An updated computer model tends to support what Rossi has been saying about SSM operation during his one year test. Over the last several years I have written about positive feedback thermal system models and described their behavior. The way to obtain significant values of COP is to control the magnitude of the internal feedback processes so that a negative slope is obtained within the curve that defines Input Drive Power as a function of LENR device Core Temperature.
Once the drive power is sufficient for the core temperature to reach the negative slope region, the existing positive feedback forces the temperature to translate upwards. If the system is of type 2 design the device will settle upon an operating temperature level within the second positive slope region above the negative slope. With this type of device the COP can become excellent and the temperature will automatically return to ambient if the constant input drive power is removed. This is the ideal operating mode using active input power control when thermal latching is not desirable. Another typical case is for the LENR device to continue to rise in temperature until it self destructs under circumstances that are likely to exist unless careful engineering is applied. This unfortunate situation appears to be commonly encountered by groups attempting to replicate the Rossi ECAT. If a low COP is acceptable the thermal feedback can be reduced sufficiently to prevent this occurance, but, a COP of less than 3 is not likely to be world changing. Of course there are many circumstances under which a device that would thermally destruct can be safely controlled by a PWM input drive signal or perhaps with sufficient 'linear' negative feedback. I have spoken of these measures on several occasions and will not discuss that again at this particular time. Methods of increasing the positive feedback loop gain are sometimes obvious. Enclosing the LENR device within a thermally insulating structure is one way that it can be accomplished. Also, my model demonstrates that the level of feedback within an ECAT type system can be adjusted by modifying the coolant flow rate so that its temperature is controlled. I have taken a typical computer system model that latches into SSM operation with the input drive removed and simulated an increase in the coolant flow rate. At the higher flow rate the coolant temperature behaves in a calculated manner increasing its ability to remove heat power from the core. As a result, the total system converted into an ideal type 2 design and began to cool toward ambient temperature as required for shut down. I suspect this is what Rossi is doing and describing within his journal. Extreme COP would be observed during the SSM periods which could be indefinite in length if the proper design is empl oyed. One can restrict the coolant flow rate to reduce the system startup drive power and time to achieve full output power. In this case the total energy delivered to the coolant during this phase can be trapped within the device causing its temperature to rise. The higher temperature coolant becomes less efficient at removing thermal power from the core allowing positive feedback to take control at a lower core temperature that translates into a lower input drive power. Once the core reaches the desired temperature the coolant flow rate can be increased to the ideal operating level. The final coolant flow rate can be set for device temperature latch if SSM is desired, or set to a higher rate if active control is required. My computer model also suggested that it may be desirable to port heated coolant from the overall hot output source of the system into fresh ECATS that are being placed into operation. This action can significantly reduce the input power, but the amount of improvement depends upon the ratio of the active core temperature to the coolant temperature. That ratio is very much engineering determined and would need to be carefully taken into account. A factor in favor of the use of this particular scheme is that the values of the coefficients that determine the overall core feedback stability are extremely critical in a high COP system. The coolant flow rate can thus be used to tweak those coefficients to a useful degree. Dave
