*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. >>>>>> >>>>> >>>>> >>>> >>> >> >
