Solar Fire Drawings

Drawings for the Solar Fire Concentrator
These drawings don't yet have dimensions, since these will calculated automatically with the Prometheus Calculator. By doing the calculations in calc we'll be easily able to redimension the machine and convert between metric and Imperial.

Base, Post and Beam - Drawing
This is the Improved Base, Central Post and Main Beam for the Solar Fire P32. 

Here the hinge to raise and lower the boiler is placed directly on the base.

In the model we built in Rajkot we placed the hinge above the frame which meant the piping had to go out of the main post, go around the hinge and then back into the main post. That created 4 more connections on each pipe, so 8 in all. However, it allowed us to lower the boiler without dismounting the frame. But we soon discovered that this isn&#8217;t necessary, since the frame can be easily supported by stilts in order to remove a piece, or in this case lower the boiler. The boiler isn&#8217;t meant to be lowered all that often, so the inconvenience of supporting the frame to do so is outweighed by a simpler more efficient design (pipe corners lower efficiency and more importantly more prone to leaking than a solid straight pipe).

So with this hinge design it&#8217;s possible to have the pipe setup as shown in the Structure Concept Animation.

There are no measurements, since the calculation of all the measurements will be incorporated into the Prometheus Calculator.

Frame
The frame is fairly simple.

 

It is just a square. I haven&#8217;t yet added the support trusses between each double beam as there may be some formula somewhere for the best distance between each truss, but there are trusses.

There are no measurements, since the calculation of all the measurements will be incorporated into the Prometheus Calculator.

Micro Boiler Steam Generator
The boiler on the Rajkot model of the Solar Fire P32 has a convex bottom, however a concave bottom would be more efficient (light has a chance to bounce around and it would create a hot air cushion underneath). The base of the cylinder may have to be strengthened.

 

See the Structure Concept Animation</a> for where the piping goes.

Of note : the main post and the boiler do not rotate, the central post is fixed and the frame rotates around in.

There are no measurements, since the calculation of all the measurements will be incorporated into the Prometheus Calculator</a>.

Mirror Angle Setting Jig
This is the heart of making the Solar Fire P32</a>. This jig allows us to place our mirrors at the correct angle in doors. See the Reflector Setting Concept Drawing</a> for the basic idea of how it works.

<span class='spip_document_671 spip_documents spip_documents_center'> <img src='http://www.solarfire.org/local/cache-vignettes/L750xH563/04-P6110042-76dff.jpg' width='750' height='563' alt="" style='height:563px;width:750px;' />

Basically it&#8217;s just a triangle, where we can change the base (bottom rod shown next to the tube it slides into to). By changing the distance of the base we can control the interior angle of the mirror (between the mirror rod and the row it sits on).

At the top is where our control rod slides. What holds the control rod is a tube welded to another tube that slides on the end of a bolt. That bolt can be moved back and forth to control the "tilt" of each mirror rod. All the mirror rods are not on the same plane, the outer mirrors are tilted forward compared to the inner mirrors, so we must also control this angle by creating a triangle perpendicular to the first triangle.

The correct interior angle and tilt angle are calculated by the Solar Fire Simulator</a>.

The other rods you see are simply to provide a moving support for the base rod to keep it perpendicular.

Precision here is essential since any angle error will be multiplied by the distance to the focal point, so any dimension that affects the angle of the mirror must be extremely precise, a game of millimeters. Lateral error, as in where the mirror is actually placed, is less important since a 1cm error will result in light hitting 1 cm away from where it should, which is not such a big deal since the boiler bottom of at least 50 cm across.

There are no measurements, since the calculation of all the measurements will be incorporated into the Prometheus Calculator</a>.

Mirror Bending Device
Bending the mirror is essential for the Solar Fire P32</a> to function efficiently. By bending a 60 x 15 cm mirror we can create a focal point of 5 x 15 cm, so a x12 focus.

If there are 360 mirrors on the machine, that means an upper limit of x4320 concentrations, which is a lot better than 360. Now this upper limit can&#8217;t possibly be reached, as reflective loss, focal aberration, errors will reduce the concentration factor in practice, but x250 - x500 can be achieved with standard tools. Over x1000 can be achieved with advanced tools.

<span class='spip_document_672 spip_documents spip_documents_center'> <img src='http://www.solarfire.org/local/cache-vignettes/L750xH563/05-P6110045-c8c6a.jpg' width='750' height='563' alt="" style='height:563px;width:750px;' />

This is a side view. The rod is smooth, fits in a tube, fixed on a flat piece of steel (both by welding or epoxy) which is fixed to the mirror (by epoxy). The triangle then places pressure on the ends of the mirror forcing it to bend and creating a focus. See the Solar Fire P32</a> for a video explanation.

On the Solar Fire P32</a> built in Rajkot we used a threaded rod so that by tightening a nut the triangle was pushed down. However, threaded rod created practical problems annoying to solve (accuracy problems). So with a smooth rod we simply slide something on the rod that can "stick" to it. Call it the Q device.

<span class='spip_document_673 spip_documents spip_documents_center'> <img src='local/cache-vignettes/L750xH563/06-P6110048-15777.jpg' width='750' height='563' alt="" style='height:563px;width:750px;' />

There are no measurements, since the calculation of all the measurements will be incorporated into the Prometheus Calculator</a>.