Backyard Aquaponics
A place to discuss aquaponics

That's pretty cool. Is there an easy to source liquid that has a higher thermal expansion rate than water?

I think it important the the water does not expand.

It is the air that expands and contracts. The water acts like a piston.

I think that pipe and tube dimensions are pretty important so as the thing works properly.

Oh, it seemed to me like the water expansion was what moved the air.

Hi Tamo ...

I think the air expands, and moves the water.. which causes air pressure changes in the last column in an oscillating fashion which can be used to drive a simple two valve pump. I am not sure whether a liquid with better expansion properties would make it work better or worse. You could be onto something!

The photo of the one from desoto and the diagram of the fruit jar one are quite good.

I bet dimensions are pretty critical and a good way of using solar to get good temperatures for the warm side (solar collector?) and shade etc for the cool side would be good.

I think these sometimes don't self start...

I just contacted Morris Dovey from the DeSoto link above.

Morris was very helpful and indicated that his fluidyne system needs more improvement but that it does work very well so far. Any help regards optimisation of dimensions would be well recieved.

Morris suggested that the hot side needs to be as hot as you can get it from a solar colector. He said that temperatures up in the upper 90 deg C area would be good! The thing works on temperature difference so the cold side should be as cool as possible. He suggested using pond water to cool the cold side. Apparently he has managed to attain a 9 inch stroke so far and is aiming for 18 inches with his design and says that it is self starting. He says that he needs to develop his system more in order to optimize the dimensions. The system can be easily be used to pump either water or air.

I think that maybe despite a large temp difference requirement regards hot and cold sides of the system maybe this could work in certain areas of Australian extreme sunshine.

If we could manage to get one that could work on Hot side painted black in the sun and cold side in shade .. even if it were slow to deliver ...

would be great!

I constructed a "liquid piston"/fluidyne pump a few years back. At a lift of about one foot the pump could move 300 gallons of water in a day when a propane flame on the hot side. I once had a set of plans, but the problem is that scaling it up never worked.

i've seen one built as well and I came to the same kind of conclusion.... they work and it's amazing, but a hamster running in a wheel is more powerful, making them pretty useless.

Would a guinea-pig work better??? Especially if it was fed Prawns not Shrimp?

I have a feeling that such a system, if tuned and dimensioned well will work, albiet slowly in a Sun/Shade environment.

One tube painted white .. in the shade...

One tube painted black .. in full sun..

But it is only a gut feeling.

But if it is cheap to make, no parts to wear out and uses free solar energy ... only has to dribble a little and raise water or air a small height it might be worth the investment in some pipework.

Just thinking out loud....

BTW .. I have several Bandicoots visit our backyard most evenings... (Marsupials the size of extremely large rats, more like the size of hedgehogs) .. they are very tame. My daughter has got to the stage where she can pat them, stroke them and can even put her fingers inside mom's pouch ! (Rear facing - unlike Kangaroos).

Maybe I should set up a bandicoot training wheel and link it to a diaphragm pump to supply air in the evenings to my fish tubs?

When I clean 55 gallon drums if I shoot hot (from the hose being in the sun) water into them and then roll or shake them a bit they blow of lot of pressure when I open the bung! I have always thought all you would need is use a sprayer/injector to alternate between sprays of solar hot water and cool tap water to cause "large" pressure changes. At that scale it really does not take much temp change to cause large volume changes.

Will those solar fountain pumps push enough pressure to use a spray head?

The solar pump idea won't scale up very easily.

I have pictures of a kid constructed spiral pump that is very low energy input, yet will move about a gallon of water per minute. 80 foot of lift is possible. The High Peaks Water Lifters constructed it as their entry for the Water Works Tech Challenge 2008 in San Jose Calf yesterday. 200 teams built projects. We were to only ones from New York, and did a live web cam entry into the museum from Westport NY.
Follow this link:
http://techchallenge.thetech.org/the_challenge.cfm

They used an overshot water wheel but, wind power could be used turn to a spiral pump. I have pictures. Now if I could just figurer out how to compress the files, I would post them here for you to see. Or I could send them for you all to view, if you send me a request with your email address.

I should have told you all about the Challenge sooner, you might have kids that could have entered too, via web cam.

Oh one more thing.
Engineering done correctly, is social work.

Matt

Sparkchaser ...

I think you are a science teacher or involved in Sci - Eng teaching somehow too!

That looks like a great challenge...

Two of my classes have particpated in a one day National Science and Engneering event. They did really good in the heats.



I wonder if a low temperature differential (Sun / Shade) is enough to make a machine such as the fluidyne kick off ... albiet very slowly?

(I do understand that dimensions are important .. but would it be possible for one to lift water only a few inches, very slowly using passive solar power?

I taught Phsysics for 8 years and but am really just an engineer. I do work with the county 4H and Cornell out of Ithica NY. They supplied the web cam we used to enter the Challenge from NY. The schools are teaching to pass tests in this part of the country. The Challenge supplies an open ended problem for the kids to solve and build. And the kids get to see how others solved the same problem. That was the most fun for me, seeing the Team evaluate how well the others were doing, and they were suggesting corrections. There needs to be a balance with some hands on application of what has been learned in the classroom.

You want to try a team for next year?

You can push water much farther than you can pull it, so a pump based on suction will not work well over 33 feet. And a soda bottle will colaspe under even a mild vacuum so I think a more rigid container will be required.