Help with old solar thermal engine

Long story looking for a short answer.
Many years ago I read a book that had a design for an interesting solar pump and I was wondering one has plans for one or can help me make up my own. And as always I'm looking to go as cheap as possible.
The pump used a closed double acting cylinder. When one end was heated the gas inside expanded which pushed the rod. This rod action did a couple of things:
1) It moved the mirror(s) so that the sun was moved to the opposite end of the cylinder to restart the cycle. 2) It moved a second rod in a second cylinder which pumped water. [IIRC, the original used the weight the mirror assembly to help pump the water]
I know this is probably an inefficient way to do it as well as being a very low pressure, very low volume and possibly noisy pump but I only need 15 to 20 gal per day for my animals. If I could get more volume out of it I could use it as a start for a 'geothermal' AC for my house.
I'm having some problems figuring out how to build it. The first problem is the 'heat' cylinder. Any ideas how to build one or where I might be able to find something used I could 'adjust' to work? I don't think a standard pneumatic cylinder would work because of the temperatures it would be exposed to.
The next problem is what gas to use. I think the original used freon or propane. Would the new stuff (132a??) work?
Then there's the fact that the mirror will have to track the sun so that the focal point will remain on the cylinder. I was thinking a trough type parabolic mirror that would slide on a track. This would pretty much eliminate the need for the mirror to have to be reaimed throughout the day. The problem I see with this is because the mirror would slowly slide down the cylinder causing the temp on both sides of the cylinder to equalize and stop the engine. That means I would have to have some kind of 'tipping point' so that once the cylinder reaches a point the mirror moves all at once.
Thanks for any help.

no spam wrote:

Long story looking for a short answer.
Many years ago I read a book that had a design for an interesting solar pump and I was wondering one has plans for one or can help me make up my own. And as always I'm looking to go as cheap as possible.
The pump used a closed double acting cylinder. When one end was heated the gas inside expanded which pushed the rod. This rod action did a couple of things:
1) It moved the mirror(s) so that the sun was moved to the opposite end of the cylinder to restart the cycle. 2) It moved a second rod in a second cylinder which pumped water. [IIRC, the original used the weight the mirror assembly to help pump the water]
I know this is probably an inefficient way to do it as well as being a very low pressure, very low volume and possibly noisy pump but I only need 15 to 20 gal per day for my animals. If I could get more volume out of it I could use it as a start for a 'geothermal' AC for my house.
I'm having some problems figuring out how to build it. The first problem is the 'heat' cylinder. Any ideas how to build one or where I might be able to find something used I could 'adjust' to work? I don't think a standard pneumatic cylinder would work because of the temperatures it would be exposed to.
The next problem is what gas to use. I think the original used freon or propane. Would the new stuff (132a??) work?
Then there's the fact that the mirror will have to track the sun so that the focal point will remain on the cylinder. I was thinking a trough type parabolic mirror that would slide on a track. This would pretty much eliminate the need for the mirror to have to be reaimed throughout the day. The problem I see with this is because the mirror would slowly slide down the cylinder causing the temp on both sides of the cylinder to equalize and stop the engine. That means I would have to have some kind of 'tipping point' so that once the cylinder reaches a point the mirror moves all at once.
Thanks for any help.
I think your referring to a "Stirling" engine. A stirling is exothermic,

ie there is no internal combustion required for it to operate. It depends on an external heat source such as solar to expand the inert gas to move the cylinder. The gas moves to the cool side of the engine where it contracts and moves the cylinder the opposite direction. It is a totally closed system, ie there is no intake or exhaust. Do a search on STIRLING. Most of the hits will be small kits and/or toys, but there are a few companies working on large scale systems.
Ron

The pump used a closed double acting cylinder. When one end was heated the gas inside expanded which pushed the rod. This rod action did a couple of things:
1) It moved the mirror(s) so that the sun was moved to the opposite end of the cylinder to restart the cycle. 2) It moved a second rod in a second cylinder which pumped water. [IIRC, the original used the weight the mirror assembly to help pump the water]
I know this is probably an inefficient way to do it as well as being a very low pressure, very low volume and possibly noisy pump but I only need 15 to 20 gal per day for my animals. If I could get more volume out of it I could use it as a start for a 'geothermal' AC for my house.
I'm having some problems figuring out how to build it. The first problem is the 'heat' cylinder. Any ideas how to build one or where I might be able to find something used I could 'adjust' to work? I don't think a standard pneumatic cylinder would work because of the temperatures it would be exposed to.

I think your referring to a "Stirling" engine. A stirling is exothermic, ie there is no internal combustion required for it to operate. It depends on an external heat source such as solar to expand the inert gas to move the cylinder. The gas moves to the cool side of the engine where it contracts and moves the cylinder the opposite direction. It is a totally closed system, ie there is no intake or exhaust. Do a search on STIRLING. Most of the hits will be small kits and/or toys, but there are a few companies working on large scale systems.

You might be able to call it that but it's not what I think of when I hear Stirling engine. From what I remember the engine ran because the moving mirrors (IIRC, there were two in the original) heated one side of the cylinder then that cylinder moved the mirrors as well as pumped water. No gas is moved only expanded and contracted. Think of a double acting hydraulic cylinder.
I guess you could do the same thing by using the sun to heat water and use valves to run the hot water over one side than the other but that would add another set of problems. Pumping water, switching valves etc.
Anyway its not the theory I have a problem with its the physical design. Mainly how I can get the focal point to switch from one side of the cylinder to the other in one quick motion. Also how long the arms of each cylinder (the heat and the pumping) I would need and how fast I could run it w/o it falling apart.

On Mar 27, 10:46 am, "no spam" wrote:

Long story looking for a short answer.
Many years ago I read a book that had a design for an interesting solar pump and I was wondering one has plans for one or can help me make up my own. And as always I'm looking to go as cheap as possible.
The pump used a closed double acting cylinder. When one end was heated the gas inside expanded which pushed the rod. This rod action did a couple of things:
1) It moved the mirror(s) so that the sun was moved to the opposite end of the cylinder to restart the cycle. 2) It moved a second rod in a second cylinder which pumped water. [IIRC, the original used the weight the mirror assembly to help pump the water]
I know this is probably an inefficient way to do it as well as being a very low pressure, very low volume and possibly noisy pump but I only need 15 to 20 gal per day for my animals. If I could get more volume out of it I could use it as a start for a 'geothermal' AC for my house.
I'm having some problems figuring out how to build it. The first problem is the 'heat' cylinder. Any ideas how to build one or where I might be able to find something used I could 'adjust' to work? I don't think a standard pneumatic cylinder would work because of the temperatures it would be exposed to.
The next problem is what gas to use. I think the original used freon or propane. Would the new stuff (132a??) work?
Then there's the fact that the mirror will have to track the sun so that the focal point will remain on the cylinder. I was thinking a trough type parabolic mirror that would slide on a track. This would pretty much eliminate the need for the mirror to have to be reaimed throughout the day. The problem I see with this is because the mirror would slowly slide down the cylinder causing the temp on both sides of the cylinder to equalize and stop the engine. That means I would have to have some kind of 'tipping point' so that once the cylinder reaches a point the mirror moves all at once.
Thanks for any help.

That is a Sterling Cycle Engine. Lots of articles, how-tos, etc on the 'net.
M.E.N. back in the good days had an article (I think it was a series) on an automatic sun tracking dish that used nothing but sunpower.
Harry K

no spam wrote: ....

Many years ago I read a book that had a design for an interesting solar pump and I was wondering one has plans for one or can help me make up my own. ....

I can't help you with that design but a quick websearch came up with all kinds of things.
http://www.rotarystirlingengines.com/sexbaloon.htm http://www.linux-host.org/energy/sstirling.htm http://en.wikipedia.org/wiki/Stirling_engine
Anthony

no spam wrote:
| I'm having some problems figuring out how to build it. The first | problem is the 'heat' cylinder. Any ideas how to build one or | where I might be able to find something used I could 'adjust' to | work? I don't think a standard pneumatic cylinder would work | because of the temperatures it would be exposed to. | | The next problem is what gas to use. I think the original used | freon or propane. Would the new stuff (132a??) work? | | Then there's the fact that the mirror will have to track the sun so | that the focal point will remain on the cylinder. I was thinking a | trough type parabolic mirror that would slide on a track. This | would pretty much eliminate the need for the mirror to have to be | reaimed throughout the day. The problem I see with this is because | the mirror would slowly slide down the cylinder causing the temp on | both sides of the cylinder to equalize and stop the engine. That | means I would have to have some kind of 'tipping point' so that | once the cylinder reaches a point the mirror moves all at once.
I have a web page showing a bit of a current project to develop a liquid-piston Stirling (fluidyne) powered pump at the link below. The current plan is to build the engine and pump using off-the-shelf 4" CPVC. The only moving parts will be air, water, and check valve mechanisms.
The web page shows construction and testing of a parabolic trough, but the high temperatures (724F) tend to melt the engine plumbing. It appears that a same-area flat plate collector may solve that problem as well as allowing the pump to run (more slowly) on hazy or light overcast conditions.
I'm not sure if this is close to what you want, but it may provide a few ideas that you can use.
I just recently added a short video of one of our early test fluidynes running (with an electrical heat source) to show how simple these critters can be.
BTW, the fluidyne runs silently - and the only noises from the pump will be the soft "click" of the check valves and the gurgle of water...
-- Morris Dovey DeSoto Solar DeSoto, Iowa USA http://www.iedu.com/DeSoto/StirlingProject.html