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Presentation about the current status of Tonatiuh, an open source program for the optical analysis of solar concentrating systems.
Citation preview
• Program background
• Design goals
• Implementation approach
• Current status
• Comparison with SolTrace
• Experimental validation
• Usage example
• Conclusion
• Acknowledgments
Index
Tonatiuh, in Mesoamerican religion, Nahua sun deity of the fifth and final
era (the Fifth Sun). In most myths of the Mesoamerican Nahua peoples,
including those of the Aztecs, four eras preceded the era of Tonatiuh, each
ended by cataclysmic destruction. (Ref.: Encyclopædia Britannica)
Program background
Simulate the optical behavior of solar concentrating systems, providing detailed information regarding the flux distributions incident upon its surfaces.
Design Goal
• Simulate most concentrating systems of interest.
• Be easy to learn, use, and maintain.
• Be easy to improve, and extent.
Design Goal
Design Goal
Tonatiuh
Design Goal
• Full-fledge public Open Source
project
• C++ (object-oriented)
• Leveraging on well established
open source libraries and tools
Implementation approach
Implementation approach
Implementation approach
Implementation approach
video channel
developers blog
users group
main web site
Current status
• Ray tracing and plug-in architecture fully implemented and operational.
• Program able to model a large variety of reflective concentrating systems.
• Users around the world are using it, reporting bugs, and providing valuable feed back.
• Ray tracing and plug-in architecture fully implemented and operational.
• Parallel computation capabilities fully implemented and operational.
• Scripting, dynamic help, and self-updating capabilities in well-advanced development stages.
• Continuous extreme programming development with monthly release cycles consolidated.
Current status
• Able to model a large variety of reflective and refractive solar concentrating systems.
• Successful comparison with SolTrace to the point that Soltraceis evolving to adopt Tonatiuh characteristics (e.g. it is being rewritten in C++, its user interface is being modernize, etc.)
Current status
Since the opening of the
Tonatiuh website in June
2008, it has received 23,496
visits, which came from 147
countries / territories.
Current status
Comparison with
SolTrace
SOLTRACE
• C++ (former Borland
Delphi) Monte Carlo
Ray Tracer
• Windows-based
• Simple GUI
• Commercial use,
closed development
Comparison with
SolTrace
TONATIUH
• C++ object oriented
Monte Carlo Ray
Tracer
• Plug-in architecture.
• Operating system
independent
• State-of-the-art GUI
• Open source
Comparison with
SolTrace
Parabolic Dish Parabolic Trough Solar Furnace
Parabolic dish
Tonatiuh
SolTrace
Power at the target
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
Tonatiuh
SolTrace
Parabolic dish
Frequency distribution of photons
Parabolic dish
Tonatiuh
SolTrace
Maximum flux density
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
Tonatiuh
SolTrace
Parabolic trough
Power at the target
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
Parabolic trough
Tonatiuh
SolTrace
Frequency distribution of photons
10 20 50 100 200 500 1000
0
50
100
Thousand raysDif
fere
nc
efo
rmT
on
ati
uh
refe
ren
ce
va
lue
Maximum Flux Density
Tonatiuh
SolTrace
Parabolic trough
Maximum flux density
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
NREL solar furnace
Tonatiuh
SolTrace
Power at the target
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
Tonatiuh
SolTrace
NREL solar furnace
Frequency distribution of photons
Radius (m)
Fre
qu
en
cy
NREL solar furnace
Tonatiuh
SolTrace
Maximum flux density
Diffe
rence
fro
m T
onatiuh’s
estim
ate
(%
)
• Tonatiuh and SolTrace generate similar estimates
– In the comparison differences never exceeded 2.4%, and were negligible in most cases.
• Both trace similar number of photons to converge in their estimates
– Between 1 to 2 millions, depending on the value being estimated.
SolTrace comparison
conclusions
The general goals of the experimantal validation exercise were:
• To test Tonatiuh’s flexibility to be adapted to simulate real experiments performed on a relatively complex system.
• To test the usefulness of Tonatiuh as a design and analysis tool.
Experimental validation
• To adapt and use Tonatiuh to simulate several experiments that were carried out at the Plataforma Solar de Almería(PSA) during the testing of a secondary concentrator, and compare Tonatiuh’s solar flux estimates with experimental results.
Goals of the experimental
validation
Use as input values to Tonatiuh:
• The appropriate measured values if available.
• Reasonable “a priori” estimates determined without using any experimental results from the secondary concentrator tests to simulate.
Boundary conditions
• Develop a new sunshape plug-in based on a more realistic sunshape model than the pill-box.
• Develop a new shape plug-in to facilitate the simulation of the hexagonal CPC secondary concentrator.
• Define an “a priori” set of input values for each of the test to simulate.
Execution steps
Execution steps
CSR = 30%
Sunshape: Distribution of radiance (W/m2 sr) as a function of the angular distance from the centre of the solar disc.
New, more realistic, sun shape plug-in.
Execution steps
Buie’s sunshape
model
L=f(DNI,CSR)
CSR = 30%
Equivalent probability
density function
CSR = 50%
New, more realistic, sun shape plug-in.
Execution steps
Million of rays
Relative error
standard deviation (%)
New, more realistic, sun shape plug-in.
Execution steps
New shape plug-in to facilitate the simulation of the hexagonal CPC secondary concentrator.
Execution steps
Execution steps
Execution steps
Execution steps
Test # 01
Configuration
Test # 02
Configuration
Execution steps
TEST 01 TEST 02
Date 10-15-1990 10-30-1990
Solar time (hh:mm:ss) 12:18:00 13:15:00
Direct Normal Irradiance (W/m2) 932 975
Sunshape type Buie sunshape Buie sunshape
Circumsolar ratio (%) 0,9 0,9
Transmissivity (%) 100 100
Number of heliostats 2 14
Heliostats reflectivity (%) 87 86
Heliostats optical quality (mrad) 1,55 1,55
Reconcentrator reflectivity (%) 77 77
Reconcentrator optical quality (mrad) 1,55 1,55
Test results
Total Power
(kW)
Average Flux
(kW/m2)
Maximum
Flux (kW/m2)
Measured 31,04 38,32 241,37
Tonatiuh 29,92 36,94 230,80
Relative error (%) -3,59 -3,59 -4,38
Total Power
(kW)
Average Flux
(kW/m2)
Maximum
Flux (kW/m2)
Measured 164,76 203,40 1.050,99
Tonatiuh 174,98 216,02 1.181,39
Relative error (%) 6,20 6,20 12,41
TEST 01
TEST 02
Results: Test # 01
Measured
Tonatiuh
Results: Test # 02
Measured
Tonatiuh
• Tonatiuh has been able to predict the total energy, the average and peak fluxes, and the overall shape of the flux distributions at the exit of the secondary concentrator, using only “a priori” and measured input values.
Experimental validation
conclusions
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 5º
Sun Elevation: 10º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 20º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 30º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 40º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 50º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 60º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 70º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 80º
Usage example:Parabolic Trough Incident Angle Modifier
Sun Elevation: 90º
Usage example:Parabolic Trough Incident Angle Modifier
• Tonatiuh is a flexible an accurate tool for the analysis and design of complex solar concentrating systems operating under real working conditions.
Conclusion
• Since 2004, Tonatiuh’s development is being supported at the University of Texas at Brownsville by DOE and NREL under Minority Research Associate (MURA) Program Subcontract ACQ-4-33623-06.
• Since 2006, it is being also supported by the National Renewable Energy Centre of Spain (CENER), which is contributing the core development team, and providing overall project coordination.
Acknowledgments