Documents disponibles écrits par cet auteur

Development and evaluation of a prototype solid particle receiver / Nathan P. Siegel in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 2 (Mai 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 2 (Mai 2010) . - pp. [021008/1-8] Titre : Development and evaluation of a prototype solid particle receiver : on-sun testing and model validation Type de document : texte imprimé Auteurs : Nathan P. Siegel, Auteur ; Clifford K. Ho, Auteur ; Siri S. Khalsa, Auteur Année de publication : 2011 Article en page(s) : pp. [021008/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Computational  fluid  dynamics  Solar  absorber-convertors Index. décimale : 621.47 Résumé : A prototype direct absorption central receiver, called the solid particle receiver (SPR), was built and evaluated on-sun at power levels up to 2.5 MWth at Sandia National Laboratories in Albuquerque, NM. The SPR consists of a 6 m tall cavity through which spherical sintered bauxite particles are dropped and directly heated with concentrated solar energy. In principle, the particles can be efficiently heated to a temperature in excess of 900°C, well beyond the stability limit of existing nitrate salt formulations. The heated particles may then be stored in a way analogous to nitrate salt systems, enabling a dispatchable thermal input to power or fuel production cycles. The focus of this current effort was to provide an experimental basis for the validation of computational models that have been created to support improved designs and further development of the solid particle receiver. In this paper, we present information on the design and construction of the solid particle receiver and discuss the development of a computational fluid dynamics model of the prototype. We also present experimental data and model comparisons for on-sun testing of the receiver over a range of input power levels from 1.58–2.51 MWth. Model validation is performed using a number of metrics including particle velocity, exit temperature, and receiver efficiency. In most cases, the difference between the model predictions and data is less than 10%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Development and evaluation of a prototype solid particle receiver : on-sun testing and model validation [texte imprimé] / Nathan P. Siegel, Auteur ; Clifford K. Ho, Auteur ; Siri S. Khalsa, Auteur . - 2011 . - pp. [021008/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 2 (Mai 2010) . - pp. [021008/1-8] Mots-clés : Computational  fluid  dynamics  Solar  absorber-convertors Index. décimale : 621.47 Résumé : A prototype direct absorption central receiver, called the solid particle receiver (SPR), was built and evaluated on-sun at power levels up to 2.5 MWth at Sandia National Laboratories in Albuquerque, NM. The SPR consists of a 6 m tall cavity through which spherical sintered bauxite particles are dropped and directly heated with concentrated solar energy. In principle, the particles can be efficiently heated to a temperature in excess of 900°C, well beyond the stability limit of existing nitrate salt formulations. The heated particles may then be stored in a way analogous to nitrate salt systems, enabling a dispatchable thermal input to power or fuel production cycles. The focus of this current effort was to provide an experimental basis for the validation of computational models that have been created to support improved designs and further development of the solid particle receiver. In this paper, we present information on the design and construction of the solid particle receiver and discuss the development of a computational fluid dynamics model of the prototype. We also present experimental data and model comparisons for on-sun testing of the receiver over a range of input power levels from 1.58–2.51 MWth. Model validation is performed using a number of metrics including particle velocity, exit temperature, and receiver efficiency. In most cases, the difference between the model predictions and data is less than 10%. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Incorporating uncertainty into probabilistic performance models of concentrating solar power plants / Clifford K. Ho in Transactions of the ASME. Journal of solar energy engineering, Vol. 132 N° 3 (Août 2010) 

Public ISBD [article]  in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031012/1-8] Titre : Incorporating uncertainty into probabilistic performance models of concentrating solar power plants Type de document : texte imprimé Auteurs : Clifford K. Ho, Auteur ; Gregory J. Kolb, Auteur Année de publication : 2011 Article en page(s) : pp. [031012/1-8] Note générale : Energie Solaire Langues : Anglais (eng) Mots-clés : Probability  Solar  power  stations Index. décimale : 621.47 Résumé : A method for applying probabilistic models to concentrating solar-thermal power plants is described in this paper. The benefits of using probabilistic models include quantification of uncertainties inherent in the system and characterization of their impact on system performance and economics. Sensitivity studies using stepwise regression analysis can identify and rank the most important parameters and processes as a means to prioritize future research and activities. The probabilistic method begins with the identification of uncertain variables and the assignment of appropriate distributions for those variables. Those parameters are then sampled using a stratified method (Latin hypercube sampling) to ensure complete and representative sampling from each distribution. Models of performance, reliability, and cost are then simulated multiple times using the sampled set of parameters. The results yield a cumulative distribution function that can be used to quantify the probability of exceeding (or being less than) a particular value. Two examples, a simple cost model and a more detailed performance model of a hypothetical 100-MWe power tower, are provided to illustrate the methods. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...] [article] Incorporating uncertainty into probabilistic performance models of concentrating solar power plants [texte imprimé] / Clifford K. Ho, Auteur ; Gregory J. Kolb, Auteur . - 2011 . - pp. [031012/1-8]. Energie Solaire Langues : Anglais (eng) in Transactions of the ASME. Journal of solar energy engineering > Vol. 132 N° 3 (Août 2010) . - pp. [031012/1-8] Mots-clés : Probability  Solar  power  stations Index. décimale : 621.47 Résumé : A method for applying probabilistic models to concentrating solar-thermal power plants is described in this paper. The benefits of using probabilistic models include quantification of uncertainties inherent in the system and characterization of their impact on system performance and economics. Sensitivity studies using stepwise regression analysis can identify and rank the most important parameters and processes as a means to prioritize future research and activities. The probabilistic method begins with the identification of uncertain variables and the assignment of appropriate distributions for those variables. Those parameters are then sampled using a stratified method (Latin hypercube sampling) to ensure complete and representative sampling from each distribution. Models of performance, reliability, and cost are then simulated multiple times using the sampled set of parameters. The results yield a cumulative distribution function that can be used to quantify the probability of exceeding (or being less than) a particular value. Two examples, a simple cost model and a more detailed performance model of a hypothetical 100-MWe power tower, are provided to illustrate the methods. DEWEY : 621.47 ISSN : 0199-6231 En ligne : http://asmedl.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JSEEDO00013200 [...]

Methodology to assess potential glint and glare hazards from concentrating solar power plants / Clifford K. Ho in Transactions of the ASME. Journal of solar energy engineering, Vol. 133 N° 3 (N° Spécial) (Août 2011) 

Public ISBD [article]  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 [...]

Radiation boundary conditions for computational fluid dynamics models of high-temperature cavity receivers / Siri Sahib S. Khalsa in Transactions of the ASME. Journal of solar energy engineering, Vol. 133 N° 3 (N° Spécial) (Août 2011) 

Public ISBD [article]  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 [...]