First of all, variable conductance is not to the point.  The issue is not
whether one can vary the conductance or anything else -- rather the issue
is the _control_ of that variance.

Secondly, the technology you describe involves a solid phase.  My request
was for a cite of prior art for the technology you describe.  The
Thermacore technology does not fit your description.


On Sat, Jun 22, 2013 at 9:03 PM, Axil Axil <janap...@gmail.com> wrote:

> *http://www.thermacore.com/products/variable-conductance-heat-pipe.aspx*
> **
> *Heat pipes have this ability for Variable Conductance, here is what
> thermacore does.  *
> **
> *How Does a Variable Conductance Heat Pipe Work?*
>
> All heat pipes can be made variable conductance by introducing a small
> mass of Non conducting gas NCG(shown schematically below). Because NCG is
> swept to the end of the condenser by the condensing working fluid vapor, it
> blocks a portion of the condenser, effectively reducing its conductance. If
> the ambient temperature increases, decreasing the available temperature
> difference between the condenser and the ambient, the operating temperature
> of the heat pipe will increase. This causes the operating pressure (i.e,
> saturation pressure of the working fluid at the heat pipe operating
> temperature) to increase, compressing the NCG into a smaller volume. The
> result is that more of the condenser area is available to condensing
> working fluid. This limits the increase in the operating temperature of the
> heat pipe and the component mounted to it, much as in the case of a
> Constant Conductance Heat Pipe (CCHP). Ideally, the increased conductance
> of the condenser offsets the increase in the ambient temperature and the
> heat pipe operates at a constant temperature.
>
> The degree of control depends on the working fluid saturation curve, the
> desired operating temperature set point, the ranges of ambient temperature
> and heat load and the volume of gas relative to the volume of the vapor
> space in the condenser.
>
>
>
>
> On Sat, Jun 22, 2013 at 8:43 PM, James Bowery <jabow...@gmail.com> wrote:
>
>> If you have indeed come up with something that is as elegant as the
>> passive power output from LFTR for the E-Cat HT, my apologies for
>> misunderstanding your proposal and my congratulations.
>>
>> Can you cite any patent numbers that use this sort of passive temperature
>> control using Li heat pipes?  Can you select the desired operating
>> temperature at the reactor surface with it, as I believe the free
>> convection approach can?
>>
>>
>> On Sat, Jun 22, 2013 at 12:26 AM, Axil Axil <janap...@gmail.com> wrote:
>>
>>> A passive thermostat that reduces the flow of lithium liquid in a heat
>>> pipe is what you were after.
>>>
>>> It uses  the same passive expansion mechanism that is used in the LFTR.
>>>
>>> What is the problem?
>>>
>>>
>>>
>>>
>>> On Fri, Jun 21, 2013 at 11:26 PM, James Bowery <jabow...@gmail.com>wrote:
>>>
>>>> You must not be much of an engineer if you are so willing to blow off
>>>> explicit mention of passive control, Axil.  Do you have any engineering
>>>> background in critical systems -- by which I mean systems that, if they
>>>> fail, they kill people?
>>>>
>>>> I do and they didn't.
>>>>
>>>>
>>>> On Fri, Jun 21, 2013 at 10:21 PM, James Bowery <jabow...@gmail.com>wrote:
>>>>
>>>>> You sacrificed passive control without acknowledging that was the goal
>>>>> of my proposal.
>>>>>
>>>>>
>>>>> On Fri, Jun 21, 2013 at 8:03 PM, Axil Axil <janap...@gmail.com> wrote:
>>>>>
>>>>>> *A *lithium heat pipe provides enough thermal capacity and power
>>>>>> transfer density than you could ever want or need. Gravity is not a 
>>>>>> factor.
>>>>>>
>>>>>>
>>>>>>
>>>>>> The heat transfer can be controlled by a temperature regulation of
>>>>>> the liquid lithium return flow. More flow results in more cooling through
>>>>>> heat transfer through phase change from liquid to vapor. This phase 
>>>>>> change
>>>>>> mechanism is 1000 more powerful than convection cooling. **
>>>>>>
>>>>>> * *
>>>>>>
>>>>>> * *
>>>>>>
>>>>>>
>>>>>> On Fri, Jun 21, 2013 at 8:42 PM, James Bowery <jabow...@gmail.com>wrote:
>>>>>>
>>>>>>> Systems like the LFTR have passive high temperature thermal control
>>>>>>> based on thermal expansion of a near-critical mass density.  As the
>>>>>>> temperature increases, thermal expansion produces a rapid drop in power
>>>>>>> production thereby stabilizing the reactor core.
>>>>>>>
>>>>>>> Systems like the E-Cat HT are solid state and, in any event, are not
>>>>>>> dependent on critical mass density, but another approach to utilization 
>>>>>>> of
>>>>>>> thermal expansion might work:
>>>>>>>
>>>>>>> Thermal Convection
>>>>>>>
>>>>>>> To make thermal convection work, passive (free) convective forces
>>>>>>> must be large enough to move enough thermal capacity past the power 
>>>>>>> source
>>>>>>> and must be in a regime where the rate of cooling exceeds the power
>>>>>>> production at the target temperature.
>>>>>>>
>>>>>>> The 3 variables one has to play with to reach the target temperature
>>>>>>> are material thermal properties, power density of the E-Cat and g 
>>>>>>> forces.
>>>>>>>  Of these three, only g forces and power density are amenable to 
>>>>>>> continuous
>>>>>>> alteration via centrifugation and reactor fabrication respectively.
>>>>>>>
>>>>>>> In my ultracentrifugal rocket engine patent, the g-forces are so
>>>>>>> enormous that enormous fluid flow, hence enormous thermal capacity flow
>>>>>>> enables relatively small heat exchange surfaces to cool the engine.  A
>>>>>>> material that might be worthwhile analyzing in this regard is NaCl 
>>>>>>> (sodium
>>>>>>> chloride) with a melting point near the high end of the E-Cat HT, and a
>>>>>>> heat capacity comparable to that of H2O.  It is problematic to run 
>>>>>>> molten
>>>>>>> NaCl in an ultracentrifuge due to material strength limits as they 
>>>>>>> detemper
>>>>>>> at high temperature.
>>>>>>>
>>>>>>> On the other hand, power density might be reduced to the point that
>>>>>>> the heat capacity flow rate, even under only 1-g, might be sufficient.
>>>>>>>
>>>>>>> Clearly some arithmetic needs to be done here.
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>

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