Unfueled Test Report (Obvious)

Many thanks to Obvious for sharing the following about an unfueled test. I think reports like this can be very valuable for replicators and replication students. This was originally posted on this thread.

A quick summary of a test last night (no fuel):

I added ceramic paste to the outside of my tube that has been run many times, that has a thin enamel coat “wetting” the coil to the tube. This was before deciding that the paste is a bad idea, and it was already baked on, so no going back. I will do a proper data analysis later (bit busy right now), but these are the notable parts.

The temperature delta between outside and inside is greatly increased. I could formerly get the exposed surface to vey close to the interior temperature. Now it is very much lower in temperature.

The delay period of both thermocouples to reaching a steady state takes much longer. I would guess the time period has doubled, maybe more. This is due to increased thermal mass, no doubt. At higher temperatures it seems less noticeable than lower temperatures, but it is significant.

The interior temperature was greatly increased at the same power level. This might seem like a good thing, but I think it is very bad. My previous maximum temperature was about 780°C, now 1075°C, at around 523 W.
I think it there was a LENR event at my current maximum temperature, the tube would fail, the contents would boil, the coil windings would melt, the TC maximum rating would be exceeded (in no particular order). The interior heat cannot be removed fast enough with exterior insulation, and there is now a long delay before it would be noticeable. If I were to bring the exterior to 1200°C, then the inside would be well over 1500°C now, maybe much hotter.

I think that NO EXTERIOR INSULATION would be best for testing, and the coils should be designed to make the correct heat externally. The inside heat will be hotter anyways. This way coil problems can be seen, the coi ls will remain oxidized properly, and internal heat will not cause instant failures. If any insulation is used, it must be very thin, very high heat conductive, etc.,until other problems are sorted out.

The tradeoff for higher inside heat with exterior insulation is poor heat release to the outside. If excess heat occurs at a rate that the heat cannot be conducted away, there will be certain failure of the device. Maximum heat radiation is required for successful experiments. Any quality PID control of heat needs the most fast-acting, lowest Delta T, and representative temperature reading it can get.

  • Obvious

    The internal thermocouple has a severe case of green rot after the test. This is interesting considering the tube was open to the air. The high heat must essentially force the air density to drop, and keep fresh air out by expanding it’s effective volume when it tires to enter, so hardly any actually gets in. Something to consider when designing internal heater tube devices.

    The chromel element is subject to what is known as “green rot.” When this happens, the chromium becomes oxidized and turns green and corroded. This occurs in reduced oxygen environments from 815° to 1,040°C. Such depleted-oxygen environments are called reducing, and K-type thermocouples should never be used in either reducing or cyclically oxidizing and reducing atmospheres. Also, they should not be used in sulfurous environments because they will become brittle and break rapidly. The presence of chromium makes them unsuitable for vacuums, save for short periods of time. This is because vaporization may occur.


  • Obvious

    There is a pink coloration of the cement directly and exactly over a heater coil where my thermocouple was stuck to the cement during the test. The pink is concentrated in the inner part of the cement. Since the TC insulation was silica braid, it is not derived from the jacket. The braid is pure while silica, slid over a bare wire type K thermocouple.

  • Dr. Mike

    Rather than a change in thermal mass, the differences observed after coating the heater wires may be due to a change in the emissivity of the reactor. A lower emissivity in the coated reactor would make it lose heat slower from radiation and reach a higher tempwerature for a given power setting. These results do indicate that considerable effort is needed to built reproducible reactors.
    Dr. Mike

    • Obvious

      I think it is both emissivity and thermal mass doing things. The time to get the temperature to stabilize at a set voltage from the earlier step is much longer now, and the cooling down steps are also much longer. This is complicated by the fact that it is getting hotter, which would take longer anyways, so a more detailed/organized look is needed. It does have significantly more mass (I’ll weigh it now that it is fully baked dry, but I bet it is at least 30% heavier).

  • Sanjeev

    See this remarkable idea by Valeriy Tarasov
    I’ve edited the side view for more clarity.

    • Sanjeev

      Which reminds me of this –

    • Dr. Mike

      This is a fairly obvious design for a future reactor where the device is being used to heat something real. You may even want to add a high frequency coil on the outside of the outer tube to control the reaction once a nuclear reaction has begun.. I think the heater on the outside of the fuel might be a little better for studying LENR. Do you see any advantage of this design for studying LENR?
      Dr. Mike

      • Obvious

        This is a neat idea, but I bet it would be a pain to test with and seal properly. It does put the show on display better, should a reaction occur.
        A bundle of small tubes surrounding a single heater might work well, and then several blanks, replicates, duplicates and loaded tubes could be run all at once.

        • Zack Iszard

          I think most crucially, if a local overheat occurs due to a runaway LENR event, diagnosing that apart from a simple heater coil failure would be much more straightforward. This design circumvents one of the “I don’t know what happened” outcomes entirely. If it could be done simply (even packing of fuel in the interstice between the alumina tubes), it is a superior design. That’s a big ‘if”, though.

          However, Obvious’ suggestion of a cluster of small tests and controls is much more clever, if consistent conditions could be assured. Perhaps heating an insulated box or cylinder with test cylinders inside? Thermal homogeny inside is a must But with one heater and many tests, a LENR event ought to be more obvious – the test tube that gets way hotter for no reason. Couple the cluster design with good IR video and high-quality calibrated thermocouples (random TC-to-tube assignment after calibrating all TCs?), and you have one very bulletproof evidence source. Small size of test samples and more modular design makes a failure less painful, also.

          • Obvious

            Brian Ahern was doing some tests pretty much as you suggest. 4 at once in a kiln. The first couple of tests were not eventful, but it I haven’t heard if any more were run. The kiln sort of tests if the coil is needed also, but without a positive result there is no evidence either way.

            • Gerard McEk

              Yes, I think the electromagnetic field may be crucial, so in that case this design is not very useful.

              • Sanjeev

                Actually, to test that theory, one can wind an additional coil on the outside and play with the frequencies and amplitudes of the fields as desired, independently of the power supply. You can go to very high intensity fields in this way of any frequency.

                • Gerard McEk

                  That is exactly what I intend to do: Develop a controller, able to do this: Frequencies up to 2 kHz, short high current pulses with a high dI/dt.

        • Sanjeev

          I thought of the bundle of tubes surrounding the central heater too. But then I thought they will heat each other, drowning any signal. But two tubes are feasible on on each side of the heater, one empty and one with fuel. So they will not “see” each other but will surely get the same input power.

          • Obvious

            An empty tube, maybe even uncapped, between each tube might help separation and even out the heat a bit. Perhaps triangular tubes with one point facing in would be even betterr for tube separators.

        • US_Citizen71

          It could be moulded with only one open end making it no more difficult to seal than MFMP’s swagelok based design. But you would need a master mould maker or a good friend at CoorsTek.

      • Sanjeev

        Yes I see a few advantages.

        The heater is nicely insulated, so it will take less power to reach high temperature.

        One TC can be placed inside the heater (assuming its wound on a hollow tube), which will give more control of the temperature, compare to a TC placed far away.

        Another TC placed in contact with the tube with powder will give more control over the temperature of the fuel, as it is very near to the powder, no more runaways.

        The cross section of the space with powder is small (can be 1 or 2 mm, which makes sealing easy.(Depends actually).

        The fueled tube is in direct contact with air, so forced cooling is easy (cold water or cold air).

        I hope someone will implement it, so we can see the actual performance.

        • Dr. Mike

          Using a thick outer covering of steel would not prevent hot spots since steel’s thermal conductivity at 15-50 W/m/K is essentially the same as Al2O3 (30 W/m/K). With alumina having a relatively high thermal conductivity, the temperature on the inside wall of the alumina tube is only going to be a few degrees above the temperature of the outer tube wall. If the outer wall was cooled too much, it would be difficult to maintain a LENR reaction . As I mentioned in previous posts, it is going to be quite an engineering problem to design a reactor that can deliver heat to an actual thermal load, and even more of a problem if that thermal load is varying.
          Dr. Mike

          • Sanjeev

            Thanks Dr Mike, I agree about the thermal conductivity of steel, its only marginally better than alumina. Nickel is another option for that, high thermal conductivity and melting point.
            I guess then Parkhomov’s use of SS as fuel container was not very useful.

    • Valeriy Tarasov

      I would like to clarify (for Dr. Mike and others) three points about the suggested inside-out design of the reactor.

      1. The inside-out design allows to deliver heat to “a consumer” better than the tested now design (used in the replications by MFMP members, Parchomov, Denis Vasilenko) exactly because of the principle of the inverted scheme. Why? It is because of the temperature gradient from heater inside to outside reactor tubes. The heater placed inside will maintain the temperature and LEN reaction (at certain temperature because of heater) in the layer of fuel more close to heater and the outer layer of fuel can have lower temperature, because of delivering heat to the “consumer”, without the danger to shut down the LENR in the whole fuel completely, or to allow LENR to run away. From my point of view the temperature gradient of the fuel from inside to outside is a key for stable LENR and heat production.

      2. Sealing of the inside-out designed reactor at both ends is not difficult and not different from the tested design. Instead of roads with cement in the already tested design, the rings (as it was written, between the outer and inner reactor tubes) with cement can be used with the same efficiency as for the tested design.

      3.1. Dr. Mike is right and the “coil on the outside of the outer tube to control the reaction once a nuclear reaction has begun” can be easily used in this design. I.e. not only temperature but also pulsed magnetic field can be used to maintain the LENR.

  • Sanjeev

    This FB post by MFMP is also helpful:

    The problem with “bare” reactor is that it will cool too fast and lenr will not trigger, or you will spend too much power heating it. There has to be a sweet spot between the two extremes which would depend on the embodiment/design of the reactor.
    If the rate of heat release from lenr is too steep, you may need to use forced cooling to keep it in control.

    • James Andrew Rovnak

      Yes an atmosphere for the LENR process to take root in keeping ultra low energy neutron production for isotope formation in balance with thermal radiant heat loss is key. Note both Rossi & Parkhomov have experience extend period of self sustaining mode of operation. Bumping this condition with external power input could keep process at any generation point as Rossi has amply demonstrated for his client. He now experiences long periods of operation with no heat input. COP infinite – simply great! Similar to moving a nuclear plants neutron flux level up & down with control rods by altering some few delayed neutrons from either getting into fission chain or not! I’m really interested in your time constants for control purposes as Denis Vasilenko’s PID controller eventually melted his fuel element a couple of days ago, but it was a beautiful glowing limit cycle especially after dark on an approximate 15 second limit cycle. Nice work Obvious! I’m sure he was playing with the LENR process or it was playing with him?

    • Jouni

      Perhaps the coil could actually be inside the pipe-like compressed ring-like active dust formation. Ouch, sealing surely problematic.
      Induction heating, and then trying all possible activation methods,
      hmm hmm 🙂

    • Obvious

      Perhaps for a commercial device, but too much energy spent to trigger it is not a problem until it becomes a problem, IMO. The real problem is triggering it long enough to measure it. Of course the exterior insulation could be fine tuned at some point. Clearly Rossi has managed it.