Dear Bob, and dear all, I call for review, as I don't master planck and boltzmann law, with emissivity curves.
>From what I've heard, what i've read on the Optris datasheet, I've made some assumption and computed few things about lugano and optris... see here https://docs.google.com/spreadsheets/d/1v4QYFuzSHjsEGYBXeO_5M1me9BxbdvXRQjjUiL5sJFg/pubhtml The most interesting is probably that I've concluded that the Optris is measuring something, that for a given emissivity, is simply nearly proportional to the temperature minus 217C... my reasoning is the following : Optris is an array of bolometer which measure the radiation received in the 7.5-13um wavelength window I assume it is a perfect square window then I assume the emissivity is stable over the window my computation is done by integrating the planck law over this window, for each temperature in the range... This is approximative, but it does not look very sensible over the window shape, not the number of steps the result is a curve that is nearly linear (affine), crossing zero at 217C. then start the assumption that maybe be wrong in my preview logic I assumed that emissivity was constant over the spectrum. It is clearly not true. I have few question : is the emissivity over bandwidth stable for a material ? or is the shape of the emissivity vs wavelength changing ? are the emissivity curves who state it is 0.4 at 1450C and 0.7 at 450C, in fact an effective integration of the previous curve over the planck law. practically GSVIT (as MFMP) state that emissivity over 7.5-13um is about 0.9-0.95. however maybe that for a given temperature, because much light is emitted at frequency where emissivity is low, the effective emissivity for stefan boltzmann law is much lower ? in that case, this mean that we should do the following : - assume the temperature was measured on a grey body of emissivity 0.90-0.95 by the Optris, and maybe correct the temperature accordingly. - assume that heat was radiated as for a grey body whose emissivity is described as in Lugano report (0.7-0.4) -> I've no previous knowledge in that domain, so don't laugh... treat me like student ;-) 2015-03-07 18:46 GMT+01:00 Bob Cook <[email protected]>: > Eric-- > > I have reservations as to the some of the statements for the following > reasons: > > 1. I take emissivity to be the ratio of specific power (energy/unit > area/unit time) of all EM radiation (photons)being emitted from a > *SURFACE* of a body at thermal equilibrium (one that is at a constant > surface temperature) to a similar body with similar EM emissions and at the > same SURFACE temperature and that is a "black body". Thus, emissivity for > alumina will be different for different temperatures, and for sure Ni fuel > and/or liquid AlLiH4 may be different than alumina itself. > > 2. I am not at all sure that the Lugano test was ever at thermal > equilibrium, because I concluded it was controlled in its reaction rate by > potentially changing conditions around a sweet spot of conditions. > > 3. I doubt that the thermal conductivity of alumina used in the test as > well as the transmission of the spectrum of EM radiation being produced at > the LENR reaction through the alumina to the outside surface is well > known, particularly at 1400 degrees C. > > 4. At best the Optiris camera can determine a spectrum of radiation being > emitted from a surface and from deeper levels away from a surface. *Without > calibration* I do not understand how the camera can determine temperature > of a surface. It may be able to tell something about how a measured > spectrum of EM radiation approaches the S-B prediction for a "black body". > I doubt the camera is 100% effective at measuring all EM frequencies, > particularly those which are soft x-rays and those at the > sub-infrared levels. I doubt that the alumina acts as a black body for > soft x-rays. The soft x-rays may be important and be directional rather > than isotropic. > > In summary the data of most interest to me is how the surface temperature > changes with time as a function of input electrical power. This would be > the best indicator of energy production over and above the electrical > input. > > However, even observed temperature changes at a surface should be > understood and predictable with a *validated thermal model* with > appropriate geometry, heat capacity, heat sinks, exothermal chemical > reactions, heat transfer coeff's. etc. > > The Swedes, Levi, etal., may very well be working on such a model to > supplement their conclusions about excess heat from the Lugano test. Their > validation of such a model will be key. They should take their time and > get it right. > > This type of analysis is what Dave Robertson and Gigi did for the Mizuno > experiment and were able to make very consistent predictions of measured > temperatures. This is what I would call good engineering and will be > necessary to coming up with good theory. > > Bob Cook > > > > > > > *From:* Eric Walker <[email protected]> > *To:* [email protected] > *Sent:* Friday, March 06, 2015 11:00 PM > *Subject:* Re: [Vo]:Critique of Levi et al. Lugano experiment > > On Fri, Mar 6, 2015 at 11:47 AM, Jed Rothwell <[email protected]> > wrote: > > Some recent experimental measurements by the Martin Fleischmann Memorial >> Project (MFMP) highlighted a possible error in the Hot-Cat calorimetric >> measurement; the calorimetric measurement we are referring to is described >> in the document known as “TPR2” or Lugano Report. . . . >> > > Let me see if I can capture the growing consensus concerning the Lugano > test: > > - The Lugano test reported an excess heat of 1.5 MWh over the course > of a 32 day run of the HotCat. The excess heat was calculated using the > output of an Optiris camera and an emissivity obtained using a single > method. This emissivity was fed into the Stefan–Boltzmann formula to > obtain a value for the radiated power. > - The assumed emissivity was not adequately double-checked, e.g., > using a thermocouple, a spot of refractory paint or a table of measured > emissivities for various types of alumina. > - There is reason to believe that the value that was used for the > emissivity in the Lugano report was too low, leading the Stefan–Boltzmann > formula to give a radiated power that was significantly higher than was > actually seen in the experiment. > - A lower radiated power, and, hence, temperature, would be consistent > with other observations from the Lugano test, including a lack of failure > of different components of the HotCat that might be expected at a > temperature of 1400 C, which was reported by the authors. > > Does this capture the consensus? Does anyone disagree or have > reservations about any of these statements? > > The authors of the Lugano test were largely the same as the ones that put > together the initial third-party test for the E-Cat. Does the faulty > analysis of the Lugano test cast doubt on the conclusions of the earlier > test? What does all of this say about the odd suggestion that the core of > the HotCat was so hot and bright that the heating elements cast a shadow? > > Eric > >
