From: ames!FNALD.FNAL.GOV!DROEGE
Subject: Heat pulses in P&F cells
Reply-To: ames!FNALD.FNAL.GOV!DROEGE
Organization: Sci.physics.fusion/Mail Gateway
Date: Thu, 9 Apr 1992 23:34:47 GMT

This discussion of D absorption in "anomalous heat" experiments is 
being conducted in public rather than as a private message to Dieter 
Britz in the hope that others might be interested.  If, as John 
Stimson says "is this simply a newsgroup for cro-magnon pop-science 
fans...?", readers think it is not of common interest I will take it 
private.  Let me know. 

I have been trying to make sense of temperature measurements taken 
in P&F type cells for several years.  The general cell design is 
shown on p 244 of the Como proceedings. The cell is about 3 cm dia 
by 15 cm tall and has a volume of 100 cc.  The bottom two thirds of 
the cell contains electrolyte and is surrounded by a heavy aluminum 
spool piece.  The top of the cell contains the re-combiner and 
sticks up into air.  The cell bottom and electrolyte are cooled by 
conduction to the aluminum spool.  The top and catalyst are 
convection cooled to air.  A baffle at the bottom of the catalyst 
reduces internal cell convection.  The heat transfer between the 
catalyst section and the electrolyte is thought to have a time 
constant much longer that the 1 minute measurement interval.  The 
cell contains 60 cc of 2N D2SO4 + .1 N LiOD electrolyte.  The Pd 
cathode volume is 0.037 cc and the area is 0.57 cm sq. 

A thermometer (thermister) in a glass tube is positioned near the 
center of the electrolyte volume.  A thermometer (solid state) is 
taped to the outside of the tube at the top to measure the catalyst 
temperature.  Note that is not easy to get a good measurement of the 
catalyst temperature as re-combination likely takes place at a hot 
spot which can move around over several square inches of catalyst. 

A constant pressure servo continuously measures the cell gas volume.  
We interpret an increase in gas volume as being due to absorption of 
deuterium by the cathode leaving behind un-recombined oxygen to be 
measured.

We have been running for the last thirty days with a current saw 
tooth which starts at 40 ma per sq cm, ramps to 600 ma per sq cm 
over a half hour, then returns to 40 ma per sq cm.

We observe with McKubre et. al. that cells are noisy.  He says (Como 
p-436) "For both electrodes there was a 'high-frequency' fluctuation 
of the excess power with periods of aprox. 0.1 - 1h which correlated 
with cell pressure variations, characteristic of partially 
intermittent operation of the catalytic recombiner."

While some measurements are consistent with intermittent 
recombination, others indicate to us that gas pulses in and out of 
the cathode.  We note that the gas volume stays constant during the 
first half of the ramp.  This indicates that at low gas evolution 
rates the catalyst keeps up with the gas production.  At the higher 
rates, there are both sudden decreases (larger) and increases in gas 
volume.  In our naive view, we would think that the catalyst would 
work better at the high rates, since it is hotter.  The cell 
contains at least 10x the catalyst area needed for the current.  
Physical observation seems to confirm the pulsing.  Storms seems to 
have observed similar behavior. We would welcome comments by 
experts. 

Now for an event of the type that puzzles me.  During the higher 
current portion of the ramp, we occasionally observe a sudden 
decrease in volume of typically 2 cc, or 100 relative volumes of 
deuterium (2/.037 *2). On the same one minute sample time the cell 
temperature increases by .15 C and the catalyst temperature 
increases.  There is a temporary change in heat balance but the long 
term heat balance is consistent with zero to the present calibration 
- about 4 mw.  

Interpretation #1

The cathode blows out 4 cc of deuterium.  This is combined with 
oxygen in the catalyst to cause it to get warmer.  The result is a 2 
cc loss in volume.  Since at high loading, loss of gas is exothermic, 
the cathode gets hotter and thus the electrolyte becomes warmer.  
But note that this indicates (60cc*.15*4.1)  40 joules for 4 cc of 
deuterium or 224 Kj per mole.  This seems very large.  What am I 
doing wrong?

Details of the measurement indicate that this is not coupling 
between the catalyst and the electrolyte.  I have destroyed a lot of 
thermometers to prove they are not noisy.  The temperature signals 
are 10x to 50x noise.  I really think the measurements are correct 
as stated.  We have been observing this phenomena for two years in a 
variety of cell configurations.  While the present ramp obscures 
thermal measurements, when run at steady current heat measurements 
show pulses.  They do not come often enough to be differentiated 
between net heat pulses, and a long endothermic reaction followed by 
a short exothermic reaction. 

Interpretation #2

This interpretation is too bizarre to be put before the eyes of 
skeptics.  Will send in a plain brown mail message to those who ask.  
But this is why we keep working. 

Tom Droege
Newsgroups: sci.physics.fusion