I like your approach, Dave. To fit reality, you need to take into
account two major variables. These are the diffusion rate and the
solubility of H in the Ni. Both determine the rate at which H can get
to the NAE where it enters into a nuclear reaction. The diffusion rate
increases with temperature while the concentration of H decreases. At
some high temperature these two competing effects will produce a
stable condition. Above this stable temperature, increased
temperature will reduce the power output while below the stable
temperature, increased temperature will increase the power. This
stable condition apparently occurs at a very high temperature when Ni
is used, but at a much lower temperature when Pd is the metal. This
fact makes Ni more useful as a source of energy than Pd. The best
design would be based on achieving this stable temperature without a
need for control. Rossi has apparently not mastered this ability.
The concentration of H in the Ni can be increased by increasing the H
activity in the gas. This can be done by either increasing pressure or
by bombarding the Ni with energetic H+ ions. This additional
variable should be added to your model because this method can greatly
increase the power and allow for control without using temperature as
the controlling variable.
Ed Storms
On May 25, 2013, at 10:54 AM, Andrew wrote:
Dave,
It seems that your model of heat conductivity leads to a system
equation that's a linear first order differential equation, if I'm
not mistaken. That's a tractable system to deal with from a
simulation and control point of view, and as such lends itself to
numerical optimisation techniques.
Andrew
----- Original Message -----
From: David Roberson
To: vortex-l@eskimo.com
Sent: Saturday, May 25, 2013 9:36 AM
Subject: Re: [Vo]: ECAT Drive PWM Issues
Fran, my model takes into account the rate of heat transfer out of
the device by using a parameter that simulates a thermal positive
feedback loop. And, as you suggest this depends greatly upon the
rate of heat generation with temperature and the thermal resistance
that it delivers that heat into. Another way to think of this
effect is to consider what would happen to a block of active
material which is surrounded by a perfect heat conductor. In this
special case, any additional heat that is generated is immediately
absorbed by the conductor and can not raise the temperature of the
block. This would be a stable condition and the COP would be low.
Now, if you modify the surrounding heat conductor by increasing its
thermal resistance then any newly generated heat from within the
block would result in an increase in its internal temperature in a
positive feedback manner. The resistance can be increased until it
reaches a point such that a tiny incremental input of heat to the
block results in a temperature increase of the block that causes
additional heat generation slightly larger than the initial
increment. Rossi appears to operate above this resistance point
when his device has the desired performance.
That was a lot of words and I suspect is not clearly written. The
meat of the description is that there will be a temperature that
depends upon the heat sinking where the device becomes unstable and
begins to proceed toward melting. My model suggests that this is
the temperature above which Rossi should operate his device to
achieve good COP. The model further indicates that you can
maintain control of the device while operating above this point as
long as you reverse the process before a second temperature trip
point is reached that leads to run away. It is important to realize
that operation within this region is unstable unless a drive
waveform is applied with the proper characteristics.
In the radio world this type of device would be referred to as a
negative resistance component. Rossi must be relying upon the
energy generated in this mode for his large gain. The hard part is
to keep the ECAT from getting out of control since he is operating
on a sharp balance to obtain good COP.
I am not modeling any process that occurs beyond the two temperature
trips that I described since operation above the second one is
destructive. Operation below the first temperature point results in
a COP that is too low to be useful. I have included energy loss due
to a 4th order radiation process in some of my runs, but so far I
find that control issues occur before this has significant effect.
I believe as you do that operation with a heat exchange fluid will
be easier to control. This also allows Rossi to adjust the flow
rate which could be used to modify the thermal resistance factor and
thus total loop dynamics. For example, he could raise the
temperature at which the core become unstable thereby compensating
for different core activities.
My model operates upon the average behavior of an ECAT type device.
It assumes that the design has been developed by good engineering
processes. If the design team allows the system to harbor
inconsistent heat transfer such as would occur with too many and too
large in size hot spots, then there is no control technique that
will work effectively. I suspect that much effort will center
around making sure this issue is handled.
Dave
-----Original Message-----
From: francis <froarty...@comcast.net>
To: vortex-l <vortex-l@eskimo.com>
Sent: Sat, May 25, 2013 7:16 am
Subject: re: [Vo]: ECAT Drive PWM Issues
Dave, I think you we are both in agreement with the initial post of
Ed’s thermal analysis, http://www.mail-archive.com/vortex-l%40eskimo.com/msg80803.html
but it does not mention the difference between the destructive
test in open air and the unit in normal operation which is
constantly bathed in a heat extracting fluid.. are you modeling this
in your SPICE calculation? The thermal circuit in the destructive
test only has air cooling to keep the runaway at bay and represents
a softer – more fragile target for the waveforms to temporarily
exceed while I think the reactor in heavy heat sinking mode would
have much higher tolerance for controlled PWM excursions into areas
that would be considered runaway if not for the steady drain.
Fran
[Vo]: ECAT Drive PWM Issues
David Roberson Fri, 24 May 2013 23:30:52 -0700
I was adjusting my spice model of the ECAT when I decided to
determine how
important it is to keep the device operating within the normally
unstable
region at all times. Here I refer to the unstable region as that
operation
range where the ECAT would tend toward over heating unless under
control.
There is no end to the questions which keep arising as to how heat
can be
applied in the proper format to keep an unstable device operating
under control
when it is capable of putting out more heat than required to drive
it. And,
the ECAT tends to operate best when the COP is equal to 6 which
clearly is
within this mode.
One day this will be accepted. For now, I want to mention that it
is important
to keep the ECAT operating near the ultimate thermal run away
region. If the
device temperature is allowed to drop too far before the drive
returns then the
COP degrades significantly. And, as is somewhat demonstrated by the
waveforms
shown in the recent report, the length of time that the temperature
hesitates
at its greatest level is determined by how by Coupon Companion"
id="_GPLITA_0"close to that ultimate run away
temperature the device operates.
My test runs demonstrate that the ECAT needs to be operating at a
maximum
temperature near to its ultimate thermal run away point and that the
variation
in output temperature needs to be maintained low by timing of the
PWM drive.
Both of these requirements should be met if the ECAT is to deliver
the desired
COP of 6 and remain stable. My spice model offers good guidance
even though it
can only approximate a real device.
Dave
