2. LINEAR FFRSNEL LENS COLLECTOR
In this collector one side consists of linear grooves on the surface of
the refracting material and flat on the other side.
The angle of each groove make the optical behavior similar to
spherical lens.
The beam radiation which is incident normally, it converges on the
focal line, where a receiver tube is to absorb the radiation.
Concentration ratio-10 to 30
Temperature-150-300
3. • Types: Imaging and Non-imaging
• Imaging lens- Segments used with curved cross section and
produce sharp image.
• Ex: Spherical,Cylindrical.
• Non-imaging-Segments used with flat cross section and do
not produce sharp image.
• Application: In solar power such as focusing sun light on a
solar panel.
5. CIRCULAR FRESNEL LENS CONCENTRATOR
• The lenses are used in silicon solar cells or gallium arsenide solar
cells as receiver where high flux is desired.
• The lens is divided into a number of thin circular zones.
• The lens approximates a thin spherical lens by the adjusted each
zones.
• Concentration ratio-as high as 2000
• If less than 2000 that obtained from a paraboloidal reflector.
8. CENTRAL TOWER RECEIVER
• The solar power tower is also known as central tower power plant
or heliostat power plants.
• It is a type of solar furnance using a tower to receive the focussed
sunlight.
• They have flat movable mirrors, to focus sun’s rays.
• Material: 40% potashium nitrate,60% sodium nitrate. They have
high heat capacity.
9. • Design: Flat glass, thermal storage to store the heat in molten
salt containers to continue producing electricity while the sun
is not shining.
• Steam is heated to 500°C to drive turbines that are coupled to
generators which produce electricity.
• Advantages: Higher temperature, lower receiver losses
requirment of flat mirrors,suitable for high temperature
process heat application.
12. HEMISPERICAL MIRROR CONCENTRATOR
• Spherical mirrors are the simplest type of concentrator and are easily to
build and use.
• It consist of a hemispherical fixed mirror a tracking observer and
supporting structures .
• All rays entering the hemisphere .
• After reflection cross the paraxial line between focus and mirror surface.
• The absorber at the center of curvature intercept all reflected rays.
• So its axis is aligned with solar rays passing through the center of the
sphere.
13. • Advantage: It helps in reducing the cost by replacing an
expensive large receiver by a less expansive reflecting or
refracting area.
• It increases the intensity by concentrating the energy
available over a large surface into a smaller surface.
Disadvantage: A number of complications arise because of non
uniform flux on absorber, wide variation in shape,
temperature and heat behavior of absorbing.
