Posts by LDM

Paradigmnoia

Using the total weight of the Lugano ECAT (452 gram) I did a calculation of the Durapot density in the following way

First the volumes of the Durapot casted volume and that of the internal rod with insert where both determined by measuring the volumes from the FEM model.

The results where :

Volume Durapot cast-----------------------1.611E-4 m^3

Volume internal rod with insert---------1.232E-5 m^3

Furthermore the total internal length of heater wire was determined to be about 120.36 cm.

Using for the AWG wire a weight of 12.5 g/m the weight of the internal heater wire is 15.045 gram

Using for the internal Alumina rod with insert a density of 3900 kg/m^3 the weight of the rod with insert is 48.048 gram

Thus the weight of the Durapot cast is 452 - 15.045 - 48.048 = 388.907 gram

Deviding this by the volume of the Durapot cast gives a density of the Durapot of 2.414 g/cm^3Indeed in the range you measured !

Quote from Paradigmnoia

I'll have to wind a coil around the piece to heat it up enough. I have an assortment of unused coils so should be no problem.

I don't think that I have ever managed to get anything as hot as even 1400 C (real temperature) before, except when the coil burned out of Slab#1 and molten ceramic spewed out.

Whatever temperature you use, we should likely see a difference

Quote from Paradigmnoia

I did shake the cement, but this piece is not heat cured. Not sure how much that will make a difference. I will bake it out and see if anything changes. The SG does seem low.

One company uses the following firing process

heating rate: 22°C/min to 1000°C, 3.6°C/min from 1000 to 1670°C; Hold time: 1 hour at 1670°C; natural cooling.

And states that this increase the density then from 2.2 g/cm^3 to 3.4 gr/cm^3

So baking out will likely make a difference

Quote from Paradigmnoia

Looks like the SG is 2.52 , or a density of 2520 kg/m³

I'll test it a couple more times.

That is even less then the value I had.

Are you using vibration to make the cast more dense before curing ?

I think I will work on a prelimanary test first with the old FEM model to see what the general effect is of those differences before upgrading to a more accurate model.

Hope to find some time next week to do that test.

Quote from Paradigmnoia

I was only watching the minutes but not seconds counter just for a rough idea how long. I can do it better now that I have nailed down the input power levels required to hit the two different temperatures.

It was three minutes raising the temperature and dropping (zero input) it down between the 1295 and 1410 temperatures. Basically it means I was lucky on the way up that I didn’t turn it up too much. (I can easily give it enough power to burn it down). I can test it again today with proper time keeping. Problem is the TC temperature is not the IR temperature for that test. I think that the 1295 needs to be 1300 C also. The plots in the Lugano report are smoothed so the corners of the turns have lower lows and higher highs than the source numbers from Table 7. It is the turns I am matching...

I don't think it is important how the temperature is measured

Also it is not even important to get the exact same temperatures as in the report.

The time constant is not very much dependent on those.

I also have another question.

From a study on the mechanical properties of Alumina 98% castable (I should have it somewhere but can not find it quickly) I remember a density of the the cured castable of 3120 kg/m^3 instead of the 3900 kg/m^3 for high density Alumina.

Did you ever measure the density of the the casted Durapot after curing ?

If not, can you do so so that we have the right figure for the simulations ?

Paradigmnoia

Para, do you have for me the natuaral time constant (0.632 of the step) for your rod when rising the temperature ?

You mentioned about 180 seconds, but I have no clue to what the reference value that was.

Reason is that that 180 seconds was much more then what I simulated (See post #10).

This was a reason for me to look again at the old simulation FEM data and must admit that for the density of Alumina I mistyped and used a value of 390 kg/m^3 instead of 3900 kg/m^3.

So I intend to redo this, but also with a better power distribution and the temperature dependency of material properties entered as piecewise linear curves instead of fixed values.

However a simulation run takes a lot of preparation time and every simulation run itself takes 4 to 6 hours on my computer.

As such it will take quite some time before I have gathered enough data to analyse.

If the results are interesting enough I will in the future publish them in this thread.

Paradigmnoia

Thank's for putting all this effort into investigationg this in more detail.

One thing what I see is that for both files with a 150-900 C calibration range the values are about equal.

Also for both files of the extended calibration range of 200 - 1500 C the values are equal.

But the 150 -900 range has lower values then those of the 200 - 1500 range.

I wonder why this should be the case.

When using the iterative approach based on the formula published by Optris and the published n values in post #412 I get when starting with a temperature of 366.6 degree C and an emissivity of 1, a temperature of 567.4 degree C with a n vale of 2.189.

Using as the maximum error band the published values above and below the 2.189, then the target temperature must lay between 556 and 576 degree C.

The iteration with the Optris for the used extended temperature range of 200 - 1500 C of 560 degree C is indeed in this range.

Paradigmnoia

I can confirm that your above Optris conversions agree closely when I tried it using the .RAVI file suggested.

Thank's for double checking !

You may have noted that the emissivity adjustment required to align the Optris-DB2 values to the Lugano numbers is only about an increase of 0.02, but ranges from 0.015 to 0.026 from E=0.76 to E= 0.5 .

Why would you need to adjust the emissivity values ?

And while the changes are small in absolute values, as percentage changes they are significant

See table below

Emissivity Lugano----------Emissivity Optris corrected--------Difference--------Percentage

--------1.00---------------------------------0.999----------------------------- -0.001------- ---- -0.10

--------0.76---------------------------------0.776-------------------------------0.016--------------2.11

--------0.71---------------------------------0.729-------------------------------0.019--------------2.68

--------0.69---------------------------------0.710-------------------------------0.020--------------2.90

--------0.68---------------------------------0.701-------------------------------0.021--------------3.09

--------0.62---------------------------------0.644-------------------------------0.024--------------3.87

--------0.50---------------------------------0.527-------------------------------0.027--------------5.40

Unfortunately, when using the Padua Reheat 620 C file, I get different conversion numbers

The adjustment here required to match the Lugano temperatures is almost exactly half of that required for the DB2 file.

Any reasons which you can think off why these would differ ?

The main differences between the Padua reheat and the DB2 Optris settings are the 150 - 900 C calibration zone rather than 200 - 1500 C zone, and the Optris bolometer emissivity setting of 0.95 instead of 1.0 .

Since the full range is calibrated why would being in the middle of the range would make a difference.

I expect that when saving to the file, the (corrected) sensor signal representing the amount of heatflux arriving at the sensor, possibly already corrected for the background temperature, is stored in order when changing emissivities afterwards to always start with the the correct flux.

450 C is almost in the middle of this calibration range, so it is the ideal range for this temperature.

I think that the full range is calibrated and that the error margins in the range are the same for all temperatures.

I note also that retroactively setting the background temperature or camera bolometer emissivity makes zero difference to the calculations the Optris performs on a stored .RAVI file. The original values are retained, as they are a critical part of the primary measurements.

For the background temperature I also noted that this makes no difference. (see remark above)

Also since what I expect is that the corrected sensor signal representing the heat flux is stored, original emissivity settings will not make any difference. In that case it becomes only a question of afterwards calculating using the formula.

Based on the above numbers, I suggest that the Optris Device emissivity was set to 0.9 for the Lugano test. (Alternately the Device Transmissivity setting may have been changed).

Am curious how you arrive at that conclusion

(The Optris fixed bolometer setting is different from the measurement area emissivity settings, and is located in the software Device settings folder, along with transmissivity settings, background settings etc.)

Know where to find those settings

That should result in correct conversions from one camera emissivity to another that are consistent with the Lugano report Table 2a and 2b.

As what I expect that the corrected sensor signal is stored then indeed also the bolometer emissivity will not effect later calculations.

It may also explain the variances noted for the dummy.

?

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.

Quote from Shane D.

That would mean Rossi either; never gave up the real formula, or IH could not get the exact ingredients Rossi used to make it work. And the story lives on.

This reminds me of something I investigated a long time ago

Somewhere it was stated that Rossi visited a small town in Sweden (Don't remember the name of the town anymore and lost the information)

I wondered what Rossi was doing in such a small town and using Google I investigated the companies which where there.

Besides some in the wood industrie, one stood out.

It was a small company which by using PECVD (Plasma enhanced chemical vapor deposition) produced custom metal powders.

As such I was wondering if his nickel powder came from there.

Lugano heater configurations for an inflated dummy run

For the Lugao dummy run we got the following values for the power of the different sections

(see post #424)

The powers for the different sections in case temperatures where inflated where

Rods---------------119 Watt

Caps-----------------87 Watt

Ribs----------------202 Watt

For the ECAT heater configuration we can investigate the possible power distribution options by varying the coil diameter and the coil length. The additional straigth wire length under the end caps and in the rods is then determined by the total coil resistance of .41 Ohm.

The calculated power distrubution should then have appoximately the same values as reported above.

The following heater configurations where evaluated

coil 8 windings, diameter 9 mm, coil lengths 19 - 28 cm

coil 8 windings, diameter 10 mm, coil lengths 19 - 28 cm

coil 9 windings, diameter 10 mm, coil lengths 20 - 28 cm

coil 9 windings, diameter 9 mm, coil lengths 20 -28 cm

coil 9 windings, diameter 8.5 mm, coil lengths 20 -28 cm

coil 9 windings, diameter 8.0 mm, coil lengths 20 -28 cm

coil 10 windings, diameter 10 mm, coil lengths 20 - 28 cm

coil 11 windings, diamter 10 mm, coil lengths 20 - 28 cm

The evaluation of the power distributions for the above evaluated configurations did not give any one which approximates, even with a large margin, the calculated section powers for the inflated dummy run.

This while for a non inlated dummy run there are several possible heater coil configurations which are close the the calculated values.

This is one of the strongest indications that the Lugano dummy run temperatures where measured correctly and thus where not inflated.

Quote from StephenC

interesting about the low frequency cut off as being a way to measure the temperature..

I stated that it was the upper cutt-off frequency of the intensity versus frequency profile.

This is the high frequency cutt-off, not the low frequency cut-off.

And you are rigth that the upper frequency cutoff is determined by the Bremsstrahlung.

Since the high frequency cutoff for thermal Bremsstrahlung is determined by the factor

e ^-hν/kT

We conveniently determine the cutoff point being where the above factor becomes 1/e then this means that

hν/kT = 1

Or

ν= ( k/h) x T = 2.08E10 x T

Plasma temperature

For a dense plasma, the temperature of the plasma can be calculated by using the upper cutt-off frequency of the intensity versus frequency profile.

The relationship is : ν = 2.8E10 x T

For the temperaure of 8111 degree K which was used for the SK the upper frequency would have been

ν = 2.8E10 x 8111 = 2.27E14 Hz

The corresponding wavelength is then λ = 3E8/2.27E14 = 1.32E-6 or 1.32 uMeter

This wave length is in the near infrared region.

The rest of the dense spectrum should then have been at lower wavelengths, likely most of the infrared region.

If the plasma temperature was derived in the way described above, then if the plasma would for the given temperature instead have followed Planck's law, the peak value would following Wien's displacement law have been at a frequency of

λ = b/T

b = 2,897 77 × 10−3 K·m

or

λ= 2,897 77 × 10−3 / 8111 = 357.3E-9 (357.3 nanometer)

But as Bruce__H has shown in the pictures he posted, the spectrum is clearly not following the Planck curve and does not have a peak at 357.3 nanometer.

So why did Rossi state that the spectrum peaked at 357.3 nanometer.

Maybe because in that way he could refer to Wiens displacement law and the Stefan-Bolzmann formula for a black body instead of having to refer to a more complex plasma theory ?

Or is he by not showing the spectrum in the infrared region trying to hide information on the working of the SK ?

As usual we are not much learning from the information that was presented and it was for us not very convincing.

Lugano active run period 3 recalculation if temperatures where inflated.

The attached spreadsheet contains a recalculation of the Lugano active run period 3 if the temperatures where inflated due to using broadband instead of in-band emissivities on the Optris thermal camera.

The recalculation assumes that a factor of 2/3 was already included in the reported rod powers.

However since it was not expliciy stated that the Lugano testers applied this factor 2/3, the sub page for the rod powers in the spreadsheet also includes the calculation for the case that the factor 2/3 was not applied.

Note also that since the calculations are based on average temperatures, the results must be interpreted as approximate values.

The recalculation with the established lower temperatures results in a total convective and radiated power of 1102 Watt assuming the factor of 2/3 was applied to the reported rod powers.

If the factor of 2/3 was not applied to the rod powers the total calculated power would have been 1042 Watt

The total applied electrical power for this run was 755 Watt.

Quote from Bruce__H

The right-hand tail of the theoretical blackbody spectrum I showed before follows the Raleigh-Jeans law. It looks like it falls off faster in your Figure 3.4 because wavelengths and intensities are shown on log scales there, but it is the same curve as I show. Rossi's SK spectrum falls off much faster.

Agreed that the log scales disturbes the picture and that Rossi's spectrum falls off much faster and I have no clue why this is the case.

However I don't know if the vertical scale of Rossi's spectrum is representative for the energy.

Maybe Paradigmnoia can say more about this since he seems to know the type of equipment used for measuring the spectrum.

Quote from Paradigmnoia

LDM ,

If we consider the Miami 1 cm² “core” of the 4x4 inch (~330 cm²) to be the optically thick part and ignore the larger part, are we correctly measuring the bulk of the radiant power using Wien et al.?

Like measuring a glowing tungsten filament through the frosted glass of a bulb. If we compare the spectra shown to a blackbody, is there a reasonable place to put a BB peak, with the information provided so far?

I did not yet investigate methods used to determine the correct temperature for a dense plasma.

So as you I am also curious how you can do that.

This plasma thing is something I am doing on the sidelines since I also still are doing some research/simulation on the Lugano test.

So I am not deep into it yet.

But as you I am also wondering if for the SK the calculations are valid.

Quote from Bruce__H

There are multiple weirdnesses about Rossi's January presentation of the SK, but the weirdest of all involves his treatment of the SK spectrum. Of course lots of people have noted that the spectrum doesn't look very blackbody - ish, but probably many don't understand how out-of-bound it is.

If the medium is optically thick, radiation generated is only moving a short distance within the medium (relative to its size) before being absorbed again - the
shape of the spectrum is set by the balance of both emission and absorption processes. In an optically thick region, this amounts to constraining the
spectrum to be not more efficient than a black body.

Consequently, the spectrum turns over at low frequency a drops with a power-law dependence identical to the drop-off in intensity at low frequency seen in the
Raleigh-Jeans part of the blackbody spectrum (figure 3.4)

Figure 3.4

Effect of optical thickness on the Bremsstrahlung spectrum. At low frequencies self-absorption modifies the spectrum to follow the Raleigh-Jeans
part of the blackbody curve. This spectrum is typical of dense ionised gas such as found in star formation regions.

Quote from seven_of_twenty

I don't know what Celani and the Swedes now have to say about Rossi.

After the Lugano test, on many forums, including this one, the errors which could have been made where shown in many interesting discussions.

The Lugano testers in my opion certainly would have gone over these comments and made up their minds if there was no excess heat or there was.

If they had concluded that there was no excess heat and that Rossi had conned them, they would have stopped their involvement with Rossi.

Nevertheless Levi,Hoistad, Essen and Petterson showed up at the QX demonstration in Stockholm.

Quote from Bruce__H

Thanks for the re-explanation.

This still leaves open, however, the issue of how you would use the Wien relation for Rossi's SK data. How would you do that?

I wouldn't

As outlined by others and looking at the spectrum, it is not dense for all frequencies.

And I realy have no idea how much energy is involved in the thin part and the thick part.

As such I have no idea if we can apply the Stevan-Boltzmann black body equation to the SK and how well it would fit the situation.

Also we need the correct plasma temperature and I don't know if that was measured correctly.

Only if Rossi would have explained why he could use the black body Stefan_Bolzmann law during his sales pitch we might have known more.

But he is not very good in explaining the technical things he does, wether they work or not.

Quote from Bruce__H

I am having trouble following your reasoning. It seems to me to both contradict what you said earlier and even (in the final sentence) be self-contradictory. Could you restate it please?

OK, Using the theory for plasma radiation , when calculating the power of a thick plasma, this leads to the formula for the thick plasma power of J = σ T⁴

This is the same formula as for the power of a black body, but was not calculated assuming that the plasma was a black body, but is derived in another way

Since the formula of the thick plasma power is the same as that of a black body, one can incorrectly assume that the thick plasma is a black body.

But it isn't, only the formula for calculating the power is the same.

And since the thick plasma doesn't have the properties of a black body. you can't match both temperature curves.