OT- Stirling engine calculations

tom_stalcup

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Hey folks... I was thinking about starting a home project, and figured I'd ask if anyone here had any experience with these items.

I play a lot of computer games.... For 6-10 hours at a stretch sometimes. Between the graphics card and the processor, my computer at home puts out a LOT of heat. In the wintertime, I don't need to keep my shoes on to keep my feet warm.(a nice touch)

Since I'm already producing the heat, I wanted to try to add something to USE that heat(and the air from the vent fans) to run an additional fan at the intake of my computer. I'm not looking for anything horribly cost efficient to make, as long as it's energy efficient in the long run. This is going to be a learning project more than anything else.

I've been digging around on Google for the last few days, and reading up on the various sites that are out there.

It appear that most stirling engines are designed to run a higher delta-Temp than I'm going to get out of my computer tho....

THIS site sells a small model that runs from a relatively low delta-Temp (4 degree c), but the only thing it has to do is keep the wheel turning. I'm really not sure it would be able to do enough work to actually move any air, and I don't know enough about the calculations involved to find out(but I'm working on it).

Has anyone played around with a small version of one of these?

How much work (realistically speaking) can you expect to get out of something like this with a differential temp of about 20 degrees?(for example... I haven't taken any measurements yet)
 
This is personal opinion but I think you are going about it backwards, heat is detrimental to any electrical device in the long run.

Years ago I used dual Celeron 300MHz CPUs to build a server running over 500MHz. I built it inside a small refrigerator, with dessicant, to prevent heat and other issues.

I know, Celerons do not support dual cpu systems, figure it out.

Allow it to run hot for long periods and you with constantly have failures...IMO.
 
Sterling engines very interesting.

There is a local person who using sterling engines and photo cells to power his home. He is completely off the grid.

Yes, you can get a sterling engine that would run off the the exhaust heat from your computer but it would generate more energy than you computer consumes. How would you duct the computer exhaust into the sterling engine?

Think about it. All the energy you put into you computer is converted into heat in the end.

Sterling engines may be in our future as energy prices rise.
That local person is an engineer that read one my articles and called me. I was just as interested in what he had to say about how he supplied all his own energy and the fact he lived only a couple miles away.
 
Tom,

I think that you would produce more heat from the second fan then you would remove

A 379.00 "conversation piece"? I would like to know how it works

I think its like having a electric car and carring around a generator to charge the cells, you would need such a large generator that the car would need more power to carry the generator so you would need more batteries to produce more and a bigger generator to charge the bigger batteries....bla bla bla


Ok try this a air to water heat exchanger that you could ???hmmm
 
Well, THIS person sells a plan and kit for a lot less than $379..... As long as you want to put it to together yourself(which I do)

My system is doing an excellent job of removing heat from the processor and other components, and re-distributing it into the people space. I just want to find a use for the excess heat other than keeping my toes warm in the wintertime. :)



Yes, you can get a sterling engine that would run off the the exhaust heat from your computer but it would generate more energy than you computer consumes. How would you duct the computer exhaust into the sterling engine




I hadn't got that far yet... I'm still at the stage of figuring out what the size range of the device could be for a low heat differential system like this one, and still be able to move a fan blade effectively.

All of the things I've been reading seem to imply that in order to do any useful amount of work from a small differential, you need to increase the size of the engine to compensate accordingly.



I was thinking along the lines of putting a section of ductwork on the back of the computer going up another foot or so, with a heat transfer plate (of some kind) at the upper end connected to the bottom of the stirling engine(the heat side), and an opening at the back a couple of inches lower that the top of the ductwork to let the moving air escape. (sort of like a chimney)



My current motherboard isn't using a fan to cool it, but has a heat pipe setup going to a set of cooling fins..... I may end up trying to connect something up to the cooling fins to transfer the heat directly instead of blowing air across it.



My processor has a fairly decent fan on it...



My graphics card has a built-in fan on it with a bunch of heat fins surrounding the fan.

Heck... I may just run a small fan from it and point it at me instead of back into the computer...


More information... This isn't for any horribly practical purpose on my part. I just think it would an interesting way to get involved in stirling engines, and expand my own horizons accordingly. I just don't know at this point if a small engine like this CAN actually produce enough energy to do something remotely useful, or if it's just relegated to conversation piece status... But I'm willing to give it a shot.
 
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A debate came about in the HYDROGEN thread that stated "You can not get more out than you put in." A standard computer power supply is capable of 300 watts total, therefore the heat generated (regardless how hot you think it is) will not be able to exceed the PS watt rating. I would think in general that the heat is secondary and less than 1/3 (or more) of the wattage capabilities of the PS.

Since I brought up the hydrogen thing; I am writing a paper on the possibilities of using it as a fuel in conjunction with electrolysis and batteries. I knew the principle they were using but could not explain it. I now know that many of y'all did not study the issue enough to provide an informed opinion...you just ASSUMED.
 
rsdoran said:
Since I brought up the hydrogen thing; I am writing a paper on the possibilities of using it as a fuel in conjunction with electrolysis and batteries.

Ron,

Could you post the paper on your site when you are finished, I would like to read it.

Thanks
 
energy lost and found

rsdoran said:
I would think in general that the heat is secondary and less than 1/3 (or more) of the wattage capabilities of the PS.
Where does the power go if not to heat? The all energy a system uses eventually gets converted to heat unless it is stored as some form of potential energy.

When I was in nuclear power school we were asked where does all the energy the reactor produces go? It all goes into the ocean in the form of heat eventually. If not the submarine would get very hot quickly. Some power may be stored temporarily in the form of electrical power in batteries.

The problem tom_stalcup will have is capturing as much as the heat as possible.

PhilipW, that is an interesting link. Too bad the prices weren't posted. I have been told the sterling engines are very expensive because not many are made. It will be interesting to keep an eye on Wispertech. I wonder how the units they have sold are holding up.
 
How about running a Peltier TEC chip in reverse mode,IE, heat delta in and DC out?
I have a few 1" chips for a solar cell project I'm dinking with. I'll reverse mode one and record the results.

Rod
 
Peter Nachtwey said:
Where does the power go if not to heat? The all energy a system uses eventually gets converted to heat unless it is stored as some form of potential energy.

Or used in some form of kinetic energy (like all those fans). In trouble shooting a server recently I discovered something rather disturbing... the fans were drawing ~150W just by themselves!
 
Peter Nachtwey said:
Unless you have found a frictionless environment, kinetic energy quickly gets converted to heat.

Well ok, good point... I was thinking in terms of the electronics essentially producing only heat where the fans move air (and produce a little heat at the bearings, etc), but you are correct, in the end it all winds up as heat after friction.
 

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