I would expect the water filled tube to absorb roughly the same amount of heat power in the liquid form as when it boils since the heat must pass through the pipe surface area. Actually, liquid water is a better conductor of heat than the vaporized water that remains after the control temperature is reached. It is not obvious that the heat transfer rate above the adjusted boiling point is adequate to put the brakes on in a real life system unless a lot of energy is always diverted to the special cooling section which would not be desirable.
In order to have a useful system, it is necessary for the heat power being delivered to the load to greatly exceed the heat power absorbed by the control section. That is why I mentioned some form of highly effective coolant spray, etc. that kicks in at the right time. If tight enough control is maintained, the amount of spray cooling could be minimized. I have a strong suspicion that system delays and thermal path delays will tend to make control difficult in real devices. We also need to plan for the initial heating needed to reach the positive feedback operation region. It is interesting to note that the point where positive feedback takes over can be significantly below the true self sustaining critical temperature. This is helpful since the resistive heating power can be reduced with an active cooling control technique. I am confident that Rossi and others will be able to invent techniques which allow them to control the amount of heat power absorbed from the core by the coolant. Something as simple as modulating the fluid flow rate could be effective as long as a sink for the extra heat is available on demand. Rossi used flow adjustment in some of his earlier demonstrations to rescue his device from thermal run away. When I refer to COP as being much larger under the active cooling process, I have mentally separated the actual amount of power needed to control the system from the power generated by the device. Of course, infinite system COP would be calculated if the control energy is ultimately derived from the generated heat which is true in practical cases. I prefer to keep these two separate for comparison purposes. Dave -----Original Message----- From: Robert Lynn <[email protected]> To: vortex-l <[email protected]> Sent: Wed, Oct 9, 2013 2:42 pm Subject: Re: [Vo]:ECAT Active Cooling Control That would be a very simple means of providing excellent high temperature control. A coil of tube inside the reactor containing water with a pressurised cold reservoir attached to one end to keep it filled with water and a pressure relief valve at the other end to release steam above a certain pressure. The pressure release setting could control the temperature very accurately, at any point from 100°C to 6-700°C, and the steam from the pressure relief valve could be sparged into a water tank for simple calorimetry. The water filled tube would absorb relatively little energy until the rector temperature rose above it's set point, at which point it would absorb a huge amount of energy with small temperature increase. Would give safe reliable hot-cat operation without danger of thermal run-away. On 9 October 2013 16:18, <[email protected]> wrote: On 9/10/2013 12:20 PM, David Roberson wrote: I finally got around to checking my ECAT model performance with active cooling control and the results were very interesting. First, I applied normal heating to the device which leads to thermal run away conditions if allowed to go beyond a certain critical core temperature. As expected, the model showed that the ECAT began a path toward melt down. The path to destruction would proceed even when the original drive is removed since the critical temperature was exceeded. Then, I allowed the model to continue heating for a period of time and applied the brakes quickly with a new load that withdraws a significant amount of extra heat power from the system. This might be possible in real life if for instance a phase change coolant were sprayed onto the core directly. The extra cooling must be applied continuously while the temperature drops and until an optimum trip temperature is reached. The turn around point must be above the normal critical temperature since no additional heating is required to achieve a condition where thermal run away can begin anew. The model demonstrated that this type of cycle could be repeated indefinitely while the total power being generated by the device is significantly above that safely obtained by heating control alone. I would assume that a cooling method similar to that suggested above would take less input power than the standard heating process that I have modeled earlier so this type of control would result in a higher COP for the system. The model also demonstrated that a continual application of the extra cooling resulted in the cores return to room temperature as desired. Actually, the powerful cooling was not required to be applied once the critical run away point was passed. In this case, the core would be subjected to positive feedback that forces it toward turn off by itself. It is evident that a hybrid type of control system that uses both power resistive heating as well as active cooling would perform the function. If both techniques were available it might be possible to keep the ECAT temperature very near the critical point in which case the COP would be extremely high. For this type of tight control to work the loading as well as all the other parameters which cause the critical temperature to vary must be kept under tight control. This might be possible. Good to see someone thinking! In fact I think the problem is really simple. (And there should be no "extremely high" for overunity devices - if they are not beyond infinity then you haven't got an engineer worth his salt working on it). There should be no need even for an active system. You simply need a passive system that presents a steeper load onset with temperature (cooling effect) than the (expected) exponential power increase with temperature produced by the reaction. With a few moments thought you can come up with a really simple one:- Put the reactor into a stainless thermos flask, cover it with water, and heat it up with its internal heater until the overpressure release of the flask starts to leak steam. Disconnect the power and it should self-regulate and hiss away for hours or days and there is your demo (until it runs out of coolant). If you want a continuous system, then you might need to put it on an electronic scale and organise a little pump to inject more coolant very slowly to just keep the weight constant. Consider a Thermos flask that is capable of keeping tea hot for maybe 6 hours. If we have a 2 liter flask and the temperature drops from 100 down to 70 degrees in 6 hours, then that represents an total heat loss of 4.2kJ/kg/K * 2kg * 30K => 250kJ or an average heat loss rate of 2.5*10^5J/(6h*3600s/h) => 12watts. If we do the calculation a little bit better and assume that it is an exponential decay which is heading for 20C after infinite time then we get a time constant of 12.8h, and the rate of heat loss at the start is simply the total heat divided by the time constant (4.2*10^3*2*(100-20)/(12.8*3600)) => 14.6watts. So this means that if we supply 15 watts of power by some means, then whatever is in the flask will eventually reach boiling point and stay there. So if the reaction can produce more than 15 watts of power while it is held at 100C, then it must remain at this temperature because as soon as it rises above 100C, the water will boil and steam will exit the flask providing an almost infinite heat sink capability (boiling water can easily consume kilowatts of power without allowing the temperature to rise significantly). If 100C is not hot enough then we can either pressurise it (with a simple overpressure valve), or go to a lot more trouble and use a higher boiling point fluid. The sort of silicone oil that they use in diffusion pumps comes to mind. You would need to have a closed system (at least not allow oxygen to get to it I think) but you could easily get boiling points around 300C which could be further raised by pressure. Mercury would be an excellent boiling point coolant for 360C and up. (It used to be used and worked very well in diff pumps before people got all paranoid about it). Rossi's "December Test" suggested a power generation capability of ~2kw while being held at a peak core temperature of approx 500C. The "March Test" suggested a power generation capability of 530w while being cycled around a temperature of approx 320C at the core. Provided the core reactor in the two cases is very similar, we can use these two points to solve Arrhenius' equation for the temperature dependence of the reaction rate. We get a pre-exponential factor of 1.6*10^5 and exponential (activation energy / R) factor of 3380. Arrhenius' equation thus suggests a power generation rate dependent on temperature given by Power = 1.6*10^5Exp-(3380/Temp in K). Using this equation to see what happens at 100C tells us that it should generate a power output of 18.6 watts. So Rossi's reactor should in fact work and generate steam continuously if simply put in a thermos flask and warmed up to 100C! If we were to pressurise a well insulated container to a reasonably easy to obtain pressure of say 10 atmospheres (giving a water boiling temperature of 180C) we would expect to be able to generate 92 watts in a continuous manner. If we were to set up a mercury cooling loop, then we could run it continuously at kilowatt levels with no active control and just a small pump to inject the condensed mercury back into the pressure chamber.
