The Experts below are selected from a list of 35028 Experts worldwide ranked by ideXlab platform
Hiroshi Tanaka - One of the best experts on this subject based on the ideXlab platform.
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tilted wick solar still with flat plate bottom reflector
Desalination, 2011Co-Authors: Hiroshi TanakaAbstract:This paper presents a theoretical analysis of a tilted wick solar still with a flat plate bottom reflector extending from the lower edge of the still on four days (the spring and autumn equinox and summer and winter solstices) at 30°N latitude when the still's inclination is fixed at 30° and the reflector's length is the same as the still's length. We propose a geometrical model to calculate the solar radiation reflected by the bottom reflector and then absorbed on the evaporating wick. We also performed a numerical analysis of heat and mass transfer in the still. We found that the bottom reflector can reflect the sunrays to the evaporating wick and increase distillate productivity of the tilted wick still when the reflector's inclination is larger than about 15° on the spring and autumn equinox and winter solstice, and 25° on the summer solstice, and the average distillate value for four days is greatest when the reflector's inclination is about 35° and would be about 13% greater than that of a conventional tilted wick still.
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experimental study of a basin type solar still with internal and external Reflectors in winter
Desalination, 2009Co-Authors: Hiroshi TanakaAbstract:A basin type solar still with internal and external Reflectors was constructed and then examined in outdoor experiments in winter in Kurume, Japan. The external reflector was inclined slightly forward to make the reflected sunrays hit the basin liner of the still effectively. The daily productivity of a basin type still can be increased about 70% to 100% with a very simple modification using internal and external Reflectors. The experimental results and the theoretical predictions are in fairly good agreement, especially on clear days.
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increase in distillate productivity by inclining the flat plate external reflector of a tilted wick solar still in winter
Solar Energy, 2009Co-Authors: Hiroshi Tanaka, Yasuhito NakatakeAbstract:Abstract This paper presents a theoretical analysis of a tilted-wick solar still with an inclined flat plate external reflector on a winter solstice day at 30°N latitude. The daily amount of distillate of a still with an inclined reflector would be about 15% or 27% greater than that with a vertical reflector when the reflector’s length is a half of or the same as the still’s length.
K Terwilliger - One of the best experts on this subject based on the ideXlab platform.
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optical durability of candidate solar Reflectors for concentrating solar power
2007Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4 mrad half-cone angle for at least 10 years outdoors with a cost of less than $$13.8/m{sup 2} (the 1992 $$10.8/m{sup 2} goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, front-surface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10 year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10 year or more aggressive 20 year lifetime goal.
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optical durability of candidate solar Reflectors
Journal of Solar Energy Engineering-transactions of The Asme, 2005Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4 mrad half-cone angle for at least 10 years outdoors with a cost of less than $13.8/m 2 (the 1992 $10.8/m 2 goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, front-surface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10 year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10 year or more aggressive 20 year lifetime goal.
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optical durability of candidate solar Reflectors
Solar Energy, 2004Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4-mrad half-cone angle for at least 10 years outdoors with a cost of less than $13.8/m2 (the 1992 $10.8/m2 goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, frontsurface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10-year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10-year or more aggressive 20-year lifetime goal.Copyright © 2004 by ASME
Robert Magnusson - One of the best experts on this subject based on the ideXlab platform.
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broadband guided mode resonant Reflectors with quasi equilateral triangle grating profiles
Optics Express, 2017Co-Authors: Shanwen Zhang, Robert MagnussonAbstract:We present the design of broadband guided-mode resonant Reflectors consisting of a grating layer with quasi-equilateral grating profiles and a homogeneous layer made of silicon on glass. Using the coordinate-transformation-based differential method of Chandezon (the C method) to determine the optimized base angles of the grating and thickness of the homogeneous layer, we arrive at example reflector designs for TM polarization. We quantify the effects of deviation of the parameters, simulate the inner magnetic field distribution at resonance wavelengths, and compute the tolerance in the incident angle of the optimized broadband reflector. For broadband structures with different thicknesses of the homogeneous layer, the base angles of the triangles are all close to 60°. The optimized reflector has reflectance of R0 > 99% across a 567 nm bandwidth in the 1432-1999 nm wavelength range with fractional bandwidth of Δλ/λcenter ≈33.3%. Base angles play a critical role in determining the reflection bandwidth and the quasi-equilateral triangle profile is found to be the optimal configuration. This model can be used to design broadband guided-mode resonant Reflectors operating in different spectral bands and guide the fabrication of these devices with diamond-tip based grating ruling engines.
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wideband Reflectors with zero contrast gratings
Optics Letters, 2014Co-Authors: Robert MagnussonAbstract:We present wideband resonant Reflectors designed with gratings in which the grating ridges are matched to an identical material, thereby eliminating local reflections and phase changes. This critical interface thus possesses zero refractive-index contrast; hence “zero-contrast gratings.” We design Reflectors with zero-contrast gratings and high-contrast gratings and compare the results. For simple gratings with two-part periods, we show that zero-contrast grating Reflectors outperform comparable high-contrast grating Reflectors. An example silicon-on-glass reflector exhibits a 99% reflectance bandwidth of ∼700 nm for zero refractive-index contrast Δn=0, whereas a high-contrast device with Δn=2 yields a bandwidth of ∼600 nm. It follows that local Fabry–Perot modes residing in the grating ridges and reflecting off a high-contrast interface are not the root cause of wideband reflection.
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wideband leaky mode resonance Reflectors influence of grating profile and sublayers
Optics Express, 2008Co-Authors: Mehrdad Shokoohsaremi, Robert MagnussonAbstract:We apply inverse numerical methods to design compact wideband Reflectors in which a periodic silicon layer supports resonant leaky modes. Using particle swarm optimization to determine appropriate device thickness, period, and fill factors, we arrive at example reflector designs for both TE and TM polarized input light. As a properly configured grating profile provides added design freedom, we design Reflectors with two and four subparts in the period. In TM polarization, a particular single-layer two-part reflector has 520 nm bandwidth whereas the four-part device reaches 600 nm bandwidth. In TE polarization, the corresponding numbers are 125 nm and 495 nm, respectively. We provide a qualitative explanation for the smaller TE-reflector bandwidth. We quantify the effects of deviation from the design parameters and compute the angular response of the elements. As the angle of incidence deviates from normal incidence, narrow transmission channels emerge in the response yielding a bandpass filter with low sidebands. The effects of adding a silica sublayer between a silicon substrate and the periodic silicon layer is investigated. It is found that a properly designed sublayer can extend the reflection bandwidth significantly.
C E Kennedy - One of the best experts on this subject based on the ideXlab platform.
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optical durability of candidate solar Reflectors for concentrating solar power
2007Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4 mrad half-cone angle for at least 10 years outdoors with a cost of less than $$13.8/m{sup 2} (the 1992 $$10.8/m{sup 2} goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, front-surface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10 year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10 year or more aggressive 20 year lifetime goal.
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optical durability of candidate solar Reflectors
Journal of Solar Energy Engineering-transactions of The Asme, 2005Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4 mrad half-cone angle for at least 10 years outdoors with a cost of less than $13.8/m 2 (the 1992 $10.8/m 2 goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, front-surface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10 year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10 year or more aggressive 20 year lifetime goal.
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optical durability of candidate solar Reflectors
Solar Energy, 2004Co-Authors: C E Kennedy, K TerwilligerAbstract:Concentrating solar power (CSP) technologies use large mirrors to collect sunlight to convert thermal energy to electricity. The viability of CSP systems requires the development of advanced reflector materials that are low in cost and maintain high specular reflectance for extended lifetimes under severe outdoor environments. The long-standing goals for a solar reflector are specular reflectance above 90% into a 4-mrad half-cone angle for at least 10 years outdoors with a cost of less than $13.8/m2 (the 1992 $10.8/m2 goal corrected for inflation to 2002 dollars) when manufactured in large volumes. Durability testing of a variety of candidate solar reflector materials at outdoor test sites and in laboratory accelerated weathering chambers is the main activity within the Advanced Materials task of the CSP Program at the National Renewable Energy Laboratory (NREL) in Golden, Colorado. Test results to date for several candidate solar reflector materials will be presented. These include the optical durability of thin glass, thick glass, aluminized Reflectors, frontsurface mirrors, and silvered polymer mirrors. The development, performance, and durability of these materials will be discussed. Based on accelerated exposure testing the glass, silvered polymer, and front-surface mirrors may meet the 10-year lifetime goals, but at this time because of significant process changes none of the commercially available solar Reflectors and advanced solar Reflectors have demonstrated the 10-year or more aggressive 20-year lifetime goal.Copyright © 2004 by ASME
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optical performance and durability of solar Reflectors protected by an alumina coating
Thin Solid Films, 1997Co-Authors: C E Kennedy, Russell V Smilgys, D A Kirkpatrick, J S RossAbstract:Solar thermal electric power systems use large solar Reflectors to concentrate sunlight to generate electricity. The economic viability of these systems depends on developing a durable, low-cost reflector. The goals for such a reflector are specular reflectance above 90% for at least 10 years under outdoor service conditions and a large-volume manufacturing cost of less than $10.8/m{sup 2} ($1.00/ft{sup 2}). Currently, the best candidate materials for solar Reflectors are silver-coated, low-iron glass and silvered polymer films. Polymer Reflectors are lighter in weight, offer greater system design flexibility, and have the potential for lower cost than glass Reflectors. A promising low-cost reflector consists of a silvered polymer protected by an optically transparent alumina coating. The coating is deposited by an ion-beam-assisted physical vapor deposition (IBAD) technique. Samples of this reflector have maintained high optical performance in accelerated testing at the National Renewable Energy Laboratory for more than 3000 hours. Solar Reflectors produced using this technique may represent an opportunity to bring solar power generation to reality.
Zoran T Pavlovic - One of the best experts on this subject based on the ideXlab platform.
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variation of reflected radiation from all Reflectors of a flat plate solar collector during a year
Energy, 2015Co-Authors: Zoran T Pavlovic, Ljiljana T KosticAbstract:In this paper the impact of flat plate Reflectors (bottom, top, left and right Reflectors) made of Al, on total solar radiation on a solar collector during a day time over a whole year is analyzed. An analytical model for determining optimum tilt angles of a collector and Reflectors for any point on the Earth is proposed. Variations of Reflectors' optimal inclination angles with changes of the collector's optimal tilt angle during the year are also calculated. Optimal inclination angles of the Reflectors for the South directed solar collector are calculated and compared to experimental data. It is shown that optimal inclination of the bottom reflector is the lowest in December and the highest in June, while for the top reflector the lowest value is in June and the highest value is in December. On the other hand, optimal inclination of the left and right side Reflectors for optimum tilt angle of the collector does not change during the year and it is 66°. It is found that intensity of the solar radiation on the collector increases for about 80% in the summer period (June–September) by using optimally inclined Reflectors, in comparison to the collector without Reflectors.
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optimal position of flat plate Reflectors of solar thermal collector
Energy and Buildings, 2012Co-Authors: Ljiljana T Kostic, Zoran T PavlovicAbstract:Abstract In this paper the results of the influence of position of the flat plate Reflectors made of Al sheet on thermal efficiency of solar thermal collector with spectrally selective absorber are presented. Analytical and experimental results on determination of the optimal position of flat plate solar Reflectors during the day time over the whole year period are shown. Both numerical calculation and experimental measurements indicate that optimal angle position of the bottom reflector is the lowest (5°) in December and the highest (38°) in June for collector fixed at β = 45° position. The thermal efficiency of thermal collector without Reflectors and with Reflectors in optimal position has been determined. Though the thermal efficiency of thermal collector decreases slightly with the solar radiation intensity, the total thermal energy generated by thermal collector with Reflectors in optimal position is significantly higher than total thermal energy generated by thermal collector without Reflectors. These results show the positive effect of Reflectors made of Al sheet and there is an energy gain in the range 35–44% in the summer period for thermal collector with Reflectors, which is expected to reduce the cost pay back time.
