chp stirling generator maker project

[duck]

I hope to get an old stirling generator running and display it in my home. Six years ago after purchasing it I tried to aquire spefications / refferance information from the manufacturer and they said the project was canceled six years prior and everything was lost.
The unit closely resembles the 1kw / 1hp stirling engines in other chp units and I hope to possibly locate service manuals from other companies that would give me a place to start.

[Tom Booth]

Who was the manufacturer?

[duck]

Rinnai is the manufacturer. kazuchikaito@rinnai.co.jp was the last person contacted and his reply was "We are very sorry that we cannot assist you anymore because the development of CHP had already stopped a long time ago". The only thing they offered to help me with was paying for it to be returned to them.

[Tom Booth]

Those engines were the same, or at least based on the 1kw Infinia technology.

Generally speaking, these engines were hermetically sealed, technology designed for NASA to be launched into space where it would never be possible to service the thing.

Unless it was abused, severely overheated or something, my guess would be, it should still work by just putting some heat to it (and maybe cooling?).

Have you ever done anything at all with it to try to get it running?

Basically the same engine deployed at the Tooele Army Depot:

https://galvanizeit.org/project-gallery ... army-depot.

My 3kw engines little brother.

[duck]

The unit appears to be unused. I haven't tried to get it running yet. I am unsure of the gas used or the best way to see if there is adequate volume. From what I've reasearched putting heat to it involves a heat exchanger designed for the spific fuel used. One heat exchanger refferance; https://www.intechopen.com/chapters/62541 and I've found others. Using a thermostaticly controlled electric band heater was going to be my first step with tap water for cooling. Not sure what the temperature ranges would be.
Started getting a little blurry eyed at some of the information available, such as https://www.mdpi.com/1996-1073/10/10/1609. The manufacturer does have references to it on the web; https://www.rinnai.co.jp/en/ir/sharehol ... kabu23.pdf.

[Tom Booth]

." I am unsure of the gas used or the best way to see if there is adequate volume."

Not sure what you mean by this. Gas to burn to heat it like propane or natural gas, or gas to put inside to pressurize it, such as helium.

By "adequate volume" it seems to indicate you need to put gas into something.

I would think that engine would have already been pressurized with helium and hermetically sealed.

Does it have a valve of some sort to fill the engine with working fluid? (presumably that would be helium).

Or are you talking about the volume of some fuel tank or bottle?

[Tom Booth]

... From what I've reasearched putting heat to it involves a heat exchanger designed for the spific fuel used. One heat exchanger refferance; https://www.intechopen.com/chapters/62541 and I've found others. Using a thermostaticly controlled electric band heater was going to be my first step with tap water for cooling. Not sure what the temperature ranges would be.
...

While it is true that different heater heads would be used for optimal efficiency in a permanent installation, just for testing briefly, to see if it runs, it really shouldn't make much difference.

I know the SunPower Stirling units, I was informed anyway, could not operate without some control circuit, though someone told me they were able to get one to run as a cooler with a Variac. I don't think the Infinia were as "fussy" about the heat source, but that's just a guess.

I'm hoping anyway, because I'm in the same situation, but my engine was a test engine and definitely has a fill valve and probably needs periodic recharging as no valve could be 100% leak proof. It was empty (unpressurized) when I got it.

I'm under the impression that production engines were welded shut in a pressurized chamber so as to be permanently hermetically sealed so the working gas would virtually never leak out, but not easily serviceable if it ever did either.

[Tom Booth]

Your engine is essentially, I believe, basically identical to the engines in this video. Though the video is IMO misleading. The residential CHP units were discontinued, not because it didn't work or there was no demand. They don't sell engines to pig farmers.

But, what he says about it being "maintenance free" and that it will "never break" you can probably bank on, unless the unit was disabled by drilling a hole in the casing or some such thing

https://youtu.be/OadiysJS3f0?si=2nZaSUcJLxjfe1l4

https://youtu.be/iKxRwJgo0d4?si=EWSl-d3Q5Qme_kJO

[duck]

Yes, there's a valve.

Stirling engine can be designed to use either hydrogen, helium, or nitrogen all with the same efficiency for the same temperature.
Reference: https://www.physicsforums.com/threads/i ... e.1010009/
If helium is the most likely gas, what grade / pressure?

It looks to have two thermocouple connections and a power leads. The 1 hp liner alternator I believe is 1000 watts at 220 volts.
The tempature probes are probably used to controll and verify proper temperature differential. The ac output mabey rectified due to the frequency variability.

[Tom Booth]

Yes, there's a valve.

Stirling engine can be designed to use either hydrogen, helium, or nitrogen all with the same efficiency for the same temperature.
Reference: https://www.physicsforums.com/threads/i ... e.1010009/
If helium is the most likely gas, what grade / pressure?
...

Good question. I've been struggling with the same problem trying to locate specs.

The only clue I've found really, was an old magazine article interviewing an Infinia representative who was basically bragging about the superiority of the Infinia engine over previous engineering effort to create a high power Stirling that require pressurization to hundreds of atmospheres.

One of the bragging points was that the Infinia only required relatively low pressure. "about 500 psi".

“We use helium because it has a high thermal coefficient, which lets it absorb a lot of energy,” explains Talda. “In fact, the only gas that can absorb more energy is hydrogen, and it has its own problems with corrosion, being explosive, and even more slippery and hard to contain than helium. And we pressurize the helium to about 500 psi to make it denser so it can trap and transfer even more heat.”

https://www.machinedesign.com/markets/e ... nditioning

How reliable that is, or if it is applicable to your engine, I don't know, but that is still rather high pressure.

I'm using, or will be using pure helium from a welding gas supplier. There was a shortage at the time, so I had to wait several months, and suppliers are reluctant to sell it "to just anybody off the street". As I was rather rudely informed, priority goes to hospitals that use it in MRI machines and other critical uses, especially during a shortage.

I got a friend with an established welding shop to get my bottle filled, even then, they (not the same supplier I went to) put him on.a waiting list, but I did eventually get it and surprisingly the price seemed very reasonable.

Another problem was locating high pressure connectors compatible with the fill valve on my engine.

Ordinary shop compressor fittings are only rated for no more than about 150 to 200 psi.

I did eventually locate the appropriate connector made by the same company that manufactured the fill valve for the military, but as they don't sell direct to the public I had to order one from a retailer who no longer carried the thing, but I at least got a part number and found one on eBay.

When I got the thing it was in a plastic bag with a label that to my surprise was marked: customer: INFINIA special order, or something to that effect.

Is that a picture of the fill valve on your engine?

Looks like a standard high pressure valve, such as used with paintball gun tanks.

That would have been my other option. Redrill and tap the hole and install a different valve.

Then another problem is finding a pressure gage that works at such a high range with fittings compatable with all the other stuff.

Getting everything together just to make it possible to fill the thing has been a long ordeal, and I still don't have any specs.

Probably I'll just end up purging the tank, I mean the engine, because I did pressurize it with plain air a few times to about 100psi with my shop compressor.

Then try adding helium a little at a time.

Since the thing is frictionless and oil free, Not sure what harm using ordinary (dry, don't want rust) air would due but just to be on the safe side, I'm more comfortable with an inert gas.

I'm also interested to find out if the engine will run without pressurization. Or what the minimum pressurization would be to get useable power, how much difference does 50psi more or less make? What about other inert welding gas that is more readily available?

Anyway, another thing I have yet to do is wire up a panel for a load. I bought enough old style incandescent light bulbs to make 3000 watts and switches and sockets so I can turn them on a few at a time.

The variable ac straight from the engine should power incandescent bulbs without a rectifier or inverter and I also can't afford a battery bank to absorb that kind of power, incandescent bulbs are going cheap these days.