Was the Lugano broadband emissivity iteration done on the Optris ?
From the text written in the Luagano report it has been concluded that broadband emissivities where used on the Optris and thus the measured temperatures where inflated.
The Lugano report describes in detail how using an iterative procedure which uses emissivities from the broadband emissivity curve of alumina is used to arrive at the temperature and emissivity used.
It has been assumed that this procedure was done on the Optris and if this has been the case then this would have led to inflated temperatures.
On the other hand we have some indications that this has not been true.
The following investigations contradict the broad band emissivity use on the Optris :
1. Evaluation of the Lugano dummy run
For a non inflated dummy run the difference between applied power and calculated power form radiation and convection was investigated in post #393.
The result was that there was a difference between applied and calculated power of 1.6 %
For a dummy run with inflated temperatures the difference between the powers was -13.5 % (see post #424)
Since the error for a non inflated dummy run is much less then for an inflated one this indicates that the temperatures of the dummy run might not have been inflated.
2. FEM simulation of the Lugano ECAT
Using thermal finite element simulation on a model of the Luagano ECAT we see that the simulated temperatures are quite near those of the reported (Non inflated) temperatures , an other indication that the reported temperatures of the dummy run where correct (See post #465)
3. Evaluation of the power distribution
Comparing the powers dissipated in the rods, the end caps and the ribbed area of the ECAT with the powers dissipated by the heating wires in those sections revealed that for a non inflated dummy run there are several close matches, but there are no close matches for an inflated dummy run. (See post #543)
So there are doubts if what has been concluded from the written text in the Lugano report, that broadband emissivities where used on the Optris, is correct.
So I decided to repeat the different emissivity settings of the iterations shown in the Lugano report with the Optris software itself.
As input the dogbone2_cal_full.ravi file from the second MFMP dogbone thermal test was used with the Lugano style profile for the different measurement areas.
I used the temperature of measurement section 10 with an emissivity setting of 1.
Also the background temperature was decreased from 23 degree C to the 21 degree C as reported in the Lugano report.
The file was then started and then stopped at 24 minutes and 07 seconds at which time the temperature of section 10 was 366.5 degree C, almost the same temperature as the starting temperature of the first iteration in the Lugano report.
Then for all broadband emissivities used during the iterations shown in the Lugano report the Optris temperatures where determined by changing the emissivities with the Optris PI connect software.
The tabulated values together with those reported in the Lugano report are given in the following table :
Emissivity----------Temperatures------------Temperatures
---------------------Lugano iteration----------Optris iteration
----1.00-------------------366.6------------------------366.5
----0.76-------------------426.6------------------------432.1
----0.71-------------------443.1------------------------450.3
----0.69-------------------450.3------------------------458.3
----0.68-------------------454.0------------------------462.4
----0.62-------------------478.3------------------------489.4
----0.50-------------------541.2------------------------559.7
As can be seen there is a difference between the values reported in the Lugano report and those obtained when changing the emissivities on the Optris.
This difference becomes larger for lower emissivity values. For the lowest used emissivity of .5 the difference is 18.5 degree C.
Because the temperatures reported in the Lugano report are different from those obtained with the Optris software this leads to the conclusion that the iteration proces as outlined in the Lugano report can not have taken place with the Optris.
Thus it is also not likely that broadband emissivities in the Lugano report where used with the Optris.This is in agreement with points 1, 2 and 3 above.