3KW Stirling Engine - Pics provided

[Tom Booth]

I've been debating with myself, to check and see if there is pressure by just pressing on the valve, or not

If there was pressure, testing could let some pressure out so then the pressure would be low.

Well, I thought the chances of the engine still being pressurized we're pretty slim.

There is also a hole in the valve protector:

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Does that indicate the valve blew at some time? Punching a hole from the high pressure?

Maybe somebody put the hole there to make letting pressure out easier? That seems unlikely.

Anyway, I got a kitchen fork and pressed on the valve core.

A little gas blew some moisture and dirt out of the valve stem for a second, then nothing.

It seemed clear the valve was still holding in some pressure, but probably no more than might be caused by ambient temperature/pressure fluctuations. It is very hot out today.

The valve, otherwise, seems to still work. That is, it held in what little pressure there was. The spring and seal seem, at least basically functional

https://youtu.be/E0hhpm9_jls

[Tom Booth]

One concern has been the possibility that due to overheating at some time, the engines permanent magnet/piston associated with the linear generator could have been demagnetized.

For something like that to happen, the engine would have to be severely overheated above the Curie temperature of the magnets, whatever that might be. It could be different for different types of magnets

https://en.m.wikipedia.org/wiki/Curie_temperature

For a strong Neodymium magnet this could be as low as about 600° F

https://youtu.be/cSPxXzOaevU

As far as I can tell, this engine looks good. Indicated by the compass I bought on the return trip home, it spins, pointing towards the engine even from several feet away.

[yellow88fiero]

Nice tests - I look forward to see you pull it apart. It would be interesting to try a test if you can pressurize it a bit first. That way you see if any power comes out of the plug.

It will be interesting to see.

[Tom Booth]

I'm a little reluctant to just pressurize it and try to get it going.

If anything happened to get into it the extremely close tolerances... Condensation? Oxidation/rust? Worn parts?

None of that is very likely, but possibly having been decompressed for possibly years, even before you got it.

I'd like to try it out to see if it would run, but I'd also like to see what it might take to rebuild. See what's inside etc.

Anyway, I found this article about an Infinia solar dish installation at Fort Carson. Just south of the Denver area, near Colorado Springs.


https://archive.sltrib.com/story.php?re ... y.html.csp

That would apparently have been sometime after this engine was being tested, presumably at a university in the same area.

I have a kind of "clean room" I used, mostly for finishing furniture. If I'm ever going to take the thing apart, probably now would be the best time

Either way there is some risk.

If it were still pressurized, even a lfew psi I'd go ahead and pressurize it, but there was really nothing.

I'll think about it.

Probably it will continue ridding around in the back of my truck for a while untill I figure out a way to get it down into the shop.

After 2000 miles, I can't imagine a few more would do any harm I also want to take it around to some people in the area I've talked with about building engines before. There is a pretty well equipped machine shop that does aerospace type work on the one hand and some Amish on the other. And possibly the local paper. A news story about the engine, and the shop opening, could possibly generate some interest.

[Tom Booth]

I haven't had much luck trying to figure out, or find anything regarding this plug and what the various pins might be for:

Resize_20220807_114239_9240.jpg (217.99 KiB) Viewed 9932 times

Apparently industrial or mil spec type connector. Most likely military IMO given the apparent gold pins.

I've looked through dozens of online catalogs and can't find anything exactly like it

From what I've read various places about these engines, they produce ac current initially or internally, which is rectified to DC.

Then an inverter was used to revert the DC back to standard AC according to the end use. Different inverters were used to adapt to the power requirements of different countries.

So, perhaps this plugged into an inverter.

The wires, however, seem relatively light weight, which suggests pretty high voltage.

Could the inverter be internal? I kind of doubt it.

3000 watts DC current at high voltage would certainly have a tendency to arc like crazy, I would think.

[Tom Booth]

Well, here is a clue, though not much help so far:

Resize_20220807_125059_9297.jpg (177.79 KiB) Viewed 9931 times

AMPHENOL C10 664640-06P 0914

Stamped on the side of the connector.

This turns up in a search

https://www.mouser.com/ProductDetail/Am ... 52Bw%3D%3D

Non-stocked Circular MIL Spec Connector.

Maybe something here:

https://amphenol.com/markets/military/a ... s-circular

[Tom Booth]

I found this image in a PDF showing the location of the power inverter.

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As I figured, it is external to the engine itself. The PDF

https://apps.dtic.mil/sti/pdfs/ADA607481.pdf

Is quite voluminous, 110 pages, so I've barely begun to scan through it. There may be some additional clues.

[Tom Booth]

Some additional images of the inverter attached to the base of the support pole:

Resize_20220807_151817_7000.jpg (99.89 KiB) Viewed 9927 times

So, unless the diodes/rectifier is also external, what comes out the wires, I would expect, should be DC current

Why six pins?

Presumably the two big pins in the middle would be the main power. The others may be auxiliary power connectors for the tracking motor and cooling pump/fan.

Don't know what else they might be.

All the other wires just seem to be temperature sensors. A big high temp sensor for the focal point and a bunch of smaller probes for various other areas.

Being a permanent magnet generator, it shouldn't need pressurization or anything to test it really. Just hit the end of the engine with a rubber mallet or something.

That should get the piston vibrating enough for some output, as in the Blade Attila tear down video. I don't think that was an Infinia engine, but basically the same thing.

[Tom Booth]

From what I can deduce from this Infinia patent, the rectifier circuit would likely also be external, as it uses language such as:

"
The circuit includes a rectifier to convert the alternating current from the generator to direct current, the rectifier having a first port and a second port, the rectifier first port in communication with the output port of the generator; and a direct current to alternating current inverter to convert the direct current from the rectifier to alternating current, the inverter having a first port and a second port, the first port of the inverter in communication with the second port of the rectifier."

https://patents.justia.com/patent/8559197

Sounds like there is the AC output from the engine which then connects to the rectifier, which then connects to the inverter. There is also mention of a capacitor in there somewhere.

This makes sense because diodes are prone to failure and having the rectifier internal to a hermetically sealed and pressurized engine.would create great difficulties for something as simple as replacing a burned out diode.

Not much can go wrong with the generator windings.

Probably I would do something like engine(AC) > rectifier(DC). > Battery bank > DC to AC inverter > final AC power output

[Tom Booth]

The quick disconnect on this engine appears to be just the ordinary stainless high pressure inert gas type used for welding gas, such as sold by Airgas, and readily available.

Resize_20220807_222721_1358.jpg (30.05 KiB) Viewed 9923 times

https://www.airgas.com/

Surprisingly, I found that regular industrial or "universal" quick connects sold at the local hardware store for air compressors also fit, but should probably not be used anything above 150 psi (or possibly up to 300 psi the maximum the quick connect hose on my shop air compressor is rated for, but I wouldn't push it. The compressor is only rated for 155 psi Max)

https://youtu.be/rmBUIo9VEgQ

I may try seeing what this thing can do, if anything, just on ordinary compressed air. It seems it is possible anyway, as just about any common shop compressor hose could hook up to this thing, surprisingly

I've had more trouble just finding the right connectors for my regular air tools.

BTW, the sound in the background of the video is some Amish horse and buggies passing by the house. Very common around here, especially Sunday evenings.

[Tom Booth]

I found a two prong connector at the local auto parts store that fit into the power plug on the engine.

Thumping on the end of the engine with a rubber mallet produced a reading of about 1 or 2 volts

I didn't hit it very hard. Basically just wanted to see that the piston is able to move freely, is actually in there and that the generator is capable of producing power output

The tag that stated "do not assemble" had me wondering. Maybe this was just a housing rather than a complete engine


https://youtu.be/AKuqiKhCdNI

Seems good to go!

[yellow88fiero]

I always thought the tag was basically do not assemble to the rest of the solar dish and such. The engine definitely had everything built with all the sensors. Glad to see that the piston is moving and producing.

[Tom Booth]

Getting this engine was a huge undertaking and all kinds of worries have gone through my mind, from, there may be no engine at all, and it's all some elaborate prank or a scam, but I thought it was worth taking a chance, and glad I did.

It's not every day someone pops in here with a NASA engineered Stirling engine. I'm still in a bit of shock/disbelief. I can't thank you enough.

While it seems like the ultimate pinnacle of Stirling engine development, I also feel there may be room for additional improvement

The cooling jacket is only 2 inches from the heating surface, and according to that "final report" the engine produced about 3x more output in the form of hot water than as actual electricity

It is also still apparently based on the1800's idea that a heat engine produces power by throwing the heat away to a "sink" as quickly as possible.

For all the millions of dollars and high tech engineering that has gone into the thing, it only produces the equivalent power of a small push mower type IC engine and weighs like 100 time more and 5 times bigger. Compare that with a typical modern IC generator of comparable output that can be carried around like a lunch box.

Don't get me wrong, I'm not complaining. An IC engine can't make electricity from sunshine, or wood, coal, kerosene, or corn cobs, still.

The only thing burning gasoline does, really, is heat the air in the cylinder to make it expand. A Stirling engine SHOULD IMO be able to perform just as well.

Who am I to say NASA got it all wrong, but, to one degree or another I actually believe that.

I've run small model engines I've put together, that seem to produce zero "waste" heat, and ran some experiments that look as though there is actually negative "waste heat".

By "negative waste heat" I mean, it seems like the cold side of the engine actually gets colder instead of throwing off heat to a "sink".

Anyway, I've already learned a few things by studying and reading about this engine, the NASA patents possibly associated with it etc. And of course it gives me something to show off.

I took it over to the AMISH this morning, then around to a local machine shop.

The local Amish community has actually shown the greatest interest in Stirling engines. Sometimes when someone asks what that thing is on the back of my truck I say simply, it's an Amish generator.

Other times, it's one of those engines NASA uses to power the space station, or...

It's a generator that will run on firewood or coal...

Of course, more questions and more involved explanations generally follow.

[Tom Booth]

This is kind of interesting.

This same 3 Kw engine was also tested using an alternative arangement.

A trough type solar collector (or other heat source) could be used in conjunction with a phase change salt thermal storage for 24 hour power generation.

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Something like that might actually be more practical for a homeowner type setup. A trough collector on the ground does not require tracking, just occasional seasonal adjustment for one thing. Of course, the heat storage is easier with a trough than having the collector/engine suspended up in the air.

Pg. 106

https://www.nrel.gov/docs/fy13osti/58484.pdf

Due to the lower temperatures produced by the salt storage medium, though, the engine only ran at a little more than half it's maximum power. (1900 watts).

Probably that would be preferable to a constantly fluctuating power output during the day that the drops to zero at night.

[yellow88fiero]

I like the sodium/sand layer type design. Seeing this now would have made me try it that way. Even if just directly heating a sand layer. Reminds me of the recent news on the sand batteries - but this would be a more direct way to go from the heat to electricity.

I am glad you are doing the tests and research. I think it adds a lot to the forum and everyone else reading and watching the videos you are producing. Glad you were able to get it. I hope more people start interacting with this thread as well.