I suspect that a change of the temperature of the incoming water will cause a disturbance to the loop. Rossi must allow sufficient margin for his drive to account for this behavior since it will no doubt be encountered. It would be a good idea for him to control the coolant flow rate on the fly as a means to compensate for this type of change.
Rossi now discusses having the internal temperature at around 1000 C while the coolant is heated up to 500 C. I have long waited for him to make such a statement since the earlier testing did not indicate this situation. Of course, he allowed radiation to cool the hot cats which now must be designed to work at a reasonable cooler output temperature. The thermal resistance of this heat flow path directly impacts the positive feedback loop and must be controlled for a reliable product. As I mentioned previously, he would be wise to keep the coolant at a zero flow rate condition at startup to enable the positive feedback to begin at a lower net temperature and input power. The coolant could be heated quickly under this condition at the lower input power level. The thermal masses of the system components and the coolant itself would retard the temperature rate of rise which would give him time for his control loop to initially stabilize. It is not clear whether or not the coolant should be rapidly allowed to resume flow at its design value. The shape of the flow transition might be used to his advantage. The mention of negative resistance is a subject that I am comfortable with. I have used this type of analysis for many years in the design of oscillator networks. In the ECAT case, it is required in order for the COP to be much greater than unity. Positive resistance appears in the form of heat transferring into the coolant. At a given temperature, the thermal resistance can be expressed in a differential form. The slope of the curve that defines core node temperature as a function of heat output power being absorbed by the load is one of the important factors in determining the net resistance of the system. This slope at a given temperature yields the positive load thermal resistance seen by the core. The internal power generation process of the core itself yields the other resistance term. That one is negative since heat power is being generated by the core in greater quantities as the temperature rises. The slope again is also important and represents the instantaneous negative resistance at a given core temperature. The interaction of the input heating power with the balance of the system is a bit complex but important. It determines the temperature at which the positive feedback takes control. It likewise allows control of the complete system as discussed in previous posts. Dave -----Original Message----- From: MarkI-Zeropoint <zeropo...@charter.net> To: vortex-l <vortex-l@eskimo.com> Sent: Thu, Jan 2, 2014 1:44 pm Subject: RE: [Vo]:Linear Operation of ECAT Modeled Sounds like one of Rossi's controllability issues may come from the temperature stability of the cooling fluid itself. Dave's explanation sounds as if the control loop is expecting a rather consistent cooling fluid inlet temperature... and that may be the case if running off the city water supply (at least no major differences in water temp for a running faucet), but if one gets a sudden drop of several degrees on inlet water temp, what will that do to the control loop??? -Mark Iverson On Thu, Jan 2, 2014 at 10:33 AM, Jones Beene wrote: From: David Roberson Could you offer a simple description of the behavior of the negative differential resistance function that you mention? Looks like you are already doing something similar. Wiki has an entry for the electronic version. The image of the curve is an ascending double hump, so if your model accommodates that already, then that may be why it is so intuitive. If one is plotting P-in vs. P-out then there is good control functionality to the top of the first hump, where the negative feedback would start to show itself. https://www.google.com/search?q=negative+differential+resistance&client=firefox-a&hs=bBT&rls=org.mozilla:en-US:official&tbm=isch&tbo=u&source=univ&sa=X&ei=JKTFUo6jBcvxoASVpoCABw&ved=0CDwQsAQ&biw=1146&bih=675
