Again how serious this is depends on the temperature difference between the inner and outer shell no. If that was serious you would expect the top edge of a picture of the hot cat to have unsharp color shade because the top edge should represent the heat of the outer shell. I have not find such an indication and either it is completely black or the difference is neglible. Am I wrong?
On Fri, Oct 10, 2014 at 11:52 PM, Alan Fletcher <a...@well.com> wrote: > At 02:22 PM 10/10/2014, Alain Sepeda wrote: > > Hi, > among the skeptic argument one of the only that is not laughable is the > one of goatguy... > maybe is it because I don't understand it well... > > He seems to say > - that alumina is not a grey body, but transparent, and that emissivity > must be mixed with translucidity when considering the radiation of heat... > - and maybe that one effect could came from changing resistors that are > more or less hidden "optically"... > > I propose a kind of group work, > > I propose that people with competence, analyse goagguys arguments, and the > report. > > 1- can someone explain first the point of goatguy on the fact that alumina > is transparent... > is it noticeable ? does it change the way radiation equation are computed > or is it simply emissivity change ? > what can be the order of size of the error induced ? > > > I did a bit of research. eg > http://en.wikipedia.org/wiki/Transparent_ceramics > > a) It CAN be made completely transparent to visible light > a) The kind used in the hotcat is most likely opaque to visible light > > > Most ceramic materials, such as alumina > <http://en.wikipedia.org/wiki/Alumina> and its compounds, are formed > <http://en.wikipedia.org/wiki/Ceramics_processing> from fine powders, > yielding a fine grained polycrystalline microstructure > <http://en.wikipedia.org/wiki/Microstructure> which is filled with > scattering centers comparable to the wavelength of visible light > <http://en.wikipedia.org/wiki/Visible_light>. > > The "shadows" of the wires in figs 12 are problematic ... but we don't > have enough information to figure out if they are actually the result of > light, or if they represent zones of different thermal conductivity, as in > the first independent test (which had a steel outer cylinder). > > But it's proably transparent to IR , and if so I believe (without proof > ... but see Jones Beene's > http://www.mail-archive.com/vortex-l@eskimo.com/msg98226.html > http://www.mail-archive.com/vortex-l@eskimo.com/msg98253.html ) that it > DOES affect the power calculation. > > Right now I'm changing my position from "positive" to "inconclusive". I > have another post ready to send. > > > >
