First issue: 08/02/2015
Introduction
Some recent experimental measurements by the Martin Fleischmann Memorial Project (MFMP) highlighted a possible error in the HotCat calorimetric measurement; the calorimetric measurement we are referring to is described in the document known as “TPR2” or Lugano Report. In particular, in the report of the MFMP experiment the following consideration is stated:
“The main revelation was that the emissivity required for the camera to correctly interpret the temperatures on the surface was very close to 0.95. When we plugged in the emissivities cited from literature in the Lugano report (0.8 to 0.4), the apparent temperature was 1200° to 1500°C at 900W in.“
GSVIT already long ago had suggested that the measures and the calorimetric analysis performed by the Lugano Report authors (in the following AA) (G.Levi, E.Foschi, B.Höistad, R.Pettersson, Lars Tegnér, H. Essén) contained a fundamental error since they considered the Alumina as a gray body, as far as thermal radiation is concerned.
The experimental measurements by MFMP were carried out on a replica device (a simulacrum of the real HotCat), confirmed what was only a hypothesis by GSVIT and, where correct, they allow to affirm that the method adopted by the TPR2 AA to calculate the reactor surface temperature (and therefore the amount of heat irradiated) was incorrect.
In general, it is difficult to define the error generated from a wrong method setup on the outside temperature and radiated power measurements, since it is not sufficient that the simulacrum be identical in shape, dimensions and materials. Actually, Alumina can assume 7 polymorphic forms with different crystalline structure and industrially the word “pure Alumina” starts to be used for 99% purity. We want to recall here the results of the analysis of samples of the HotCat Alumina as reported in TPR2:
“The results confirmed that it was indeed alumina, with a purity of at least 99%. Details of this analysis will be found in Appendix 2.“
However, although the presence of small percentages of impurities can alter its characteristics (what is exploited to make it fit better various applications) we did not succeed in finding in the literature a significant correlation between impurities and the Emissivity value (ε).
Assuming that MFMP used an alumina very similar to the HotCat alumina, the resulting error in the Radiated Power estimation could be close to 2. In a similar way, the surface temperature would be overestimated by a few hundreds degrees; thus, considering that a wrong temperature measurement has a direct impact also on convection transferred heat by: Q=h*A*(TsTamb), the error on the estimation of the emitted Power may be even higher.
Errors of this level of magnitude would be so important to question seriously the Report content and its conclusions.
Analysis
As previously highlighted in a technical analysis coming from Alan Fletcher, AAs adopt as their calorimetric method a measurement of Radiated Power based on the well known StefanBoltzmann law linking the Power emitted to (T)^{4}, where T is the object absolute temperature. This measurement technique requires full knowledge of the value of the surface Emissivity of the object whose temperature one would like to estimate; the reason is that the temperature of the body is a key element for the calculation of the Power radiated through the StefanBoltzmann law.
The TPR2 AA decided to measure the HotCat temperature by using only a thermo camera (model Optris PI160) and it is worthwhile to remember that they also said that it was not possible to place a reference thermocouple directly onto the reactor surface to establish a reliable reference of the actual temperature:
“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.“
(This is a claim already disputed in the past because incomprehensible; this claim was proven wrong by MFMP that, instead were successful in placing it). The AA decided to calibrate the camera, used for measuring the surface temperature, according to this procedure:

The temperature provided by the camera is fed to a diagram that maps the Emissivity temperature of pure Alumina (Figure 6 of TPR2)

The diagram is checked to verify if the Emissivity value actually corresponds to the read temperature

When no match is found, the camera Emissivity settings are adjusted until a perfect match between the temperature indicated by the camera and the temperature on the ordinate of the Emissivity/Temperature diagram for Alumina is met

Eventually, the camera Emissivity is set to the found value
This method is correct only if the Alumina surface behaves as a gray body and the used diagram contains Emissivity data [see Note 1] for Alumina very similar to the one actually used. One has to remember that the Emissivity ε of a material is the fraction of energy radiated from the material compared to the energy radiated by a blackbody of the same temperature. Since the blackbody Emissivity is by definition unitary , any real object has Emissivity less than 1: if this value does not depend on the wavelength (λ) such material is called gray body. If instead the Emissivity versus wavelength has a completely different shape, such a material cannot be defined a gray body. This is, for example, the case of Alumina.
In practice, the AA did not adopt any of the techniques suggested by Optris GmbH (IR camera manufacturer) on page 10 of this document to estimate the correct Emissivity value:
Experimental Determination of Emissivities. In the addendum you will find emissivity dates for various materials from technical literature and measurement results. There are different ways to determine the emissivity.
Method 1: With the help of a thermocouple. With the help of a contact probe (thermocouple) an additional simultaneous measurement shows the real temperature of an object surface. Now the emissivity on the infrared thermometer will be adapted so that the temperature displayed corresponds to the value shown with the contact measurement. The contact probe should have good temperature contact and only a low heat dissipation.
Method 2: Creating a black body with a test object from the measuring material. A drilled hole (drilling depth ≤ ⅓) in thermal conducting material reacts similar to a black body with an emissivity near 1. It is necessary to aim at the ground of the drilled hole because of the optical features of the infrared device and the measuring distance . Then the emissivity can be determined.
Method 3: With a reference emissivity. A plaster or band or paint with a known emissivity, which is put onto the object surface, helps to take a reference measurement. With an emissivity thus adjusted on the infrared thermometer the temperature of the plaster, band or paint can be taken. Afterwards the temperature next to this surface spot will be taken, while simultaneously the emissivity will have to be adjusted until the same temperature is displayed as is measured beforehand on the plaster, band or paint. Now the emissivity is displayed on the device.
The AA have made use of specific “Dots” (whose Emissivity value is known) only for the measurement of some parts (the cable rods) whose materials (at much lower temperatures) were not analyzed and verified:
“Dots” of known emissivity, necessary to subsequent data acquisition, were placed in various places on the cable rods. It was not possible to perform this operation on the dummy reactor itself (and a fortiori on the ECat), because the temperatures attained by the reactor were much greater than those sustainable by the dots.
…
It was not possible to extract any samples of the material constituting the rods, as this is firmer than that of the reactor.
It should be noted that (see Figure 1) the Alumina (Al_{2}0_{3}) Spectral Emissivity values are known in literature and in particular those within the measurement bandwidth of the Optris OP160 thermal imager, this band ranging from 7.5 to 13 µm.
The Emissivity values ε = f (λ, T) are well documented in the publication by the US Department of Commerce National Bureau of Standards, Volume 7 (1971):
Precision Measurement and Calibration – Radiometry and Photometry
As shown in Figure 2A, 2B and Figure 3, for example, for temperatures ranging from 1200K to 1600K (i.e., from about 930 to 1330°C), the Spectral Emissivity measured values, within the camera measurement range, are between 0.85 and 0.95.
In addition to scientific literature, the results of the MFMP measurements show as well how the Alumina Spectral Emissivity value of their simulacrum varies greatly depending on the wavelength λ, for wavelengths close to 10 µm, i.e. in the ordinary camera range, this value is about 0.95 as confirmed by the document : Handbook of the Infrared Optical Properties of Al_{2}0_{3}. Carbon, MgO and Zr0_{2}. Volume 1 (an excerpt of which is available at this link), while the measured value of Total Emissivity (see Figure 4) to be used for calculating the power radiated, for a T around 1000°C, is less than half that value. Note how precisely in the neighborhood of these temperatures (which are probably those taken from the HotCat during the test) one has minimum Emissivity, which in some measurement results to be lower than 0.3.
Furthermore, these measures show that the dispersion of the Total Emissivity real data, at the same temperature, well exceeds the error and the uncertainty that the AA are mentioning in TPR2:
The error associated with the plot’s trend has been measured at ± 0.01 for each value of emissivity: this uncertainty has been taken into account when calculating radiant energy.
In the AA report [ref. 3], R. Morrell, Handbook of properties of technical & engineering ceramics, Part 2, p. 88, in the comments for chart in Figure A4. 10, the author suggests readers should not to take that chart too literally:
“Such data should be considered tentative because it is known that emissivity can vary with grain size, porosity and surface finish through varying degrees of translucency and optical scattering.“
(In TPR2 Figure 6, Plot 1 was reportedly derived from this table).
The main issue at this point is the fact that the right way to proceed for AA would have been to use the Spectral Emissivity values for temperature measurements (for example, 0.90–0.95 similar to the values reported by MFMP) and the Total Emissivity value for the calculation of the radiated power by means of the StefanBoltzmann formula (typically 0.40 at high temperature). To be noted how these issues show how awkward (and in some ways not very cautious) was the choice to adopt this type of calorimetry.
The value of Emissivity to be used for the thermal imager during acquisition is much higher than that to be used for calculating the Radiated Power. If we consider an operating temperature of 1000°C, the peak spectral emission maximum (Wien peak), is approximately 2.3 µm.
Since the Alumina Total Emissivity, as also reported in Figure 6 of the Report, decreases with increasing temperature (i.e., the decrease of the peak emission wavelength), the Total Emissivity to be used for power calculation actually coincides with the value indicated by the diagram (@ 1000°C it is about 0.4), while in the case of the temperature measurement by thermal imager, even if we are observing a body at 1000°C, the value of Emissivity to be used (i.e. the Emissivity within the camera measurement Spectrum) will still be what is appropriate for the reading range of the camera used (7.513 μm in this case).
As already noted in other occasions, in order to reduce the Emissivity error problem, those taking measurements in foundries or in the analysis of ovens do not use ordinary cameras (as that used by the AA), but cameras with a reading window in the field 35 μm. In our case, the choice of a camera with a reading window equal to 7.513 μm for certain aspects appears to be conditioned by the fact that only in that spectral range Alumina shows an Emissivity close to 1.
As an example, Figure 5 shows the Spectral Irradiance at a temperature of 1200K.
For an immediate comparison we calculated and report:
a) the blackbody spectrum @ T=1200K (blue curve)
b) the grey body spectrum @ T=1200K, with 0.45 Total Emissivity (gray curve)
c) the Alumina spectrum (red curve), according to Al_{2}0_{3} Spectral Emissivity data @ T=1200K, based on the National Bureau of Standards data (see Figure 2). The missing ε=f(λ) values were obtained by interpolation.
Integration of the Black Body Spectrum @ T=1200K provides the theoretical value of Irradiance (Radiant Power RP) that turns out to be 117,573 W/m2. On the other hand, if integration is carried out only within the thermal camera measurement range (7.5 – 13 μm), one gets the RP value in the measurement bandwidth. Under these conditions, as a consequence of the used values, it is evident that the Grey Body with 0.45 Emissivity (value set in accordance with the TPR2 Plot1 @ T 1200K) has an irradiation significantly lower compared to the Alumina body while being at the same 1200K temperature.
Under these conditions the Black Body RP is 9.96 kW/m2 and, taking the ratio between the Alumina RP (9.4 kW/m2) and that of the Grey Body RP (4.48 kW/m2), one get a 2.1 factor clearly indicating the presence of a large measurement error due to incorrect use of Emissivity parameters.
In the same way, Figure 6 shows the Spectral Irradiance at a temperature of 1400K. As before, for the sake of comparison we calculated and report here:
a) the blackbody spectrum @ T=1400K (blue)
b) the Grey body spectrum @ T=1400K, with 0.4 Total Emissivity (gray)
c) the Alumina spectrum (red) according to data for Al_{2}0_{3} Spectral Emissivity @ T=1400K, coming from National Bureau of Standards (see Figure 2). Missing ε=f(λ) values were obtained by interpolation.
Similarly, integration of the Black Body Spectrum @ T=1400K provides the theoretical value of Irradiance (Radiant Power RP) equal to 217,819 W/m2. Integration limited to the camera spectral range of measurement (7.5 – 13 μm), provides the RP value in the measurement bandwidth. Under these conditions, as a consequence of the used values, it is evident that the Grey Body with 0.4 Emissivity (value set in accordance with the instructions in the Plot1 TPR2 @ T 1400K) has an irradiation significantly lower compared to the Alumina at the same temperature.
In these conditions the Black Body RP is 13kW/m2 and the ratio between the Alumina RP (12.4 kW/m2) and the Grey Body RP (5.2 kW/m2), provides a 2.38 factor indicating the presence of a measurement error due to incorrect use of the Emissivity parameters.
To be noted that in Figures 5 and 6 the diagrams on the left side show the evolution of the spectrum of Planck as a function of frequency (f). Given the characteristic of inverse proportionality between frequency and wavelength, the left part of the diagram as a function of the wavelength (λ) [the diagram on the right] corresponds to the right side of the diagram as a function of the frequency and vice versa.
Figure 7 shows the link between Radiant Power and Temperature with reference to a measurement in the spectral range 7.5 – 13 μm. The black curve reports precisely the Black body Radiant Power that acts as a reference and calibration curve for the camera.
The graph takes the Emissivity ε as parameter in order to show how it affects the estimation of actual body temperature when measured using this IR camera methodology.
For example, let us consider the 1100K T1 temperature detected by a thermal imager with a wrongly set 0.45 Emissivity (correct value 0.90).
The RP deduced from the graph of Figure 7 for ε=0.45 (about 4 kW/m2) is in fact the one that competes to the curve with ε=0.90 but for an actual temperature T2 of only 800K (temperature overestimated by 300K).
Based on these temperature values, applying the StefanBoltzmann relation: P=ε*σ*(T^4Tamb^4) to calculate the thermal power per unit area radiated by a body (σ=5.67*10^8 [W/(m2*K4)] and Tamb 300K, i.e. 27°C), we obtain:
Pmeas(T1) = ε1*σ*(1100^4300^4) = 40.4 [kW/m2]
Preal(T2) = ε2*σ*(800^4300^4) = 14.7 [kW/m2]
To compare through the SB the power radiated, the Total Emissivity (for these temperatures from the TPR2 Plot1 ε1=0.49 and ε2=0.65) should consider. The ratio between Pmeas and Preal is 2.7 and this result indicates a large overestimation of the thermal power radiated from the body.
Nevertheless, the error may be even higher. Consider for example a temperature T1 of 1320K (about 1050°C) as seen by the camera which has been set (incorrectly) the value of emissivity 0.42 derived from the Plot1 TPR2 instead of the correct value 0.90.
The RP can be deduced from the graph in Figure 7 for ε between 0.40 and 0.45 (about 4.8 kW/m2) is actually the one that pertains to the curve ε = 0.90 but with an actual temperature T2 of only 880K (overestimation of the temperature = 440K).
Based on these temperature values, applying again the SB equations:
Pmeas(T1) = ε1*σ*(1320^4300^4) = 72.1 [kW/m2]
Preal(T2) = ε2*σ*(880^4300^4) = 19.8 [kW/m2]
As in the previous example, the Total Emissivity is considered for the SB (for these temperatures from the TPR2 Plot1 ε1=0.42 and ε2=0.59). The ratio between Pmeas and Preal is 3.6 i.e. still a huge overestimation of the thermal power radiated by the body and if, under these conditions, even higher Tmeas values were considered, it is not possible exclude that the error term (which continues to rise quickly, as well as the thermal power overestimation) would be even worse.
Coming back for a while to measurements and data in the MFMP report, it is interesting to see how what we report here is not just theory. The MFMP Test case is represented in Figure 8.
The MFMP have made a change in the emissivity value, by changing the camera settings, applying the change for comparison only to certain observed areas. The value has been changed from 1 to 0.7 for zones 7, 8 and 9.
Let us consider, for example, the area 7 of the device captured by the camera. The corresponding effect on the temperature indicated by the camera is to increase the read values from 985.7°C to 1276.5°C (a change of more than 290°C).
The following Figure 9 (where the area of interest in Figure 7 has been expanded) shows good agreement between the MFMP experimental data and the calculation of the temperature error that would be expected after the erroneous setting of Emissivity, due for example to the uncertainty on the actual value to be applied.
Finally, applying the SB to this Test case and using data of Total Emissivity (as from TPR2 Plot1), one would gain an overestimation of actual radiated thermal power by a 2.6 factor.
Experimental verification on a Alumina tube
A further experimental verification of the fact that the Emissivity of the Alumina in the field of 814 μm is approximately 0.95 was obtained by performing a simple test that makes use of a Pyrometer (a thermal imager was not available).
As can be verified by consulting the instrument Instruction Sheet, the Fluke 80TIR Pyrometer has a window spectral response 814 μm very similar to that of the camera used by the AA in TPR2 (7.513 μm) and the instrument is calibrated for a 0.95 Emissivity.
Since the highest operating temperature for this instrument is 260°C, it was decided to limit the alumina temperature at about 160°C. The Pyrometer analog output signal (1 mV/°C) was sent to a milliVolt meter with full scale 200mV.
According to references, the Alumina Spectral Emissivity curve is weakly affected by the temperature so that the measurement is still significant. The AA as well made their calibration (or intended calibration) at a temperature of 450°C while the measures on the HotCat were performed at much higher temperatures.
We used a pure Alumina tube (99.7%) by Sceram, 27mm outer diameter, 20mm inner diameter, 150mm length (code AAH01700, type C799 – DIN VDE 0335).
Four ceramic 68 ohm resistors (10W), in parallel, were inserted in the tube, as shown in Figures I and II.
A direct current coming from a stabilized power supply fed the resistors. To ensure good heat exchange between the resistors and the alumina tube, Portland dry powder cement filled any internal cavities, as shown in Figure III.
A type K thermocouple connected to a thermometer was placed within the alumina tube, as shown in Figure IV.
As shown in Figure V, the whole system was insulated with mineral wool to reduce the thermal exchange thus keeping the temperature remarkably uniform.
In the central area, the thermal insulation was removed to allow reading of the tube surface temperature by means of the optical Pyrometer.
The power supply voltage was adjusted to ensure that the system was maintained at a temperature of about 160°C (power approximately equal to 10W); comparative readings were then performed. For greater safety, once a thermal steady state was reached, 3 readings were performed with time intervals of tens of minutes (Figures VI, VII, VIII); the three measures provided very similar results.
The insulation was not particularly accurate since the presence of a thermal dissipation, and then a thermal gradient between the internal area measured by the thermocouple and the surface measured by the thermometer, provides an Emissivity value lower than the actual one.
The temperature read by the Pyrometer is lower than that read by the thermocouple of about 5°C, difference in part attributable to the thermal flow. Neglecting the difference in temperature resulting from this flow, and considering that the instrument Emissivity is calibrated @ 0.95, the effective Emissivity of the Alumina tube is in a first approximation equal to:
ε = 0.95*[(160 + 273)]^4 / [(165 + 273)]^4 = 0.907
At this temperature, using the TPR2 Emissivity values (0.70 at 160 °C), the Pyrometer read error would be around 34°C.
Conclusions
The MFMP experimental data are in agreement with those reported in the literature and confirm that the procedure and the Emissivity values, used by the TPR2 AA for measurements by the thermal imager, are incorrect. The GSVIT experimental test further showed that the pure Alumina Spectral Emissivity, in the reading field of the camera used to testing the HotCat, is greater than 0.90. These data are very different from those plotted and used in the TPR2 by the AA that appear to be those related to Alumina Total Emissivity. In the 12001400°C temperature range, the TPR2 Plot1 considers an emissivity of about 0.40 while, according to the literature, the Spectral Emissivity, in the camera reading field, is stable around values close to 0.95. This kind of error can lead to a significant overestimation of the surface temperature and to an overestimation of thermal Power by a factor 2 or more. An error of such proportions (which appears likely in the light of the measurements) makes not reliable, in our opinion, the TPR2 measurement results of the heat produced by the HotCat; on the contrary, a simple Mass Flow Calorimetry, similar to the one shown in a previous Post of ours, would have been feasible and most accurate.
Nice evaluation and testing.
Shortly after I worked with MFMP on this experiment, I undertook an investigation of alumina emissivity and wrote a paper on the subject entitled, “Making Sense of Alumina Emissivity”. This paper can be found here: https://drive.google.com/open?id=0B5Pc25a4cOM2bGFtQUYyQ3M2WTA&authuser=0
One of the conclusions from the analysis was, for temperature evaluation using the Optris, a too low value was used by the Lugano team for the 7.513 micron emissivity parameter. According to my estimate, the actual temperature was not 1410C, but was 1130C instead – that is consistent with use of a ductile metal heater wire such as inconel. The other problem was that the Lugano team used the same narrowband (7.5 – 13 micron) emissivity as a broadband single value emissivity parameter to compute the radiated power. It caused them to use a too low value for computing radiant power as well. In a small sense, the effect of using a too value of emissivity for the temperature evaluation, and a too low value of emissivity for the radiant power calculation, is to cancel the error somewhat. I found an approximately 20% error in the estimated radiant power calculation due to the emissivity mistakes. Of course, due to the error in temperature, the convection calculation will overestimate the heat loss, but the convection is a smaller part of the overall power balance than that of the radiant power.
The convection tube alumina material, reported as 99% alumina, does not seem to be correct. It was tested using XRD which identifies the crystal phases present. The alumina crystallites will be easily identified, but the glassy silicates may not show in XRD because they are amorphous. It is far more likely that the HotCat convection tube was molded with a castable alumina cement (over the heater coil) that has about 2030% silicates. The reason for this belief is that the inconel heater wire would not withstand the temperatures require to fire a 99% alumina into a hard body (16001800C).
Hi Bob, thanks for commenting. I read carefully your paper and I’ve a question on Figure 10. You say that the total emissivity [you call it weighted average emissivity] can be obtained, as the name indicates, by weighting it against something. What precisely?
Figure 10 is the weighted average of the full bandwidth alumina spectral emissivity; weighted by the normalized blackbody radiation at each temperature. So, to compute the curve, for each temperature compute the corresponding blackbody radiation at each wavelength where there is an alumina spectral emissivity sample (spectral emissivity is uniformly sampled in wavelength). Compute the following:
E(T) = sum_i [ BB(i,T)*SE(i)] / sum_i [ BB(i,T)]
Where i extends over the full bandwidth of emissivity samples. Note that the division is of the completed sums. Do this for each temperature.
@Bob Higging
The formula is fine if the BB(T) is the Plank formula. What I do not understand is the fact that you removed the temperature dependency of the spectral emissivity: SE = SE(i,T). The value can vary by 10% in the range 1200K1600K (see Figure 2 above, fom National Bureau of Standards).
Moreover, from the same Figure you can see that the assumption to held the spectral emissivity constant below 2 microns does not correspond to the real values.
But, what is very difficult to accept, since it is in contrast with several papers and tables, is the shape of Figure 10. According to literature it should be a decreasing function of temperature as in Figure 4 above.
See for example DOI:
10.1088/05083443/3/3/307
If you decide to check again your curve, please note that in your E(T) function you can get a simpler expression just recognizing that the denominator is the Boltzmann law; you get one single value for every T and you do not have to sum anymore over all the samples.
However, I’m happy to see that, despite the difference in numerical values, our two approaches coincide. That means the TPR2 should be corrected ASAP.
Thank you for the close read of my paper. I have had trouble getting anyone to check the technical aspects and I appreciate your close evaluation.
The NIST data you show is very old (1971)and the IR spectrometers were not as sophisticated in that period. If you look at Figure 4, you see a graph (blue dashed) at nearly 1600C and it is pretty close to the 450C spectral emissivity data that I used for the calculations. The 1600C data was extracted from a graph in another paper vs. wave number and recalculated in wavelength. When plotted vs wavenumber, the right side of the wavelength curve was compressed in a small space and could be in error fo that peak. So it may even correspond to the Shimadzu data. The data from Shimadzu is original digital spectral emissivity data with a lot of points, so I calculated using Shimadzu data. Based on the minor difference between the 2 curves in Figure 4, with a temperature difference of 1000C, I decided to calculate presuming SE(T) is constant until I find better data for the variation with temperature.
The text equation I wrote above is for example purposes. It could be simplified; however, the computation is so fast, it makes little difference in speed.
@Bob Higgins
Could you check the position of the BB peaks in your Figures 2 & 9, please?
Again, thank you for the technical examination of my paper. I will check the BB function that I used.
@Bob Higgins
It was a pleasure to read your paper that is really clear and well written. It is not very difficult to write a good paper if you know the matter you are speaking about. At GSVIT we are sorry not to have read it before; we could have saved a lot of time. 🙂
Thank you for pointing out the possible error in the blackbody spectrum curves. It was an interesting investigation. Strictly, the numbers are correct for the blackbody spectral power DENSITY (1 Hz bandwidth) versus wavelength. However, this does not accurately represent the shape of the power associated with samples in wavelength domain. When the calculation is made with uniform sampling in the frequency domain, the shape of the curve is the same as the power curve because deltaF is a constant. However, I sampled in the wavelength domain because the Shimadzu alumina spectral emissivity curve was uniformly sampled in wavelength. What I want is the relative power at each wavelength (=lambda=L). With a constant deltalambda, the bandwidth (deltaF) is wider (in Hz) on the short wavelength end and narrower on the long wavelength end. Since I used sums for numerical integration of power, the function I calculated for blackbody spectral density versus lambda must be multiplied by deltaF (the bandwidth). Analyzing… F = c/L; therefore, dF = c(L^2)dL. This means that the curves shown must be multiplied by one over lambda squared.
I will be recalculating the figures in the paper today.
I have redone the calculations in my paper and created a new draft. I would greatly appreciate your having a look at the new charts and calculations in the paper. Here is the link:
https://drive.google.com/open?id=0B5Pc25a4cOM2Zl9FWDFWSUpXc0U&authuser=0
@Bob Higgins
I read the modified version of your paper and now Figure 10 seems to have the right shape. There are some differences in the numerical values you get against ours. This depends of course on the choice of references for experimental data. But, I definitely think that the most important is that the procedures used within our two papers are the same from a concept point of view.
To compare numerical data it would be advisable if you could provide also the reversed version of your last formula, that providing the 0.53 figure.
You will get the inverse, i.e. 1.88, that measures how the radiated power was overestimated.
PS a (0.661) figure is surviving in the last part of your paper; it should be changed into 0.48
@Giancarlo De Marchis
Thank you for finding the text error in my paper. I corrected that and put the revised version in the Google drive folder at: https://drive.google.com/open?id=0B5Pc25a4cOM2WkhYSXFyZmZ4aUE&authuser=0
I think I prefer to leave the last equation as it is. From a semantic view, it seems that using the actual/Lugano as 0.53 is describing the truth, while using the inverse equation is emphasizing the magnitude of the error. I have no motivation to criticize the Lugano team. We all make mistakes as did I in this paper. With the help of your review, I was able to correct my draft paper before more widespread distribution. The importance of this type of review activity is to identify the TRUTH. We need the truth to guide our future experiments. Had this information been available earlier, the MFMP would have spent no time in investigating heater technologies that could be used to get their reactor model to a temperature over 1400C. Since the COP is actually somewhere in the range of 2, it lends plausibility to other researchers with LENR experiments reporting a COP in the range of 2.
Excellent work, thank you. Not clear to me who is the author?
Edwin Pell
Thanks for this excellent writeup – it is well done.
Two extra factors complicating the analysis
(1) the alumina surface is ridged. That has the effect of increasing emissivities < 1 – in the same way that a rough surface has a higher emissivity. It is only a 20% or so difference and in fact tends to reduce the error due to "emissivity variation with frequency – but a small effect compared to the main one.
(2) For frequencies where the alumina is translucent what matters is not the alumina emissivity, but the emissivity of whatever inside is not alumina – the heater coil etc. Imagine the alumina was perfectly transparent – then the real emissivity could be very high or very low according to whether what you saw through the alumina was a black body or a metallic surface.
All of which makes it really difficult to conclude anything from this method of measuring power. Had the testers done a proper control (it is incomprehensible to me why they did not) or used thermocouple measurement (equally incomprehensible) there would be good data.
Of course that data would not be so much to Rossi's liking as what the Lugano report claimed.
Tom
@Thomas Clarke
Concerning point (2) it can be said that the alumina under scrutiny is translucent to the human eye but not for the thermocamera. Within the measurement range of the OPTRIS camera, the alumina is almost a black body so that its translucency is zero. The frequencies that can pass through the alumina body from the inner part of the reactor to the ambient are in the visible and near IR part of the spectrum; but the camera will not see them. It could be used as a glass window to retain the heat inside the house. A room at 27 °C radiates most of its energy at about 10 microns so that the heath is not transmitted by the alumina window.
Thanks for your appreciation
Here is my post on quantumheat.org on this subject
#14 Edwin Pell 20150205 00:11
The limited data for aluminum oxide I can find via Google says the thermal conductivity falls with rising temperature. Yet the data shows a delta T linear with watts. So if conduction is falling heat transport by another channel must pick up the slack. I guess that is radiation through the alumina.
At 1000K the peak black body radiation is at about 3um. peak wavelength time temperature is a constant. So,
500K 6um
750K 4um
1000K 3um
1250K 2.4um
1500K 2um
How does the opacity change with wavelength?
see page 22 of this reference
lehigh.edu/…/…
Not to mention the power radiated goes as the fourth power of temperature. A lot more power radiated by the inside at 1600K than the outside at 1300K. A factor of 2.3 higher rate of power/area radiation from the inside versus the outside.
It will be very exciting if the 1300C inside and 800C outside can be reproduced with far less than 900 watts when the powder is added.
Edwin Pell
link is http://www.lehigh.edu/imi/teched/JapanWS/WS09D_Zanotto.pdf
Edwin Pell
@ Message to “Sanjeev”
In other Blog, recently you wrote:
“GSVIT guys censored my comment about the dummy analysis and sent me an anonymous email asking for my ID (real full name) ……….irony !
Probably they don’t want anyone to spoil their party. I think I will put them into “useful but untrusted” category for now.”
You gave an incorrect information.
By email you received full answers to your comment, an email from our official email address and signed by GSVIT team, not “an anonymous email” you said. Moreover, as pointed out to you in our email, site’s rules are:
“Comments released here using a “nick”, hidden identity or a partial reference without the indication of complete real name and surname cannot be published in this Blog.
…
These rules are mandatory, users who do not wish to follow these rules please do not post comments here (not complain if not published)…”
see: https://gsvit.wordpress.com/benvenuti/avvisi/
Few and clear rules. What you wrote are wrong assumptions, as said many times, this is not a Blog that accepts anonymous, nick or partial name; read carefully notice before post comments or worst before to issue an hasty judgments.
We suppose that you have a name and surname (is it correct?) so we hope that you will be able to understand that your comment is based on prejudice and your ignorance of rules of this Blog.
I’ve been reading both your writeup here, and Bob’ Higgins’ writeup referenced above, with interest.
The precise analysis of the calorimetry in this case is remarkably complex, but your clear accounts have certainly dealt with the main issues. I’m particularly impressed with the clarity of Bob’s account, and the detail in yours.
The one difference (that leads to Bob estimating 1100C and you estimating maybe 800C) is in what effect the known wrong estimate of 8u – 11u band emissivity (0.4 used in Lugano paper, should be 0.9) on correct temperature for a measured temperature of 1400C.
Bob assumes that the band radiance scales with T as T^4. Your graph above shows that the band radiance scales as more like T^n where n lies between 1 and 2. This is also expected from the fact that the low frequency limit of the black body equation is linear in T, and the fact that the band is well on the low frequency side of the peak. From a black body band radiance calculator such as:
http://www.spectralcalc.com/blackbody_calculator/blackbody.php
We can discover that the band radiance 3370 from the measured temp (1400C) multiplied by 0.4, and divided by 0.9, gives a band radiance of 1498 corresponding to that from 775C. This is very close to your calculation (800C). (Units of band radiance here don’t matter because they cancel).
It is also interesting why the reactor looks to glow orange at this low temperature, if it does. My suggestion is this. The heating element wrapped round the reactor will be hotter than the alumina surface. Although the band radiance is determined as above by the Alumina, which is opaque at 10u, the visible radiance is determined by the heating element. Now however we cannot know clearly what is the power. The heater wire may be hotter than the surface, but also the heater emissivity is unknown and the heater wire surface area less than that of the Alumina. The calculation of total radiance is now very complex and different at different wavelengths,
So: the Alumina temperature is securely measured at around 800C – much lower than suggested in the Lugano Report. Other factors then make it very difficult to determine the radiant power, although a best guess would be to take this as what is expected from Alumina at this temperature (a total emissivity of about 0.6). It is surprising to me that the Lugano testers do not correct their great error in this matter.
(the additional correction for ridges on emissivity does change these figures but not by very much).
Tom