The Incandescent W Experiment
Run 2 - 19AUG98
For Run 2 we decided to add a 1 ohm series resistor inside the calorimeter enclosure, on the power supply side of the 400 mfd filter capacitor already inside the calorimeter enclosure.
We also changed the Teflon sleeving around the W rod from the ordinary thick-walled Teflon tubing used in Run 1 to a piece of 1/4" OD Teflon rod drilled out to accept the W rod snugly. Approximately l cm of the W rod protruded from the end of the Teflon rod.
As in Run 1 we filled the cell with 150 grams of fresh 0.5M K2CO3 solution.
We had some difficulty getting Run 2 underway. Upon applying electrolysis power for the first time, we observed that no gas was evolving from the cell. An investigation revealed that an O-ring was misplaced. We assembled the cell properly and tried again. The second time, after about an hour of operation at "warm-up" voltage levels, the top popped off the cell. We discovered that the cold trap was too cold and the inlet tube had frozen over blocking the exiting gases. We reconfigured the cold trap to cool only the lower portion of the trap vessel and started the run for the third time.
This plot shows the raw results of Run 2. The warm-up phase lasted for about 1.75 hours, during which time the cell current (Icell) was nearly 4 amps. NOTE: We have added the caloric value of the theoretical quantity of evolving gas to the Pout values in these plots.
At 1.75 hours we increased the cell voltage (Vcell) to about 160 volts. Icell dropped to around 1 amp and and cathode became quite incandescent.
As you can see, the Pin data becomes erratic during this mode of operation. This occurs despite the use of adaptive filtering in the Clarke-Hess power analyzer.
At about 2.95 hours, a single bad reading in the Tin signal caused the P-D temperature control algorithm to make a large bipolar excursion. This, of course, resulted in a corresponding excursion in the Pout signal.
After3.5 hours, most of the exposed W rod had been consumed and the operation of the cell became extremely erratic. We turned off the input power at about 4 hours.
This scope screen capture shows the voltage (top) and current waveforms during the warm-up electrolysis portion of the run. The "1->" symbol on the left side of the display shows where zero volts is for the voltage trace. The "2->" symbol below it shows where zero amps is for the current trace.
As you can see, the voltage is rather ripply, due to the high current .
BTW, these waveforms are collected at the point in the circuit where the power analyzer is located.
Under these conditions, the measured gas flow rate varies from 90% to 85% of theoretical.
This screen shows the situation at the beginning of incandescent mode. Note that the voltage ripple has diminished greatly. The current still shows a 120 Hz pulse to recharge the capacitors and there is some evidence of the maelstrom going on in the circuit around the cell but it is far reduced from earlier observations without the filter capacitors.
Here the measured gas flow rate varied from 72% to 105% of theoretical...we do not understand the variations yet.
This screen shows the situation near the end of the run when the exposed area of W rod was quite small. The time scale on this screen is 5X slower than the first two. You can see that the current pulses for recharging the capacitors have become quite erratic now and don't appear to occur every 8 ms as they did before.
The cell was making a "ragged" sound during this period, like the sound of a stick being dragged along asphalt pavement at 15-20 mph.
Under these conditions, the measured gas flow rate was only 46% of theoretical! Yes, our correction to the Pout values using the theoretical rate of gas evolution was significantly wrong here but the resulting error is insignificant. Total current was only 0.8 amps so the correction was about 1.2 watts (1.48*I). According to the measured gas flow we should have only added ~.6 watts to the Pout values here. This is only about 1% of the nominal input power at this time.
This is the same plot as before except that the Pin values have been smoothed by an exponential filter with a 150 second time constant. The wild jitter has thus been eliminated and you can clearly see that there is no real indication of excess heat.
We weighed the cold trap in the exiting gas line at hour 2 (124.7 grams) and again at the end of the experiment (124.7 grams)! Astonishingly, no change in weight was observed. Apparently there is no significant evolution of water vapor from the cell. This is surprising since Tcell ranges up to 80+° C during the run.
It doesn't appear that the 1 ohm R had a beneficial effect on this run. During the warm-up phase, this R was rather overloaded with 4 amps going through it...16 watts! We will remove this R for run 3 and add smaller, lower impedance capacitors, in parallel across the existing electrolytic capacitors to better suppress high frequency noise.
The 1/4" dia Teflon rod protecting the W rod worked great. It was essentially undamaged after the run.
Keep those comments coming. Every suggestion is welcome and is given serious consideration.