Posted by Morris Dovey on September 30, 2009, 10:58 pm
[Posted earlier to alt.solar.thermal, and posted here because I know
there are folks here with a lot more pump knowledge than I have]
I've been tinkering with fluidynes (there's some background info on-line
at http://www.iedu.com/DeSoto/Projects/Stirling/ for anyone who might be
interested) and last night I made a conceptual sketch of a fluidyne well
pump and thought I'd post it, hoping that folks here might be able to
spot at least obvious problems.
I've drawn it to scale, with a 100 mm bore fluidyne engine - and with 50
mm water pipe extending to a depth of 5 m. I've uploaded the sketch to
http://www.iedu.com/DeSoto/Projects/Stirling/5mPump.jpg and plan to
rework as needed (your critique will help!) and incorporate into a web
page if/when I can arrive at something that should work. Please keep in
mind that I'm not a pump expert but am eager to learn. :)
The check valves are located halfway between the surface and the bottom
of the well pipe, with the hope that this arrangement will help avoid
pulling sand/rocks into the check valves.
The loop of pipe on the pump side is an attempt to avoid drawing air
into the engine if/when the well pipe drains.
Your comments will be much appreciated!
DeSoto, Iowa USA
Posted by Curbie on October 1, 2009, 2:42 am
Are you using cool well water for cold side Stirling, or would well
water temperature be availible for other cooling, solar AC?
Posted by Morris Dovey on October 1, 2009, 3:25 am
This design is strictly air-cooled, but I don't think it'd be difficult
to add a water jacket to the cold head to cool with well water.
There's a need to be careful to avoid having the water jacket become an
insulating jacket - I can imagine situations when it might take a bit of
time to move water from the bottom of the well to the water jacket, and
a significant heating of the cold head during that time might kill
oscillation before water reached the jacket.
Having said all that, my approach is to get the most simple version
working first - then see what can be done to boost performance.
The drawing was intended as a starting point for a group in a really
arid part of Argentina (they have a web page at
http://cediac.uncu.edu.ar/ges.html where you can see what they're up
to). They've already built a traditional Stirling engine and run it
successfully, so I doubt they'll have much trouble with this.
For this project they say that 100 liter/day from 5 m below the surface
qualifies as a successful outcome.
DeSoto, Iowa USA
Posted by Curbie on October 1, 2009, 9:07 pm
I see your point.
Can you explain their reasoning behind that odd regenerator, I think I
see what their up to with the multiple lines (you where up to the same
thing) , but isn't the elongated shape counter productive?
Is the something in those lines that they're trying to give up more
heat to by expanding the path's volume???
Posted by Morris Dovey on October 1, 2009, 10:18 pm
Perhaps - I don't know. The elongated path may contribute to resonance
within the system. There's a contact link on that web page and I know
the folks there speak English - but if you're not comfortable, I can ask
next time I e-mail them.
I've moved my sketch (and a bit more explanation) into a web page at
and plan to add a link to the Stirling project menu.
DeSoto, Iowa USA