3KW Stirling Engine - Pics provided

Discussion on Stirling or "hot air" engines (all types)
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

yellow88fiero wrote: Sat Jul 09, 2022 2:56 pm Let me know if you have any questions about this. I do have a few additional pictures I can share, but this is most of it.

The label does say 3KW engine. and Engine ID Y44.

If someone is interested in it, please direct message me. I haven't done anything with it in the past 2+ years and know the people on this board would likely be better then just putting it on Ebay.

Thanks.
Thanks! What a great contribution and very VERY VERY much appreciated.

https://youtu.be/6-OlbCAVBdo
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

It was a long haul in our little pickup, but headed back to the shop.
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I have one of these salamander heaters back at the shop I've been thinking maby I could hit it with:
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yellow88fiero
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Re: 3KW Stirling Engine - Pics provided

Post by yellow88fiero »

I'm am very much interested in seeing the results of the heater directly on it. Glad you were able to come out and get it. Also very glad it went to an enthusiast. Keep us all updated on what you can do with it.
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Probably the first thing to do is check the fill valve, get some kind of guage that fits and see if it is still pressurized at all.

The fact that, as a test model, it even has a "quick connect" type fill valve kind of suggests it requires fairly regular recharging.

More or less the same type of fill valve found on paint ball canisters.
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Though this Stirling engine apparently only needs 500 psi this is worth taking note of when working with high pressure air or gas:

https://youtu.be/L6IA5mGelR4

There are a number of additional videos on how to fill paintball tanks that may be useful.

Helium as an insert gas eliminates the oxygen so is probably safer in that regard but still, not a good idea to put any foreign substance into the fill valve.
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Still traveling back to NY.

Taking a break at a rest area outside Memphis Tennessee.
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Can't wait to get this thing home, but may at least stop to visit Graceland.
yellow88fiero
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Re: 3KW Stirling Engine - Pics provided

Post by yellow88fiero »

You look like you have a jet engine attached to the back of your truck.
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Just for some clarification, hopefully;

Apparently Infinia had previously gone by a different name:
"Stirling Technology Demonstration Convertor (TDC), a 55-watt space power Stirling engine prototype developed by Infinia Corporation (formerly Stirling Technology Corporation (STC)). It is essentially a free piston machine that generates electric power from a thermal energy input..."
https://www.researchgate.net/figure/Sch ... _238733121

Infinia then became, was acquired by or in some way partnered with Qnergy for a relatively brief period (a few years perhaps) but was then subsequently sold or transfered over to and/or became American Superconductor Corporation. (Numerous sources, mostly press releases)

Somewhere in there ITC (Infinia Technology Corporation) spun off from Infinia as a separate entity.

All this intertwined with NASA, which provided much of the funding as well as technology assistance, Navel intelligence, the DOE and various national and international governmental and non-governmental groups, bodies, organizations, entities, players, intertwined with energy, national security, military contracts, etc. etc.

I think, basically, when people talk about a "NASA type Stirling engine" that is synonymous with the Infinia engine. At least, the same exact familiar diagrams appear to be used for both, either/or:

NASA engine:
TDC_graphic_-_boxed.jpeg
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https://rps.nasa.gov/news/39/high-effic ... rformance/

INFINIA engine:
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https://www.researchgate.net/figure/Cut ... 572798/amp

Stirling Technology Corporation engine:
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https://www.researchgate.net/figure/Sch ... _238733121

etc.
animation_freepiston.gif
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Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

In reading through the documents included earlier, along with others related to this engine, it seems that one of the design points that "must" be met was it's intended use for forward military operations and that it would survive gunfire. In other words, built to military standards, it had to be bullet proof, so it seems.

Though mounted on a steel stand, when loading the engine, it seemed extremely heavy for it's size. With three people loading it onto the truck, it was still something of a strain to lift.

I think that likely the copper windings of the linear alternator can account for some of that weight, but certainly not all. I imagine the thickness and weight of the casing is primarily due to the above mentioned design parameters. It needed to be able to function in a front line military environment amidst bullets and bombs, so had to be built extra heavy. I don't think that the need for containing pressurized helium can alone account for the thickness of the metal casing. A paintball tank is very light weight and can hold 10X the pressure.

So,...

Likely, an engine for ordinary domestic use having a similar power output could be manufactured which would be very much lighter at a fraction of the cost.

If the engine is no longer pressurized, most likely the first thing I'll do is tear it down to see what's inside.
yellow88fiero
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Re: 3KW Stirling Engine - Pics provided

Post by yellow88fiero »

I am pretty sure the engine is the same as the pictures for used in all of their designs. I don't think it is designed any differently then the ones used for the power plant. I agree it is built heavy and extreme, but would seem like they do that to meet traditional power utility specs along with milspec. I think one of the documents had the weight of the engine in the 200-300lbs range which is inline with the one you have.

I do agree you should be able to do it lighter, that would be great in an actual light commercial application that can be sold as you mention at a fraction of the cost. I think many people showcase these free piston with basic tin cans and they work, the real key is what type of performance will you get, especially using lighter materials that may be harder to keep the tolerances they are using in your engine give it some better performance.

You may have posted this before, but I like this youtube breaking down the older version of this engine 1KW, but I think you mentioned and you can see in the video that it isn't much different in size, but the performance is now up to 3KW instead of 1KW that this one had.

https://www.youtube.com/watch?v=adLZIDxM8tQ

https://www.youtube.com/watch?v=adLZIDxM8tQ
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

I'm not 100% certain, but this could be useful anyway.

In researching these engines, I came across a NASA patent for a linear generator using "Halbach Arrays".

https://patents.google.com/patent/US10581355B1/en

It would make sense, I think, to use this to make a lighter weight, more powerful linear alternator.

There are a number of videos and such on the subject.

Seems like a rather simple way to boost the output of a generator.

https://youtu.be/ep2PAMrzwEU
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

I may have been wrong about the pressurization.

There are two areas where something is etched on the engine near the fill valve. I used some black marker ink to make one more visible.

Looks like "cold proof 1610 Psig"

Not sure if that is the rated pressurization or what it was tested at, or how much the seal at that joint is able to contain or what exactly, but the proximity to the fill valve kind of implies that is the fill pressure.

I read an interview with an Infinia executive who stated that their engine required only relatively low pressurization at 500 psi, but maybe that was in reference to the 1 kw model.
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Anyway, the engine is now safely home in the driveway.
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Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Searching the terms[ "1610 psi" pressure helium ] turned up a LinkedIn profile of a former NASA/Infinia employee who includes in his resume' :
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The time frame 2009 is the same as the date on the engine also.
Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

There is a slight, but noticeable dent in the engine. The metal there is thin. Near the hose sticking out the bottom.
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When I pulled off the hose, a considerable amount of yellowish fluid drained out. This fluid appeared to be ordinary engine coolant, such as used in an automobile radiator cooling system
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Tom Booth
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Re: 3KW Stirling Engine - Pics provided

Post by Tom Booth »

Good news, in a way, I guess

"Proof" pressure is apparently way above normal operating pressure. It generally refers to the maximum pressure that can be applied before "burst pressure" or overpressure that can result in damage to a component.

So,... more than likely a 500 psi operating pressure is correct after all.

If possible, I am attempting to get into contact with the former Infinia employees listed on LinkedIn and various other places for confirmation and to get whatever other information on this engine. A number of the profiles seem long inactive though. No luck so far.
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