The Incandescent W Experiment
Run 4,5 & 6 - 25AUG98
For Runs 4, 5 & 6 we used a thoriated W rod instead of the pure W rod used in the earlier runs. This change, recommended by Dennis Cravens to promote excess heat, made a surprising difference in the appearance of the incandescence phenomenon. With the thoriated rod, the rod temperature appears to be much higher for a given input power. The result is a very bright light emerging from the cell that looks just like ordinary firelight. Compared to the pure W rods, there is relatively little evidence of the blue light usually associated with electrical discharges.
This photo was taken with the thoriated W rod in full incandescence while the calorimeter enclosure was open. You can see the brilliant light coming from within the cell. Also visible in this photo is the outlet water temperature sensor, located in the Swagelok Tee fitting on the right.
The overall level of cell activity with the thoriated rods is quite high and the lifetime of these rods is correspondingly short. Runs 4 & 5 served mainly to demonstrate that fact and to convince us that our usual power balance calorimetry would not work well on such a short-lived and unstable experiment.
We therefore modified the data acquisition software to integrate input and output powers during the run and to display and plot the resulting energies. Using such integration we can measure the energy balance of the experiment without ever achieving the thermal equilibrium necessary for an accurate power balance measurement.
Here are the results from Run 6. The time scale is only two hours and all the action takes place over a 20 minute period towards the end of the first hour.
For the first 35 minutes we just waited for the cell to come to thermal equilibrium inside the calorimeter enclosure. This equilibrium is indicated by the Pout trace closely approaching the P=0 line near the bottom of the plot.
Simultaneous with the application of the warm-up electrolysis power, we reset the energy integrators (where the Eout trace resets to zero). The warm-up phase lasted about 10 minutes. A few minutes into the warm-up period we noticed that the cell temperature sensor was disconnected, hence the sudden appearance of the Tcell trace.
After the warm-up we turned the voltage up to about 150 volts, indicated by the sharp vertical excursion in the Pin trace. The voltage remained constant for the next ~10 minutes while the W rod glowed intensely and was rapidly eroded away. Evidence of the erosion can be seen from the declining Icell and Pin traces.
When the rod was essentially consumed we turned off the input power supply and left the calorimeter running to integrate the remaining heat energy in the cell. As you can see from the Ein and Eout traces, there is a reasonably good energy balance for the entire run. The final Ein value is 134,505 joules compared to 131,376 joules for Eout. NOTE: The Eout value has already been corrected for the theoretical quantity of escaping H2 and O2 by adding Icell*1.48 to each Pout value.
Regarding the escaping gases, we observed a striking discrepancy between the actual gas evolution rate and the theoretical rate predicted by the average cell current. When the thoriated W rod was incandescent, we measured gas flow rates up to 4 times higher than expected...even with a good cold trap in the gas line to condense and remove water vapor escaping from the cell!!!
Presently we do not have any explanation for this anomaly. We are considering ways to analyze the gas stream to determine the composition of the extra gases. Suggestions for this analysis are most welcome.