High current in a supercooled wire?

  • Thread starter Thread starter PhiowPhi
  • Start date Start date
  • Tags Tags
    Current Wire
AI Thread Summary
The discussion focuses on the feasibility of applying a high current of 50kA for 100ms through a supercooled copper plate conductor without causing damage. The resistance of the conductor at room temperature is 0.0000843 Ohms, which drops to 0.0000117 Ohms when cooled to -196°C using liquid nitrogen. Key calculations indicate that approximately 30kW of power would be generated, raising questions about the cooling time, liquid nitrogen volume needed, and the effects of induced magnetic fields. The experiment is deemed dangerous, requiring stringent safety measures, and the discussion highlights the importance of understanding heat transfer and the skin effect in such scenarios. The thread was ultimately closed due to safety policy concerns.
PhiowPhi
Messages
203
Reaction score
8
I'm trying to understand heat-transferring process and the maximum amount of current and coolant required to apply and maintain(for a short-duration) high current in a certain conductor, before I start considering an experiment, I'd rather have my work correct in-terms of the calculations and predictions of what might happen.

The conductor is a copper plate, the dimensions: 250mm H x 5mm W x 10mm T
Weight: 111.58 grams

Can this conductor sustain 50kA in a duration of 100ms without fusing/melting?

Since it's a plate, I used https://www.eeweb.com/toolbox/trace-resistance online calculator for a quicker computation of the resistance and confirmed it with my own work they are approximately the same, the resistance at room temperature is: 0.0000843 Ohms.

The idea here is to have the conductor initially cooled to -196°C using liquid nitrogen, using the same calculator above I changed the temperature to -196°C, and now R = 0.0000117 Ohms

Using Ohm's law I'm assuming that the applied voltage(##V##) would be: ##0.0000117\Omega \times 50kA## = ##0.585V## The power is ≈ ##30kW##

Now when working out the heat transfer and the rate of transfer I lose myself, it's like all the things I studied in Physics 101 and Chem. 101 faded away... here are some questions I couldn't figure out aside from the initial one:

1) How long would it take to cool the plate from RT(20 - 25°C) to (-196°C) to apply the 50kA?
2) How much(volume) liquid nitrogen would I need to sustain this process for 100ms?
3) How long would it take to cool the wire(or transfer all the dissipated power) for a re-run(somewhat relates to Q1)?
4) Would the induced magnetic field have any ramifications? I assume a large spike if disconnected quickly due to the induced EMF.

The reason I considered liquid nitrogen is to reduce the resistance greatly, and cool the system rapidly, however, I think water would be a good substitute? Or even air cooling? Or possibly both or all?
I'm pretty sure due to the rapid boiling of liquid nitrogen I'd require a lot of it.
 
Engineering news on Phys.org
This experiment is far too dangerous for anyone with limited technical knowledge to contemplate doing . If it had to be carried out for some real purpose then stringent safety precautions would be required .
 
Have you considered the skin effect?

To calculate this you will need to know your waveform and its bandwidth.

The heat of fusion of nitrogen is 5.56 kJ/mol. So to dissipate 3000 joules (30,000 kW over 0.1 sec), a bit over 4 mols of vaporized N2. This gets into the Leidenfrost area I think.
 
Last edited by a moderator:
Closed pending moderation.

Edit: we will go ahead and leave this closed due to safety policy.
 
Last edited:
  • Like
Likes PhiowPhi
Very basic question. Consider a 3-terminal device with terminals say A,B,C. Kirchhoff Current Law (KCL) and Kirchhoff Voltage Law (KVL) establish two relationships between the 3 currents entering the terminals and the 3 terminal's voltage pairs respectively. So we have 2 equations in 6 unknowns. To proceed further we need two more (independent) equations in order to solve the circuit the 3-terminal device is connected to (basically one treats such a device as an unbalanced two-port...
Thread 'Weird near-field phenomenon I get in my EM simulation'
I recently made a basic simulation of wire antennas and I am not sure if the near field in my simulation is modeled correctly. One of the things that worry me is the fact that sometimes I see in my simulation "movements" in the near field that seems to be faster than the speed of wave propagation I defined (the speed of light in the simulation). Specifically I see "nodes" of low amplitude in the E field that are quickly "emitted" from the antenna and then slow down as they approach the far...

Similar threads

Back
Top