On Fri, Nov 18, 2011 at 10:54 PM, David Roberson <dlrober...@aol.com> wrote:
> Ok, I just did some calculating about the 1% power regulation you insist > upon and it is bogus. Do you wish to prove your point? > If the output is dry steam, and the flow rate is constant, which would be the case if the heating element is exposed, then the output power is (dm/dt)(c1*deltaT1 + L + c2*deltaT2) where c1 is the specific heat of liquid water (1 cal/gK), deltaT1 is the change in temperature of the water (about 80C), L is the latent heat of vaporization (540 cal/g), c2 is the specific heat of steam (0.5 cal/gK), and deltaT2 is the temperature change of the steam. So, that means the power is proportional to (620 + .5 deltaT(in C)) Now, if you look at the temperature graph, after boiling is reached, it is pretty well between 100C and 110C, for a fluctuation of +/- 5C. Actually the std dev is quite a bit smaller. And a fluctuation of +/- 5 C results in a fluctuation in the power of +/- 2.5/620 or about +/- 0.5 % for temperature stable within a range of 1%. Now, if the heating elements are submerged, and the output flow rate varies with power, then the level is bound within a tight range, meaning, as I argued before that the average flow rate would have to be matched to the power to an accuracy of 1% to avoid either exposing the heating element or sending liquid out of the ecat. Here the 1% comes from the fact that the ecat is filled 11 times during the test, and assuming that you have to fill it to about 90% to cover the heating elements.
