Solid state hydrogen storage experiments

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
David Kunkle
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Re: Solid state hydrogen storage experiments

Post by David Kunkle » Wed Nov 16, 2016 2:20 am

Rex Allers wrote: I've thought, if nothing else, maybe the cartridges could be a way for someone who gets a D2 tank to share by filling some of these cartridges and thereby sharing and dividing the cost of purchase. This assumes many who get a tank of D2 will have more than they really need and might be willing to share some for a price, if we can come up with a workable design and procedure.
I still have most of a 100L tank of D2. In the past, I've been willing to share some, but found it illegal to ship a cylinder of compressed gas, and prohibitive to set up to do it legally. I got your same thought reading this thread. It appears to be legal to ship these cartridges. Amazing you can get 10L in there, but of course when you go from gas to solid....

On ebay I found refill fittings for about $25 that do the same thing you constructed for yourself. Allows a refill of a Hydrostik from a compressed hydrogen source. 1/8" tube lets you hook up to a compression fitting. Not bad if you don't have a lathe.
Rex Allers wrote:In the long run of trying to convert from H to D, I'm a bit concerned how hard it will be to purge the H and keep the D pure.
As far as purging, my first thought was to make a "Y" set up and valves. One end connects to the Hydrostik, one to the compressed D2 bottle, and the third to the vacuum chamber or pump. Open the Hydrostik to vacuum to evacuate it, close off vacuum source, open regulator and fill Hydrostik.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford

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Re: Solid state hydrogen storage experiments

Post by Rex Allers » Wed Nov 16, 2016 2:37 am

David,

Using vacuum to clear H from the cartridges prior to D fill is the same thing I was thinking. Perhaps a little heat on the cartridge while under vacuum too, to help it along.
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Rich Feldman
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Re: Solid state hydrogen storage experiments

Post by Rich Feldman » Wed Nov 16, 2016 7:59 am

We might have to plow some new ground if we want reasonably pure D2 in cartridges that used to hold H2. Will it take multiple cycles of evacuation, heat, and flushing with deuterium?
How can one measure protium concentration in deuterium, without a mass spectrometer? Qualitative optical spectroscopy? Assay by fusor would certainly get to the point. :-)

Here is a report from some big boys at the Savannah River Site. http://sti.srs.gov/fulltext/ms2001247/ms2001247.html They investigated design aspects of a compact (50 lb) vessel to store up to 1600 liters of tritium adsorbed in metal powder. Working temperature runs into the red-hot range. It helps if the hydride medium is also good at co-adsorbing the decay product, helium-3.

Near the bottom, they discuss disposal of these containers at the end of their life. Need to reduce the residual activity to less than 1000 curies, "a 0.00038 T/M inventory. Desorption levels are not near this level and isotopic exchange will be needed to meet waste acceptance criteria for disposal."
3h.PNG
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Re: Solid state hydrogen storage experiments

Post by David Kunkle » Thu Nov 17, 2016 2:54 am

I'd assume Hydrostiks can withstand a vacuum and not implode. Would be very easy to heat such a small cartridge, but to what temperature can they withstand?

If I read it right, these cartridges hold the equivalent of 300 psi? If allowed to come to atmospheric pressure of about 15 psi, wouldn't that still leave them with about 5% of the maximum amount of H2 they can hold? A fair bit stuck in there to mix with your D2. Just my gut feeling/guesstimate, but I think if held under vacuum with heat for some amount of time, 95%+ of the remaining H2 would be expelled. That would make a D2 refill 99.75% pure.

Short of having a mass spec, someone would have to be the guinea pig and measure neutron output of Hydrostik vs. their known supply of D2. I'm betting you'd have a hard time demonstrating the difference.


Anybody want to take a shot at converting 1000 curies of tritium to liters, then vs. 1600 liters total storage?
"Desorption levels are not near this level" Does this mean at atmospheric pressure inside the vessel?
If your experiment needs statistics, you ought to have done a better experiment.

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Re: Solid state hydrogen storage experiments

Post by Peter Schmelcher » Thu Nov 17, 2016 4:38 am

I think the cartridges should be used and refilled thread end up.

Years ago a fellow at Ballard (a poster child company for the hydrogen economy) told me about the storage of hydrogen in metals, allegedly better than liquid H in the same container volume. The container is filled about 80% with metal chips and then with repeated cycling the metal expands to fill 100% of the volume. My thinking is that the expansion process might create some metal dust that would be bad for any valve seats.

For drying the deuterium the best solution I have found is:
http://www.ebay.com/p/supelco-20619-mol ... 7675.l2644
The result should be about 200ppb residual water.

Just my 2 cents
-Peter

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Re: Solid state hydrogen storage experiments

Post by Rex Allers » Thu Nov 17, 2016 6:03 am

Peter,

The Hydrofill unit has the Stik cartridge horizontal during charge. I don't recall seeing anything in the datasheets about preferred orientation. I do get what you are saying about powdering, though. The paper that Rich just posted a link to, mentions this issue of powder as the metal hydride goes through cycles of use and they have a filter to block the powder. So, I would guess the Stiks may have a filter inside between the storage media and the valve.

The ebay link to the seives for water removal looks good but it is pretty big. The listing says it has a volume of 200 cc. I've been trying to think in terms of minimizing volume in the plumbing to avoid wasting gas.
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Rich Feldman
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Re: Solid state hydrogen storage experiments

Post by Rich Feldman » Thu Nov 17, 2016 7:42 pm

>> Anybody want to take a shot at converting 1000 curies of tritium to liters, then vs. 1600 liters total storage?

OK, David, I'll bite. 1000 curies in the form of radium-226 would be about, uh, 1000 grams. Specific activity of tritium is greater by factors of 75 (atomic mass ratio) and 130 (half-life ratio). Combined factor is v. close to 1e4, so we are talking about 0.10 grams of tritium. That's 0.4 liters, or 0.025% of the TSV's nominal capacity. Activity inside a full tank would be 4 MCi. All according to this unreviewed analysis. I think that paper says they couldn't empty the container to the 1 kCi level with just vacuum and heat. Would need to displace the last of the T with some D or H.

That residue requirement is clearly stricter, by a couple orders of magnitude, than fusioneers would need for making Deuterostiks or Deuterocores.
Anybody want to read the paper more carefully & find their actual desorption methods and numbers?

Here a different maker's hyped presentation of a little cartridge for 10 normal liters of H2, that has a different plumbing connection: http://www.pragma-industries.com/produc ... ride-tank/ Their page for a broader product line has this chart:
PCI_curve.jpg
PCI_curve.jpg (30.98 KiB) Viewed 3278 times
Text explains the typical "plateau" curve in terms of a shift between two solid-state phases. Maybe they mean plateaus when viewed sideways. The charge/discharge hysteresis amounts to a pretty substantial pressure ratio. The storage medium in Horizon products might be different, but I bet its PCI curves are qualitatively similar to the ones in this chart.

Literature for this tritium-storage unit, made for bio labs, touts the benefits of its hydride medium: depleted uranium metal. :-) http://lablogic.com/life-sciences/instr ... tri-sorber
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Rich Feldman
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Re: Solid state hydrogen storage experiments

Post by Rich Feldman » Mon Nov 21, 2016 9:03 pm

On a rainy Saturday, I took one Brunton hydrogen core and reactor on a visit to John McMaster's shed, to be x-rayed. John is registered at this forum and has posted a thing or two.
Letting the pictures speak, here are primitive fluoroscope images of the storage cell and the fuel cell USB charger unit.
fluoroscope.jpg
fluoroscope.jpg (7.22 KiB) Viewed 3242 times
fluroscope.jpg
Next we took close-up images using a USB-connected dental sensor. First the "stik" valve area:
capture_010.png
The valve head seems to be screwed into the cylinder body, I think with an O-ring seal and some radio-opaque stuff on the threads. Same image after "enhancement" makes it easier to see that stiks have balls.
capture_010e.png
Our oblique view, actually taken first, seems to show more space between ball and the externally visible pusher.
capture_002e.png
Who among us will be first to sacrifice a 'stik for destructive inspection?
Reactor images to follow.
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Re: Solid state hydrogen storage experiments

Post by David Kunkle » Sat Nov 26, 2016 12:31 am

Rich,

I think I finally gleaned the relevant info from the paper: http://sti.srs.gov/fulltext/ms2001247/ms2001247.html
I don't think the results are so good for us. Figure 7 is the most relevant. Q/M is the ratio of atoms of H,D, or T to atoms of Ti. 2.0 is maxed out. Comparing absorption and desorption Q/M ratios tells the story. They start at 0 Q/M, and reach about 1.9 after absorption. After 2 days of vacuum and 700C, they reach about .2 Q/M after desorption. That leaves about 10% of the original H still stuck in the Ti.

"Here a different maker's hyped presentation of a little cartridge for 10 normal liters of H2, that has a different plumbing connection: http://www.pragma-industries.com/produc ... ride-tank/"
This 10L cartridge seems closer to what we'd be using. Their chart that you posted seems to show the room temp desorption line getting down to .1% by weight which would be acceptable. Do you read the same thing off that? I realize there are probably large differences between the two, but why would the T storage unit, after 700C even, show such a large remnant compared to the 10L cartridge?

I'm not sure either gives us any decent info to go off of for what we'd be using and doing.
My last thought is that it would be great if we could get cartridges from the factory line that were never filled.
If your experiment needs statistics, you ought to have done a better experiment.

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Re: Solid state hydrogen storage experiments

Post by Rex Allers » Sat Nov 26, 2016 2:27 am

David,

If you look back through this thread, the Brunton Hydrocores come filled but the Horizon Hydrostiks come empty. Maybe we will have to only use clean Hydrostiks for D.
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