Stirlingengineforum.com

Today I was introduced to the uncertainties surrounding the world helium supply. The local gas supplier, when I showed up there today to get my helium tank filled, said that they haven't been able to get any for the past few months. Infact, the supply has been rather sporadic for the past three years.

Somehow though, the local Walmart, Target and Dollar stores are still well stocked
Until the (alleged) helium shortage is over, if it is ever over, the AirGas guy said he doesn't think anyone will ever be able to buy helium ever again... (????)

Most articles on "helium shortage 4.0" seem to think things will be back to normal by the end of this year.

Anyway, due to the uncertainties surrounding the helium supply, I may just try seeing how this engine performs using more readily available gasses. I will have to do some research.

I sent off for one of these digital torque meters with a "trace" feature. that records the force used to remove or tighten bolts. When the time comes, I can get some idea about the torque specifications.

https://youtu.be/QjyGj0ct5aw

Just picked up this little high pressure compressor pump locally, from FB marketplace.

Supposed to go up to 4500 psi or 300 bar.

It's a few years old, but apparently was only used a few times. Should be able to get 500 psi out of it.

I liked it, over buying a new one, not just for the price but also it's already set up with a small water pump for the cooling system, extra hoses and high pressure gages and a couple, what look like high pressure diving scuba type air tanks.
So I don't have to depend on any supplier for compressed gases.

Hmmm...

Maybe there are more of these engines left?

I came across this website while looking for specs on the Infinia dish engine:

https://solarpaces.nrel.gov/project/tooele-army-depot

It says status is "non-operational"

However, plugging the latitude and longitude into Google Earth dives down to this image:

I count 429

Google Earth share link:

https://earth.app.goo.gl/?apn=com.googl ... 0132t,360r

Apparently a different style or version of engine though.

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

Additional info on the Tooele site:

https://archive.sltrib.com/article.php? ... type=CMSID

https://www.hnc.usace.army.mil/Media/Im ... 000789328/

Apparently, Infinia filed chapter 11 during the course of installation.

It's not entirely clear, but possibly, years later, there was an installation to store the energy produced there?

http://energystoragemedia.com/go-electr ... epot-utah/

Anyway, I've been having some difficulty in finding appropriate couplers or adaptors to connect the compressor with the existing valve on the engine.

I was wrong about the AirGas quick connect. It is only rated for something under 200psi.

I may end up having to remove the existing valve and replace it with something compatible with the compressor fittings. There seems to be plenty available in the 5000psi range intended for scuba diving, air guns and paintball that fit this compressor but not the valve on the engine.

The types that do fit seem rated for no more than 500psi max, which is a bit iffy.

I'm assuming the valve on the engine is original. Possibly custom made. If I could find some specifications, that might help, but not easy to find.

If 500psi is the cold fill pressure, what would the pressure get up too when the hot end is at 800° or whatever? Any ordinary Schrader valve rated even at 500psi would likely blow out.

Maybe the Tooele army Depot has some information.

The various YouTube videos at least show what looks like the same fill valve:

I was prepared for an arm breaking challenge, the valve took a standard 17mm wrench.

Surprisingly though, it took no effort to take off. It seemed little more than finger tight.

The valve had some numbers which were not visible previously:
The numbers helped.

Unfortunately the valve is apparently no longer manufactured, but there are some, or one at least, available from a surplus guy on eBay:

https://www.ebay.com/itm/304082254188

Or from the website:

https://www.gearheadsurplus.com/listing ... -part-bre2
Looks identical

Unfortunately, nothing about the matching female quick coupler. Nothing on the Staubli website anyway.

Good news I guess is, they are still in business, so maybe I can give them a call and find out something.

Fully disassembled, quite a heavy duty valve. This did not come off a bicycle tire, but basically the same sort Schrader type fill valve.

I don't have any doubt it could handle the pressure of 500psi easily

Coincidentally ?

The high pressure air lines and other fittings on my just aquired Yong Heng compressor use the same threads as the high pressure valve on the Stirling engine.


Finding an alternative quick coupler to replace the Staubli shouldn't be any problem, infact... With the extra hoses and adaptors, I think I may already have some.

They've already been tested/used by the guy I bought it from to some 4000 psi for filling the scuba tanks.

Maybe this, good to 5000 psi


8MM Male Quick Head Connection Check Valve One Way Foster Fill Nipple Kit M10 x 1 https://a.co/d/fEbBeUl

This is as close as it is possible to get using street view.

The 429 solar powered Stirling engines are in the distance behind this gate.

Google Earth link:

https://earth.app.goo.gl/AsFQKX

Apparently, though "bankrupt" Infinia continued hiring to complete the installation.

https://www.seia.org/sites/default/file ... i8V8H1.pdf

Just some musings;

That valve, which, I imagine, having been custom manufactured for Infinia, under military contract, presumably, at untold cost, has the same threads as an (under $10) paintball valve with the same functionality.

As Mike Ward CEO and president of Infinia said:


Yes, I agree, just steel and mirrors, so it should be quite inexpensive to build.

And not really any need for the whole parabolic mirror tracking system, probably. A trough type dish could be made out of aluminized mylar (space blankets)

Well, so could a dish for that matter:

https://www.solaripedia.com/13/130/Sola ... Power.html

https://youtu.be/8CLRTa_ocmo

As far as pressurization. The only technical specification I've been able to find so far comes from news sources such as:

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.

(Tim Talda, Infinia’s director for system electronics and controls)

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

About operating temperature:

Sunlight gets concentrated in an 800-to-1 ratio, which would raise the temperature at the heat-resistant nickel-alloy concentrator to 2,000°C if the Stirling generator didn’t extract heat from it and keep it at about 650°C

Rather than try to make fittings that are on the compressor do double duty, I've just sent for some more to install on the engine. They should be here in a few days.

All the helium is contained in a welded metal structure so little leaks out. “We use about 60 grams of helium, or about 12 cubic feet at 60°F and atmospheric pressure, and it should last the 25-year life of the PowerDish,” says Talda.

From the above cited article.

If that is the case, that is actually not very much helium at all Less than one "jumbo" canister from Walmart or Target.

https://www.target.com/p/14-9-cu-ft-jum ... A-18808942

Considering the space inside the engine is largely taken up by the displacer, piston and generator windings, there is not really that much area left to fill.

Another thing I checked, as far as possible,..

A local machinist looking at the engine wanted to know if it was all stainless, or had to be.

I wasn't sure, but he said, he could probably make the engine parts, but stainless would be very expensive.

I knew from working in a scrap yard years ago that stainless steel is not attracted to a magnet. So I got a magnet to check.

Apparently the engine is mostly steel, ( not stainless ) as the magnet readily stuck to the casing, all but the heater end, which was not magnetic.

I had thought that a steel casing might cause some issue with the magnets in the linear generator, so I had assumed the engine was 100% stainless steel.

I did notice, however a bit of rust here and there.

Also in the photos of the engines exposed to the elements, at the Tooele army Depot there appears to be considerable rust on those engines


Looks rather rusted to me anyway.

That is actually very good news IMO. The less expensive to manufacture the better.