Stirling water pump for electricity

[matthew]

Hello!
I plan to build such an engine, just a little more powerful.
The problem is I do not have any plans, I need all dimensions.

[matthew]

http://www.youtube.com/watch?v=b1BpGswGbRs

[fullofhotair]

Matthew,
Why do you want to make a stirling engine to pump water to make electricity? Why dont you just use the stirling engine to directly generate electricity? How much electricity do want to produce? That will determine the size of engine you need.

[matthew]

The fact is that I like the cooling provided by the water.
I want to produce 10-20W and the heat will come from a wood stove. The water should easily take the heat away.

[matthew]

If I could get more power, that would me great.

[MC_Hamster]

The water doesn't really 'cool' anything in the long run. It does allow for better transfer of heat away from the 'cold side', but if you're just pumping that same water back on, you're just bringing the heat straight back. You can use more water, but that just delays things (bigger thermal mass, takes longer to heat up and cool down again). You could add a 'mister' to make droplets and increase the surface area to allow faster heat transfer from the water back to the atmosphere, but that's adding extra pressure and takes more work.

So unless you're planning on piping that water away somewhere to either some sort of radiator/heat exchanger to let it cool back down, or are replacing it with fresh, cold water... it's not doing a whole lot over extended operation.. and if you're powering that off the engine itself, then you need to work out if the power you gain from that brief period of extra cooling is worth the power drained by the pump.

If you're pumping water to begin with (eg the old Ericsson Rider pumps, as shown by Jay Leno here: http://www.jaylenosgarage.com/at-the-ga ... ndex.shtml and NB that even though it bears the 'Ericsson' name - that's not an Ericsson cycle engine, it's pure Stirling), then 'buffering' some of that water to help cool the engine is a fine idea.. but if you're circulating water around purely for the sake of the engine, then it's really a closed loop that can only possibly be a power drain on the engine.

At least, that's how my brain's seeing it, anyway.

[Ian S C]

Pumping water to generate electricty is extremely inefficient, first the ware pump has a low efficiency through friction ect. Second, the generator will be about 50% efficient, so if the over all efficiency of that section of things is half that of the pump, Cut out the pump, drive the generator direct. For water cooling use a thermosyphon system, this works OK even in very small engines. Ian S C

[matthew]

Of course I want to use the water side just for the cooling, the power will come from the piston. I want to pressurise the sistem at a few bar and drive the water through a radiator which could heat a nearby room.
I want my engine to be versatile, I plan on building more engines if everithing works fine, some could be used as pumps.

[matthew]

I belive this model could be turned into an linear alternator, of course using other kinds of materials.
http://www.youtube.com/watch?v=G2CCDwwRfhw
Although the efficiency would be lower, the overall cost would be diminished.

[matthew]

MC_Hamster, your link is great, the problem is there is no scheme there.

[fullofhotair]

Matthew;
Do you have plans for that u-tube stirling engine? I really like it. I dont believe it is as simple as it looks. Iam afraid if you build just what you see it wont work. If your going to heat it on top of a wood stove you wouldnt want to use plexiglass or plastic like the one in the video. It is nice to see the workings of the interior. They dont show the water pump, to bad.

[Ian S C]

They don't show the heating system, or very much for that matter.
Mathew, have you built a reasonably complex engine of any sort, if not get a design for a fairly simple Stirling Engine, and build it. A fairly simple engine, of moderate size should be able to produce 5 to 10W. It's called research and developement, everyone does it, a tin can motor could be a good start. Ian S C