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

  • The glowing twisted wires are quite visible in the Lugano photos. The caption of one photo suggests that the twisted leads are glowing due to conduction from the reactor, which is silly. The wires are glowing orange hot because up to 50 A are passing through them.


    Correct. The heater wires all produce the same amount of heat per cm from wherever they are connected to the positive rail and back to where they are connected to the negative rail.

  • Paradigmnoia  


    About 5 cm leads of each of three twisted heater coil wires exit the Caps at both ends of the “reactor”. About 1 cm each is used at the clamp connection to the C2 cables. This leaves about 4 cm each, or 12 cm combined of Kanthal resistance wire inserted into the rods, at each end, heating the Rod ends.


    Correct
    So for both sides the total length of heating wires in the rods totals 2 x 12 = 24 cm


    About 30% of the total heater coil twisted wiring is contained in the Caps and the extensions into the Rods.


    We consider two situations


    1. Heating coil extends under the end caps


    Since the length of the caps totals 80 mm and the total length of the ECAT is 280 mm

    80/280 = .285 or close to 30% of the total power is dissipated in the end caps

    This amounts to .3 * 480 = 144 watts

    Again that is if the heating coils continue within the end caps


    To take also into account the length of the heating wires in the rods then we need to calculate with heater wire lengths instead of the section lengths above.

    If we assume the heater coil spacing being equal to the rib spacing (69 ribs) and the coil diameter is assumed to be approximate 2 cm, then the total heater wire length under the ribs is 438 cm and the total heater wire length under the end caps 175 cm

    Total heater wire length is then 24 + 175 + 438 = 637 cm

    Amount of power in the rods is (24/637)x480 = 18 Watt

    Total power in the end caps is (175/637)x 480 = 132 Watt

    Total power in end caps and rods = 18 + 132 = 150 Watt


    2. Heating coil ends at the end caps


    In this case there is 2 x 3 x 4 cm = 24 cm of heater wire under the end caps

    24 cm is in the rods

    438 cm is under the ribs

    Total heater wire length in this case is 24 + 24 + 438 = 486 cm

    Amount of power in the rods is (24/486)x480 = 23.7 Watt

    Total power in the end caps is (24/486)x 480 = 23.7 Watt

    Total power in end caps and rods = 23.7 + 23.7 = 47.4 watt Watt


    The 47.4 Watt in the rods and the end caps in this case is not enough to supply about 110 Watts measured in the rods

    So despite what is shown in figure 2, the heating coils must have continued under the end caps if we have 69 windings of heater coil under the ribs.


    Therefore, roughly 30% of the total input power is fed to the combined Caps and Rods, or ~ 15 % into each end, or, 7% into the end of each Rod bundle (but not 100% of that actually goes to the Rods due to the loose fit of the Rods to Caps.


    Case 1 (heating coils extend under the end caps)

    ----We have 100 x (150/480) = 31.25 % in rods and caps

    ----Of which 100 x (18/480) = 3.75 % in the rods

    ----And 100 x (132/480) = 27.5 % in the caps


    Case 2 (Heating coil ends at the end caps)

    ----We have 100 x (47.4/480) = 9.88 % in rods and caps

    ----Of which 100 x (23.7/480) = 4.94 % in the rods

    ----And 100 x (23.7/480) = 4.94 % in the caps


    The glowing twisted wires are quite visible in the Lugano photos. The caption of one photo suggests that the twisted leads are glowing due to conduction from the reactor, which is silly.


    Indeed


    The wires are glowing orange hot because up to 50 A are passing through them.


    Note that the above calculations and the simulations I did are when the coil under the ribs has 69 windings. (Same as the number of ribs)

    However figure 2 in your post (Was that from the patent application ?) shows 3 x 9 = 27 windings of the heater coil and that can make a large difference for the calculations.

    Wonder if figure 2 is a concept drawing or that the details are also correct

    Maybe someone can tell me more from photographs ?

    I will anyway also analyze the case with 27 windings and do also a FEM simulation for that situation and see if in that case enough power can be get into the rods. (May take some days)

    Thanks for your input ! (And thanks for the many edits so that i was able to refer to figure 2 :-) )

  • LDM ,

    When I worked out the specifications for the windings, using steam-engine.org calculator, I ended up with 30 wraps in the reactor main body area, 10 wraps for each of the three windings. This in turn gives 7 mm spacing between each adjacent winding (21 mm spacing for each coil winding).


    The number of twists unit length for the heater windings is important to getting the resistance and overal length of each winding into the correct range (fit the reactor space and have the correct amount sticking out the ends, using the correct Kanthal wire size).


    (This from memory, but I posted the steam-engine page with filled-in parameters in here quite some time ago, and made such a winding to verify the calculator [which works very well indeed]. I will have to find the steam-engine calculations to see if the spacing included one of the windings’ diameter within the spacing, or not).


    Edit: The steam engine website had some upgrades, so old bookmarks don’t seem to insert the values into the boxes correctly, and new bookmarks aren’t saving the specifications.

    The calculator credits the leads with 23.8 % of the total Joule heat/length of the windings. Wrap spacing is 21 mm between each coil loop for each coil, so the spacing between adjacent coils is close to 4 mm, with a twisted wire diameter of 2.9 mm.


    One coil: (settings for steam-engine). Three required.

    Kanthal A1

    Round,twisted

    Twist pitch 2.9 mm

    2 strands

    AWG 15

    Target resistance 0.41 ohms

    Inner diameter of coil 10 mm

    Leg length total 175 mm

    Wrap spacing 21 mm


    Results:

    Resistance wire length (twisted pair) 734 mm

    Wire length 559 mm (coil part)

    Wraps 10.15

    Helix angle 25.7 degrees

    Leg power loss 23.8 %

    Heat capacity 10059.67 mJ/K

    Heat flux 200 mW/mm2


    Stable output: 1700 W @ 26.4 V

  • Lugano dummy run thermal FEM simulations - FEM model adaptions-Heater coil update 1


    Thanks to the input from Paradigmnoia a preliminary FEM model upgrade will be made to test the effect of a heater coil with 3 x 10 windings.

    The test will be to discover if with such a heater coil configuration enough power can be transferred into the rods.

    In the calculations below I did not use the steam-engine.org calculator as PARA did, but instead used a spreadsheet to calculate the coil parameters necessary for the FEM model update.

    A minor difference with my calculation compared to the data PARA supplied is that my heater coil is 200 mm in length while he calculated for a coil length of 210 mm. (Makes it easier for me to update my current FEM model).

    I don't think this will result in a major difference for the prelimary FEM simulations.

    Also I will use a coil diameter of 1 cm in calculating the powers to be applied to the different sections.


    If we have 3 coils of 10 windings each then my spreadsheet calulations are giving the following data for a coil length of 200 mm and coil diameter of 1 cm


    Under the ribs each of the three coils has a wire length of 37.24 cm

    Total coil wire length under the ribs 3 x 37.24 = 111.73 cm

    Total heating wire length under both end caps 24 cm

    Total heating wire lengths in both sets of rods 24 cm


    Total heating wire length is then 24 + 24 + 111.73 = 159.73 cm


    Power dissipated under the ribs (111.73/159.73) x 480 = 335.76 Watt

    Power dissipated under the end caps (24/159.73) x 480 = 72.12 Watt

    Power dissipated in the rods (24/159.73) x 480 = 72.12 Watt


    Total power in end caps and rods is 72.12 + 72.12 = 144.24 Watt


    The total electrical power dissipated in the ECAT is 335.75 + 72.12 = 407.88 Watt

    Electrical power dissipated in the rods is 72.12 Watt

    Total power dissipated by the rods was calculated in the dummy run recalc as 118.38 watt

    So 118.38 - 72.12 = 46.26 Watt into the rods has to come from the ECAT as thermal power.

    (46.26 / 2 = 23.13 Watt for each end cap)


    This seems already quite feasible and possible much easier to accomplish then my old calculation with 69 turns and 2 cm coil diameter.

    So I now have to work on an update of the FEM model and then do some preliminary simulations with the above data to see where we stand.

  • LDM ,

    Using steam-engine, the wire twist rate, lead length, coil spacing etc, could be fine-tuned to get a 20 cm coil exactly... 🙂

    I had to do that last one from memory, in a few minutes, and didn’t spend much time dialling in the coil size.


    BTW, the Rods I found to be a nearly intractable problem (especially with no FEM). There is poor to incomplete information on them, and far too many opinion answers to questions than data answers to questions associated with them for my liking.


    I am still interested to see if it looks like the 2/3 factor was applied (or not) to the Rods in the Active Runs in the report (even if the method used was flawed anyway), since the numbers reported and the supporting data supplied are not clear on that point.