Horace Heffner"
There was 700 grams of H2O which was heated for only ten
seconds. Mizuno was not using much power, but the heating rate
of 700 grams of water in figure on page 31 shows a rise in
water temperature of 60 C in about 10 seconds. This would
constitute an energy input of 176,400 Joules!
Page 14 describes the input parameters - 15 volts and 1.5 Amps.
This is a power input of 22.5 watts for 10 seconds but the
power apparently accepted by the water was (DeltaT) (Mass of
water) (1 calorie/gram)(4.2Joules/calorie) /10seconds =
60(700grams) (4.2)/10 = 17,640 watts.
That is a gain of 780 for power output versus power input.
Elsewhere he calculates the gain in that same range.
This explosion was NOT due to "just" a few cc of hydrogen in
the headspace,
Of course not, but that few cc, ignited, is plenty to pop the
rubber top and ignite the large volume in the 1L-6 incubator.
Or, even just a sudden boil off is probably enough to expose
the electrodes and cause an ignition.
The previous run provides the "active" setting but it cannot be
presummed that there was significant residual hydrogen in the
hood - such as if the exhaust fan totally failed - and even if
there was this is totaly unnecssary and moreover inconsistent with
this kind of sudden power increase in the cell.
If we are to accept everything Mizuno says, the explosion actually
could NOT have been casued by hydrogen at all ! That's right, a
hydrogen explosion it totally inconsistent with this situation -
as it would have casued an explosion long before the 10 seconds,
and the water in the cell COULD NOT have attained that
temperature.
At only 3-4 seconds the surface temperature of the cathode, down
to a micron or so was already near its melting point. If hydrogen
had been there, it would have exploded then - ending the episode
and not allowing further heat-up of the water.
The Stephan-Boltzmann law defines the maximum power per unit area
that a perfect emitter of radiation (blackbody) can sustain. The
total cathode area exposed to the electrolyte is a length of 1.5
cm. The cathode diameter is 0.1 cm. The maximum area exposed to
the electrolyte is 0.47cm2. The power is 17,640 watts, so the
power per unit area is 374,000 watts/cm2. (In reality, only about
10% of this cathode surface area is heated, so these calculations
below (from Brian Ahern) are truly conservative.
Power/area = sigma T ^ 4
Where s = sigma = 5.7 x 10-8 W/m^2/degreeK = 5.7 x 10^-12
W/cm2/degreeK
T^4 = 374,000/5.7 x 10^-12 = 6.6 x 10^+16
T = ~ 16,0000K
IOW if we are to believe Mizuno the cause of the explsoion was
rapid heating and sublimation of the surface of the cathode (a few
mils of tungsten blown off, resulting in the pitted appearance)
probably caused by nuclear reactions - together with the flash
steam that this cathode surface-boil-off would have created. A
hydrogen explosion, or residual hydrogen left over from the
previous run would have ended this episode long before the 10
seconds - so that possibility is eliminated.
Given this, personally I am suspicious of Mizuno figures or at
least wishing that an isoptic analysis of the metal surface had
been made, since that is the only way to prove a real nuclear
reaction. BTW - the most active part of the surface area could not
have been tested as it must have alreadu boiled off.
Jones
