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Specifications of the High-Flux Solar Furnace

We list specific details of various components and functions of NREL's High-Flux Solar Furnace under the following 10 areas:

Target/Image

  • Focal point nominally located 152.4 cm (60 in) above floor
  • When using XYZ table top: focal point must be 35 cm (14 in) max above table
  • With turning mirror: focal point 106.7 cm (41.6 in) above floor
  • Without secondary:
    • Total power (@1,000 W/m2): 10 kW
    • 94% energy inside 10 cm (4 in) circle
    • Peak concentration: 2,500 suns
  • With reflective secondary: average concentration > 20,000 suns
  • With refractive secondary: average concentration > 50,000 suns

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Heliostat

  • Total area: 31.8 m2 (342 f`t2)
  • 20 facets 71.1 × 111.8 cm (56 × 44 in)
  • Back-silvered low-iron 3-mm glass
  • Slope error: 0.5 mrad
    • mrad specularity
  • Solar-weighted reflectivity: 95%

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Primary concentrator

  • 25 hexagonal facets, 12.5 m2 (135 ft2) overall
    • 762 mm (30 in) across flats (0.5 m2 or 5.38 ft2)
    • Spherical mirrors ground to 14.6 m (47.8 ft) radius of curvature
    • Front-surface ultraviolet-enhanced aluminum
    • Slope error: 0.2 mrad
    • mrad specularity
    • Solar-weighted reflectivity: 84%
    • Delivered power to target: 10 kW @ 1,000 W/m2 direct normal irradiance
  • Target located 7.01 m (23.0 ft) from center facet
  • f/D = 1.85 (D = diameter of circle enclosing all facets)
  • 30° off axis
  • Convergence angle of beam: about 30°
  • 6.9° below horizontal

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Secondary concentrators

  • Reflective
    • Non-imaging compound parabolic
    • Acceptance angle: 14 degrees
    • Entrance diameter: 6 cm
    • Exit diameter: 14.7 mm
    • Truncated to 80% of full height
    • Power at exit: 3.5 kW
    • Average flux concentration: 21,000
    • Reflective surface is protected silver
  • CPV Homogenizer
    • Truncated pyramid design
    • Entrance aperture: 149.8 mm × 149.8 mm, length 387 mm
    • Exit aperture: 100.3 x 100.3 mm
    • Maximum intensity over aperture: 630 suns
    • Uniformity: ±5% over aperture
    • Alternate secondary (internal cooling): 147 × 148 mm and 81 × 82 mm (about the same intensity and uniformity as above); both use protected silver reflective coating

Alternate secondary concentrator configurations are possible depending on the experimental needs.

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XYZ table

  • Speed: adjustable 0–2 cm/s (0–5 in/s)
  • X (lateral) travel: 122 cm (48 in)
  • Y (focal length) travel: 183 cm (72 in)
  • Z (vertical) travel: 152±46 cm (60 ±18 in)
  • Nominal focal point: 152 cm (60 in) off floor; minimum table height 117 cm (46 in)
  • Precision: ±0.05 mm
  • Capacity: 180 kg (400 lb) cantilevered 61 cm (24 in) off center
  • Maximum deflection: 6.4 mm (0.25 in) at max capacity
  • Programmable via PC

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Attenuator

  • Vertically opposing two-plate design or Venetian-blind type
  • Speed and acceleration adjustable up to 1 m/s and 2 m/s2
  • Travel time: 1.5–15 s to full-open or full-closed
  • Located 1.78 m (70 in) from target (max flux: 25 suns); opening 1.275 wide × 1.320 m tall
  • Operable in manual or automatic (from data acquisition system) mode
  • Can provide flux control based on signal input, e.g., pyrheliometer input for constant flux or thermocouple input for constant temperature

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Shutter

  • Fast acting: travel time about 0.5 s either opening or closing
  • Programmable to any position
  • Actively cooled
  • Located 84 cm (33 in) from target
  • Operable in manual or automatic (from data acquisition system) mode
  • Can control shutter on signal input through LabView (e.g., thermocouple)

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Data acquisition

  • National Instruments LabVIEW program and hardware
  • Monitors temperatures, solar radiation (W/m2), and wind speed
  • Temperature measurements can be tied into HFSF control (shutter, attenuator, blinds)
  • Available for research equipment control
  • Current input for 40 type-K thermocouples (to be expanded)
  • Analog input for 17 components (to be expanded)
  • Versatile configuration to accommodate any variety of research

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Miscellaneous features

  • Turning mirror to redirect beam to horizontal target
    • Front-surface aluminum mirror
    • Solar-weighted reflectivity: 92%
  • Flexibility in experiment size and orientation
  • Wide range of flux levels: 10–2,000 W/cm2 with secondary
  • Remote viewing of target with LaserCam cameras
  • Pyrometers operating at 2–2.7 or 8–14 microns; temperatures to 1,000°C or 3,000°C
  • Gas flow manifold system with four MKS flow controllers ranging from 2,000 to 30,000 sccm
  • Exhaust hood above experimental area
  • Drill press and hand tools

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Utilities

  • Electrical: 120 V, 208 V, and 208 V 3-phase power available
  • 3 kVA Clary and 1.5 kVA Liebart uninterruptible power supply
  • Compressor: 7 scfm @120 psi
  • Water: city and deionized water available
  • Chillers: NESLAB HX750, >40,000 Btu/h @ 6 gpm 50% propylene glycol
  • Thermo-Scientific chemical hood

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Publications

J. Martinek, C. Bingham, and A.W. Weimer, Computational modeling and on-sun model validation for a multiple tube solar reactor with specularly reflective cavity walls. Part 1: Heat transfer model, Chemical Engineering Science 81 (2012) 298–310.

J. Martinek, C. Bingham, and A.W. Weimer, Computational modeling of a multiple tube solar reactor with specularly reflective cavity walls. Part 2: Steam gasification of carbon, Chemical Engineering Science 81 (2012) 285–297.

P. Lichty, X. Liang, C. Muhich, B. Evanko, C. Bingham, and A.W. Weimer, Atomic layer deposited thin film metal oxides for fuel production in a solar cavity reactor, International Journal of Hydrogen Energy 37(22) (2012), 16888–16894.

P. Lichty, C. Perkins, B. Woodruff, C. Bingham, and A. Weimer, Rapid high temperature solar thermal biomass gasification in a prototype cavity reactor, Journal of Solar Energy Engineering 132(1) (2010), 7 pp.

C. Bingham, A. Lewandowski, K. Stone, R. Sherif, U. Ortabasi, and S. Kusek, Concentrating photovoltaic module testing at NREL's Concentrating Solar Radiation Users Facility, NCPV and Solar Program Review Meeting Proceedings, 24–26 March 2003, Denver, Colorado (CD-ROM), 6 pp.

SunLab Test Facilities. Solar Thermal Electric Program SnapShot (Fact sheet)
DOE/GO-10097-433 (1997).

M.J. Hale, C. Fields, A. Lewandowski, C. Bingham, and R. Pitts, Production of fullerenes with concentrated solar flux (1994).

M.L. Olsen, E.L. Warren, P.A. Parilla, E.S. Toberera, C.E. Kennedy, G.J. Snyder, S.A. Firdosy, B. Nesmith, A. Zakutayev, A. Goodrich, C.S. Turchi, J. Netter, M.H. Gray, P.F. Ndione, R. Tirawat, L.L. Baranowski, A. Gray, and D.S. Ginley, High-temperature, high-efficiency solar thermoelectric generator prototype  (2014).

A. Lewandowski, Deposition of diamond-like carbon films and other materials processes using a solar furnace, Materials Technology 8(11/12) (1993) 237–240.

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