"Very sharp" -just means that the power is applied nearly
instantaneously. Not any more power, just whatever equals E2 /R.
However the temperature gradient would indeed be higher, so the wire
would expand sooner than the matrix around. If the matrix temperature
rises and falls a lot during a small part of a line cycle, stress might
get pretty high. But isn't the wire a near-zero expansion/temperature
Ol' Bab -who was an engineer...
On 3/17/2015 4:02 PM, Axil Axil wrote:
In these triac light dimmers, the rise/fall times are very sharp maybe
in the nanoseconds. That means that a lot of instantaneous power is
being feed into the heater wire as the power pulse starts when the
leading edge waveform is used.
On Tue, Mar 17, 2015 at 4:56 PM, Axil Axil <janap...@gmail.com
According to Jack, the reaction did not happen in the fuel, but in
the insolating layer. The fuel composition does not matter. IMHP,
what matters is the exact nature of the heater current.
On Tue, Mar 17, 2015 at 4:38 PM, Robert Ellefson
<vortex-h...@e2ke.com <mailto:vortex-h...@e2ke.com>> wrote:
Fantastic! I’m really stoked to hear of your progress. I
think your powder recipe sounds very interesting, and I would
love to know more about the details of the reactants. It
sounds like you’ve come up with a mixture which may contain
one or more key ingredients not yet identified as being of
primary significance to the high-gain modes of these systems.
If I may fire away:
What size Fe2O3 and TiH2 grains were present?
Is this mixture generally not hygroscopic, and therefore is
curing the reactor’s sealant a simple matter as compared to LAH?
Are you tumbling or milling these reactants, or performing any
other notable processing steps, prior to putting them into the
Thanks for sharing, and keep up the great work!
*From:*Jack Cole [mailto:jcol...@gmail.com
*Sent:* Tuesday, March 17, 2015 1:08 PM
*To:* email@example.com <mailto:firstname.lastname@example.org>
*Subject:* Re: [Vo]:melted alumina tube
The input power was ~260W. I don't know what the R value of
the insulation is. I had the cell surrounded by high purity
alumina powder and covered with a thin sheet of ceramic
insulation. I used standard 120V AC 60hz with a triac type
dimmer switch (chops the waves starting at V=0). I'll have to
check with the manufacturer to see what the remaining 5% of
the tube is. The heating element was Kanthal A1. It's
strange that the heating element was able to completely melt
at points. In the past, it has always failed before melting.
I was using INCO type 255 nickel, TiH2, LiOh, KOH, aluminum
powder, and Fe2O3. Good idea on the small amount of fuel
which should cause some localized melting.
The fact that the fuel was a small diameter cylinder seems to
suggest that it was fully expanded in the tube and shrunk down.
On Tue, Mar 17, 2015 at 2:02 PM, Bob Cook
<frobertc...@hotmail.com <mailto:frobertc...@hotmail.com>> wrote:
It looks like you had a pretty good reaction.
What was the input power? What is the R value of the
insulation on the outside of the electric coils? What was
the nature of the electrical input--frequency etc? And
what is the electrical heating element material? If you
have an acetylene torch, see if you can melt a piece of
the tube that melted.
The tube may have had glass fibers incorporated in order
to improve strength. You indicated it was 95% pure. What
was the other 5%?
What was you fuel mixture? You may want to try a small
fuel loading and see if the same intense reaction
happens--all else the same.
Try the test with a iron core instead of a fuel load and
determine if there is an apparent magnetic field which
would hold the iron core in position when direct current
is applied to the heating coil. An alternating current
would of course change the magnetic field and may make for
null reaction conditions.
Try 2 or 3 t/c's if you can--one inside and two outside
to get a measure of the temperature gradient along the
tube. Also another easy way to determine temperatures is
the use of thermal sticks on accessible surfaces. Welders
use these to determine preheating temperatures. They may
provide a cheap temperature measure for you.
Keep it shielded--good luck.
----- Original Message -----
*From:*Jack Cole <mailto:jcol...@gmail.com>
*Sent:*Tuesday, March 17, 2015 9:39 AM
*Subject:*Re: [Vo]:melted alumina tube
To add a couple of more details. The agglomerated
piece of material is extremely hard. I tried to break
it off with pliers, but it seemed like it would take
more force than to break the entire cell. The
resistance wire is extremely difficult to separate
from the cell. I plan to open the cell with a diamond
blade later today to see if more can be learned about
what took place (e.g., evidence of melting on the
inside of tube). I was able to get one piece of the
resistance wire pried from the tube. There were
indentations in the cell.
As a follow-up experiment, I need to run it without
the fuel to the same power levels to see if the same
On Tue, Mar 17, 2015 at 9:42 AM, Jack Cole
<jcol...@gmail.com <mailto:jcol...@gmail.com>> wrote:
I had an interesting experiment yesterday. This
was my first time using a triac to regulate input
power and sealing the tube with a compression
fitting. Unfortunately, my thermocouple failed.
Take a look at the alumina tube and the evidence
for melting. The furnace sealant which I coated it
with completely melted and agglomerated to the
bottom of the cell (also appears to be mixed with
The tube was purchased from China and is
purportedly 95% pure. It was supposed to have a
continuous operating temperature of 1500C.
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