Parabolic Trough

It’s easy to build a low-cost parabolic trough, similar to the ones used for example at Desertec, for experimental purposes.

I suggest designing the base to be split into several segments to be used with 1000mm x 500mm polished stainless steel reflector material.

The tool used to calculate the support structure can be found here.

A technical drawing (1:10) is available here: parabolic trough_technical_drawing

A series of tests showed the capabilities of the new mirror mounting.

To get 700ml water to boiling temperature, one of the four modules (500mm x 918mm) took 7min. If the absorber is preheated, the water already starts boiling in less than 5min.

In the following tests, the absorber was filled with cooking oil to determine the maximum temperature of the module.

The highest temperature was 138°C after 4-5min with the poor, quickly black lacquered aluminum tube.

That’s not that bad for a first test and optimizing the absorber will most likely increase efficiency

Further steps are:

  • Try to get a ” cheap ” vacuum absorber tube.
  • Try different materials for the tube.
  • Aluminum has good thermal conductivity (235W/(m·K)) but it is cooled down too fast by the fluid inside the tube and shadowing effects.
  • In my opinion, it would be better if the tube acts as a capacity and could store the heat, which could then be transmitted more steadily.

See also the Parabola Tool if you want to build your own.

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