you explain the new shape of the reactor covering, with the <||> <||> <||> shapes, as a required increase of convection ?
what I see in that reactor is dozens of engineering innovations, not so sexy as LENR, but the kind engineer do everyday to make rocket fly. 2014-10-13 23:21 GMT+02:00 David Roberson <[email protected]>: > I decided to review my ECAT simulation model to see if it were reasonable > to achieve a COP of around 3.5 while operating within a non thermal runaway > region under steady state conditions. The earlier runs and model tended to > indicate that it is quite precarious to operate the ECAT at a COP of > greater than 2 without the pulse wide modulation input power waveform. > > Once a decision is made to operate within a potentially unstable region, > it becomes necessary to turn the input power on and off periodically to > prevent thermal run away. To the best of my knowledge, Rossi has used this > type of operation until the latest test. In that demonstration the input > drive is relatively constant and operation in the so called SSM mode not > used. > > The new HotCat expels the internal heat through a combination of radiated, > convected and conducted paths. The radiation path is quite useful when one > attempts to prevent thermal run away conditions since a small increase in > surface temperature results in a large increase in thermal radiation. > Everyone by now has seen that the radiation goes up proportional to the > forth power of the temperature and that puts the brakes upon increases in > extra power generation due to internal temperature increases. > > My main question was related to understanding how he now can operate > without having to worry so much about overheating and thermal run away > while that was such a problem before. The trick apparently is in the > geometry of the device. A large surface area is available to radiate away > the escaping heat at a manageable surface temperature. Also, the surface > of the main cylinder is specially treated with grooves to enhance thermal > escape due to convection. > > This carefully constructed design is capable of removing enough heat to > quench the positive feedback action that the internal core would normally > encounter at the elevated operating temperatures. My model needed to take > into account the new geometry features that were not present in the earlier > devices. > > When I first ran a simulation of the new device I noticed that it was easy > to limit the maximum temperature since the radiation was so efficient at > handling the extra internal heat energy generated by any moderate increase > in core temperature. I model the core heat generation by means of a > polynomial power series and as long as the main terms contributing to the > core heating are below forth order, a stable operating point is obtained. > It would be useful to have the actual power series from an operating > device, but that is apparently too much to expect at this time. > > A problem appeared when the input power was removed. As expected the > temperature dropped a large amount in the core, but it reached a point of > stable continuous output. This situation would not be tolerable and > fortunately not seen within the test. I scratched my head and then > realized that a cure to the problem was available. I adjusted the > coefficient of the linear term that represented the convection heat > emission and found that a value could be chosen that allowed the output > temperature to continue downwards when input drive is removed. This > adjustment very much falls into line with the real device since a lot of > effort was expended in designing the groove structure. > > When the dust settled I had an opportunity to figure out exactly what was > required to achieve a stable system. The surface area of the device must > be designed so that convection currents carry away more heat than is > generated within the lower temperature regions. This is needed to ensure > that a low temperature latching performance is not obtained. Also, the > surface areas must be able to radiate the correct amount of heat at the > desired operation point. In that case, the sum of the drive power and the > internally generated core power has to match the power that is emitted due > to radiation, convection and conduction. > > This new model is amazingly simple in structure but demonstrates > interesting insight into operation of the new CAT. Operation with a COP of > approximately 3.5 did not seem to be too difficult with the optimum > parameters according to the latest model. I plan to continue to evaluate > my model as time permits and new data and questions arise. > > Dave >
