ok, transparency won't change the result.note that if ridge increase emissivity of the IR measured by the cam, it also increase the emissivity used to compute the output...in my rough computations, I join your result on temperature (I'm even more pessimistic with a peak at 750C) , but it also have impact on the 450W baseline, and on the output sensitivityif you integrate emissivity error on both side of the balance, something real remain, which may explain the transmutations.It appear if you simply compare the input power change with temperature change...only excuse to reach COP=1 is to have a lower emissivity than assumed already, which is not coherent with the initial hypothesis and corrections.
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 450W 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
another source of question is that calibration looked correct at low temperature, which seems incoherent with initial hypothesis (why emissivity would increase with temperature from 400 to 800C).