Display More@Thomas Clarke
re reading new articles on IR cam, it seems that unlike modern pyrometers which are multicolor, all (usual) IR cam are just dumb wideband bolometer semiconductor array, with IR filtering optic in front. This is what Optris camera says, and there is no hope to have anything better.
yes, I agree with your approach.
As i said earlier a key question is how the IR cam estimate temperature. My estimation integrating bolometer response to the 7.5-13um was that it was nearly linear.
this mean that emissivity have a linear effect on estimated temperature (relative to about 220C)...
quickly computin
with 1450C estimated, if emissivity in the 7.5-13µm is not 0.4 but 0.9 (x2.25 more) then temp is 744C 1017K. e~0.53. T^4 ~ 1.07e12 -> p~.57
with 1250C estimated, if emissivity in the 7.5-13µm is not 0.4 but 0.9 then temp is 675C 948K.e~0.57. T^4 0.81e12 -> p~0.46
the ratio of power is 1.23, while for electricity it is +12% from 800 to 900W
during the calibration at 450C if emissivity was 0.9 instead of 0.7 , temperature would be 400C 673K. e~0.75. T^4 ~ 0.205e12 -> p~.15
compared to 900W the change in eT^4 power is x3.7, while power in x2
compared to 800W the change in eT^4 power is x3.06 while power is x1.72
there is many things to account :
- first change the calibration temperature with the same algorithm. here this decrease calibration temp by 50C
- estimate change in power between the various stable states and compare with electric power.
- intégrate convection (I did not do that her...)
- integrate temperature difference on the body (I did not do)
with that simplified computation there are incoherence that appear :
- the change from 450W to 900W seems to cause x3.7 instead of x2 power increase, from 400 to 745C, implying a COP of 1.85
- the change from 450W to 800W seems to cause x3.06 instead of x1.72 power increase, from 400 to 675C, implying a COP of 1.71
- the change from 800 to 900W seems to cause 23% increase instead of 13% with a 70C change in temperature from 675 to 745C
to correct that discrepancy one should assume emissivity is 0.2 at high temperature, which is not logical since even if alumina is transparent, finally metal below radiates, and moreover fins and grains decrease reflectivity.
anyway the solution si maybe in the detailss :
- the convection
- the local temperatures
the computation should be remade totally, as in the report, but with new emissivity assumption.
There is even a worst (best) hypothesis :
- assume that alumina is black and opaque in the IR range as we do here, not only because alumina is opaque and black at this wavelength, but because the fins and grains increase the emissivity.
- consider that the full reactor is either opaque at some wavelength, but else it is transparent with dark heating element below, with reflectivity reduced (thus emissivity improved) because of fins and grains
-> this could mean simply that total emissivity is much higher, that transparency is null, and that reflectivity is very reduced, leading why not to emissivity about 0.9
This would lead to the similar result a Lugano report, but at lower temperatures.
I don't say it is good by accident, I say that not only it is a dubious report, but that may even fall to the good COP value by accident.
-> a bit pathetic. I agree.
more positively, I propose from quick computation, that a fair COP of 1.7+ is observed, even taking extreme but realist hypothesis on emissivity.
-> this is to be checked as convection and temperature variation on the surface, may push the result to the COP 1.0 neutral value.
Alain,
I'm not quite sure how you are re-estimating temperature - but you are getting this wrong.
For a rough calculation:
1401C = 1624K
the total (entered by profs) / band emissivity is 0.4/0.9 => the real temp is 449C if Rayleigh-Jeans applies
This is too low because of various approximations in the above (Rayleigh -Jeans does not exactly apply) which underestimate the effect, and ignore other issues.
However my calculations are more accurate, with numerical integration from exact Planck curve, etc, and give COP=1.07.
When you estimate the "acceleration" because teh difference here is small you need to do the estimation accurately, and incorporate the fact that the adjustment based on diffeence in emissivity is larger for the higher temperature than the lower one. This exactly cancels with your difference.
If you agree with this all is good. If you disagree could you say how?
Now I agree with you there are many uncertainties in this calculation, which I summarise in my paper. If you expected a priori that this experiment would give extraordinary results you could use the uncertainties to justify COP > 1, maybe max COP = 1.5.
However what is the point of that? You might as well not look at the experiment and keep your a priori idea that COP > 1. The experiment has not in anyway validated this.
In fact the experiment excludes COP > 1.5.
There are then problems.
(1) Would Rossi really have given to the profs a device with COP of only 1.5 if he had usable e-cats? Why would he do this? He wanted positive results for a patent application.
(2) The COP is not temperature dependent (see my calculations). This makes it much more likley this COP is in fact due to errors
This reactor was supposed by the Profs and Rossi to be a definitive test of whether (or not) his stuff works. Rossi himself has often said he is not yet sure whether his stuff works. The results of this experiment are negative. You could get a higher possible COP from an experiment with a non-working device just by making the experiment more innacurate!
