Cylindrical and Flat Solar Collector Geometries: Theory and Experiment
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![Page 1: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/1.jpg)
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Photo by Greg P. Smestad
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Direct sunlight
Glass Tubes
Index-Matching Fluid
CIGS
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d/D6 = 1d/D6 = 2d/D6 = inf
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Equinox Tilt = Latitude
Replicated: D. C. Beekley and G. R. Mather, Jr., “Analysis and experimental tests of a high-performance evacuated tubular collector,” DOE/NASA CR-150874, 1978. Manuscript Freely obtained at: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf
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Solar Hour Solar Hour
Latitude = 40° Tilt = 28°
d = 2D6
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf
Latitude = 40° Tilt = 28°
White-Panel Backplane d = 2D6
![Page 8: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/8.jpg)
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Cylindrical Tubes
The theory indicates flat
panels should be better around
noon, while the tubes are better in
early and late hours
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19790008199_1979008199.pdf
1.0
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![Page 9: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/9.jpg)
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Photo by Greg P. Smestad
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![Page 12: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/12.jpg)
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Region Flat Panel
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![Page 13: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/13.jpg)
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!.18)'$%@*An*P.&D#/*A.^/'*First glance: cylindrical tube panel (Solyndra) performs better than flat panel (Solar Frontier) Second glance: we need to normalize for differences in solar cell active area Third glance: there is the characteristic kink in the curve due to critical angle phenomenon
Elec
tric
al
3 September 2012 Latitude = 37.3492°
Longitude = -121.9381° Altitude = 20 m
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![Page 15: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/15.jpg)
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First glance: flat panel (Solar Frontier) performs better than cylindrical tube panel (Solyndra) Second glance: we are gaining some power from the open regions in the panel, but not doubling Third glance: the kink is still there due to critical angle phenomenon
Elec
tric
al
3 September 2012 Latitude = 37.3492°
Longitude = -121.9381° Altitude = 20 m
White-Panel Backplane
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![Page 16: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/16.jpg)
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28 October 2012 (AM1.5 Conditions) Latitude = 37.3492°
Longitude = -121.9381° Altitude = 20 m
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Site data and time infolatitude in decimal degrees (positive in northern hemisphere) !"#!$%&longitude in decimal degrees (negative for western hemisphere) '(&(#%!)(ground surface elevation (m) 20.0time zone in hours relative to GMT/UTC (PST= -8, MST= -7, CST= -6, EST= -5) -8daylight savings time (no= 0, yes= 1) 1start date to calculate solar position and radiation 3-Sep-12start time 12:30 AMtime step (hours) 0.5number of days to calculate solar position and radiation 1Bird model parametersbarometric pressure (mb, sea level = 1013) 1013ozone thickness of atmosphere (cm, typical 0.05 to 0.4 cm) 0.225water vapor thickness of atmosphere (cm, typical 0.01 to 6.5 cm) 2aerosol optical depth at 500 nm (typical 0.02 to 0.5) 0.26aerosol optical depth at 380 nm (typical 0.1 to 0.5) 0.3forward scattering of incoming radiation (typical 0.85) 0.85surface albedo (typical 0.2 for land, 0.25 for vegetation, 0.9 for snow) 0.2Bras model parameterBras atmospheric turbidity factor (2=clear, 5=smoggy, default = 2) 2Ryan-Stolzenbach model parameterRyan-Stolzenbach atmospheric transmission factor (0.70-0.91, default 0.8) 0.8
Calculation of solar position based on NOAA's functions and clear-sky solar radiation based on Bird and Hulstrom's model, Bras model, and Ryan and Stolzenbach's model.
On horizontal surface
![Page 20: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/20.jpg)
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Solar Spectrum = AM1.5 CIGS QE = NREL literature 3 September 2012 Latitude = 37.3492° Longitude = -121.9381° Altitude = 20 m White-Panel Backplane
Solar noon results only shown on central tube
Pe,tube (tracing) = 2.53 W
Pe,array = 101.2 W
![Page 21: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/21.jpg)
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Note: irradiance on back surface of tube
Pe,tube = 2.53 W comparable to
experiment
1.30 pm
![Page 22: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/22.jpg)
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Comparison of Solyndra cylindrical tube panel: experiment and ray trace model – good agreement. Variations due to solar source assumptions, such as atmospheric conditions Indicates that software ray-tracing model validates virtual design method. El
ectr
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3 September 2012 Latitude = 37.3492°
Longitude = -121.9381° Altitude = 20 m
White-Panel Backplane
![Page 23: Cylindrical and Flat Solar Collector Geometries: Theory and Experiment](https://reader033.fdocuments.in/reader033/viewer/2022052620/557761d3d8b42a472c8b494c/html5/thumbnails/23.jpg)
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