Jones Beene: >David, I like you analysis, but has anyone seen evidence of meltdown? After all, AR has claimed to have built hundreds of reactors in the last few years. Given Rossi's flair for the dramatic, my guess is that he would proudly show-off a picture of a meltdown, if he had it. < You may be right Jones, but it is easy for me to accept the fact that the nickel powder would melt quickly if the device went out of control and its internal temperature became excessive. There may be nothing different in appearance from the outside for him to show. >But even if there is no visual proof of meltdown, "positive feedback" is surely a significant description of one (of several) dynamical forces operating in the system, but it may not be a major impediment, since it may be a slow kind of feedback. It is fruitless to base firm conclusions on what Rossi has said over the past 20 months, since much of it is self-contradictory but his first reactors were made of copper, which is not exactly ideal for any system where rapid runaway is remotely possible; plus he claims to have had reactors unattended in self-powered mode for months, using almost no feedback.< The rate at which the positive feedback responds is one factor that is high upon my wish list. Rossi has refused to reveal any information about this behavior cloaking it under secrecy. I am giving it my best with regard to drawing conclusions with limited data and it is true that my thoughts may become nothing but a house of cards. My problem is that I want to see this technology more forward as quickly as possible and am doing all that I can to achieve that goal. If and when Rossi chooses to share good data, my model might help in the development of sound products. >The risk of meltdown could be another "Rossi-ism" for an imaginary scenario based on strong belief, much like the unproved gamma radiation, or the unproved nickel-to-copper transmutation, etc. Let's not forget that his Italian employees, if there really are any, suffered through a cold winter in Bologna with the "megawatt" BigCat sitting on the loading dock, as frigid as steel and bare nuts can get in Italy, so to speak.
And if the recent HotCat was really balanced at ~1000C in actual testing (to be released in the future, of course) and in such a way that the net heat generated exactly matches the heat that is escaping from its surface, then that indicates inherent auto-control should not be too difficult to achieve, no?< I would hate to attempt to count all of the serious questions that have arisen with Rossi. You choose to mention just a few. I used my model to analyze the surface radiation stability concept and the results make sense to me. If you make the assumption that the HotCat has 1000 C at its surface and radiating heat equal to the amount of internally generated heat then I would expect the device to stabilize at that point. The heat loss is proprotional to the 4 th power of the surface temperature. If the heat generation process is dominated by a 3 rd order or lower term, then any differential increase in temperature will cause more radiation to be emitted than internal heat generated. This constitutes a region where the loop gain of the positive feedback has become below 1 and the system has reached stability. The behavior I just described was simulated on my imperfect model, but the results tend to make sense. There are many interesting characteristics revealed that I can describe in detail later if you wish. >IOW - if there is a balance of positive and negative feedback at various plateau levels, then it should be possible to have some kind of emissive control with greater precision using a larger surface and thermal mass instead of the small reactor surface. The large surface area presumably would radiate at a predictable rate in the 100 C range if the interior was stable at 400C - well below the 1000C. Would you agree that this kind of inherent control is possible with larger area/lower temperature, based on the HotCat results being relatively accurate? Of course, what I have in mind relates more to the Reiter-effect (ZeoCat) than to the Rossi-effect, but either way, what is severely lacking in all of this, after 20 months of "warm regards" evasiveness, is long-term data ... data that changes a laboratory curiosity into a commercially relevant prospect. In actuality - Reiter has offered significantly more proof of continuous gainful operation than has Rossi.< I do not understand your question very well, but I will attempt to answer it as best as I can. The way I define negative or positive feedback is related to feedback systems with loop gain. To do this I take the slope of the power output versus temperature for the device at a certain test temperature. As an example at 500 C a small change in core temperature generates a measurable small change in power. Lets say a 1 degree C core temperature change results in additional heat power being generated of 10 watts. This is the first slope that I would calculate which is 10 watts per 1 degree C. Now this heat power must exit the core through a thermal resistance of some amount. Lets choose .2 degree C rise per 1 watt of additonal heat power. My loop gain calculation would yield the product of these two figures or 10 watts / 1 Deg C * .2 Deg C / 1 watt = 2. Since we know the heating must be the same sign as the original drive heat then this would be positive feedback with a gain of 2 which is unstable. You can perform the same calculation at every core temperature and the resulting loop gain varies. Without much more data from Rossi's measurements I have no reason to believe that there would be many plataues in the loop gain. But I think it is safe to assume that a grossly hot device would limit heat production and thus reduce the loop gain until stability is achieved. I am being forced to walk within the fog, but it is the best that I can do. You mention some form of emissive control as a way to achieve a stable system. I would prefer to use increased fluid flow to extract that additional heat which leads to interior cooling of the device. This is the active cooling that I endorse. Of course in the real world applications Rossi must use some medium to conduct the heat away from his machine unless he wants to sell space heaters that are capable of causing serious fires. I agree that you could probably add a thick walled cylinder to the present one which would increase the surface area until a lower temperature is reached on the new area. This would require that the net heat power radiated is the same as before and I would suppose that the internal core temperature of the device remains constant. The question of stability will still be present in this new configuration. If you are interested in operation where control is required, then by definition something must be able to modify device operation. Presently, a core heating unit performs that task and it is simple and inexpensive to operate. Active cooling might be capable to control of the high temperature region, but it can not recover a device that heads toward a cold future. I believe that an ideal device would use both means of control. You and I are both frustrated by the lack of good data. Maybe someone needs to light a fire under one of those CAT tails! Dave
