Yes, it might be possible to control the device by limiting the fuel as you suggest. Once you sense something and use that information to adjust the fuel, you have enclosed the positive feedback inside a negative feedback loop. Are you thinking of running the device effectively open loop by fixing the amount of fuel supplied? If you do it this way I would expect it to behave pretty much as I first discussed. It would be quite difficult to achieve perfect balance for long stable operation.
I think of an IC engine as a constant power device that works into a variable load. Inside the cylinder it does exhibit positive feedback as the fuel burning progresses across the cylinder. This more or less guarantees that most of the fuel will be burned and converted into heated gas. The heated gas then of course drives the piston, etc. Power is absorbed by the engine due to friction that increases with engine speed(assuming no load idle conditions). A balance can be struck in this case at a reasonable engine speed. It is not clear exactly what Rossi is doing with his device. Of course he continues to insist that the COP will be 6 in every query, so I must assume this is a limit he endures. He also continues to state that his device runs on a duty cycle where it is driven for a period of time and then allowed to cool downward which is a characteristic of a positive feedback system. I constructed a simple model of a positive feedback system of this sort and it did behave in a manner similar to what Rossi suggests. The time frame for the drifting self sustaining mode can be extended if you are willing to allow the device to approach the point of no return of thermal runaway. Of course, if he uses active cooling that can be called upon to make the thermal reverse, then far better control is possible. I suggested this to him on several occasions last year but have seen no indication that he relies upon it thus far. Perhaps this type of control has been incorporated into his design but not revealed to keep us guessing. It is interesting to note that DGT is effectively doing this with their design and have a higher COP according to their documentation. I guess Celani does have one major factor going for him as he attempts to achieve self sustaining operation. The energy radiates away from his device as a fourth order of the temperature. This falloff rate would tend to hold the output temperature relatively constant as the generated power increases. One would need to take a careful look at the dynamics of the complete system to determine whether or not this would lead to stable operation. You might discover that the wire self distructs while at the same time the outside temperature is reasonable. Dave -----Original Message----- From: mixent <[email protected]> To: vortex-l <[email protected]> Sent: Tue, Aug 21, 2012 10:39 pm Subject: Re: [Vo]:What a self-sustaining demonstration by Celani might accomplish In reply to David Roberson's message of Tue, 21 Aug 2012 20:50:39 -0400 (EDT): Hi, [snip] > >The self sustaining mode that we refer to is generally considered a positive feedback system. Unfortunately, when the gain becomes infinity the output becomes unstable. In that case, it is either rising toward some high temperature point that eventually reaches a stop or falling back toward low temperature which would not further our cause very much. The high point might actually damage the device and stop the LENR effects. You can prevent these problems by starving the device of fuel. I.e. control the fuel supply rate such that it doesn't get a chance to self destruct, while still running with positive feedback. When this is done, you can operate the device at any desired temperature. That fact makes me suspect that this is what Rossi is currently doing with the help of NI. Note the IC engines also run with positive feedback. The burn or "explosion" which takes place in the cylinder has positive feedback. A local increase in temperature ignites surrounding gas, which then rises in temperature, igniting even more gas etc. etc. The overall power output of the engine is regulated by controlling the rate at which fuel (and air) is supplied. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
