At 08:42 AM 5/8/2010, Jed Rothwell wrote:
Shanahan is proposing the oldest and least credible prosaic
explanation for cold fusion:
"Once current stops, the driving force to load the Pd electrode with
hydrogen is removed, and the system seeks to obtain equilibrium
under the new state by releasing gas, converting the situation from
an electrolysis cell to a gas unloading experiment. At the point
where electrical contact was broken, the cell gas was very nearly a
stoichiometric mixture of hydrogen and oxygen."
With Fleischmann's open cell, that is completely wrong, as Abd
noted. The cell head space is filled with water vapor only, with no
significant amount of oxygen.
"Significant hydrogen release will occur because the electrolytic
loading was equivalent to many atmospheres of hydrogen gas pressure
exposure, but the hydrogen present will inhibit complete Pd unloading. . . ."
This is nonsense. See Fleischmann's response to Morrison about this,
p. 10 and 11:
<http://lenr-canr.org/acrobat/Fleischmanreplytothe.pdf>http://lenr-canr.org/acrobat/Fleischmanreplytothe.pdf
Fleischmann addressed this definitively and quantititatively. I
addressed it intuitively and qualitatively. Fleischmann's approach
is, of course, definitive and mine could easily be wrong.
But it should have been obvious. The kicker is this "equivalent to
many atmospheres of hydrogen gas pressure exposure." No, the D2
pressure at the cathode is roughly one atmosphere through the whole
experiment. The deuterium is absorbed by the cathode, not because of
pressure (which is used in gas-loading experiments to increase the
loading beyond 1:1, or to more rapidly reach 1:1 at least), but
because palladium is hungry for deuterium. The absorption of
deuterium by palladium is exothermic; therefore the deloading is
endothermic. In the Arata experiments, you can see, from rapid
loading, a substantial release of heat. So I'd expect deloading to
cool the cathode, but quite slowly. It's like any kind of
evaporation, which generally cools the substance evaporating.
You know, an experiment could be made more efficient, I'd think, by
circulating deuterium gas over the cathode somehow, instead of simply
letting it escape. Not full-closed, only a little pressure would be
allowed, but the same deuterium levels at the cathode might be
maintained with less current, as the deuterium pressure increased,
the current would be lowered with a feedback control. Presumably
there would be some kind of pump to recirculate the deuterium.
As the deuterium deloads, if there is adequate oxygen, the deuterium
might oxidize at the surface, but this would be slow if it happens at
all. In any case, it should be easy to measure the oxygen
concentration near the cathode.
This is a truly appalling error; I saw Shanahan make many like this
in his comments on Wikipedia. It is just a made-up explanation with
no depth, and certainly no attempt to make predictions. Fleischmann
knows, from long experience, the deloading that occurs when the
generation of deuterium at the cathode surface stops, and how long it
takes for the effective sublimation to take place.
