Why coils heat from the center out

[asknoble]

I've seen a few theories posted on why this occurs which have been partially correct. The posts are heat sinks at the end of the coil, although this is not sound theory for such an exaggerated heating from the center of the coil. If we were to heat an entire dripper to 1400F and attach a long thick length of wire between the positive and negative posts, the wire will still heat from center outward, (ignoring the wire immediately adjacent to the posts). Why? Because our wires are thermally conductive and heat transfer occurs through conduction as well as convection in a coil while the wire is producing heat energy linearly (not a linear temperature) at the same time creating the ramp bell curve of temperature over the length of wire. This relationship is inversely proportional with the thermal conductivity of, and the square of the diameter, per length, of wire used. Another way to think of it is that the wire itself is increasing it's own temperature by a given amount per watt above what the existing temperature already is.. Imagine a 3" length of wire where if the center 1" of wire increased 1F/sec, and the two on each side also increased 1F/sec, the center portion will increase it's temperature above the temperature increase given to it by the 1" from the left and right, vice from the edge of the wire with less heat transferred to it compare the the center length with two 1" legs on each end. In reality, this last example doesn't actually work really well since there are not 3 divisions of resistive wire lengths creating heat, but a near infinite division of segments heating wire producing and transfering that heat to the next guy. So that's why! I won't beat a dead horse on why the coil legs wont glow, that is the post heat sink's fault.

Fun Fact: temperature bell curves graphed out between uranium matrices, cladding, and coolant looks just like a Darth Vader helmet! (and would for our coils as well)

 

[Bad Ninja]

Nice theory buried in that wall o text.
Break a post into paragraphs and it will be easier to read.

Ther are a few contributing factors:

As the entire coil heats up, the outer edges are cooled by air while the radiant heat it sandwiched between coils near the center.

Peak resistance is in the center of the coil, and that where it heats first.

 

[crxess]

Okay then.....
Been dealing with coils for some 45yrs., but thanks for the refresher.

 

[Bad Ninja]

Okay then.....
Been dealing with coils for some 45yrs., but thanks for the refresher.

Did you really read all that?
Whew!
I just read the title. That post made my brain hurt.
Lol

 

[Kprthevapr]

I've seen a few theories posted on why this occurs which have been partially correct. The posts are heat sinks at the end of the coil, although this is not sound theory for such an exaggerated heating from the center of the coil. If we were to heat an entire dripper to 1400F and attach a long thick length of wire between the positive and negative posts, the wire will still heat from center outward, (ignoring the wire immediately adjacent to the posts). Why? Because our wires are thermally conductive and heat transfer occurs through conduction as well as convection in a coil while the wire is producing heat energy linearly (not a linear temperature) at the same time creating the ramp bell curve of temperature over the length of wire. This relationship is inversely proportional with the thermal conductivity of, and the square of the diameter, per length, of wire used. Another way to think of it is that the wire itself is increasing it's own temperature by a given amount per watt above what the existing temperature already is.. Imagine a 3" length of wire where if the center 1" of wire increased 1F/sec, and the two on each side also increased 1F/sec, the center portion will increase it's temperature above the temperature increase given to it by the 1" from the left and right, vice from the edge of the wire with less heat transferred to it compare the the center length with two 1" legs on each end. In reality, this last example doesn't actually work really well since there are not 3 divisions of resistive wire lengths creating heat, but a near infinite division of segments heating wire producing and transfering that heat to the next guy. So that's why! I won't beat a dead horse on why the coil legs wont glow, that is the post heat sink's fault.

Fun Fact: temperature bell curves graphed out between uranium matrices, cladding, and coolant looks just like a Darth Vader helmet! (and would for our coils as well)

 

[VaporDaze]

Because magic and tornadoes

 

[mauricem00]

I thought they acted that way because thats the way the vape gods want them to act welcome to ECF

 

[crxess]

Blower resistor, 65 Mustang

Needs some wick an lic'

 

[Revelene]

I'm sure there is a great thread body... hidden behind that wall of text.

Because magic and tornadoes

Seems pretty logical to me.

 

[jambi]

Okay then.....
Been dealing with coils for some 45yrs., but thanks for the refresher.

Heh, not me! I thought it was because Electricity raced into the coil from both ends, colliding in the middle and causing an Ex-plos-ion.

 

[crxess]

Heh, not me! I thought it was because Electricity raced into the coil from both ends, colliding in the middle and causing an Ex-plos-ion.

I thought that was the Battery

 

[herb]

Did you really read all that?
Whew!
I just read the title. That post made my brain hurt.
Lol

LOL , at least you attempted it before the brain hurt , i just glanced at it and said "no chance" and moved on.

 

[Douggro]

Blower resistor, 65 Mustang

Needs some wick an lic'

And that design served well right into this century. Alter resistance on the ground side of the circuit to regulate the fan speed. Simple, effective.

 

[Ryedan]

I've seen a few theories posted on why this occurs which have been partially correct. The posts are heat sinks at the end of the coil, although this is not sound theory for such an exaggerated heating from the center of the coil. If we were to heat an entire dripper to 1400F and attach a long thick length of wire between the positive and negative posts, the wire will still heat from center outward, (ignoring the wire immediately adjacent to the posts). Why? Because our wires are thermally conductive and heat transfer occurs through conduction as well as convection in a coil while the wire is producing heat energy linearly (not a linear temperature) at the same time creating the ramp bell curve of temperature over the length of wire. This relationship is inversely proportional with the thermal conductivity of, and the square of the diameter, per length, of wire used. Another way to think of it is that the wire itself is increasing it's own temperature by a given amount per watt above what the existing temperature already is.. Imagine a 3" length of wire where if the center 1" of wire increased 1F/sec, and the two on each side also increased 1F/sec, the center portion will increase it's temperature above the temperature increase given to it by the 1" from the left and right, vice from the edge of the wire with less heat transferred to it compare the the center length with two 1" legs on each end. In reality, this last example doesn't actually work really well since there are not 3 divisions of resistive wire lengths creating heat, but a near infinite division of segments heating wire producing and transfering that heat to the next guy. So that's why! I won't beat a dead horse on why the coil legs wont glow, that is the post heat sink's fault.

Fun Fact: temperature bell curves graphed out between uranium matrices, cladding, and coolant looks just like a Darth Vader helmet! (and would for our coils as well)

Hi asknoble and welcome to ECF!

So I think you're saying that if you have three coils really close to each other the center coil will get the hottest, the two outer coils will run at a lower temperature and the legs will be the coolest. Please correct me if I got that wrong

I'm not going to touch on what's happening when the legs get the hottest because that's a completely different issue.

 

[sonicbomb]

I thought it was because Electricity raced into the coil from both ends, colliding in the middle and causing an Ex-plos-ion.

Electrons azz-plode, get it right.

 

[WharfRat1976]

I've seen a few theories posted on why this occurs which have been partially correct. The posts are heat sinks at the end of the coil, although this is not sound theory for such an exaggerated heating from the center of the coil. If we were to heat an entire dripper to 1400F and attach a long thick length of wire between the positive and negative posts, the wire will still heat from center outward, (ignoring the wire immediately adjacent to the posts). Why? Because our wires are thermally conductive and heat transfer occurs through conduction as well as convection in a coil while the wire is producing heat energy linearly (not a linear temperature) at the same time creating the ramp bell curve of temperature over the length of wire. This relationship is inversely proportional with the thermal conductivity of, and the square of the diameter, per length, of wire used. Another way to think of it is that the wire itself is increasing it's own temperature by a given amount per watt above what the existing temperature already is.. Imagine a 3" length of wire where if the center 1" of wire increased 1F/sec, and the two on each side also increased 1F/sec, the center portion will increase it's temperature above the temperature increase given to it by the 1" from the left and right, vice from the edge of the wire with less heat transferred to it compare the the center length with two 1" legs on each end. In reality, this last example doesn't actually work really well since there are not 3 divisions of resistive wire lengths creating heat, but a near infinite division of segments heating wire producing and transfering that heat to the next guy. So that's why! I won't beat a dead horse on why the coil legs wont glow, that is the post heat sink's fault.

Fun Fact: temperature bell curves graphed out between uranium matrices, cladding, and coolant looks just like a Darth Vader helmet! (and would for our coils as well)

 

[sonicbomb]

 

[mauricem00]

Blower resistor, 65 Mustang

Needs some wick an lic'

now that you've put this ideal out there I'M sure it's just a matter of time before some kids tries it and we see another story about how dangerous e-cigs are.

 

[budda503]

You're just trying to sound smart.

It's obviously science

 

[Revelene]

I think we all know what Walter White would say about this...