From: fsmith@kean.ucs.mun.ca
Subject: Re: Heat pulses in P&F cells
Organization: Memorial University. St.John's Nfld, Canada
Date: Mon, 13 Apr 1992 19:05:25 GMT

In article <920409175943.208004be@FNALD.FNAL.GOV>, ames!FNALD.FNAL.GOV!DROEGE writes:
> 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
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