Posts by Paradigmnoia

    So where are the trolls, ne're do wells, cynics, outright haters, and henchmen of Rossi's competitors with regard to Parkhomov's apparently astonishing replication of Rossi's hot dry cat experiments. One old but skilled in the art retired Russian scientist working in his kitchen sink seems to deliver the truth that exposes the usual armchair miscreants and what they are worth. What say ye.

    I say show me some evidence. A reasonable chunk of data would be nice.

    The summaries and highlights aren't good enough for me.

    The fact that Parkhomov's work is inspired by the Lugano demonstration does not inspire me at all, and these are not replications in the strict sense. I do like that Parkhomov seems to done some things to improve the experiment, but less data is being supplied with each iteration it seems. I am looking forward to his paper on the last reported work.

    Don't forget the window team showing up on the day Wong was there to inspect the mezzanine for his report, a year after the Plant was shut down. Like the windows were missing for two years? LOL.


    And, gosh, the mezzanine windows appearing and disappearing (depending on one's point of view) for the benefit of the Google Steet View camera car, while the test was on.

    *sigh*

    Is he doing experiments?

    After going through the Lugano Style vs real external alumina temperature curve exercise, there is little doubt to me that Rossi experimentally determined the ranges in which he would like the device to be tested in: where the peak dummy temperature should be, the minimum reported dummy temperature, the high 'COP' range, the maximum temperature the Optris could deal with and probably the best material to inflate the IR temperature with.


    Although it is possible that the Lugano demo accidentally ended up being tested in the way most likely to get a good contrast from dummy to active using IR, it is unlikely this was left to chance, and more likely that it was intentionally designed and encouraged to be that way.


    (The Optris cannot report more than 1524.7 C, no matter what emissivity setting is used.)

    Yes I do. No need for the later snide comment. Rossi's thesis was on relativity: do you not consider that hard science?


    I would like to know more about this thesis of Rossi.

    Wickedpedia suggests that it was about a combination of phenomenology and relativity (which does not sound like hard science to me).

    Of course visible and UV light can burn things. A magnifying glass focussing the sun should demonstrate visible light heating sufficiently.

    UV carries much more energy than IR or visible light per photon.

    The KAW samples at 1 kHz, which is asynchronous with the 60 Hz AC, and is integrated over 1 second for the display. So that is 16.67 samples per each full sine in, at a slight offset from the previous sample position on the sine each cycle. Not ideal, but probably not bad. The power is calculated by measuring a large shunt within the KAW and uses a proprietary power measurement chip. Maybe someone can calculate the potential sampling error across the partial sine spectrum if they like. I am measuring power going into the SSVR supply, not going out, so the line is eating up some of the distortion.


    Obviously there is better measurement equipment available. Do I care to spend even more for greater accuracy? Maybe one day. It is sufficient for the present application, IMO. At least I am attempting to capture all the input power including the input circuitry losses.

    You should not try to use a cheap meter like the KILL-A-WATT to measure power delivered through a triac. The output of a triac is a chopped sinusoid with a sharp falling edge partway through the cycle. Even a good RMS meter can have trouble accurately measuring waveforms with sharp edges. The input current to the triac dimmer has the same sharp edges.


    As I suggested earlier, if you instead deliver power through a Variac (autotransformer), the sinusoidal waveform is preserved and any decent meter will do the RMS measurements with high accuracy.

    The Kill-a-Watt measures consumed power surprisingly effectively, even when a triac is supplied. The amps cannot be trusted with a triac, however, but I do record it anyways. As it is, I measured the true RMS voltage at the coil with a good meter, and measured resistance of the coil over the entire temperature range. The V2/R reports almost exactly the same number as the watts on the Kill-a-Watt, with some error due to resistance rounding on the meter to one decimal place.

    If we are talking about the same spectrum range then indeed the radiant energy received in that band has to be constant and translating temperature with it's emissivity is for that spectrum range defined.


    Yes, that is what I meant.


    Also there is the question if n is indeed 3. Optris states that it is between 2 and 3.

    Some calculations I did in the past gives me the impression that it is about 2.75, but the difference in calculations using 2.75 or 3 is only small.


    I have the definition for the derivation of n as used in the Optris equation somewhere. It also explains why n is 21 for the shortwave end of the IR spectrum, as in the image that Whyttenbach posted a long time ago. The number is not a fixed value, (as is represented in the image), but has to do with the relative proportion of the power that is contained in various wavelengths or spectral ranges within a true blackbody spectrum. I'll try and dig up the source so I don't muddy up the explanation further.


    Also ask about the transmittance of 9 %

    Seems high to me, so I wonder if the Alumina they tested was partly doped or was processed to have a high density increasing the transmittance.


    Reviewing the Manara paper, it says it was a sample of "fused" alumina. It may or may not be equivalent to other types of alumina.


    According to a Rozenbaum paper: (2009, Texture and Porosity Effects on the Thermal Radiative Behavior of Alumina Ceramics":

    "As emissivity in the transparent zone depends on extrinsic parameters, it is not possible to predict the spectral value of emissivity only by the knowledge of intrinsic parameters (refractive index and extinction coefficient) and the thickness of a material. Indeed, as explained before, the modifications in the semitransparent and transparent zones were essentially due to the bulk texture and porosity. In the opaque zone, the increase and the spectral modification of the emissivity were mainly due to the structure of the ceramic surface. These results show for instance the necessity to have the exact characteristics of a ceramic to measure correctly its temperature with an optical pyrometer."

    LDM ,

    I agree that incorporating more of the long wavelengths will reduce the integrated in band emissivity.


    Perhaps since once a temperature is assigned to a particular emissivity using a particular bandwidth, translations to other emissivities at a new respective temperature using the same bandwidth is essentially independent of the bandwidth used. This is the basis of my in band radiant power matching scheme that I used in early calculations that ended up supporting Clarke's paper when I initially disagreed with it. This assumes that the radiant power received by the detector is constant, no matter what the user selected emissivity setting and the respective temperature reported by the camera or pyrometer is.


    I will attempt to email Mr. Rozenbaum and Mr. Manara and see if they are willing to share some spreadsheets of alumina spectral and total emissivity values.

    Nice work !


    What power setting did you use for these results ?


    Maximum input was 358 W and 5.06 A (at ~ 120 V AC in) , including SSVR losses (according to the Kill-A-Watt), at 68.3 V true RMS measured right at the coil input.

    I think (guess) the SSVR dissipates about 1 W per amp (it has a giant heat sink and is rated for 25A), and two indicator bulbs on the power supply use 0.3 W when the SSVR output is disconnected.


    I also discovered that the cylinder convection-radiation calculator I was using assumes adiabatic conditions for the ends, so I need to add convection-radiation calculations to account for the ends of the cylinder so my watts in matches the calculated watts out better before working out accurate-ish 'COP's and guessing at the real total emissivity of the Durapot.


    Edit: the Kill-A-Watt amps seem a little suspect... the watts should be good, but I will have to look into how the amps are dealt with when feeding a triac-like waveform. The power supply is plugged directly into the Kill-A-Watt, however.

    Rossi has $10M or so. You should ask him for money to further develop this interesting COP 4 device.


    If I did my math correctly, the average temperature of the cylinder at the end of testing was 814 C, so about a 'COP" of 5 may have been accomplished.

    That is using from left to right, 2.1 cm @ 727 C, 1.0 cm @ 850 C, 1.5 cm @ 894 C, 1.0 cm @ 880 C, 1.0 cm @ 767 C. (Measured carefully by pyrometer scanning and glow intensity).

    The lengths of the cool outer ends are exaggerated somewhat, as they are the coolest temperatures recorded for each end, and as such are less than the actual averages over the ends.

    Also, just double-confirmed the Optris software (using the MFMP dogbone2_cal_full.ravi file) that setting the emissivities, and reiterating to match as in the Lugano report does work for arbitrary temperatures, for comparison.


    For example, at 805.1 C (by thermocouple and IR at 0.94 E setting), the actually tested Lugano-style reiteration ends up at 1510 C at an E of 0.39 by IR pyrometer.

    The Optris software shows for 805.2 (as close as it would go) at 0.94 E , 1510.8 C at 0.39 E

    This also seems to indicate that the difference in detector emissivity sensitivity between the Optris camera (7 to 13.5 micron) and the pyrometer (8 to 14 micron) is negligible.


    Cylinder cooking away again.

    It turned almost grey after cooling with fine, sooty coating, probably pyrolusite.

    Pyrometer emissivity setting decreased from last test. Possibly crystalization change after cooking to 650 C previously, resulting in MnO2 rejection. If the black coating does not burn off tonight, I will see about removing the coating after it cools to see if it interferes with the emissivity. Might be able to turn it into Mn3O4 tonight? (If it is Mn anyways)

    Alan Smith ,

    This was a bit more of a challenge compared to the way I usually make things, which although infuriating at times, was worth the learning curve.


    Normally I design a coil to max out right about the maximum voltage I can easily supply using my favourite wire size. Other than adjusting the coil diameter, the coil size ends up being whatever size it needs to be.

    This time I had a final size range in mind, and worked out whatever needed to happen to get it there, within a limited final length range to eat up the problems that wouldn't easily go away some other way.

    From past experience, I was able to anticipate and attempt to offset a bunch of problems that I expected. But until it all comes together, the true range of difficulties is hard to assess on a fresh build.


    For example, I preferred doing a two-part mold, horizontally, but getting the thermocouples where I wanted and keeping them there was problematic, as well as keeping the coil centered without any support, so I did the vertical one-piece mold instead, which had other difficulties.


    However, despite some power supply uncertainties, total emissivity uncertainty, and lack of precise input measurements, the cylinder is getting in the general range of being as hot as the input power and convection-radiation formulas predicted. That in itself is a useful outcome. With some improvements suggested by the last test, it should be possible to predict much more closely the performance of an improved version before it is constructed.

    Why not use a Variac to drive your coil? You can get a 1000 VA Variac for ~ $70 on Amazon. That will let you set any voltage (power) input and does not create EMI like a Triac-based dimmer circuit.

    I probably will do exactly that. I wasn't originally anticipating that the coil was going to be so voltage sensitive until I ran the numbers a little later than perhaps I should have, so I was improvising with what was on hand.

    I can remove the transformer altogether and just be careful with the SSVR dial for another test. The steps will be more coarse, but that is probably better than the unimproved set-up I used last night.

    Well, test one of the cylinder was completed late last night.

    A few issues to sort out, and a few surprises.


    The apparent IR pyrometer emissivity started out similar to the the Slab... 0.91 from 20 C to 100 C, then at 144.8 C it jumped up to 0.96 V, remained there to 372.1 C where it went to 0.97, then dropped smoothly from there to 0.93 at 658.7 C , when I shut it off. So the apparent emissivity is higher than previously found. I'll rotate the cylinder 180 degrees to check for a hot spot where I was aiming the pyrometer for this test.


    The transformer is unhappy, and was getting real hot. Way too hot at a cylinder temperature of 658.7 C, which is why I shut it down. The transformer also consumes too much power relative to the cylinder, (and so it gets hot). This makes the cylinder power consumption difficult to reconcile with the output power. Probably the triac-like waveform doesn't agree with the transformer, and using the center tap and one lead for output possibly is another problem. So a better power supply solution needs to be worked out.


    The cylinder is cooler on one end than the other for a greater distance. This is obvious when glow heat begins, and with the pyrometer also. Maybe when the Durapot was being poured in it floated-stretched the bottom end of the coil in the mold a bit. A stiffer wire should be used when another one gets cast, but that messes up the length of the coil... I'll have to work through some permutations. It is also feasible to pass some very thin stiff wires through the silicone mold (to be removed immediately after pouring) that will hold the coil wraps from up-down movement when pouring in the Durapot. I did something similar to that to keep the Slab coils from moving around, since there were four continuous parallel coils that wanted to twist themselves to odd angles at the slightest provocation.


    On the other hand, it didn't explode into a shower of red hot fragments, so that was good.

    Overall, not too bad for a first version of a new design.

    Just an additional complication which you hint at here but do not explicitly say. What also matters is the translucency of the paint. At frequencies where (for the used thickness) it has low opacity the emission characteristics revert back to those of the underlying material. And opacity can vary greatly with frequency just as emmissivity can.

    I recall discussing this idea in 2015. At that time, before any idea of paint had settled upon the Lugano conversational milieux, the discussion rotated around the effect of the alternately opaque or luminous coil wires through the semitransparent alumina wavelengths.


    The optical thickness of alumina becomes important to the discussion, and as it turns out, the amount of alumina to reach optical thickness, generally, is very little. Otherwise special emissivity paints could scarcely be a thing. I think the papers of Rozenbaum as well as Manara et al. get into the optical thickness measurements of alumina, SiO2, and MgO. The thickness required to affect the transmissive, rather than opaque parts of the spectral emissivity, I do imagine, would need to be greater for the former than the latter, as typically the optical thickness of ceramics is correlated to porosity more than other properties. (Increases in density are effectively decreases in porosity, and increasing porosity increases light scattering). The scattering effect of porosity is such that the opaque region of emissivity increases in emissivity with increased porosity. The surface coating therefore only needs sufficient thickness and porosity to scatter light effectly in the semitransparent range enough to reset the emissivity profile to that of the coating. This critical thickness can be as thin as 8 to 10/1000 of an inch (0.2 to 0.25 mm) (Wade, 1959, figure 17, showing thickness of zirconia to block inconel emissivity at 1200 F.)



    Manara, J., et al, 2008: Bavarian Center for Applied Energy Research (ZAE Bayern), Wuerzburg, Germany, "Determining the Transmittance and Emittance of Transparent and Semitransparent Materials at Elevated Temperatures", 5th European Thermal-Sciences Conference, The Netherlands, 2008.


    Rozenbaum, O., et al., 1999: Centre de Recherche sur les Materiaux a Haute Temperature-CNRS, 45071 Orleans Cedex 2, France, "A spectroscopic method to measure the spectral emissivity of semi-transparent materials up to high temperature", Review of Scientific Instruments, Volume 70, Number 10, October 1999.


    Rozenbaum, O. et al, 2009: "Texture and Porosity Effects on the Thermal Radiative Behavior of Alumina Ceramics". International Journal of Thermophysics, Springer Verlag, 2009, 30 (2), pp.580-590


    Wade, R., 1959: Langley Research Center, Langley Field, VA, "Measurements of Total Hemispherical Emissivity of Several Stabily Oxidized Metals and Some Refractory Oxide Coatings", National Aeronautics and Space Administration Memorandum 1-20-59L


    [Note that Wade, 1959, is the source for the "alumina on Inconel" Total emissivity that appears in many IR camera and pyrometer emissivity tables, often (and incorrectly) suggested for the in-band IR detector emissivity setting]

    What about using Kantal wire to make a series resistor ?


    Also a bit sketchy, having another hot (electrically and thermally) wire in the experiment area.


    There is a center tap on my isolation transformer output side, so good to go there. Luckily the current should be fairly low, so hopefully it won't protest too much.

    It looks to be about 56 to 57 V true RMS maximum output, which should get me to 'COP" 4.5, and keep the cylinder in the safe-ish range of around 820 C external. In theory.

    (Assuming it doesn't explode as the coil wire expands)... safety goggles and leather apron on, fire extinguisher at ready...


    I might fire it up tonight. I'll skip the rectifier since it isn't helping anyways.