dimensional coordinate space defined by the choice of critical temperature. The advantage of this framework is that it allows exploration of the performance advantages of working fluids for which full thermodynamic properties are not yet available. Predictions of the model for common fluids were examined and conclusions regarding optimal fluids for solar Rankine systems are discussed. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit / R. Pokhrel in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041006/1-8] Titre : Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit Type de document : texte imprimé Auteurs : R. Pokhrel, Auteur ; J. E. Gonzalez, Auteur ; T. Hight, Auteur Année de publication : 2011 Article en page(s) : pp. [041006/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Composite  materials  Differential  scanning  calorimetry  Graphite  Latent  heat  Melting  Phase  change  materials  Solidification  Thermal  conductivity  Thermal  energy  storage Résumé : The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Analysis and design of a paraffin/graphite composite PCM integrated in a thermal storage unit [texte imprimé] / R. Pokhrel, Auteur ; J. E. Gonzalez, Auteur ; T. Hight, Auteur . - 2011 . - pp. [041006/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041006/1-8] Mots-clés : Composite  materials  Differential  scanning  calorimetry  Graphite  Latent  heat  Melting  Phase  change  materials  Solidification  Thermal  conductivity  Thermal  energy  storage Résumé : The addition of latent heat storage systems in solar thermal applications has several benefits including volume reduction in storage tanks and maintaining the temperature range of the thermal storage. A phase change material (PCM) provides high energy storage density at a constant temperature corresponding to its phase transition temperature. In this paper, a high temperature PCM (melting temperature of 80°C) made of a composite of paraffin and graphite was tested to determine its thermal properties. Tests were conducted with a differential scanning calorimeter and allowed the determination of the melting and solidification characteristics, latent heat, specific heat at melting and solidification, and thermal conductivity of the composite. The results of the study showed an increase in thermal conductivity by a factor of 4 when the mass fraction of the graphite in the composite was increased to 16.5%. The specific heat of the composite PCM (CPCM) decreased as the thermal conductivity increased, while the latent heat remained the same as the PCM component. In addition, the phase transition temperature was not influenced by the addition of expanded graphite. To explore the feasibility of the CPCM for practical applications, a numerical solution of the phase change transition of a small cylinder was derived. Finally, a numerical simulation and the experimental results for a known volume of CPCM indicated a reduction in solidification time by a factor of 6. The numerical analysis was further explored to indicate the optimum operating Biot number for maximum efficiency of the composite PCM thermal energy storage. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Structural design and analysis of the toroidal heliostat / Chuncheng Zang in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041007/1-6] Titre : Structural design and analysis of the toroidal heliostat Type de document : texte imprimé Auteurs : Chuncheng Zang, Auteur ; Zhifeng Wang, Auteur ; Wenfeng Liang, Auteur Année de publication : 2011 Article en page(s) : pp. [041007/1-6] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Heliostat  Solar  power  tower  Structural  design  Finite  element  methods  Spinning  elevation Index. décimale : 621.47 Résumé : Heliostat is an important component in the solar power tower station because its cost, optical performance, and mechanical performance have great influence on the overall property evaluation of the station. The T-shape heliostat tracking the sun in the azimuth-elevation mode has been commonly developed and successfully applied in many stations. In recent years, some researchers have developed spinning-elevation heliostats and have analyzed their optical performance. In this paper, the structure of a 16 m2 toroidal heliostat tracking the sun in the spinning-elevation mode is designed, and the mechanical performance of the structure under wind load is analyzed by means of the finite element method. The trends of force, moments, and vibration modes with the change in elevation have been presented, and the classic status is analyzed in detail when their maximum values occur. Furthermore, the advantages and disadvantages of a toroidal heliostat in reducing the cost are discussed compared with those of a traditional T-shape heliostat. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Structural design and analysis of the toroidal heliostat [texte imprimé] / Chuncheng Zang, Auteur ; Zhifeng Wang, Auteur ; Wenfeng Liang, Auteur . - 2011 . - pp. [041007/1-6]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041007/1-6] Mots-clés : Heliostat  Solar  power  tower  Structural  design  Finite  element  methods  Spinning  elevation Index. décimale : 621.47 Résumé : Heliostat is an important component in the solar power tower station because its cost, optical performance, and mechanical performance have great influence on the overall property evaluation of the station. The T-shape heliostat tracking the sun in the azimuth-elevation mode has been commonly developed and successfully applied in many stations. In recent years, some researchers have developed spinning-elevation heliostats and have analyzed their optical performance. In this paper, the structure of a 16 m2 toroidal heliostat tracking the sun in the spinning-elevation mode is designed, and the mechanical performance of the structure under wind load is analyzed by means of the finite element method. The trends of force, moments, and vibration modes with the change in elevation have been presented, and the classic status is analyzed in detail when their maximum values occur. Furthermore, the advantages and disadvantages of a toroidal heliostat in reducing the cost are discussed compared with those of a traditional T-shape heliostat. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

A Comparison of long-term wind speed forecasting models / Petros P. Kritharas in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041008/1-8] Titre : A Comparison of long-term wind speed forecasting models Type de document : texte imprimé Auteurs : Petros P. Kritharas, Auteur ; Simon J. Watson, Auteur Année de publication : 2011 Article en page(s) : pp. [041008/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Forecasting  theory  Maintenance  engineering  Purchasing  Scheduling  Time  series  Wind  power Index. décimale : 621.47 Résumé : This paper presents a time series analysis of historical observations of wind speed in order to project future wind speed trends. For this study, 52 years of data have been used from seven suitable stations across the UK. Four parsimonious models have been employed, and the data were split into two different segments: the training and the validation data sets. During the fitting process, the optimum parameters for each model were determined in order to minimize the mean square error in the predictions. The results suggest that the seasonal pattern in wind speeds is the most important factor but that there is some monthly autocorrelation in the data, which can improve forecasts. This is confirmed by testing the four models with the model having considered both autocorrelation and seasonality achieving the smallest errors. The approach proposed for forecasting wind speeds a month ahead may be deemed useful to suppliers for purchasing base load in advance and to system operators for power system maintenance scheduling up to a month ahead. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] A Comparison of long-term wind speed forecasting models [texte imprimé] / Petros P. Kritharas, Auteur ; Simon J. Watson, Auteur . - 2011 . - pp. [041008/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041008/1-8] Mots-clés : Forecasting  theory  Maintenance  engineering  Purchasing  Scheduling  Time  series  Wind  power Index. décimale : 621.47 Résumé : This paper presents a time series analysis of historical observations of wind speed in order to project future wind speed trends. For this study, 52 years of data have been used from seven suitable stations across the UK. Four parsimonious models have been employed, and the data were split into two different segments: the training and the validation data sets. During the fitting process, the optimum parameters for each model were determined in order to minimize the mean square error in the predictions. The results suggest that the seasonal pattern in wind speeds is the most important factor but that there is some monthly autocorrelation in the data, which can improve forecasts. This is confirmed by testing the four models with the model having considered both autocorrelation and seasonality achieving the smallest errors. The approach proposed for forecasting wind speeds a month ahead may be deemed useful to suppliers for purchasing base load in advance and to system operators for power system maintenance scheduling up to a month ahead. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Performance characteristics of a 1 kW scale kite-powered system / David J. Olinger in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041009/1-11] Titre : Performance characteristics of a 1 kW scale kite-powered system Type de document : texte imprimé Auteurs : David J. Olinger, Auteur ; Jitendra. S. Goela, Auteur Année de publication : 2011 Article en page(s) : pp. [041009/1-11] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Wind  energy  Alternative  energy  Kite-powered  system Résumé : A 1 kW scale kite-powered system that uses kites to convert wind energy into electrical energy has been studied to determine its performance characteristics and establish feasibility of steady-state operation. In this kite-powered system, a kite is connected to a tether that transmits the generated aerodynamic forces on the kite to a power conversion system on the ground. The ground-based power conversion system consists of a rocking arm coupled to a Sprag clutch, flywheel, and electrical generator. Governing equations describing the dynamical motion of the kite, tether, and power conversion mechanism were developed assuming an inflexible, straight-line tether. A steady-state analysis of the kite aerodynamics was incorporated into the dynamical equations of the kite-powered system. The governing equations were solved numerically using a Runge–Kutta scheme to assess how performance parameters of the system such as output power, cycle time, and tether tension varied with wind speed, kite area, and aerodynamic characteristics of the kite. The results showed that a 1 kW scale system is feasible using the proposed design concept with a kite area of 25 m2 and wind speeds of 6 m/s. Preliminary efforts to build and test a working 1 kW scale kite-powered demonstrator are also reported. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Performance characteristics of a 1 kW scale kite-powered system [texte imprimé] / David J. Olinger, Auteur ; Jitendra. S. Goela, Auteur . - 2011 . - pp. [041009/1-11]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041009/1-11] Mots-clés : Wind  energy  Alternative  energy  Kite-powered  system Résumé : A 1 kW scale kite-powered system that uses kites to convert wind energy into electrical energy has been studied to determine its performance characteristics and establish feasibility of steady-state operation. In this kite-powered system, a kite is connected to a tether that transmits the generated aerodynamic forces on the kite to a power conversion system on the ground. The ground-based power conversion system consists of a rocking arm coupled to a Sprag clutch, flywheel, and electrical generator. Governing equations describing the dynamical motion of the kite, tether, and power conversion mechanism were developed assuming an inflexible, straight-line tether. A steady-state analysis of the kite aerodynamics was incorporated into the dynamical equations of the kite-powered system. The governing equations were solved numerically using a Runge–Kutta scheme to assess how performance parameters of the system such as output power, cycle time, and tether tension varied with wind speed, kite area, and aerodynamic characteristics of the kite. The results showed that a 1 kW scale system is feasible using the proposed design concept with a kite area of 25 m2 and wind speeds of 6 m/s. Preliminary efforts to build and test a working 1 kW scale kite-powered demonstrator are also reported. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Assessment of solar power tower driven ultrasupercritical steam cycles applying tubular central receivers with varied heat transfer media / Csaba Singer in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041010/1-12] Titre : Assessment of solar power tower driven ultrasupercritical steam cycles applying tubular central receivers with varied heat transfer media Type de document : texte imprimé Auteurs : Csaba Singer, Auteur ; Reiner Buck, Auteur ; Robert Pitz-Paal, Auteur Année de publication : 2011 Article en page(s) : pp. [041010/1-12] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Cost  reduction  Solar  power  stations  steam  power  stations Index. décimale : 621.47 Résumé : For clean and efficient electric power generation, the combination of solar power towers (SPTs) with ultrasupercritical steam cycle power plants could be the next development step. The methodology of the European concentrated solar thermal roadmap study was used to predict the annual performance and the cost reduction potential of this option applying tubular receivers with various appropriate high temperature heat transfer media (HTM). For the assessment, an analytical model of the heat transfer in a parametric 360 deg cylindrical and tubular central receiver was developed to examine the receiver's efficiency characteristics. The receiver's efficiency characteristics, which are based on different irradiation levels relative to the receiver's design point, are, then, used to interpolate the receiver's thermal efficiency in an hourly based annual calculation of one typical year that is defined by hourly based real measurements of the direct normal irradiance and the ambient temperature. Applying appropriate cost assumptions from literature, the levelized electricity costs (LEC) were estimated for each considered SPT concept and compared with the reference case, which is a scale-up of the state of the art molten salt concept. The power level of all compared concepts and the reference case is 50 MWel. The sensitivity of the specific cost assumptions for the LEC was evaluated for each concept variation. No detailed evaluation was done for the thermal storage but comparable costs were assumed for all cases. The results indicate a significant cost reduction potential of up to 15% LEC reduction in the liquid metal HTM processes. Due to annual performance based parametric studies of the number of receiver panels and storage capacity, the results also indicate the optimal values of these parameters concerning minimal LEC. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Assessment of solar power tower driven ultrasupercritical steam cycles applying tubular central receivers with varied heat transfer media [texte imprimé] / Csaba Singer, Auteur ; Reiner Buck, Auteur ; Robert Pitz-Paal, Auteur . - 2011 . - pp. [041010/1-12]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041010/1-12] Mots-clés : Cost  reduction  Solar  power  stations  steam  power  stations Index. décimale : 621.47 Résumé : For clean and efficient electric power generation, the combination of solar power towers (SPTs) with ultrasupercritical steam cycle power plants could be the next development step. The methodology of the European concentrated solar thermal roadmap study was used to predict the annual performance and the cost reduction potential of this option applying tubular receivers with various appropriate high temperature heat transfer media (HTM). For the assessment, an analytical model of the heat transfer in a parametric 360 deg cylindrical and tubular central receiver was developed to examine the receiver's efficiency characteristics. The receiver's efficiency characteristics, which are based on different irradiation levels relative to the receiver's design point, are, then, used to interpolate the receiver's thermal efficiency in an hourly based annual calculation of one typical year that is defined by hourly based real measurements of the direct normal irradiance and the ambient temperature. Applying appropriate cost assumptions from literature, the levelized electricity costs (LEC) were estimated for each considered SPT concept and compared with the reference case, which is a scale-up of the state of the art molten salt concept. The power level of all compared concepts and the reference case is 50 MWel. The sensitivity of the specific cost assumptions for the LEC was evaluated for each concept variation. No detailed evaluation was done for the thermal storage but comparable costs were assumed for all cases. The results indicate a significant cost reduction potential of up to 15% LEC reduction in the liquid metal HTM processes. Due to annual performance based parametric studies of the number of receiver panels and storage capacity, the results also indicate the optimal values of these parameters concerning minimal LEC. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Renewable hydrogen from the Zn/ZnO solar thermochemical cycle / Julia F. Haltiwanger in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041011/1-8] Titre : Renewable hydrogen from the Zn/ZnO solar thermochemical cycle : a cost and policy analysis Type de document : texte imprimé Auteurs : Julia F. Haltiwanger, Auteur ; Jane H. Davidson, Auteur ; Elizabeth J. Wilson, Auteur Année de publication : 2011 Article en page(s) : pp. [041011/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Carbon  Chemical  energy  conversion  Hydrogen  production  II-VI  semiconductors  Renewable  energy  sources  Solar  energy  conversion  Zinc  compounds Index. décimale : 621.47 Résumé : Flexible energy carriers are a crucial element of our energy portfolio. In a future in which a significant fraction of our energy comes from renewable sources, renewably produced fuels will be vital. The zinc/zinc-oxide thermochemical redox cycle is one approach for producing hydrogen using solar energy. This paper explores the level of carbon taxation necessary to make the cycle competitive with hydrogen production via methane reforming. In addition, the time frame for economic viability is assessed through the use of experience curves under minimal input, midrange, and aggressive incentive policy scenarios. Prior work projects that hydrogen produced by the zinc/zinc-oxide cycle will cost between $5.02/kg and $14.75/kg, compared with $2.40–3.60/kg for steam methane reforming. Overcoming this cost difference would require a carbon tax of ($119–987)/tCO2, which is significantly higher than is likely to be implemented in most countries. For the technology to become cost competitive, incentive policies that lead to early implementation of solar hydrogen plants will be necessary to allow the experience effect to draw down the price. Under such policies, a learning curve analysis suggests that hydrogen produced via the Zn/ZnO cycle could become economically viable between 2032 and 2069, depending on how aggressively the policies encourage the emerging technology. Thus, the Zn/ZnO cycle has the potential to be economically viable by midcentury if incentive policies—such as direct financial support, purchase guarantees, low interest rate loans, and tax breaks—are used to support initial projects. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Renewable hydrogen from the Zn/ZnO solar thermochemical cycle : a cost and policy analysis [texte imprimé] / Julia F. Haltiwanger, Auteur ; Jane H. Davidson, Auteur ; Elizabeth J. Wilson, Auteur . - 2011 . - pp. [041011/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041011/1-8] Mots-clés : Carbon  Chemical  energy  conversion  Hydrogen  production  II-VI  semiconductors  Renewable  energy  sources  Solar  energy  conversion  Zinc  compounds Index. décimale : 621.47 Résumé : Flexible energy carriers are a crucial element of our energy portfolio. In a future in which a significant fraction of our energy comes from renewable sources, renewably produced fuels will be vital. The zinc/zinc-oxide thermochemical redox cycle is one approach for producing hydrogen using solar energy. This paper explores the level of carbon taxation necessary to make the cycle competitive with hydrogen production via methane reforming. In addition, the time frame for economic viability is assessed through the use of experience curves under minimal input, midrange, and aggressive incentive policy scenarios. Prior work projects that hydrogen produced by the zinc/zinc-oxide cycle will cost between $5.02/kg and $14.75/kg, compared with $2.40–3.60/kg for steam methane reforming. Overcoming this cost difference would require a carbon tax of ($119–987)/tCO2, which is significantly higher than is likely to be implemented in most countries. For the technology to become cost competitive, incentive policies that lead to early implementation of solar hydrogen plants will be necessary to allow the experience effect to draw down the price. Under such policies, a learning curve analysis suggests that hydrogen produced via the Zn/ZnO cycle could become economically viable between 2032 and 2069, depending on how aggressively the policies encourage the emerging technology. Thus, the Zn/ZnO cycle has the potential to be economically viable by midcentury if incentive policies—such as direct financial support, purchase guarantees, low interest rate loans, and tax breaks—are used to support initial projects. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Scaling effect of direct solar hot water systems on energy efficiency / U. C. Arunachala in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041012/1-10] Titre : Scaling effect of direct solar hot water systems on energy efficiency Type de document : texte imprimé Auteurs : U. C. Arunachala, Auteur ; M. Siddhartha Bhatt, Auteur ; L. K. Sreepathi, Auteur Année de publication : 2011 Article en page(s) : pp. [041012/1-10] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : HWB  equation  Scale  mapping  Scaling  Thermosiphon  systems  Forced  circulation  systems Index. décimale : 621.47 Résumé : Scale formation in risers and header of direct solar hot water systems is a problem in places where hard water is being used. In this paper, the effect of scaling on energy efficiency indices such as instantaneous efficiency, mass flow rate, and overall heat loss coefficient are quantified by Hottel–Whillier–Bliss equation in the case of thermosiphon and forced circulation systems. The effect of scaling on mass flow and heat transfer rate for both the systems are quantified with experimental validation. Experimentally found mass flow rate is 50% of the analytical mass flow rate for a clean riser and agrees 99% for the case of riser with 3.75 mm scale thickness. This is due to the extreme change in pressure gain in the narrow region. Scale mapping is done for the entire solar hot water system to study the nature of scale growth. The complete footer and nine risers for the length of 150 mm from footer are free from scaling in axial and radial direction. This is due to the low water temperature in the region. The major portion of header and risers for the length 180 mm from the header are completely blocked due to maximum temperature of water in that region. A scale prediction model is brought out based on the experimentally observed scaled water heaters in the field. It reveals that the major parameters to be considered for the correlation are water total hardness and calcium hardness. It is seen in the thermosiphon system that the mass flow rate decreased by scaling affects energy efficiency more than that caused by the heat transfer rate. The scaling effect is more predominant in thermosiphon systems than in forced circulation systems. The analytical study reveals a drop in instantaneous efficiency of 39.5% in thermosiphon system and 7.0% in the case of forced circulation system for the scale thickness of 3.75 mm. The difference between mass flow rate in scaled and unscaled condition is less in forced circulation but much higher in thermosiphon system. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Scaling effect of direct solar hot water systems on energy efficiency [texte imprimé] / U. C. Arunachala, Auteur ; M. Siddhartha Bhatt, Auteur ; L. K. Sreepathi, Auteur . - 2011 . - pp. [041012/1-10]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041012/1-10] Mots-clés : HWB  equation  Scale  mapping  Scaling  Thermosiphon  systems  Forced  circulation  systems Index. décimale : 621.47 Résumé : Scale formation in risers and header of direct solar hot water systems is a problem in places where hard water is being used. In this paper, the effect of scaling on energy efficiency indices such as instantaneous efficiency, mass flow rate, and overall heat loss coefficient are quantified by Hottel–Whillier–Bliss equation in the case of thermosiphon and forced circulation systems. The effect of scaling on mass flow and heat transfer rate for both the systems are quantified with experimental validation. Experimentally found mass flow rate is 50% of the analytical mass flow rate for a clean riser and agrees 99% for the case of riser with 3.75 mm scale thickness. This is due to the extreme change in pressure gain in the narrow region. Scale mapping is done for the entire solar hot water system to study the nature of scale growth. The complete footer and nine risers for the length of 150 mm from footer are free from scaling in axial and radial direction. This is due to the low water temperature in the region. The major portion of header and risers for the length 180 mm from the header are completely blocked due to maximum temperature of water in that region. A scale prediction model is brought out based on the experimentally observed scaled water heaters in the field. It reveals that the major parameters to be considered for the correlation are water total hardness and calcium hardness. It is seen in the thermosiphon system that the mass flow rate decreased by scaling affects energy efficiency more than that caused by the heat transfer rate. The scaling effect is more predominant in thermosiphon systems than in forced circulation systems. The analytical study reveals a drop in instantaneous efficiency of 39.5% in thermosiphon system and 7.0% in the case of forced circulation system for the scale thickness of 3.75 mm. The difference between mass flow rate in scaled and unscaled condition is less in forced circulation but much higher in thermosiphon system. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Economic analysis and life cycle assessment of concrete thermal energy storage for parabolic trough power plants / D. Laing in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041013/1-6] Titre : Economic analysis and life cycle assessment of concrete thermal energy storage for parabolic trough power plants Type de document : texte imprimé Auteurs : D. Laing, Auteur ; W. D. Steinmann, Auteur ; P. Viebahn, Auteur Année de publication : 2011 Article en page(s) : pp. [041013/1-6] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Thermal  energy  storage  Solid  media  Concrete  Modular  operation  concept  Life  cycle  assessment  Parabolic  trough  power  plant Index. décimale : 621.47 Résumé : For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. One important aspect in storage development is the storage integration into the power plant. A modular operation concept for thermal storage systems was previously suggested by DLR, showing an increase in storage capacity of more than 100%. However, in these investigations, the additional costs needed to implement this storage concept into the power plant, such as for extra piping, valves, pumps, and control, had not been considered. These aspects are discussed in this paper, showing a decrease in levelized energy costs with a modular storage integration of 2–3%. In a life cycle assessment a comparison of an AndaSol-I type solar thermal power plant with the original two-tank molten salt storage and with a “hypothetical” concrete storage shows an advantage of the concrete storage technology concerning environmental impacts. The environmental impacts of the hypothetical concrete based AndaSol-I decreased by 7%, considering 1 kW h of solar electricity delivered to the grid. Regarding only the production of the power plant, the emissions decreased by 9.5%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Economic analysis and life cycle assessment of concrete thermal energy storage for parabolic trough power plants [texte imprimé] / D. Laing, Auteur ; W. D. Steinmann, Auteur ; P. Viebahn, Auteur . - 2011 . - pp. [041013/1-6]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041013/1-6] Mots-clés : Thermal  energy  storage  Solid  media  Concrete  Modular  operation  concept  Life  cycle  assessment  Parabolic  trough  power  plant Index. décimale : 621.47 Résumé : For parabolic trough power plants using synthetic oil as the heat transfer medium, the application of solid media sensible heat storage is an attractive option in terms of investment and maintenance costs. One important aspect in storage development is the storage integration into the power plant. A modular operation concept for thermal storage systems was previously suggested by DLR, showing an increase in storage capacity of more than 100%. However, in these investigations, the additional costs needed to implement this storage concept into the power plant, such as for extra piping, valves, pumps, and control, had not been considered. These aspects are discussed in this paper, showing a decrease in levelized energy costs with a modular storage integration of 2–3%. In a life cycle assessment a comparison of an AndaSol-I type solar thermal power plant with the original two-tank molten salt storage and with a “hypothetical” concrete storage shows an advantage of the concrete storage technology concerning environmental impacts. The environmental impacts of the hypothetical concrete based AndaSol-I decreased by 7%, considering 1 kW h of solar electricity delivered to the grid. Regarding only the production of the power plant, the emissions decreased by 9.5%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code / H. Aa. Madsen in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041014/1-14] Titre : Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code Type de document : texte imprimé Auteurs : H. Aa. Madsen, Auteur ; G. C. Larsen, Auteur ; T. J. Larsen, Auteur Année de publication : 2011 Article en page(s) : pp. [041014/1-14] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Actuators  Calibration  Discs  (structures)  Elasticity  Turbulence  Vortices  Wakes  Wind  power  plants  Wind  turbines Index. décimale : 621.47 Résumé : As the major part of new wind turbines are installed in clusters or wind farms, there is a strong need for reliable and accurate tools for predicting the increased loadings due to wake operation and the associated reduced power production. The dynamic wake meandering (DWM) model has been developed on this background, and the basic physical mechanisms in the wake—i.e., the velocity deficit, the meandering of the deficit, and the added turbulence—are modeled as simply as possible in order to make fast computations. In the present paper, the DWM model is presented in a version suitable for full integration in an aeroelastic model. Calibration and validation of the different parts of the model is carried out by comparisons with actuator disk and actuator line (ACL) computations as well as with inflow measurements on a full-scale 2 MW turbine. It is shown that the load generating part of the increased turbulence in the wake is due almost exclusively to meandering of the velocity deficit, which causes “apparent” turbulence when measuring the flow in a fixed point in the wake. Added turbulence, originating mainly from breakdown of tip vortices and from the shear of the velocity deficit, has only a minor contribution to the total turbulence and with a small length scale in the range of 10–25% of the ambient turbulence length scale. Comparisons of the calibrated DWM model with ACL results for different downstream positions and ambient turbulence levels show good correlation for both wake deficits and turbulence levels. Finally, added turbulence characteristics are compared with correlation results from literature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Calibration and validation of the dynamic wake meandering model for implementation in an aeroelastic code [texte imprimé] / H. Aa. Madsen, Auteur ; G. C. Larsen, Auteur ; T. J. Larsen, Auteur . - 2011 . - pp. [041014/1-14]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041014/1-14] Mots-clés : Actuators  Calibration  Discs  (structures)  Elasticity  Turbulence  Vortices  Wakes  Wind  power  plants  Wind  turbines Index. décimale : 621.47 Résumé : As the major part of new wind turbines are installed in clusters or wind farms, there is a strong need for reliable and accurate tools for predicting the increased loadings due to wake operation and the associated reduced power production. The dynamic wake meandering (DWM) model has been developed on this background, and the basic physical mechanisms in the wake—i.e., the velocity deficit, the meandering of the deficit, and the added turbulence—are modeled as simply as possible in order to make fast computations. In the present paper, the DWM model is presented in a version suitable for full integration in an aeroelastic model. Calibration and validation of the different parts of the model is carried out by comparisons with actuator disk and actuator line (ACL) computations as well as with inflow measurements on a full-scale 2 MW turbine. It is shown that the load generating part of the increased turbulence in the wake is due almost exclusively to meandering of the velocity deficit, which causes “apparent” turbulence when measuring the flow in a fixed point in the wake. Added turbulence, originating mainly from breakdown of tip vortices and from the shear of the velocity deficit, has only a minor contribution to the total turbulence and with a small length scale in the range of 10–25% of the ambient turbulence length scale. Comparisons of the calibrated DWM model with ACL results for different downstream positions and ambient turbulence levels show good correlation for both wake deficits and turbulence levels. Finally, added turbulence characteristics are compared with correlation results from literature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Experimental simulation of solar flash desalination / Mohammad Abutayeh in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041015/1-7] Titre : Experimental simulation of solar flash desalination Type de document : texte imprimé Auteurs : Mohammad Abutayeh, Auteur ; D. Yogi Goswami, Auteur Année de publication : 2011 Article en page(s) : pp. [041015/1-7] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Solar  flash  desalination  Condensation  solar  heating  sustainable  development  two-phase  flow  vaporisation Index. décimale : 621.47 Résumé : Experimental simulations of a sustainable desalination process have been carried out using a pilot unit. Experiments were conducted at analogous conditions to simplify design evaluation but with different values of the controlling variables to enhance analysis and modeling. The proposed desalination process, which employs solar heating and passive vacuum generation, has been theoretically simulated in earlier work. It entails flowing seawater through a condenser to preheat it and then through a heater before flashing it in a vacuumed evaporator connected to the condenser where the flashed hot vapor is condensed by the incoming cold seawater forming fresh water. All experiments were run for the same period of time starting at the same initial vacuum. Experiments were carried out at different seawater flow rates and different flash temperatures. In addition, each experiment was duplicated three times to validate its outcome. Flashing seawater at higher temperatures increases vaporization and fresh water production rate. In addition, the accumulating noncondensable gases that are slowly eroding the vacuum will decrease the overall vaporization with time, which reduces the production rate of fresh water. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Experimental simulation of solar flash desalination [texte imprimé] / Mohammad Abutayeh, Auteur ; D. Yogi Goswami, Auteur . - 2011 . - pp. [041015/1-7]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041015/1-7] Mots-clés : Solar  flash  desalination  Condensation  solar  heating  sustainable  development  two-phase  flow  vaporisation Index. décimale : 621.47 Résumé : Experimental simulations of a sustainable desalination process have been carried out using a pilot unit. Experiments were conducted at analogous conditions to simplify design evaluation but with different values of the controlling variables to enhance analysis and modeling. The proposed desalination process, which employs solar heating and passive vacuum generation, has been theoretically simulated in earlier work. It entails flowing seawater through a condenser to preheat it and then through a heater before flashing it in a vacuumed evaporator connected to the condenser where the flashed hot vapor is condensed by the incoming cold seawater forming fresh water. All experiments were run for the same period of time starting at the same initial vacuum. Experiments were carried out at different seawater flow rates and different flash temperatures. In addition, each experiment was duplicated three times to validate its outcome. Flashing seawater at higher temperatures increases vaporization and fresh water production rate. In addition, the accumulating noncondensable gases that are slowly eroding the vacuum will decrease the overall vaporization with time, which reduces the production rate of fresh water. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Spectral reflectance patterns of photovoltaic modules and their thermal effects / J. P. Silva in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 4 (Novembre 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041016/1-13] Titre : Spectral reflectance patterns of photovoltaic modules and their thermal effects Type de document : texte imprimé Auteurs : J. P. Silva, Auteur ; G. Nofuentes, Auteur ; J. V. Munoz, Auteur Année de publication : 2011 Article en page(s) : pp. [041016/1-13] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : PV  module  temperature  Thermal  modeling  Spectral  reflectance  Thermal  performance Index. décimale : 621.47 Résumé : Determination of the working temperature of photovoltaic (PV) modules is an essential task in research and engineering projects. It acquires more relevance in the current environment, characterized by increasing figures of installed PV power, module efficiency, solar applications, and operational configurations. However, most of the current procedures for temperature determination of PV modules are simply based on empirical correlations, carried out at conditions defined by some specific standards, with the corresponding lack of accuracy when modules work under real conditions. Thus, the present work looks into a formal procedure for temperature determination by conducting a power balance between the dynamic incoming and outgoing power fluxes. Some additional parameters are included when compared with classic expressions. In particular, the spectral reflectance of the tandem glass-semiconductor is measured to determine the reflected fraction of solar irradiance. The relationship between reflectance and equilibrium temperature is determined for a representative group of PV modules, and the influence that the working point exerts on the module temperature has also been taken into account. Finally, the influence of spectral distribution on module temperature has been quantified by simulations carried out by using a spectral model. In this way, determination of absolute temperature is achieved within a ±2°C range, regardless of module characteristics and climatic or operational conditions. In addition, temperature differences between PV modules that work under the same external conditions can be predicted within ±0.5°C. To summarize, a thermal model suitable for different PV modules and working configurations is presented. Some new parameters are introduced in the calculus process, and the influence of the most relevant ones has been quantified. In this way, the present work is aimed at making a contribution to the study of PV module temperature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Spectral reflectance patterns of photovoltaic modules and their thermal effects [texte imprimé] / J. P. Silva, Auteur ; G. Nofuentes, Auteur ; J. V. Munoz, Auteur . - 2011 . - pp. [041016/1-13]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 4 (Novembre 2010) . - pp. [041016/1-13] Mots-clés : PV  module  temperature  Thermal  modeling  Spectral  reflectance  Thermal  performance Index. décimale : 621.47 Résumé : Determination of the working temperature of photovoltaic (PV) modules is an essential task in research and engineering projects. It acquires more relevance in the current environment, characterized by increasing figures of installed PV power, module efficiency, solar applications, and operational configurations. However, most of the current procedures for temperature determination of PV modules are simply based on empirical correlations, carried out at conditions defined by some specific standards, with the corresponding lack of accuracy when modules work under real conditions. Thus, the present work looks into a formal procedure for temperature determination by conducting a power balance between the dynamic incoming and outgoing power fluxes. Some additional parameters are included when compared with classic expressions. In particular, the spectral reflectance of the tandem glass-semiconductor is measured to determine the reflected fraction of solar irradiance. The relationship between reflectance and equilibrium temperature is determined for a representative group of PV modules, and the influence that the working point exerts on the module temperature has also been taken into account. Finally, the influence of spectral distribution on module temperature has been quantified by simulations carried out by using a spectral model. In this way, determination of absolute temperature is achieved within a ±2°C range, regardless of module characteristics and climatic or operational conditions. In addition, temperature differences between PV modules that work under the same external conditions can be predicted within ±0.5°C. To summarize, a thermal model suitable for different PV modules and working configurations is presented. Some new parameters are introduced in the calculus process, and the influence of the most relevant ones has been quantified. In this way, the present work is aimed at making a contribution to the study of PV module temperature. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

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