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Dreams About Sterling Engines


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#1 Farming guy

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Posted 23 February 2016 - 04:32 PM

Had a dream last night that I was building small sterling engines to power small things like laptop computers, tablets, cell phones, and I can't get the images out of my head!

 

Does anyone know of anyone working on such things?

 

I saw a video of a homemade sterling engine running on the heat from a candle a few years ago, and have been wondering about how much electricity could be generated.



#2 Farming guy

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Posted 26 February 2016 - 06:45 PM

http://www.youtube.c...h?v=UvrBzwBIFhM

 

If I got it right the above link should bring you to a video of a homemade sterling engine.

 

I've been giving a lot of thought lately  to all the potential power going unused from processes that generate heat.  Just imagine people having romantic candle lit dinners with sterling engines generating electricity from the candles!  (Although I think it might be tough to sell my wife on that one!)

 

Perhaps a better idea to have sterling engines powered from the heat of a compost pile.



#3 CraigD

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Posted 26 February 2016 - 11:08 PM

There are a lot of pretty amazing small Sterling cycle engines. I’m most impressed by the LTD – low temperature difference – models that can spin a flywheel on temperature difference between room air and a bit of ice, or room air and a room heating radiator, room air and a cup of hot coffee, or even room air and water slightly cooled by evaporation. According to this page, some LTD Sterling engines will spin with only a 0.5 C difference between their hot and cold sinks!

Though these little engines are impressive, they produce hardly any power – just enough to overcome the tiny amount of friction of their well-made parts to spin a flywheel.

The power of a well-made Sterling engine is mostly a function of the size of its cold sink and temperature difference – the Sterling engine Wikipedia page gives 500 W/m2/K. So to get a lot of power, you either have to have a big cold sink, or a big hot to cold sink temperature difference, or both.

There are some pretty high-power new Sterling engine built on the “both” approach. Sweden has 3 200-foot subs that can run for weeks submerged at 5 knots using a pair of 100 HP liquid oxygen + diesel fueled Sterling engines – the Gotland class, a serious war machine. More peaceful is the 15 HP (11 KW) CleanEnergy Sunbox concentrated solar-powered Sterling Engine.

There are some interesting antiques, such as the 180 W (0.25 HP), diesel or gasoline -fueled Philips MP1002CA “Bungalow generator” from 1951, or the wood/coal/gas fueled Ericsson's water pumping engine from ca 1880.

Keep in mind that Sterling engines aren’t “something from nothing” – if you use one to generate electricity from a temperature difference produce by your house heater, you’re more than paying for it in increased heating fuel or electricity consumption. If you can find a true waste heat situation – something hot that needs cooling, like a computer heat sink – it could server double duty of cooling what need to be cooled while looking cool, but I think little Sterling engines are good mostly for their impress-you-and-your-friends-with-their-niftiness value.

You can get really nice little ones for around US$35. I’ve been hinting around gifting occasions for years, but no luck so far. :)

#4 Farming guy

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Posted 27 February 2016 - 05:12 PM

So, if you wanted to run a sterling engine off a compost pile, you should be able to collect more power in the winter?    My goal might not be to produce a whole lot of power , but enough to be useful for something.  It just seems a shame to let that energy not be used.  Besides, it would be really fun to build one!  



#5 CraigD

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Posted 28 February 2016 - 02:47 AM

So, if you wanted to run a sterling engine off a compost pile, you should be able to collect more power in the winter?

If your engine’s cold sink is air-cooled, yes. The temperature difference between the hot sink and cool sink determines the engines power, so colder air means more power. For example, if the hot sink in the compost is at 80 C and the air is 20 C in summer, 5 C in winter, the power will be 25% more in winter.
 

My goal might not be to produce a whole lot of power , but enough to be useful for something.

If your compost heap is big and hot, you could get a lot of power from a Sterling cycle engine.

I imagine what you’d want to do is make a shallow cylindrical concrete pit/tank to hold the compost, then cover it in steel, making that you hot sink. You’d then want the piston to be as big as the top of the pit. For a big heap, this would give you a hot sink with a surface area as big as a few hundred m2. You’d then want to have lots of aluminum cooling fins on the top of the short, wide piston for the cool sink. With a hot sink with an area of a few 100 m2 and a temperature difference of 60 C, you’d have megawatts of power, like a small commercial power plant.

The trick, I think, would be refreshing the compost. My guess would be you’d want to make 2 pit/engines, so you could shut one down while you were emptying and refilling it. You’d need to have a steady source of composts.
 

It just seems a shame to let that energy not be used. Besides, it would be really fun to build one!

It’s fun just imagining one. Actually designing and building one would be an awesome project

#6 haram

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Posted 01 November 2016 - 03:36 AM

"Josh “Mac” MacDowell of San Antonio Texas had a brilliant idea. He took a Stirling engine, a type of engine developed 200 years ago, and added some 21st-century technology to it. The result is a hybrid electric car so efficient that you never have to stop to recharge, reports Houston’s KHOU11."

http://www.digitaltr...-hybrid-engine/

http://www.khou.com/...0-mpg/242673922