Environmental Reflectance Degradation Of Central Receiver Test Facility (CRTF) Heliostats

1980 ◽  
Author(s):  
D. L. King ◽  
J . E. Myers
Keyword(s):  
Test Facility ◽  
Central Receiver

Heliostat Operation at the Central Receiver Test Facility, 1978–1980

1982 ◽  
Vol 104 (3) ◽  
pp. 133-138 ◽  
Author(s):  
J. T. Holmes
Keyword(s):  
Test Facility ◽  
Total Power ◽  
Peak Intensity ◽  
Central Receiver ◽  
Operations And Maintenance ◽  
Solar Noon ◽  
Mirror Reflectance ◽  
Targeting Accuracy

The operations and maintenance data and conclusions presented in this report are for the 222 heliostats that have been in use at the Central Receiver Test Facility (CRTF) from 1978 through 1980. The CRTF beam produces a total power of 5.5 MWth and a peak intensity of 2250 kW/m2 near solar noon. Improvements in the targeting accuracy have been made. The mirror reflectance is maintained near 80 percent by cleaning with rain or snow. The CRTF heliostats logged almost 300,000 operating hrs by the end of 1980.

The Design and Testing of a Molten Salt Steam Generator for Solar Application

1988 ◽  
Vol 110 (1) ◽  
pp. 38-44 ◽  
Author(s):  
W. A. Allman ◽  
D. C. Smith ◽  
C. R. Kakarala
Keyword(s):  
Molten Salt ◽  
Steam Generator ◽  
Test Facility ◽  
Process Conditions ◽  
Test Results ◽  
Overall Design ◽  
Central Receiver ◽  
And Performance ◽  
Design And Testing ◽  
Solar Application

This paper describes the design and testing of the Steam Generator Subsystem (SGS) for the Molten Salt Electric Experiment at Sandia Laboratories in Albuquerque, New Mexico. The Molten Salt Electric Experiment (MSEE) has been established at the Department of Energy’s five megawatt thermal Solar Central Receiver Test Facility, to demonstrate the feasibility of the molten salt central receiver concept. The experiment is capable of generating 0.75 megawatts of electric power from solar energy, with the capability of storing seven megawatt-hours of thermal energy. The steam generator subsystem transfers sensible heat from the solar-heated molten nitrate salt to produce steam to drive a conventional turbine. This paper discusses the design requirements dictated by the steam generator application and also reviews the process conditions. Details of each of the SGS components are given, featuring the aspects of the design and performance unique to the solar application. The paper concludes with a summary of the test results confirming the overall design of the subsystem.

scholarly journals A Flux Mapping Method for Central Receiver Systems

2011 ◽  
Author(s):  
Clifford K. Ho ◽  
Siri S. Khalsa
Keyword(s):  
Ccd Camera ◽  
Mapping Method ◽  
Test Facility ◽  
The Novel ◽  
Additional Information ◽  
Thermal Test ◽  
Central Receiver ◽  
Direct Normal Irradiance ◽  
Beam Characterization ◽  
Pixel Value

A new method is described to determine irradiance distributions on receivers and targets from heliostats or other collectors for concentrating solar power applications. The method uses a CCD camera, and, unlike previous beam characterization systems, it does not require additional sensors, calorimeters, or flux gauges on the receiver or target. In addition, spillage can exist (the beam does not need to be contained within the target). The only additional information required besides the digital images recorded from the CCD camera is the direct normal irradiance and the reflectivity of the receiver. Methods are described to calculate either an average reflectivity or a reflectivity distribution for the receiver using the CCD camera. The novel feature of this new PHLUX method is the use of recorded images of the sun to scale both the magnitude of each pixel value and the subtended angle of each pixel. A test was performed to evaluate the PHLUX method using a heliostat beam on the central receiver tower at the National Solar Thermal Test Facility in Albuquerque, NM. Results showed that the PHLUX method was capable of producing an accurate flux map of the heliostat beam with a relative error in the peak flux of 2%.

Operation of Large-Scale Pumps and Valves in Molten Salt

1994 ◽  
Vol 116 (3) ◽  
pp. 137-141 ◽  
Author(s):  
D. C. Smith ◽  
E. E. Rush ◽  
C. W. Matthews ◽  
J. M. Chavez ◽  
P. A. Bator
Keyword(s):  
Molten Salt ◽  
Power Plants ◽  
Large Scale ◽  
Solar Power ◽  
Test Facility ◽  
Plant Design ◽  
Thermal Test ◽  
Central Receiver ◽  
Solar Power Plants ◽  
Careful Design

The molten salt pump and valve (P&V) test loops at Sandia National Laboratories (SNL) National Solar Thermal Test Facility (NSTTF) operated between Jan. 1988 and Oct. 1990. The purpose of the P&V test was to demonstrate the performance, reliability, and service life of full-scale hot and cold salt pumps and valves for use in commercial central receiver solar power plants. The P&V test hardware consists of two pumped loops; the “Hot Loop” to simulate the hot (565°C) side of the receiver and the “Cold Loop” to simulate the receiver’s cold (285°C) side. Each loop contains a pump and five valves sized to be representative of a conceptual 60-MWe commercial solar power plant design. The hot loop accumulated over 6700 hours of operation and the cold loop over 2500 hours of operation. This project has demonstrated that standard commercial scale pump and valve designs will work in molten salt. The test also exposed some pitfalls that must be avoided in specifying such equipment. Although certainly not all of the pitfalls were discovered, careful design and specification should result in reliable or at least workable equipment.

Development and Analysis of the Heliostat Focusing and Canting Enhancement Technique for Full Heliostat Alignments

2012 ◽  
Author(s):  
Kyle Chavez ◽  
Evan Sproul ◽  
Julius Yellowhair
Keyword(s):  
Digital Camera ◽  
Test Facility ◽  
Total System ◽  
Test Results ◽  
Error Sources ◽  
Stationary Target ◽  
Enhancement Technique ◽  
Central Receiver ◽  
Solar Noon ◽  
Utility Scale

Central receiver power towers are regarded as a proven concentrating solar power (CSP) technology for generating utility-scale electricity. In central receiver systems, improper alignment (canting and focusing) of heliostat facets results in beam spillage at the receiver and leads to significant degradation in performance. As a result, proper alignment of heliostats is critical for increasing plant efficiency. Past tools used for analyzing and correcting heliostat alignment at the National Solar Thermal Test Facility (NSTTF) have proven to be laborious and inaccurate, sometimes taking up to six hours per heliostat. In light of these drawbacks, Sandia National Labs (SNL) and New Mexico Tech (NMT) have created the Heliostat Focusing and Canting Enhancement Technique (H-FACET). H-FACET uses a high-resolution digital camera to observe the image of a stationary target reflected by a heliostat facet. By comparing this image to a theoretical image generated via a custom software package, technicians can efficiently identify and correct undesirable deviations in facet orientation and shape. Previous tests have only proven the viability of H-FACET for canting heliostats. As a result, SNL and NMT have expanded H-FACET’s capabilities and analyzed the system’s ability to simultaneously cant and focus heliostats. Initial H-FACET focusing test results have shown improved beam sizes and shapes for single facets. Furthermore, simulations of these tests revealed an approximated system accuracy of better than 1.80 milliradians. This accuracy accounted for technician, position, and additional error sources, suggesting that H-FACET was capable of focusing facets to an even greater accuracy than those seen in the initial tests. When implemented for simultaneous canting and focusing of heliostats, H-FACET has demonstrated its capability to increase peak flux and decrease beam size. These full alignment test results demonstrated an average total system accuracy of 1.17 milliradians on five heliostats. As before, this accuracy included multiple error sources which cannot be corrected by H-FACET. Additionally, these tests revealed that H-FACET can align heliostats in about 1 hour and 30 minutes. Finally, two heliostats aligned with H-FACET maintained average accuracies 1.46 and 1.24 milliradians over a four hour window centered about solar noon. This implies that H-FACET is capable of aligning heliostats to a true off-axis alignment over NSTTF’s operating window. In light of these results, SNL has implemented both the focusing and canting portions of H-FACET at the NSTTF.

Heliostat Canting and Focusing Methods: An Overview and Comparison

2010 ◽  
Author(s):  
Julius Yellowhair ◽  
Clifford K. Ho
Keyword(s):  
Laser Beam ◽  
Test Facility ◽  
The Sun ◽  
Alignment Method ◽  
Advantages And Disadvantages ◽  
The Past ◽  
Thermal Test ◽  
Central Receiver ◽  
Look Back ◽  
The Individual

A central receiver power tower system consists of a field of heliostats that focus the sunlight onto the receiver on the tower. Heliostats typically consist of an array of mirror facets that track the sun throughout the day. To obtain the optimal concentrated solar flux on the receiver, the individual heliostat facets must be properly canted and focused. Several different methods have been used in the past for facet canting and focusing. These demonstrated methods and some new alignment concepts are under consideration for development and alignment of the 218 heliostats at the Sandia National Laboratories National Solar Thermal Test Facility in Albuquerque, NM. In this paper, we provide an overview and comparison of the different methods. The methods we consider are the gauge blocks, inclinometers, photogrammetry, fringe reflection, imaging with theoretical image overlays, laser beam projections, camera look-back, and target reflection methods. The advantages and disadvantages of each alignment method are identified based on several prescribed criteria for aligning the heliostats. Recommendations regarding the alignment method’s potential for efficiently and accurately aligning heliostat fields are provided.

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