Hose or Pipe for Heat Transfer Fluid? (Preferably Recycled)

as I'm building a solar dish collector myself,

I've looked at various systems as you

although my temps should remain under 200f,

I'm using pex tubing as a start

the other alternative would be braided hydraulic lines that any farm implement shop would carry

they're expensive, but think of the pressure and temps they carry

and I always go one size bigger that I feel I need

I agree with guest. Used hydraulic hoses are a good choice.

Silicone Rubber can withstand those temperatures. However, It seems to me that you are looking for the cheapest way out. Let's consider "hot water" PVC. Now mind you, Steam at the boiling point, 212^oF is 100^oC, however, 200^oC is 392, almost 400^oF. Silicone Rubber can accept this temperature. However, Silicone Rubber is somewhat expensive!! I suggest you use hot PVC or galvanized pipe. You can use copper, but that, too, is somewhat expensive. Now, for your best conversion, you might wish to look at a Sterling Engine, http://en.wikipedia.org/wiki/Stirling_engine. As. There are many simple designs for Sterling Engines, one is being designed by the APIX-SEProjects Group, which is on this CR4 group under Sustainability Engineering. You do need to do further research. There are many on this list, mostly under the Sustainability Engineering Division, who can help you without any cost to you, other than complete recognition and acceptance as Guru's.

Please, also, review my website, http://chtank.org.

Respectfully yours,

> the other alternative would be braided hydraulic lines

That would be a good option, depends on availability. I've yet to see anything like that in a scrap heap, but they've mostly not had automotive or agricultural parts. I'll see what I can find..

> Silicone Rubber can withstand those temperatures.

I've tried to source silicone tube previously as part of a liquid core light pipe. It was tricky, only ended up getting my hands on some because of an extremely random little stall at a flea market in Madrid. Bit costly too.

> "hot water" PVC.

CPVC? It needs to be flexible, and it doesn't look like cpvc likes temps above 105 ºC.

> or galvanized pipe. You can use copper

Flexible. I'm using copper for the section receiving heat from the parabola, tho aluminium could be used in a pinch.

> you might wish to look at a Sterling Engine,

A Stirling would be ideal, it's just a matter of practicality. I've yet to see a home built high power high efficiency design, and even buying one seems difficult and would definitely be cost prohibitive. At this stage I'm probably looking at some kind of steam turbine, but have to do a fair bit more research on what the best option is.
I was actually thinking of using a site like kickstarter or indiegogo to raise a couple thousand dollars and have a cash prize competition for people to find the best way of doing this. It's an enormous sticking point with solar microgeneration and I'm yet to find something really practical and easily constructible.

> one is being designed by the APIX-SEProjects Group

I had a look but couldn't find them. Will try again.

> What is the intended use for the stored solar heat energy?

Anything. Certainly electricity, water purification and cooking, but also things like bio char/gas/oil/diesel, heating, smelting, etc. It's an open source project where people anywhere will be able to make the things themselves and generate all their own energy.

> Are you sure you want to use an oil for the heat transfer fluid?

No, I need to do further research into what the best fluid is going to be. I've seen various kinds of oil mentioned as generally used for this, as well as antifreeze.

> Are temperatures typically below freezing?

Depends where people will be using it, but certainly a lot of the time it will be a possibility, yes.

> How large is your storage tank?

Whatever size is best. I guess for steam and possibly bio* I want the highest temperature possible without hitting the fluid's boiling/smoke point, other than that whatever mass will hold the heat at a reasonable temperature throughout the day.

> Do you really need to use a parabolic trough and pipe

The device I'm developing is the tracking system, the collector/storage is secondary. I was originally going to use a dish, but a trough is more practical and just as efficient if tracked.

> Have you considered a direct heated batch/tank system with a "cusp" reflector?

For water heating alone that would probably be sufficient, but a lot of the applications I have in mind require higher temperatures, and therefore much higher degrees of concentration. The only way to do this I've found is with a fairly accurate tracking system.

It seems to me you are a lot further along than your first inquiry indicated. Good luck on your project. As for the Sterling Engine, an Engineer from India who is connected with the APIX project is working on a practicle Sterling Engine design which would be low cost and easy for the semiskilled of the developing world to manufacture. I believe he is nearly finished with his project. I don't have the time at this moment to look him up, but I believe you can find him listed within my http://chtank.org website. Please direct you inquiry to http://www.agro-biogenics.com/Contact.htm.

I know of few plastics that can handle 400°F. You might want to look at silicone as a fixable connector for copper tubing. Since we are talking about medium Temperatures and about very slight pressure, I think this might be your best bet. If you were involved with high temperature and pressure, we would need to look at some very exotic solutions, which would require some very expensive solutions.

It is my belief that your engineering and science expertise is sufficient to overcome so many of the obstacles your are facing, keep up the good work, please. Our future depends so much on people just like you. However, be sure you record for posterity, including recording for any possible patents. Who knows, you might be the next Edison or Westinghouse or Henry Ford? There are so many great inventors in our history; America is known for its inovations.