Dual stirling generators electrically heated

Discussion on Stirling or "hot air" engines (all types)
Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Dual stirling generators electrically heated

Post by Melvin C. Redfern » Wed Aug 22, 2018 5:14 pm

So,
I am going to sandwich an electric heating element between the hot ends of two Stirling engines, each attached to a generator, one which powers the element. Anyone know any Kockum industries engineers? I am thinking of using a mechanical cooling system and was interested how the ones on Sweden's sub fleet worked.

Trevor
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Joined: Sun Nov 06, 2016 4:07 am

Re: Dual stirling generators electrically heated

Post by Trevor » Thu Aug 23, 2018 2:40 pm

Hi Melvin
Not sure what you want to do will work. If both engines are the same size and one is a heater for both, you will be trying to do the "Holy Grail", that is a perpetual motion machine. Physics show this cannot be done if you want the same power output to boyh.
Trev

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Sat Aug 25, 2018 6:46 pm

Looking at taking two of these:
https://www.inresol.se/products/inresol-v2-6
And sticking the hot ends into one of these:
https://mhi-inc.com/PG3/robust-radiator.html#t-1
If the inresol can put out a combined power of 20 kwh and the electric pipe furnace only uses 12 kwh at 700° celseus over what is required to run the engines, then feasibly one could use just 9 kwh to turn two 10 kwh Stirling generators.

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Sat Aug 25, 2018 6:49 pm

If it works, it would be a free lunch engine, not a perpetual motion machine

Trevor
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Re: Dual stirling generators electrically heated

Post by Trevor » Sat Aug 25, 2018 11:01 pm

Impressive Engines - I am not sure of the electrical robust radiator running both engines to produce 20kW. It would mean you are getting more energy out than what is going in. If you accomplish this you will go into the history books.
Give it a go and I wish you the best - There will be a lot of surprised looks if you accomplish it.
Trev

Melvin C. Redfern
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Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Sun Aug 26, 2018 10:00 am

You can cook multiple hotdogs all at once in the same campfire. So what does that have to do with anything? Picture this, an electric furnace, perfectly square, say 2 feet by 2 feet. The inside space is heated to 1200° celseus, the electricity source running from the bottom, leaving five sides free. All five of the remaining sides have a hole the size of the hot ends of these Stirling generators. You plug the hot ends of the Stirlings into the furnace, which requires say 20 kwh to run. You then still get 25 kwh out of these on the low end, 50 kwh on the upper limit. You are heating a space, and simply "cooking all the hot Stirling dogs at once, over the same electric campfire."

Trevor
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Joined: Sun Nov 06, 2016 4:07 am

Re: Dual stirling generators electrically heated

Post by Trevor » Mon Aug 27, 2018 4:22 pm

From a heat source with Sterling engines recovery is at most 35% - Very good efficiency compared to other motors.
What you are saying is fine, but all that heat is wasted - check out the other threads in this forum and you will understand.
Maybe some one from this forum can answer better than me.
Trev

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Mon Aug 27, 2018 5:18 pm

On a campfire, a lot of heat is wasted. I was talking to Omega engineering, and the idea now is, a 900° celsius pipe style furnace, inside diameter approximately 11 inches by 21 inches heated length. The V2-6 generators are only 5kwh apiece and the furnace requires 9 kwh, so only teasing out an extra 1kwh. Not really free though, remember these Stirlings require watercooling, and that requires more power than these could put out, but if these were being cooled by cold seawater forced through by the forward motion of a submarine, then these might give you enough extra power to charge batteries while traveling underwater. Would using pure CO2 at atmospheric pressure in the furnace chamber help retain heat a little better?

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Mon Aug 27, 2018 8:39 pm

https://www.omega.com/pptst/CRRS.html
Forced to backtrack on free lunch statement, the tube furnace only requires 5400 Watts to run at 900° celsius, plus it is right off the shelf. Looking at CRRS-1215/240-A.

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Mon Aug 27, 2018 8:53 pm

The Stirlings from inresol are $9,500 each, plain, going to try a cheaper mini version first. Will post upon the success or failure. Definitely want to see if filling furnace chamber with pure carbon dioxide will increase heat retention.

Trevor
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Joined: Sun Nov 06, 2016 4:07 am

Re: Dual stirling generators electrically heated

Post by Trevor » Mon Aug 27, 2018 10:55 pm

Good one Melvin - Keep the fingers crossed
Trev

Ian S C
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Location: New Zealand

Re: Dual stirling generators electrically heated

Post by Ian S C » Tue Aug 28, 2018 3:47 am

Electric al generation by a Stirling Engine of (say) 1Kw might at most develop .75 Kw to .8 Kw, a heating element might have a similar efficiency, producing say .5 Kw of heat, and the engine might take up 50% of that, it ain't gonner work mate. But an electric powered Stirling Engine is a good demonstration model, a constant heat source, easily portable, and clean.
Ian S C

Melvin C. Redfern
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Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Tue Aug 28, 2018 8:35 am

Found this cheaper tube furnace:
https://www.omega.com/pptst/CRFC.html
Looking at CRFC-112/120-C-A
500 watt, 120v
No one has ever tried this before. Looking for 2 low rpm alternators, say 500 to 1000 Watts each. The hot ends of a Stirling engine will be plugged into the hole on either side for a total of two, simply increasing effiency of heat source.

Melvin C. Redfern
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Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Tue Aug 28, 2018 8:50 am

The inresol Stirlings are supposed to make 5kwh each at 750°-900° c. The omega tube furnace will steadily heat a length of pipe 24 inches long at up to 980° c, while consuming 5.4kwh at maximum. The heated length of two inresol generators is only 20 inches. I have run a forge, I can heat a dozen pieces of iron at once so long as they fit in the forge and use the same amount of fuel and air to heat them as just heating one piece of iron, the key there is to fully utilize the hottest part of your forge fire.

Melvin C. Redfern
Posts: 10
Joined: Wed Aug 22, 2018 5:02 pm

Re: Dual stirling generators electrically heated

Post by Melvin C. Redfern » Tue Aug 28, 2018 8:59 am

Easy proof of concept, see if you can get two toy Stirlings to run off the same candle flame. Like the little ones they sell on amazon.

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