what is the most effiecient way to maintain a constant temperature in a wire?

Question

i want to run a fairly high current through a significant length of wire (possibly coiled), but i also want to keep the temperature low in order to prevent the resistance from increasing as it heats up.

any ideas? apart from superconductors!

Answer 1

Switch on a fan and make it blow towards the wire.

Answer 2

Every wire size (or cable size) has an allowable ampacity to stay below a certain temperature rise.

For example, AWG 10 wire in 'free space' (i.e. there is at least one complete wire diamater between the power-carrying wire and the next conductor) will handle 15 amperes to stay below 90 C temperature rise.

If you need the rise to be lower, you need to force ventilate the conductor (i.e. blow a significant amount of air over it - for the #10 wire listed above, about 500 cfm per amp above the 15 limit to maintain 90 C rise).

Alternatively, use a proportionately larger conductor. For example, using a #4 wire (suitable for 60 A at 90 C rise) to handle 15 A will result in an observed rise of approximately 22 C. Basically, doubling the conductor size is required to obtain a temperature rise of 25 percent of the original choice.

Answer 3

I think the question is how hot are these things going to get (how much heat)? And how much current are you talking about?

If you want to keep something at a relatively constant temperature you could consider putting it in a large bath of electrically inert fluid. Fluorinert by 3M is generally used for cooling electronic devices like supercomputers, etc... This or similar type fluids could perform the function you need. The heat would need to be removed from the fluid by some additional cooling method, but in general, large bodies of liquid (of the correct thermophysical properties) can absorb quite a bit of heat without changing temperature considerably.

You could also consider a chiller if you really need specific precision.
http://www.thermo.com/com/cda/products/product_application_details/1,1063,10805,00.html

Answer 4

You could try water cooling - this is used in some welding plants, but be very careful when using electricity and water together.

Only try this if you are using low voltage, your wire is well enough insulated and you really know what you are doing.

But remeber - voltages which are fairly safe to work with dry can be much more dangerous when wet!

Answer 5

use somekind of a transducer as a negative feedback...when the temperature rises let it cool the wire down and when it cools below a threshold,warm it up...i dont know...i hope u figure such a transducer out

Answer 6

1. make coil,put it into liquid nitrogen;2. use strong turbofan