Focal length of a parabolic cylindrical sensor

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nialaz
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Focal length of a parabolic cylindrical sensor




by nialaz » 04/02/09, 00:41

Hi,

When the rays strike the sensor parallel to the axis passing through the focal point and the vertex, these converge towards the focal point.

But assuming that the parabolic cylindrical sensor is oriented towards the sun vertically but not "horizontally" (the rays have for example 30 ° with the axis of the cylinder) then what happens?
Will the rays still converge on the right of the focal points of the sensor or not?

I ask myself this question to know if the orientation of the sensor only vertically is not sufficient.

Thank you
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chrisleblay
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by chrisleblay » 05/02/09, 03:18

A priori I think you always focus in the same place with a cylindrical parabolic concentrator.

I don't know if you saw this video on a small cylindrical parabolic concentrator.
At the end we show a temperature of -16C
Is it the outside temperature (I think so)?
and we show vapor coming out of the concentration line.
Quite powerful.

http://www.dailymotion.com/relevance/se ... ue-01_tech
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Remundo
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by Remundo » 05/02/09, 09:38

The answer is yes. But part of the rays focus on a place where the caloric tube is no longer there :D

I will make you some 3D images to illustrate. No time there :P
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by Remundo » 05/02/09, 15:14

Hop there, find the time.

Simulation by homemade mathematical model originally developed for the PHRSD.

The following 3 views describe the same unique situation from different angles, a situation corresponding to Nialaz's question (inclined radius / axis of the cylinder), unless I am mistaken ...
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nialaz
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by nialaz » 05/02/09, 22:47

Thank you for your answers. This confirms my idea of ​​only varying the angle horizontally, even if it means losing performance.
On the other hand, I think that we have to respect the parabolic form more to ensure good convergence.

Remundo, out of curiosity, under which environment / language did you develop your tool?

And thank you again for your advice.
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by Remundo » 05/02/09, 22:59

Hi Nialaz,

I am a very bad programmer. C ++, Debian and other obscurities for me give me cold sweats.

On the other hand, I do a lot of algorithmic work and I know the physics equations well.

I put it all on Maple V4 (an old version of Maple which is now V11 or 12 ...)

For your questions, this is the best parabolic form.

But the extruded parabolic is not the optimal for concentrating either, it is the parabolic of revolution.

The latter has the disadvantage of being a little more expensive than the cylindrical parabolic ...

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