Heating Help

"Steam Pumping"

What if you had a high efficiency, low-loss, low thermal mass solar collector. That means that in few minutes after exposure to sunlight, you could boil the water in the collector.

Maybe this vaporization could be harnessed to move the collector fluid without a pump or controller. It seems to me that two or three check valves could convince the steam to push the fluid around the loop even if the storage tank is below the collector.

The steam pushes out of the collector, but gets trapped downstream of the collector by a check valve. When that steam packet condenses, liquid collector fluid rushes to replace it, but another check valve forces that water to be sucked though the collector inlet. The cycle continues all day until the sun isn't strong enough to vaporize the fluid anymore. The process might be too noisy, but with the right check valves, it might sound like a coffee percolator.

A Google search for steam pumping turned up nothing, so I thought I'd check the Wall for ideas or if anyone has heard of this before.

In the 90's, the "Copper Cricket" collector was sold for a while, and I believe it had a similar pumping action. I haven't been able to find out exactly how it worked, though, and why it wasn't successful.

What's to reduce the pressure inside the collector?

Maybe I'm misunderstanding, but isn't it the case that, as long as there's enough sunlight incident on the collector, the steam pressure in it would stop any liquid from entering? I thought that's pretty much the principle behind steamback. In essence, you'd be stagnating all the time.

Hmmmm

There's a check valve on the inlet and two check valves in series on the outlet of the solar collector.

As soon as a packet of steam exits the collector and gets trapped downstream, it will condense. That huge reduction of volume will try to suck something from somewhere. The second outlet check valve will prevent downstream fluid from the expansion tank from coming back up.

So, it will suck more steam and water from the collector. Wouldn't it also cause some water near the collector inlet to be sucked into the collector?

As more and more steam exists in the collector return piping, maybe more check valves are needed all the way back to the storage tank.

sounds like the old Copper Cricket

concept. I have all the original "Cricket" info packet along with prices. be glad to fax the facts, to you.

hr

Copper Cricket info, yes

Awesome, Hot Rod, my fax # is 303 733-9189

Copper Cricket used a Geyser Pump

A geyser pump is pretty well known, but:

1. It required methyl alcohol (flammable).
2. It required the installer to pull a vacuum on the collector loop.
3. The geyser pump has to be on the roof and they are kind of ugly.

These are probably the main reasons we can't buy Copper Crickets today.

The alcohol and vacuum allowed for low temperature boiling, which pushed the fluid around the collector loop. I can't tell if they had any check valves.

Back then, there wasn't easy availability of high temperature, low loss collectors like Apricus.

vacuum, methanol, low boiling

sounds like a heat pipe evac tube :) Except the tubes can't protect against high stagnation conditions, and they come packaged it all in a very fragile glass wrapper.

I think a double walled flat plate might be the future. Perhaps two glass layers or glass and a polymer, maybe a vacuum space.

Consider the aperture area of a 4X8 flat plate compared to a 4x8 tube array. Wall to wall absorber, no spaces, no insulated header encroaching.

hr

Evacuating the air between panes of glass

Hot Rod,

If this were a practical possibility, Glass mfrs and window mfrs would be working hard on it.   I haven't seen anything yet.

I recently stumbled on an idea for window glass that is more practical but just as good- use aerogel between the panes.    Aerogel can be made transparent, but in a solar collector it doesn't have to be, diffuse glass works just fine.

under the hood

let me know if the fax arrived.

Got the fax, Man

Nice picture! It looks like they made it as attractive as possible (covered up, that is), and it doesn't stick up vertically like most geyser pumps do.

I don't think many of them are still in operation, does anyone know more?

I can post the operation description as a PDF if anyone is interested.

That thing should be

In Dan's contest.Hard enough getting people to put flat plates on their rooves, imagine one of those it looks like Procrastes' bed.

I want the PDF. Post it please, Kevin I want to see how it worked.

Copper Cricket Marketing Info from Hot Rod

A geyser pump is like a coffee percolator.
See attached

Self Pumping

We actually manufactured these systems for a while. This was before the Copper Cricket.
The pumping action was finicky and we closed our business relationship. The principals went on to making their own unit, the Copper Cricket.
I think the systems eventually stopped pumping properly, either due to installation issues
or poor performance. They usually operated with large delta T's.

Most of our systems wound up being actively pumped with AC or PV's.

This is a variation on the theme:
http://www.bubbleactionpumps.com

You could use ethanol instead of methanol. Wouldn't that make work fun!

Tom in Maine
www.americansolartechnics.com

John

I would rather see the controled flow of water from a tap water resource. There would be a valve regulated by a temp sensor... like this
http://www.youtube.com/watch?v=w5S9lXT1ZmI

It Didn't Work

For what it's worth, I set up a test for my steam pumping idea. Although I achieved steam with the e-tube collector, I didn't get any steam bubble collapsing and percolating like I had postulated.

It happened pretty much like Gordan had predicted, it just steadily did the steamback thing.

Kevin

Did you draw some vacuum?  That might encourage bubble formation and longevity.  Meddlesomely yours,  Larry

No Vacuum

I didn't draw a vacuum, but I don't see how it would help. I had no trouble generating steam. (250F at 1 psi)

I need something to condense the steam bubble quickly. Just like what you don't want in a steam heating system. In this case I want the steam hammering, because each time a steam bubble collapses, cooler water would be drawn into the inlet of the solar panel.

I think it would look just like a european syle bottle trap. Back to the lab/backyard.

Partner

What was the Methanol/Water mix you used?

Methanol mix

I think it was about 50-50

Old solar ideas never really die

Looks like the latest version is based in Virginia. www.sunnovations.com Lots of investor partners! And no mention of previous versions on their website.

As Usual, the Wall has all the info

http://www.heatinghelp.com/forum-thread/135984/Passive-Pumping-Part-II