The first step in solar energy utilization is the collection of this energy.This is done through solar collectors.A solar collector is a device used to collect solar radiation and transfer the energy to a fluid passing in contact with it.The surface of a solar collector is designed for high absorption and low emission.Solar collectors are of two types,namely,non-concentrating or flat-plate type and concentrating or focusing type collectors.
Flat-plate collector are used where temperature below 90°C are required.These collectors could be of liquid heating or air heating types.The liquid heating collectors are often used for heating water whereas the air heating collectors are used for drying of agricultural produce,space heating,heating of green houses ,etc.
Concentrating collectors employ optical system in the form of reflectors or refractors to concentrate the energy of direct solar radiation on the absorbing surface.The reflectors may be flat mirrors or in the shape of a parabolic trough or a paraboloidal dish.An array of reflectors can be used to concentrate solar radiation on a single absorbing surface.
Concentrating collectors enable the generation of much higher temperature compared to flat-plate collectors.Hence they are used for applications which need high grade heat (above 300°C)such as power generation.However ,concentration collectors need tracking arrangements which move the collectors constantly so that they receive the direct beam from the sun throughout the day and in all seasons.
In a solar power plant,solar energy is collected by large parabolic collectors.This energy is used to heat water or any other fluid.the heat is transferred to feed water to convert it into steam.The steam is used to run a turbine which drives an alternator.The heat of cooling water of the condenser may be used for some other purpose.
Solar thermal energy has the following main application:
1.Heating and cooling of buildings.
2.Solar water heating.
3.Solar cookers.
4. solar engines for water pumping water.
5.Solar drying of agricultural and animal products.
6.Food refrigeration.
7.Solar furnaces.
8.Solar electric power generation.
9.water desalination.
10.Solar greenhouses.
Flat-plate collector are used where temperature below 90°C are required.These collectors could be of liquid heating or air heating types.The liquid heating collectors are often used for heating water whereas the air heating collectors are used for drying of agricultural produce,space heating,heating of green houses ,etc.
Concentrating collectors employ optical system in the form of reflectors or refractors to concentrate the energy of direct solar radiation on the absorbing surface.The reflectors may be flat mirrors or in the shape of a parabolic trough or a paraboloidal dish.An array of reflectors can be used to concentrate solar radiation on a single absorbing surface.
Concentrating collectors enable the generation of much higher temperature compared to flat-plate collectors.Hence they are used for applications which need high grade heat (above 300°C)such as power generation.However ,concentration collectors need tracking arrangements which move the collectors constantly so that they receive the direct beam from the sun throughout the day and in all seasons.
In a solar power plant,solar energy is collected by large parabolic collectors.This energy is used to heat water or any other fluid.the heat is transferred to feed water to convert it into steam.The steam is used to run a turbine which drives an alternator.The heat of cooling water of the condenser may be used for some other purpose.
Solar thermal energy has the following main application:
1.Heating and cooling of buildings.
2.Solar water heating.
3.Solar cookers.
4. solar engines for water pumping water.
5.Solar drying of agricultural and animal products.
6.Food refrigeration.
7.Solar furnaces.
8.Solar electric power generation.
9.water desalination.
10.Solar greenhouses.
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