BLP Gas-Phase Replication Effort - Run 10….5FEB98 ………………..(best viewed with 1024 pixel display width)
Legend
Total Input Power (electrical)
Output Power (heat)
Chamber Wall Temperature (C)
Gas Temperature (C)
Gas Pressure (torr)
Filament Temperature (° C)
Room Temperature (C)
Inlet water Temperature (C)
Recently we learned that BLP uses KNO2 in the particular experiment we are trying to replicate…not KNO3, which we have been using all along. In Run 10, therefore, we used KNO2 as the catalyst.
The run starts with a manually-executed heater power control algorithm designed to get the Pout signal up to 30 watts ASAP. After about 1 hour, we applied 10 watts to the tungsten filament and left the filament voltage at that setting (~8 volts) for the duration of the run. For over 3 hours, the filament ran at 10 watts in vacuum while we waited for thermal equilibrium in the calorimeter. There was little or no sign of deterioration of the filament during this period. At hour 4.7 we filled the chamber with 2.0 torr of pure, dry H2 gas and closed off the chamber. As you can see from the Tfil trace (which actually represents the resistance of the filament), the filament was attacked immediately. It lasted about 1 hour, during which time we made periodic adjustments to the cartridge heater power to keep the total input power at 30 watts. Just before the filament burned out it was drawing only 3 watts, indicating that it's resistance had tripled due to the erosion. When the filament burned out, we adjusted the cartridge heater power from ~27 watts up to 30 watts…again to keep the total input power constant.
This constant-power strategy maintains thermal equilibrium in the calorimeter UNLESS the experiment starts producing excess heat. Unfortunately, there was no sign of excess heat in this run.
For the record, it must be noted that, since the calorimeter time-constant is about 1 hour, the filament lasted plenty long enough for us to observe any sizeable excess heat signal. For example, if the experiment had made only 10 watts of excess heat (about 1/5th what BLP claims for their version of the experiment), the Pout trace would have risen about 6 watts (more than half-way from where it stayed to the top of the screen!) while the filament was operating.
Upon disassembly of the apparatus, we see that the KNO2 has melted (coalesced, at least) into the bottom of the stainless steel vial but a careful weighing shows that there is still 0.19-0.20 grams in the vial. We measured 0.20 grams before the run and the stuff was obviously damp! There was no sign of the yellow-green powder that remained after Run 9.