From: DROEGE@fnald.fnal.gov
Subject: Status #6 Cell 4A3
Reply-To: DROEGE@fnald.fnal.gov
Organization: Sci.physics.fusion/Mail Gateway
Date: Mon, 4 Jan 1993 17:44:03 GMT

Status #6 Cell 4A3

After about 250 hours of charging, we are up to an apparent 2.9 to 1 D/Pd.

The gas charging is very curious and I do not have a good explanation.

Remember, the cell is closed with a tube going off to a motor driven syringe.  
When I talk about 2.9 to 1 D/Pd, I mean that 183.8 cc of gas has accumulated 
in the syringe since the start of charging the 0.1 cc Palladium cathode.  This 
is presumed to be Oxygen, which means that 376.7 cc of D2 has gone somewhere.  
There is no guarantee that any of this is correct, but many experiments have 
shown that early in charging when essentially all of the D2 is absorbed (by 
visual check) that the gas accumulation in the syringe matches the expected O2 
evolution as determined by the cell current.  We also reduced the current from 
1 amp to 0.1 amp for a brief time and observed about 30 cc of gas evolution 
which has taken several days to recover now that the cell is back at one 
ampere.  

The cell is presently running at one ampere.  This should produce 209 cc of O2 
and 418 cc of D2 per hour.  This is roughly 10 cc per minute, which is my data 
taking interval. 

As readers of this column will observe, we have been slowly accumulating gas 
in the syringe.  This takes place in a curious fashion.  There are occasional 
spikes in the evolved gas.  The interval between spikes is 20 minutes to 2 
hours.  The spike is typically a +5 cc change over the one minute sampling 
interval.  Over the next 5 to 10 minutes this gas increase is mostly re-
absorbed, with an accumulation at the end of a few tenths of a cc.  Over time 
this results in an accumulation of gas.  In most cases, the positive spike is 
accompanied by a cooling of the catalyst.  During the subsequent re-absorption 
the catalyst regains its former temperature.  We have not observed any spike 
where the gas accumulation exceeds the 10 cc per min of D2 + O2 evolved by the 
electrolysis.  From time to time there is a very large spike, as much as 20 cc 
having been observed, but these take several minutes to accumulate so that a 
number of one minute measurements are obtained on the up tick.  There is no 
consistent cell temperature change during these events.  

I remind you all that the catalyst tends to have hot spots.  A hot spot 
converts more efficiently and thus becomes hotter.  

Explanation A - Trickle down conversion

>From time to time a drop of condensate formed at a higher spot in the catalyst 
trickles down to an active piece of catalyst, wets it, and causes it to turn 
off.  This causes a burst of gas until another spot takes over conversion.  
This does not explain the apparent net accumulation.  To explain that we need 
the pressure surge to cause a permanent leak of a small amount of gas.

Explanation B - New Crack Theory

>From time to time a crack opens up in Palladium.  This immediately releases 
some gas.  But the new surface exposed eventually absorbs more gas so there is 
a net gas gain.  But this should cause an increase followed by a return to 
normal in the catalyst temperature.  We observe the opposite.  

Note that I am quite confident in the short term measurement ability of my 
kludge.  Less so for the long term, but the new gas switch seems to be tight.  
It was tested for leaks for several weeks.  I have ruled out things like 
ambient temperature changes (these can be seen and track the heating system 
changes to the expected value) and ambient pressure changes (careful 
observation can detect the pressure change caused by the furnace drawing in 
house air for combustion).  

There are lots of other measurements.  I will be happy to make observations 
and report back to check a theory.  Besides the cell voltage and current, we 
measure gas, cell temperature, catalyst temperature, several temperatures 
around the cell, ambient temperature, cooling water temperature, many power 
supply voltages, ADC reference calibration, and forty or so other things. 

Tom Droege

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