My "Custom" Stirling Engine Workshop

[Tom Booth]

that's super strange, but who knows.
are you sure these 2 wires are the output?
maybe there are no wires but terminals instead?

I tried looking at your videos again but couldn't really locate what might have been output terminals.

https://youtu.be/AKuqiKhCdNI?si=16WHb4SWO1IKM820

Heated slightly I got a bit more output by just bumping the engine with the rubber mallet.

https://youtu.be/8tp6iUzO3oU?si=PFth6veyknonwIyo

There is quite a lot of detail on the output terminal on this thread:

viewtopic.php?f=1&t=5463

With photos:

Resize_20220807_114239_9240.jpg (217.99 KiB) Viewed 8806 times

Resize_20220807_125059_9297.jpg (177.79 KiB) Viewed 8806 times

Part number and link to the supplier in this post.

viewtopic.php?f=1&t=5463&start=30#p17847

[stephenz]

have you tried measuring the resistance across the different terminals? specifically F and C?

[Tom Booth]

have you tried measuring the resistance across the different terminals? specifically F and C?

Haven't measured resistance, but the meter read about 20 volts AC across those two large terminals when bumping the engine with the rubber mallet.

The thickness of the power cord, or the thinness rather, can be seen in the video:

Resize_20231212_144223_3861.jpg (123.83 KiB) Viewed 8786 times

No bigger than standard 14 / 2 household wire I don't think.

[Tom Booth]

Can you intend to share the pics and dimensions record during the tear down? For sure I would like to contribute what little I can afford. That is remarkably small before a 3 kilowatt generator. I am dying to know how they made it so efficient. There's an awful lot of documentation available from NASA and SunPower.https://apps.dtic.mil/sti/pdfs/ADA607481.pdf

There is "documentation" of sorts, general information, but something like the specific psi for pressurization, actual output of the alternator, those kinds of essential specifications, all I can find is mostly off hand remarks in magazine interviews.

Anyway a tear down is not on the agenda at the moment. Before anything like that I want to charge it up with helium, run it and verify the output. See what it can do. Possibly test it using other inert gases. Apply different heat sources.

I recently rebuilt my pickup transmission because the reverse band broke, but, with a rebuilding kit and instruction manual.

This engine is likely not half as complex as an automatic transmission, but without some gasket or seal or some such thing it's likely to be destructive.

I've been looking into "non-destructive" inspection. 3D x-ray scanning. That's bound to be costly I suppose though.

https://youtu.be/5dkWxMw1y0s?si=63duqI8ViDxpvNrh

[stephenz]

have you tried measuring the resistance across the different terminals? specifically F and C?

Haven't measured resistance, but the meter read about 20 volts AC across those two large terminals when bumping the engine with the rubber mallet.

The thickness of the power cord, or the thinness rather, can be seen in the video:

Resize_20231212_144223_3861.jpg

No bigger than standard 14 / 2 household wire I don't think.

You should do when you get a chance.
I suspect the linear generator is what's used to start the engine since it's a fully sealed unit, and since it's likely designed to run at high pressure you might have a shot a being able to run it as a refrigerator. With only 2 leads it was likely to run at 60 (or 50) Hz (I forgot if it's a domestic or import unit). Once you verified the resistance is in a range that agrees with that theory, you could use a variac to safely and progressively increase the voltage and see if you can get it to oscillate at ambient pressure.

[Tom Booth]

From various accounts about it, the engine is mostly or usually self starting when it heats up, but did have some provision for giving the engine a "bump" in the event that it did not start on its own.

The exact nature and method for delivering this "bump" was not specified.

It could very well have been putting a current to the alternator as you describe. However, for free piston engines, as a general rule, a physical bump can start the engine oscillating as well.

As I reported somewhere here, the engine seems to start up VERY easily. I partially pressurized it with air, just using just my shop compressor at about 50 - 100 psi and the piston apparently started oscillating just from the compressed air passing around the piston to equalize the pressure. After some air went in the engine started producing a fairly loud hum as if it were running without any heat.

I'm pretty certain just heating the end would cause it to start up due to the expanding gas.

Anyway, I'm very reluctant to just start zapping the alternator coils without knowing exactly what I'm doing. If this was a test engine that has been sitting in storage since 2009 there is a good chance it has 20 years or more life left before it would even need a little helium to bring the pressure up.

So I'm taking a minimalist approach. If it ain't broke don't "fix" ot, trying to learn as much as possible and proceeding with caution.

The last thing I want to do is dismantle or electrically toast a perfectly good engine which is apparently the end result of $500,000,000 in R&D and quite likely the last surviving relic of some good old American ingenuity, from a period back when that actually still meant something.

[ifishtoo]

https://www.prnewswire.com/news-release ... 16287.html
https://rps.nasa.gov/resources/84/techn ... or-tdc-13/

Is the stuff old news to you guys? It's stuff I've never seen before. I'm using everything I know about databases in search engines to find this stuff.

[Tom Booth]

https://www.prnewswire.com/news-release ... 16287.html
https://rps.nasa.gov/resources/84/techn ... or-tdc-13/

Is the stuff old news to you guys? It's stuff I've never seen before. I'm using everything I know about databases in search engines to find this stuff.

It is, for me anyway. I've been following the development of these things for over a decade.with growing anticipation. When will they hit the market? When will I be able to use this incredible technology to run my home? Why can't I just buy a Stirling engine?

Well, the fact of the matter is, these engines were rolling off the assembly line back in 2009 after hundreds of millions of dollars were spent to perfect the technology.

Here is a shot from an old INFINIA brochure:

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The various companies that contracted to develop these engines under contract with NASA and the DOD have, well, no need to take my word for it.

https://youtu.be/2Yzeo4JrsNs?si=XHTCKDVbHVjCouis

[Tom Booth]

Some of the activities at the workshop:

https://youtu.be/9EaSgmoQkd4?si=MG6aF3YOB9ZmXz2d


Before investing in a 3000 watt (+) solar inverter I want to check the output. The raw high voltage AC should be able to light those old incandescent bulbs without the inverter though.

Making structural repairs on this old building (built circa 1880) can be a bit of an ordeal. The floor rafters are 3"x12". Not the sort of thing available at the local Home Depot, so I've had to get the replacement beams custom sawn at a sawmill, wait for them to season and so forth.

There were posts holding up broken beams in the way of setting up some of the shop equipment, so the repairs are necessary to make room..

There are also the main floor and a 2nd and 3rd floor where additional structural repairs are underway. Not directly related to the Stirling engine workshop, but still necessary.

I need to pick up some electrical connectors to adapt the engine output to the test panel and do up the wiring for that and a few other things, but should have things ready to do a test run very soon.

Oh, yeah,...

I also need to pick up some radiator hose from the auto-parts to hook up a cooling system. Possibly not really needed for a brief test run, but I really don't want to take any chances as far as excess heat damaging the alternator or neodymium magnet or any other sensitive components that might be in there, and a pump to circulate the coolant.
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