I don't think MFMP is ready to make any "revelations" yet. They are discovering just how hard it is to measure a temperature with certainty on a structure of a complex shape where the temperature is not constant across or in radial dimension (due to the fins). Additionally, the emissivity is not constant across the spectrum for alumina, not necessarily a constant spectrum across temperature, and will be different for different alumina compositions. Also, getting a thermocouple adequately coupled to the surface to reliable read a surface temperature is proving non-trivial. MFMP does have the advantage of having the thermocouple measurement opportunity and also the capability to measure with the Williamson pyrometer.
One thing that has become clear to all, is that the veracity of the temperature measurements depend heavily on the emissivity selected for the material. MFMP can only hope that the castable alumina ceramic emissivity of their dogbone test is similar to that of the Lugano hotCat (not a bad assumption). MFMP is considering experiments to measure a flat bulk sample of the castable alumina cement used in making the dogbone to get an idea of the right emissivity to be used with this alumina with the Optris. Measurements over temperature could be made for such a flat bulk sample with the thermocouple, the Optris camera, and the Williamson pyrometer. On Wed, Feb 4, 2015 at 9:36 AM, Lewan Mats <[email protected]> wrote: > Quote by *Martin Fleischmann Memorial Project* > <https://www.facebook.com/MartinFleischmannMemorialProject>: > > We need to do a LOT more testing over the next 2 days. Right now, we need > to better understand why the Lugano report writers thought they were > correct in using such low values for the emissivity when the Optris and > Williamson point to around 920ºC with a spot of known 0.95 emissivity and > that that is not far off the rest of the temperatures. By setting to lower > value MUCH higher temperatures are apparently seen. > > The Williamson on HUGnet reads lower than it should because of the > conversion. it was within 10 degrees of the optris when on the known > emissivity spot. > > The external B-Type thermocouple is inline, but lower as expected because > of losses in the support wires and because it cannot see the hottest point. > > The key fact shown in "DB-Calibration_16.jpg" when input power is 0.89kW, > is the internal B type thermocouple, that was reading the internal > temperature showed a little over 1300ºC, therefore it is not possible that > the external temperature could be 1276ºC (emissivity of 0.7) or 1524ºC > (emissivity of 0.45) > > > > > https://www.facebook.com/MartinFleischmannMemorialProject/posts/916638728366827?comment_id=916722188358481¬if_t=feed_comment > > > > Mats > > www.animpossibleinvention.com > > > > *Från:* Jed Rothwell [mailto:[email protected]] > *Skickat:* den 4 februari 2015 17:02 > *Till:* [email protected] > *Ämne:* Re: [Vo]:Notes from MFMP Lugano Thermal Verification -- > emissivity should have been .95? > > > > Quote from Notes: > > "The main revelation was that the emissivity required for the camera to > correctly interpret the temperatures on the surface was very close to .95. > When we plugged in the emissivities cited from literature in the Lugano > report (0.8 to 0.4), the apparent temperature was 1200 to 1500C at 900W > in. Is our cast alumina significantly different than other alumina > materials? Tomorrow we can compare several temperatures at once on a 1/2" > OD alumina tube that we purchased from McMaster Carr. . . ." > > Uh oh. That does not sound good for Levi et al. > > > > - Jed > > >
