Generate power from Outdoor Wood Furnace

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Generate power from Outdoor Wood Furnace

Postby poorpat » Mon Aug 17, 2009 7:00 am

Is it possible to incorporate a Stirling Engine to produce power
utilizing an Outdoor Wood Furnace, water temperature approximately
170 degrees F at 11 gallons per minute?? Any information or help
would be much appreciated, Thank you,
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Generate power from Outdoor Wood Furnace

Postby stan.hornbaker » Mon Aug 17, 2009 7:12 am

The output energy level of the hot water output would not be sufficent to run a Stirling engine to generate any significant electrical power output.

Such a Stirling engine would have to be designed for the energy supply conditions and again the small electrical output would not justify the expense.
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Response to Generate power from Outdoor Wood Furnace

Postby bptdude___2569 » Mon Aug 17, 2009 1:06 pm

You only listed the temperature of the water, the intended product of the outdoor furnace.

Can you measure the temperatur of the firebox and ask again?

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Response to Generate power from Outdoor Wood Furnace

Postby jol.andre » Wed Jan 13, 2010 11:39 pm

In my view, it depends on how much power you want to generate.

I have been thinking of a similar project, involving a moderate-performance, home-built Stirling using common materials and relatively low temperature differentials.
Firstly, use the fire to heat the Stirling's hot side and use the cold side to pre-heat the water.
The approximate engine design parameters could be like this:
Hot side temp: 400F (473K)
Cold side temp: 120F (323K)
Hot-Cold delta T: 150K
Theoretical Carnot cycle efficiency: (473-323)/473K = 31.7%
Mechanical efficiency of home-built engine: (I'm trying to be conservative here!) say 20% of Carnot :
20% * 31.7% = 6.3%

With a low efficiency like this, (6.3%) I hear some people laughing. Still, this little engine might be able to operate even when the outdoor furnace is running on light duty (like in Spring or Fall) and putting out just 3200W in heat, and produce 150W of mechanical power.

With an efficient permanent-magnet alternator, you might get 120W of electricity.

That isn't anywhere close to going off-grid(!), but it is enough to run the furnace's circulator pump (around 85W) continuously if needed, and charge batteries to allow occasional use of a well pump or house lighting.

If you cooled the engine's cold side with the hot water circuit, all the heat used by the Stirling would go towards heating the building, so you wouldn't be burning any extra wood to run the Stirling.

While not being a high-performance power plant, this setup would provide basic utilities to your home during a power outage: heat, tap water and some light.

Compare 120 watts of power available 24h/7 days with what you get from solar PV panel$$$ or a wind turbine (they only work when they want to), and you'll see that a home-built Stirling makes a cheaper and more dependable source of emergency power.

Anyhow, that's what I believe.
Only building it will prove the concept.
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Re: Generate power from Outdoor Wood Furnace

Postby Brent » Mon Oct 15, 2012 11:28 am

I think a low tech Stirling engine integrated with an outdoor wood furnace is perhaps one of the best applications of Stirling engines that I know of.

The power from the Stirling engine could be used to power the water pumps or air fans needed to make this a complete working system, thus totally eliminating the need for grid electricity.

If any of you wood furnace manufacturers out there need help with this, give me a call.

Brent Van Arsdell
Brent Van Arsdell
American Stirling Company
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Re: Generate power from Outdoor Wood Furnace

Postby jimmyjack » Mon Dec 17, 2012 12:49 am

I'm pump lifting water 200 to 1000 feet. These wells will pump
600 to 1500 gallons per minute. The heat source would be solar and
the cooling agent would be the water from the well. If this could
be done economically, probably 3000 units could be sold in my area
in the next 10 years. The pumps could be started with an internal
combustion engine and then switch to the Stirling when the water
began to flow. I live in an area that was once a beautiful farming
area until fuel costs became prohibitive.
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