Coil expert required...

[MoodyB]

Hey all,

I've always used a singe round wire coil for my rta's, but got bored a few days ago & ordered some Ni80 single core Claptons to try out.

Even though I thought "it'll use more juice due to there being more wire, which means more surface area to burn off the liquid"...

After a few tanks I thought that the flavour was slightly better, I got a bit more of a crackle from the coil, maybe a slightly warmer vape too but I felt it was ploughing through the juice more than my round wire builds.

So, using the puff counter on my mod, I decided to see what build used the most juice :


2.5mm single core Ni80 1.05 ohm Clapton @ 10.5w - average of 66 draws per 2ml

2.5mm 5 1/2 KA1 coil 1.14 ohm @ 10.5w- average of 65 draws per 2ml


Don't know why I thought the Clapton would use more juice, but it doesn't even though I thought it would due to it having 'more surface area'.

So, can anyone explain this to someone that can't quite grasp what's going on?

Is it the 38g wire in the clapton that's causing the added crackle & slightly warmer vape?
Or is it the Ni80 wire itself?

Just curious more than anything else.

And I'll need to try out my other rta's & see if the Vertex is just thirsty in comparison.

 

[ADDicT]

Ni80 heats up faster than KA1 which could be the reason for the crackle, but that's about all I know tbh.

 

[zouzounaki]

i think it is what you say @MoodyB , i sometimes use stainless clapton wire (hardly ever, mind) and it does sometimes tend to crackle or pop. i think it is because liquid is in the spaces between the wrap wire and it pops when you apply heat.

but i don’t find it uses more liquid either. i think that’s a myth.

 

[Mr Ripple]

Do you have less wraps on the clapton coil than the plain kanthal coil by any chance?

 

[MoodyB]

Just checked & the clapton has 1 more wrap than the plain kanthal coil.

 

[MoodyB]

i think it is what you say @MoodyB , i sometimes use stainless clapton wire (hardly ever, mind) and it does sometimes tend to crackle or pop. i think it is because liquid is in the spaces between the wrap wire and it pops when you apply heat.

but i don’t find it uses more liquid either. i think that’s a myth.

Maybe the popping is why I feel the flavour's better, as there's little bits of juice getting into my mouth.

It's is a bit more 'spitty' than a plain coil.

More power would probably fix that, but then it would be a bit too warm for a menthol juice.

 

[scrumpox]

Juice consumption is all about airflow; more airflow produces more evaporation = more juice consumption.
To maintain flavour density and warmth you need to create more heat in the coil to counter the extra airflow cooling. That's why we go for more complex coils which have a higher heat flux.

Dual coils will also go through more juice than a single coil.

Popping is juice that boils and explodes on the coil rather than evaporating into vapour. It's more prevalent when there's not enough airflow over the coil ... the juice flow excedes the evaporation.
A clapton wire will actually be increasing your wicking over a straight wire as juice occupies the space between the core and outer.

I see that you've gone from a straight wire to a clapton without increasing the power. The clapton has a higher heat flux which is why you feel it's giving a warmer vape. Normally, when vapers move up to more complex wires they have to increase the power to run them efficiently ... you're getting under-evaporation because you aren't increasing the power and adjusting the airflow to balance the heat and cooling effects.

Basically, it's building too big! No bang for buck.

 

[MoodyB]

Juice consumption is all about airflow; more airflow produces more evaporation = more juice consumption.
To maintain flavour density and warmth you need to create more heat in the coil to counter the extra airflow cooling. That's why we go for more complex coils which have a higher heat flux.

So where does the wire surface area come into it?

Thicker wire or more wraps => more surface area => more power required to heat the coil up.


If I go by steam-engine.org :

A 1ohm 3 1/2 wrap Ni80 coil will take 7.5 watts at a heat flux of 200.

A 2ohm 8 1/2 wrap Ni80 coil will take 15watts for the same heat flux of 200.


So, going by the heat flux output, both coils should be vaping at the same warmth.
Because of that I'd expect the 8 wrap coil to have better flavour due to more surface area evaporating the liquid.

Or would the flavour be the same, just that one coil would take longer to get up to temp when compared to the other?

I really should experiment again with this as I have 3 of the same rta's here, 2 of them gathering dust / for spares.

A clapton wire will actually be increasing your wicking over a straight wire as juice occupies the space between the core and outer.

That is why I was expecting my juice consumption to go up, and why I've avoided claptons mostly when vaping.

I see that you've gone from a straight wire to a clapton without increasing the power. The clapton has a higher heat flux which is why you feel it's giving a warmer vape.

Is that due to the 38g wire used in the clapton then?

Or is it because it's Ni80?

Or a bit of both?

... you're getting under-evaporation because you aren't increasing the power and adjusting the airflow to balance the heat and cooling effects.

That's why I was surprised, and confused too at the same time, when I experienced slightly better flavour ( which probably is down to spitback... ) and a warmer vape at the same watts as the simple wire build.

 

[scrumpox]

So where does the wire surface area come into it?
Thicker wire or more wraps => more surface area => more power required to heat the coil up.

If I go by steam-engine.org :
A 1ohm 3 1/2 wrap Ni80 coil will take 7.5 watts at a heat flux of 200.
A 2ohm 8 1/2 wrap Ni80 coil will take 15watts for the same heat flux of 200.

So, going by the heat flux output, both coils should be vaping at the same warmth.
Because of that I'd expect the 8 wrap coil to have better flavour due to more surface area evaporating the liquid.
Or would the flavour be the same, just that one coil would take longer to get up to temp when compared to the other?

I really should experiment again with this as I have 3 of the same rta's here, 2 of them gathering dust / for spares.

Again, I'd urge you to think about airflow. You're overthinking the heat flux theory here instead of concentrating on the practicalities of how you're vaping. The surface area of the metal in contact with wick is a factor but the efficiency of evaporation (using more juice) is more importantly about the airflow ... once the coil is up to temperature.

That is why I was expecting my juice consumption to go up, and why I've avoided claptons mostly when vaping.

You've got an unexpected result, because you increased the heat flux of the coil (and the metal mass) without changing the power input or the airflow. You've probably avoided claptons because you don't need them.

Is that due to the 38g wire used in the clapton then? Or is it because it's Ni80? Or a bit of both?

Ni80 will heat up faster, the larger coil mass of a clapton will create more heat .... eventually. Think about temperature and heat separately, they're not the same thing.

That's why I was surprised, and confused too at the same time, when I experienced slightly better flavour ( which probably is down to spitback... ) and a warmer vape at the same watts as the simple wire build.

As above, heat and temperature are not the same thing, do you follow? How do you get a coil up to temperature, how does the heat being generated vary from coil to coil, how does your airflow have to change in order to cool that heat down again before your wick burns?

If you want to perform experiments to see the real effects that matter, try wicking up and juicing different builds and pulse them (on a powered build deck or mod, not in the atty) first without airflow then with different amounts of airflow. Simulate your atty's airflow using a straw of some type. When does spitting occur, when does maximum evaporation occur? How does it vary from coil to coil, from power setting to power setting? How quickly does a coil ramp up to temp and how much heat is coming off the coil? Once you see what's happening outside the atty, then put the build into the atty and experiement with power and airflow settings to dial in your juice.

Bear in mind that what is meaningful to us as vapers using rebuildables is flavour. Juice consumption is not a meaningful target or measure, it's simply a consequence. The effective evaporation of juice in a build well balanced for the atty's chamber and your desired airflow is what gets you to flavour. Does anyone measure the pleasure of a car journey by the average MPG? Does simply increasing the MPG make it more pleasurable?

So if you're coming at this from the angle of wanting more flavour by using more juice, then you have understand how to evaporate more juice. Changing the coil only gets you so far. Vaping in essence is about heat and airflow. What works for me is to think about heat and airflow first, then think about coil size, material, surface contact area, resistance and all that good stuff.

 

[Crewella]

I've found this really interesting in an era when most 'MTL' tanks seem to come supplied with some type of clapton coil. I'm prepared to admit I'm an old-school-old-fogey that's happy with my plain roundwire micro coils at 10 watts ................ but I just look at those coils and wonder why I'd want to use them.

............ before I bin them.