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Re: PEM fuel cell deuterium generator

Posted: Wed Apr 20, 2016 1:59 am
by Charles Vorbach
Beautiful. Much less hacked together than my supply.

I am curious though, is the D2 really wet when produced from a PEM cell? Most of the diagrams I have seen seem to show the PEM membrane as impermeable to water.

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Re: PEM fuel cell deuterium generator

Posted: Wed Apr 20, 2016 2:03 pm
by Rich Feldman
Same question was addressed a couple months ago in Erik Burrows's thread.
viewtopic.php?f=45&t=10592&p=70213#p70213

It would be nice if someone found or measured how much water comes through their Hydrocar cell,
or how much water it takes to interfere with or contaminate a fusor.

With a glass cold finger or u-tube condenser and various freezing baths,
or a Peltier-cooled shiny surface exposed to the gas,
it would easy to set bounds on the dew point temperature, hence the relative humidity. In D2.

Some day when I have a working fusor with fuel cell deuterium,
one of the first experimental variations will be to skip the drier and see what happens.

Re: PEM fuel cell deuterium generator

Posted: Sat Apr 23, 2016 4:23 am
by Bob Reite
I also thought that the PEM cells were supposed to produce dry hydrogen, but after running mine for awhile, I do notice some condensation in the hydrogen output tubing, so I do have a drier between the over pressure protection system and the mass flow controller. A picture of my gas system is at download/file.php?id=8528&mode=view

Re: PEM fuel cell deuterium generator

Posted: Tue Jun 21, 2016 1:19 am
by Dave Xanatos
Just a quick design revision: note the increased diameter of the two crossover droptubes. This is to prevent too high of a pressure developing within the PEM Cell trying to push the vacuum oil through the small diameter tubing. The gas flow diameters are fine as they should never conduct oil. Also note the addition of the terminal block for easy hookup without having to mess with the PEM Cell.

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Re: PEM fuel cell deuterium generator

Posted: Fri Dec 16, 2016 2:04 am
by Brodie Reid
I plan on using this method for my Deuterium source, however I do have one question. What exactly are the oil resevoirs and if anyone could post a link to where to get them (or how to make them), I would really appreciate it!

Thanks,
Brodie Reid

Re: PEM fuel cell deuterium generator

Posted: Fri Dec 16, 2016 2:51 am
by Bob Reite
I used some old medicine bottles and rubber stoppers for my system. The photos above show a fancy custom built system. There is more than one way to do it.

Re: PEM fuel cell deuterium generator

Posted: Sat Dec 17, 2016 3:58 am
by Rex Allers
I haven't built a generator like this yet, but I have accumulated parts (PEM cell, plumbing, valves, etc.).

My thought for a buffer holding chamber for the gas was to use a small mylar balloon rather than these oil displacing chambers. My thought was that it would be easy to suck oil if you want to evacuate to keep the D2 as pure as possible, or even from the chamber vacuum if you aren't watching enough. Seemed to me the balloon could be evacuated without a problem.

Re: PEM fuel cell deuterium generator

Posted: Sat Dec 17, 2016 3:47 pm
by Rich Feldman
My story is like Rex's. Got hydrocar kits from craigslist & ebay, etc. Have a couple of Mylar balloons, but have not yet experimented with how to seal them to tubing. Found an ebay vendor who regularly sells D2O packaged in 50 gram lots for $75. You get only 45 ml because the water is, uh, heavy.

Storage in balloons misses one benefit easily achieved with gas-over-liquid reservoirs. That's "overpressure" relief in the vacuum plumbing. In case electrolytic gas production stops, we don't want a strong vacuum to develop on the PEM cell. If a PEM were supported to withstand vacuum, then we could skip the reservoirs and very-low-flow restrictor. Simply adjust electric current to set the D2 flow. No great technical problem there. Electrolytic "hydrostik" refillers run PEMs with hundreds of psi on the hydrogen side., as discussed in another thread.

[edit] Can also avoid risk of vacuum on PEM cell, by having no plumbing that connects reservoir to fusor flow control and PEM cell at the same time.

I learned that there's a well analyzed geometric shape called "Mylar balloon". From the nominal balloon size (diameter of flat circles sealed around the edge) we could figure the maximum inflated volume. I have not yet done that exercise, nor measured the volume using real fluid. I think that tables for party helium show 18" balloons needing about 1/2 cubic foot.
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Re: PEM fuel cell deuterium generator

Posted: Thu Dec 20, 2018 4:46 am
by Richard Hull
A rather inexpensive device with hydrogen and oxygen tanks (reversable PEM) for those experimenters. Might be adapatable....modifiable?

https://fuelcellstore.com/downloads/drf ... torage.pdf

Want just the reversable cell?.....

https://www.fuelcellstore.com/horizon-m ... -fuel-cell

Richard Hull

Re: PEM fuel cell deuterium generator

Posted: Thu Dec 20, 2018 5:24 am
by Rex Allers
On Richards two fuelcellstore links.

I've never seen the first one but it seems to have a lot of implementation that might be better done in ways that are more specific to meet our needs.

Second link is for a reversible device (can be a fuel cell or an electrolyser). I think we only really want to go in the electrolyser direction and the following link is slightly cheaper.
Horizon Mini PEM Electrolyzer
https://www.fuelcellstore.com/horizon-m ... ectrolyser

It's been several years since I looked into these things but I thought there might have been some advantage to the electrolyser for our intended use. Well there is a $6.50 advantage from prices listed today. Thought there was something I read once about differences that might matter, but couldn't swear to it and can't find it now.