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Principle of operation for a solar furnace
CNRS researchers have been working since 1946 to perfect the art and science of the solar furnace. After having experienced the shortcomings of using military surplus searchlight mirrors that had to be moved to track the sun, they began to consider the use of a fixed parabolic concentrator mirror illuminated by a beam of sunlight reflected from a flat mirror that moved to follow the sun: the heliostat. This simple double reflecting system developed into the large solar furnace of Odeillo, completed in 1970 with its field of heliostats.
CNRS 1000kW solar furnace
LOCATION
The 1000kW CNRS solar furnace is located in the Eastern Pyrénées near the village of Odeillo; more precisely at latitude 42° 29' 48'' north, longitude 2° 1' 49'' east, and at an altitude of 1500 m. At this location conditions are extremely advantageous for solar research: the number of hours of sunshine is generally 3000 hours/year, and the atmosphere is very dry which results in a direct solar flux from 800 W/m2 and as high as1080 W/m2 -the highest measured on site.
TECHNICAL INFORMATION
The parabolic concentrator is capable of providing a peak flux at its focus on the order of 1000W/cm2. Experiments are performed in the focal zone located 18 meters in front of the parabola.The maximum temperature that can be obtained is the stagnation temperature 3400°C, at which no power is being extracted, but in general experiments may be conducted in a temperature range of 800°C to 2500°C with the thermal power available decreasing from a maximum of 1000kW as temperature increases.
Detailed Information
Technical Information for Concentrator
The parabola
- Paraboloid of revolution with north-facing horizontal axis
- Focal distance 18 m, height 40 m, width 54 m.
- Axe focal horizontal 13 m au dessus de la troncature inférieure.
- Focal length to aperture ratio f/D = 0.3.
- Projected surface area 1830 m2 .
- 9130 facets ( average dimension 48,5 x 48,5 x 0,4 cm).
- Tempered glass with silvered rear-surface.
- Reflectivity : 0,79.
- Curvature achieved mechanically using 9 points of attachment on a metallic structure.
- Maximum deformation about 1 mm.
- Individual adjustment to aim point using 3 points.
Tower at focus
- Tower 20 m high.
- Shading : 5% of the projected surface area of parabola.
- North-facing control room at 5th floor.
- South-facing room at focal point at 5th floor.
A field of 63 flat heliostats installed on 8 terraces illuminate the large parabolic concentrator. Each heliostat is controlled so that its reflected beam is parallel to the horizontal north-south axis of revolution of the parabola.
Detailed Information
Technical details for the heliostat field
- Number : 63 heliostats installed on 8 terraces
- Surface area : 45 m2.
- Dimensions : 7.5 m (width) x 6.0 m (height)
- Weight : 5000 kg total; 800 kg from mirrors
- Number of facets per heliostat : 180 (50 x 50 x 0.75 cm)
- Type of mirror : polished, back-silvered
- Dispersion around normal : 1-2 minutes.
- Reflectivity : 0,79.
- Adjustment by optical methods.
- Tracking altazimuthal.
- Controlled by calculated trajectory.
- Aiming precision : 1/60 degree
- Total reflective surface : 2835 m2.
- Reflected horizontal beam 40 m high, 54 m wide
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