A solar furnace is an optical system for providing concentrated solar radiation. The solar furnace technique is based on reflecting solar radiation from a surface and concentrating it all in a single point.
Some solar thermal power plants use this technique to heat a working fluid. Afterward, they use this heated fluid to generate electricity. It is a way to generate electricity using a renewable energy source.
The largest solar furnace is the Megawatt Solar Furnace (MWSF), in France. Its precursor is the Mont-Louis Solar Furnace, an experimental facility that was the first in the world.
How does a solar furnace work?
A solar furnace works by using different shapes of concave reflectors. Depending on the application, there are solutions with spherical mirrors, parabolic mirrors, or paraboloid mirrors.
The reflective surface of this concentrator can be from one to one hundred square meters. When the surface is too big, it could be necessary to create a heliostat field. We can also simulate this effect by using plane mirrors oriented to assign the light to a single focal point.
Which mirror is used in a solar furnace?
The proper design of the solar furnace’s mirror is the concave mirror. It is the best option because this shape converges the parallel sun rays at a point.
Concave mirrors absorb all the incident solar radiation, reflecting it to a single focal point.
This reflected light concentrate all the thermal energy received in a big area to a focal point. The different types of concave mirrors reflect sunlight to a single focal point.
On the contrary, convex mirrors would spread sunlinght to all directions.
A flat mirror can not concentrate the ray’s direction. However, some facilities use several units of this type of mirror, orienting individually to the focal point.
Uses and applications of a solar furnace
Solar furnaces concentrate solar radiation at a focal point in order to reach very high temperatures. In some designs, they can get temperatures of around 4,000 °C. Here are some examples of the use of different types of solar furnaces:
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Electricity generation: it can supply heat energy which thermal power plants can transform into electricity. These power plants work with temperatures between 300 and 1000 degrees Celsius. The operation of these facilities is based on the transformation of thermal energy into electricity.
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Cause endothermic chemical reactions.
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Material heating: They are used to test the resistance of some materials that will be used in extreme heat sources.
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Stirling engine heat source: it is a way of directly converting solar energy into mechanical energy.
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Food cooking: On a smaller scale, solar furnaces can be used to replace conventional ovens.
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Plastic or paint aging tests.
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It is possible to create hydrogen fuel from water.
Several facilities are developed just to do research tasks, such as High-Flux Solar Furnace in the United States.