Rossi Lugano/early demo's revisited. (technical)

  • Nice work !


    From which MFMP test did you use the Ravi data ?

    The 700 Watt or 900 Watt run ?


    The minimum temperature set for the color display was somewhat high in the MFMP Ravi file and as such the cap temperatures where a flat profile showing the minimum set temperature.

    Don't know if that can be adjusted afterwards so that the real temperatures show up.


    As I stated in an earlier post the cooler cap temperatures for the MFMP run can possibly be explained by the Lugano device having its heater coil windings continue under the end caps.

    Since most issues for a calculation are now known, I could in the future do two FEM simulations. One without the heater coil extending under the end caps and one with extended heater coils.

    Maybe from the resultsing temperature profiles we can then determine what is the most likely case.


    Concerning the gaps, it does depends on what emissivity was set for the background ?

  • LDM ,

    For that particular version, I used the Thermal Validation 2017 dogbone2_cal_full , because it has a nice wide range of temperatures to work with.

    I think I have every MFMP .rav file that has been made available.


    The background emissivity is default set to 1.0 (see the box on the bottom of the screen shots).

    I can try and change it to see what it does... (changes value in the device settings)... No change. Seems to be fixed to the recording when live, and not adjustable after the fact.

    I did cheat the background emissivity once before by making a measurement box for the whole screen.


  • The minimum temperature set for the color display was somewhat high in the MFMP Ravi file and as such the cap temperatures where a flat profile showing the minimum set temperature.

    Don't know if that can be adjusted afterwards so that the real temperatures show up.


    The color palette range can be adjusted, within bounds.

    At the Optris 200 to 1500 C range, the minimum background is 175 C, so anything below that won't show up.


    Edit: Interestingly, the Optris seems to be pretty sensitive even down to "175 C" in the 200 to 1500 C range.

    To test this I put a measurement box in the empty space well above the reactor (using the 500W calibration file) , and switched the new box emissivity to 0.4, which only results in the box T going to 176.1 C from "background" 175 C.

    Doing this over the 1c box, at 175 C (effectively the background), the T jumps up to 255.6 C. This indicates that the Optris can still see the object, even though it is below the calibration range and not visible in the image.

  • Lugano dummy run with supposed Optris emissivity error recalculated

    In the attached Excel spreadsheet the total radiated and convective power of the Lugano test for the situation in which the Lugano testers would have used broadband instead of in-band emissivities on the Optris is calculated.

    Using broadband emissivities instead of Optis in band emissivities leads to the measured temperatures to be inflated and it has been assumed by many that these inflated temperatures are the reason for the positive COP values reported in the Lugano report.

    Since we have found in this forum thread some errors with respect to how radiative and convective powers have to be calulated, we can now apply the correct calculation methods to the Lugano data.

    We have done this already for the situation where we assume that the temperatures where measured correctly and have found that in that case the applied power is almost in agreement with the calculated radiative and convective power.

    In the included Excel spreadsheet to this post we do the same calculation for the case where the Lugano testers would have used broadband instead of in band emissivities when measuring temperatures with the Optris thermal camera.

    Recalculated supposed inflated temperatures due to using broadband instead of in band emissivities where imported from the spreadsheet with the recalculated temperatures (see post # 413 ) and incorporated as a separate page in the Excel file.

    The result of the recalculation is that the total convective and radiated power is 414.95 Watt, a difference of -13.50 % with respect to the applied electrical power.

    This difference of -13.50 % compared to the a difference of 1.62 % when we assume that the the temperatures where not inflated is another indication that the reported temperatures of the Lugano dummy run where likely correct.

  • So now we reach the point where we see in the report that the emissivity curve, shown in Plot 1, was “adapted” to the type of alumina used, after comparing the results of the 0.95 emissivity Kapton “dots” (maximum temperature 380 C, tested on the Rods, since they would not stick to the actual reactor). Whatever that means, since there is no other mention of this in the report, nor any plot that shows this emissivity curve adaptation.


  • The report says the dummy run used thermocouples for temperature (which were not used for the active runs).


    You just can't make this stuff up!

  • THHuxleynew


    The report says the dummy run used thermocouples for temperature (which were not used for the active runs).


    You just can't make this stuff up!


    Sure they used thermocouples in preparation of the dummy run.

    (Actual one, the one as they stated which was normally used for the ambient temperature measurement)


    But the actual temperature measurements during the dummy where done by the Optris Camera.

    However they used the ambient thermocouple to compare the measured temperature by the Optris of a reference dot on a rod with that of the thermocouple and noted that they where in close agreement.

    Then they adjusted the emissivity of the Optris to give for the rod the same reading and this should have given them for that temperature the right emissivity setting of the Optris for the type of alumina used for the rods(Which by the other density of the alumina rods could have been a little bit off)

    Having done so I would find it very strange that in that situation, when they saw that the emissivity setting they found differed very much from the broadband emissivity that they would have used during the dummy run broadband emissivities on the Optris for the ribbed area.

    And the recalculation showed that there is a large likelyhood that indeed they used the correct emissivities.


    So I can't agree with you that I am making stuff up.

    This because "the stuff" is the outcome of calculations and simulations, not something I dream up.


    Reference about the application of thermocouples in the Lugano report is given below :


    Page 3


    A thermocouple probe, inserted into one of the caps, allows the control system to manage power supply to the resistors by measuring the internal temperature of the reactor.

    This is the internal thermocouplw which is used for temperature control

    It has not to do anything with measuring surface temperatures.


    Page 4


    The IR cameras, on the other hand, were focused on circular tabs of adhesive material of certified emissivity (henceforth referred to as “dots”). The relevant readings were compared to those obtained from a thermocouple used to measure ambient temperature, and were found to be consistent with the latter, the differences being < 1°C

    Here is stated that they used a thermocouple to verify that the measured temperatures by the Optris from the thermal dots was in agreement with a thermocouple which normally was used for reading the ambient temperature.


    Page 7


    We also found that the ridges made thermal contact with any thermocouple probe placed on the outer surface of the reactor extremely critical, making any direct temperature measurement with the required precision impossible

    Here is stated that they found that measuring of the ridges with a thermocouple was very critical and would make direct temperature measurement impossible.

    As such they used the Optris for indirect measurement.


  • So now we reach the point where we see in the report that the emissivity curve, shown in Plot 1, was “adapted” to the type of alumina used, after comparing the results of the 0.95 emissivity Kapton “dots” (maximum temperature 380 C, tested on the Rods, since they would not stick to the actual reactor). Whatever that means, since there is no other mention of this in the report, nor any plot that shows this emissivity curve adaptation.


    The text in the report is :


    We therefore took the same emissivity trend found in the literature as reference; but, by applying emissivity reference dots along the rods, we were able to adapt that curve to this specific type of alumina, by directly measuring local emissivity in places close to the reference dots (Figure 7).


    They talk about an emissivity trend found in literature they used as reference, but did not state what kind of trend they referred to.

    Was it the broadband emissivity trend of Alumina they referred to or the in band emissivity trend for alumina ?

    As usual the report is very vague about this and as such makes it for the reader of the report indeed another controversial point.

    So you are right that we don't know what it means.


    Besides the above a question for you.

    If I take a horizental temperature profile from a MFMP dogbone thermal test 2, then what emissivity was used to measure those temperatures.

    My guess is that it is 1.

    I am almost sure you can tell me what it was.

  • Besides the above a question for you.

    If I take a horizental temperature profile from a MFMP dogbone thermal test 2, then what emissivity was used to measure those temperatures.

    My guess is that it is 1.

    I am almost sure you can tell me what it was.

    Using the Optris software?

    It is easy to check. I’ll load it up and find out. Will post in this message, below, the result.


    The horizontal profile uses the emissivity as set in each measurement box, or is 1.0 when not changed. See image below, where box 2 has been changed to 0.4 from 0.95

  • I took this horizental profile from the Ravi 500W file




    And think indeed that this is a profile measured with an in band Optris emissivity setting of 1

    Your picture with the different sections as in Lugano is nice and gives the average section temperatures

    However when I want tot create my own sections such as in your picture above then the program refuses and states that it can not connect to the camera.

    So I think I need to spend some time on the manual.


    But I could save some time if you could supply the average section temperatures for each section for the 500 Watt situation.

    That because I want to calculate the total convective and radiated power for the 500 W case and see if after all the calculation updates, there is still more convective and radiated power then the aupplied power of 500 Watt.

  • Sure they used thermocouples in preparation of the dummy run.

    (Actual one, the one as they stated which was normally used for the ambient temperature measurement)


    But the actual temperature measurements during the dummy where done by the Optris Camera.

    However they used the ambient thermocouple to compare the measured temperature by the Optris of a reference dot on a rod with that of the thermocouple and noted that they where in close agreement.

    Then they adjusted the emissivity of the Optris to give for the rod the same reading and this should have given them for that temperature the right emissivity setting of the Optris for the type of alumina used for the rods(Which by the other density of the alumina rods could have been a little bit off)

    Having done so I would find it very strange that in that situation, when they saw that the emissivity setting they found differed very much from the broadband emissivity that they would have used during the dummy run broadband emissivities on the Optris for the ribbed area.

    And the recalculation showed that there is a large likelyhood that indeed they used the correct emissivities.


    So I can't agree with you that I am making stuff up.

    This because "the stuff" is the outcome of calculations and simulations, not something I dream up.



    I'm not saying you are making stuff up.


    I'm saying the long list of experimental bad practice from Lugano is so extravagant that you could not make it up.

  • THHuxleynew


    'm not saying you are making stuff up.


    That's what Zeus46 already explained.

    I think I need to fly over to Liverpool to visit family and upgrade my understanding of the English language. (Have already an invitation)


    I'm saying the long list of experimental bad practice from Lugano is so extravagant that you could not make it up.


    I agree that they where very sloppy.

    Don't know if that was in general the case or that they rushed out their report too fast and made a lot of errors in it.

    However the calculation of the convective and radiated power matches up with the applied power.

    Don't know if that is that is just coincidence or not.

    On the other hand in earlier FEM simulations of the MFMP dogbone I got temperatures already close to the reported ones in the Lugano report.

    That's why I with the aquired knowledge want to recalculate the convective and radiated power of their 500W run and maybe after that a new FEM simulation.

    Maybe it will tell us somewhat more.


  • Initially that didn't work also

    If I loaded another profile then the one embedded in the Ravi file, then the colored temperature information disappeared.

    Also the configuration menu was not properly working and I had many crashes.

    This all without warnings.


    Have now installed the software on another, almost identical computer, and it is now working properly.

    Could also load the Lugano profile and use it on the MFMP Ravi data


    Thanks for the above link

  • Radiated and convective power calculation of the MFMP Dogbone thermal simulation 500W, 700W and 900W runs.


    In the attached spreadsheet the total radiated and convective power of the second MFMP dogbone thermal test was calculated.

    Temperatures of the same sections as in the Lugano report where taken from the Ravi files made available by the MFMP. This was done by replacing the embedded profile in the Ravi files by a Lugano style profile.

    The dogbone did not show up totally horizental on the Optris thermal pictures and as such the Lugano profile did not match the camera picture perfectly.

    I did not correct the profile for this. since the introduced errors where in my opinion not very significant for this comparison.

    From each file (500, 700 and 900 Watt) the temperatures for all sections where taken at the 5 minute mark .


    Then the average temperature of the ribbed area of each run was taken and this value was used to do new CFD simulations to determine the convective heat correction factor of the ribbed area for that average temperature. This since the fin spacing where the maximum heat transfer occurs is temperature dependent and this optimum spacing increases with increasing temperature.

    Otherwise stated, due to the optimal spacing shift to the right with increasing temperatures, the correction factor decreases with increasing temperatures, but is also dependent on the change in the convective heat transfer coefficient.

    For the MFMP 500,700 and 900 watt runs the correction factor was found to be relative constant with an average value of about .695


    With the above established convective heat correction factor for the ribbed area and the section temperatures the total thermal power (convective and radiated) for each run was calculated

    These thermal powers where then compared with the input powers.

    The results are :


    Run Input power (Watt)-------------Thermal power (Watt)------- Error (%)

    500 Watt-------------502------------------------- 591.14----------------------16.3

    700 Watt-------------713--------------------------916.67----------------------27.3

    900 Watt-------------895------------------------1208.77----------------------33.9


    The results confirm the earlier statement in a previous post that for the MFMP dogbone thermal test the total convective and radiated power is much more then the applied power.


    Update 3-11-2018

    For the 500 watt run the error was stated as 6.3%, however it was 16.3 %

  • MFMP dogbone thermal versus applied power. A case study


    In post #445 in this forum thread we have shown that for the second MFMP dogbone thermal test the applied electrical power differs largely from the calulated thermal power.

    This can be possibly due to one of the following reasons :


    Wrong power measurement

    Wrong temperature measurement

    Emissivity of the casting material is different


    Concerning the power measurement we can state that for the first MFMP dogbone thermal test we are able to calculate from the posted data the heater coil resistance for each setting.

    This resistance has about the same value for each run and calculating the wire resistance from the supplied heater coil winding data gives about the same value.

    Thus it is likely that the power measurments of the MFMP where correct.


    Concerning the temperature measurment we know that at least during one of the MFMP thermal tests the temperatures where measured with the Optris thermal camera and the Williamson pyrometer.

    Both where in close agreement and as such the measured temperatures with the Optris are supposed to be (near) accurate.


    The differences between applied power and calculated thermal power can also be explained if the emissivity of the material used to cast the dogbone is much lower then that for standard alumina.

    This possibility will now be investigated in this case study.


    Using the data in post #445 a rough estimate was made by which factor the emissivities of the 900 Watt run had to be lowered to bring the applied power in line with the total thermal power.

    This factor was about .7 . This means that emissivities for the high temperatures would have been closer to .30 then to the .45 for the ribbed area.

    The question now is which ceramic material can have such low emissivity values. A likely candidate is Magnesia (Magnesium Oxide, MgO).

    Total emissivity of magnesia as a function of temperaure is given in the following figure which was taken from the

    "HANDBOOK OF THE INFRARED OPTICAL PROPERTIES OF AL2O3, CARBON, MGO, AND ZrO2, VOLUME 1" by Milo E. Whitson, Jr. (1975)

    For magnesia the handbook gives the following figure :




    The dots in the figure are representing measured emissivities by several sources. As can be seen there is a wide spread between those measured values.

    The curve represents the curve fit for all these measurements. The curve is in the document also presented as a table and we take that data as a starting point .


    We now do a linear transformation on the published emissivity values of magnesia such that for the MFMP dogbone thermal tests for 500, 700 and 900 Watt the applied power is about in agreement with the thermal power. The translation used was :


    ε' = 1.02 x ε - 0.04


    The part of the original curve between 200K and 1800K together with the translated curve is given in the following figure :





    The new curve has almost the same shape as the original curve but is somewhat lower but falls largely within the upper and lower limits shown by the measurements dots in the first figure.

    We now apply the translated emissivity values of magnesia to our calculations of the thermal powers of the MFMP 500, 700 and 900 Watt runs and determine the difference between applied powers and thermal powers.

    The table below shows the differences between the calculated applied power and thermal power for both the original calculation with alumina and for the translated magnesia curve


    Run-------------Difference alumina (%)----------Difference magnesia (%)

    500 Watt-----------------16.3-----------------------------------0.94

    700 Watt-----------------27.3-----------------------------------0.09

    900 Watt-----------------33.9-----------------------------------0.95


    Conclusion of this case study is that the large differences between the applied and calculated thermal powers of the MFMP dogbone thermal test almost disappear if the MFMP dogbone was casted from a lower emssivity ceramic then alumina. Especially magnesia is a good candidate to bring applied and calculated thermal powers in line.

    Note that if instead of alumina magnesia or an other low emissivity ceramic was used it would also result in the higher surface temperatures measured during the MFMP test.



    Update for typo error : Constant factor in emissivity translation is -.04 instead of -.03


    Update 08-11-2018 : Added Excel sheet with calculation