# Stirling engines



## MELOC (Sep 26, 2005)

Has anyone had any success using a Stirling engine to run a small generator to maintain a battery bank intended for back-up? How about something that could use 185 F water as a power source? I know Stirling engines have very little power. I am wondering if it would be feasible to provide power to back-up a .7 amp motor for the outdoor furnace I am installing in the event of a power outage.


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## spacecase0 (Jul 12, 2012)

you can get lots of power from them, they are just very big with lots of pricey metal to get lots of power out of them my question is a 0.7 amp motor at what voltage ? likely 12V or 120V, but that is a factor of 10 power from one to the other


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## MELOC (Sep 26, 2005)

I'm pretty sure the circulation pump is @ 80 watts at 120 volts. The pump will probably be a Taco 007 series circulating at @ 20 gph. I'm just trying to have some fun thinking about novel back-up systems and the possibility of using the boiler itself for power. I am concerned about power outages, but a generator is not in the cards at the moment. So I started thinking about other ways of backing up the pump. A small battery bank and inverter could work, but something needs to charge it. For that matter, a stirling engine could run a small pump, but that would require a manifold and bypass...and another pump.


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## Jim-mi (May 15, 2002)

Yes I know you said "not in the works at this time" . . . .
But a Yamaha or Honda 1000i would run a circ pump that small, for a very long time on little fuel.
Wish there were items run by Stirling engines on the market........
Many folks have tried............


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## MELOC (Sep 26, 2005)

On youtube, I saw a British Stirling powered generator fueled by kerosene. It was a buggy rig, ultimately, but it had a nice compact design. In that case, I see no real benefit over simply using a fuel powered generator.

I can imagine that if you could build a stirling engine to run from 185 F water, it would probably have to have a huge displacement.


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## Jim-mi (May 15, 2002)

Under the heading . .There ain't no free lunch . .

Last I saw at the hardware store, the best grade of kerosene was $5.60 per gallon . . not much less in the bulk red dyed tanks . . . . . .


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## watcher (Sep 4, 2006)

I have looked for plans to make a 'real' one but all I've ever found are plans for little toy ones.

My thinking is to build one to use solar heated water. I don't care about efficiency, my thinking is if you only get 20% of the energy from the sun converted into usable energy its more than you had when you started.


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## Harry Chickpea (Dec 19, 2008)

Just for grins, you could consider taking a model steam engine and completely enclosing it in a sealed unit and use alcohol to create the steam. It boils at about 175 degrees, so the 185 temp of the water in a jacket pipe around and alcohol boiler could be just enough heat to create the steam to run the engine.


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## FarmTechnician (Dec 25, 2014)

I advise against stirling engines for usable power production. The size would be enormous (think old school steam engines with massive walking beams and 3ft diameter cylinders). The reason stirling engines are poor performers is because realistically the difference in pressure will never be greater than 1 Bar (14.7 psi). You would need a piston with 40+ square inches of surface area moving at 1 ft a second to produce 1 hp. Basically a 1hp stirling engine would have a 7" diameter power piston with a 12" stroke moving at 30 rpm, @ 100% efficiency. Stirling engines are about 20-25% efficient, so you will need to increase the RPMs by 4 to 5 times their value, or increase the working volumes by 4 to 5 times. 

P=T/V 

As you can see the shear size of these things makes them very unattractive for anything other than novelty.


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## ace admirer (Oct 5, 2005)

there was a company that made stirling powered water pumps,,,as others have said very low power...eriksson? i seem to remember that the british navy had sterling power submarines for their silent operation. as others have pointed out at low delta t's and low delta P's, the efficiencies aree too low. but neat engines


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## postroad (Jan 19, 2009)

Sometimes I wonder if it would be possible to make a rotary steam engine? Does that sound ridiculous or would it be doable. I know that steam turbines are common but something like a Mazda engine with high pressure steam pushing the piston dohicky.


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## spacecase0 (Jul 12, 2012)

postroad said:


> Sometimes I wonder if it would be possible to make a rotary steam engine? Does that sound ridiculous or would it be doable. I know that steam turbines are common but something like a Mazda engine with high pressure steam pushing the piston dohicky.


don't see why not, try it and tell us how it works out


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