From: Bruce_Dunn@mindlink.bc.ca (Bruce Dunn)
Subject: Re: The Dunn Summary
Organization: MIND LINK! - British Columbia, Canada
Date: Tue, 5 Jan 1993 17:01:14 GMT

Tom Droege writes:

>
> The big mystery is how P&F run.  To my knowledge they have never told us.
> The early paper said "sealed with parafilm".  What the heck is parafilm?
> But if they seal the cells, they have to vent the gas.  My guess it that
> they are Type 2, but perhaps someone can fill in.  Remember that even
> Hawkins was never in the back room, so we have to get the answer from P or
> F.


     Parafilm (tradename) is a sheet of stretchy, slightly sticky, wax.
Imagine if you can a cross between Saran wrap, paraffin wax, sheet rubber and
the skin of a bubble-gum bubble.  It comes on a roll, interleaved with paper
to keep it from sticking to itself (which it will do under moderate finger
pressure).  It is possible to make an air tight seal with it on a beaker, but
the seal won't withstand any great pressure differential (if pressure builds
up in a Parafilm sealed container, the Parafilm bulges out, followed a little
later by a "Pffft" as a hole develops).

I presume that the P&F cell is sealed with Parafilm, with a small hole
somewhere in the system for venting.  This would then qualify as a "Type 2,
no recombiner, bubbler or orifice" cell.

  The point of why I lumped together no-recombiner cells with bubblers and
orifices is that with the continued flow of gas caused by the electrolysis, a
small orifice is probably just as good as a bubbler in keeping air (and
nitrogen) from getting at the cell.  Bubblers and orifices hower do not seem
to me to be equivalent when a recombiner is used.  In this case, once
charging is finished, there is no continuous flow of gas and nitrogen could
come back in through an orifice, but not through a bubbler.


> The only first class experiment that I know of (McKubre) runs with a 100%
> D2 fill.  I guess 10,000 psi is a lot of kPa.  McKubre says that this high
> pressure completly prevents the formation of O2 bubbles.  Perhaps someone
> can explain this.  Where does the O go if it does not make bubbles?  But he
> has also claimed excess heat at the much lower 50 psi.

10,000 psi would be about 70 MPa, or 70,000 kPa (1 atmosphere is roughly 100
kPa).  Any bubbles attempting to form would be very small, squashed by the
pressure.  Perhaps oxygen simply dissolves in the electrolyte as it is
formed, as a result of the pressure.



> How about it Bruce, do you want to be keeper of the matrix?  If so I will
> start sending everything I can find.  At present I am keeping what I know
> in my head and trying to do the same job as you in trying to find a common
> thread in the successful experiments.

Sorry - but no thanks.  I am not well enough up on what everone is doing to
be able to adequately do this.  I am not an experimenter in this field.  I do
however have some practical experience in dissolved gases - I do high
pressure liquid chromatography and have to use helium sparging each morning
to flush the nitrogen and ocygen out of my solvents.

     I see from your posting that there should be a "Type 6, closed and
pressurized".  I also see that "Type 5, recombiner, syringe or bellows" has
been run with a fill of inert gases - maybe a separate classification is
needed.  Hoyt Sterns mentions yet another type of cell, with a recombiner but
evacuated after the initial generation of oxygen during charging.

     The point of my rather speculative posting was not to make an exhaustive
classification of cells, but to point out that little attention seems to have
been given to gas compositions in cells (in comparison for example with the
concentration on the surface finish, impurities etc. of cathodes).  I am
particularly struck by the fact that the most positive results seem to have
come from the more "open" cells where dissolved nitrogen levels would be
expected to be higher.





--
Bruce Dunn    Vancouver, Canada   Bruce_Dunn@mindlink.bc.ca
Newsgroups: sci.physics.fusion