Parabolic Trough CSP

Parabolic trough solar thermal collectors are one of the most common types of solar energy collectors. They are straight in one dimension then curved (as a parabola) in the two other dimensions. They use polished metal mirrors to reflect the sunlight. When sunlight enters the mirror parallel to its plane of symmetry is focused along the focal line, where objects are positioned that are intended to be heated.

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For power generation use a tube is utilised, which runs the length of the trough at its focal line. The mirror is oriented so that sunlight which it reflects is concentrated on the tube, which contains a fluid, often oil or molten salt which is heated to a high temperature by the energy of the sunlight, the hot fluid is then used to generate electricity.

The heat transfer fluid runs through the tube to absorb the concentrated sunlight. This increases the temperature of the fluid typically upto 600°C however the next generation of plants could see temperatures pushing 800°C. The heat transfer fluid is then used to heat steam in a standard turbine generator. The process is economical and, for heating the pipe, thermal efficiency ranges from 60-80%.

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The earliest use of parabolic trough solar thermal collectors dates to 1897 by Frank Shuman. It wasn’t until 1912 in Egypt when Shuman built the Worlds first solar thermal power station in Maadi. However, the arrival of cheap oil stifled development of solar energy until the 1970s when it caught interest once again. It wasn’t however until the mid-2000’s when the current generation of Parabolic trough solar thermal plant designs really started to expand Globally, firstly in the EU especially Spain, then ultimately the Middle East back to where it all started.

 

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