Alternative Temperature Control Design - Would this work instead? (wrt DNA40)

[Firecrow]

Evolv's announcement of the use of non-resistance Ni200 wire got me thinking about the whole temperature control thing.

Their design restricts your use to Ni200 (nickle write). But could temperature control with downregulation achieve the same thing if there were a reference table for wire temperatures?

If the device knows the resistance of the wire and also knows the gauge of the wire (you would have to input that as a variable), what if a reference table (through research) was done to determine the temperature kanthal heats to, to determine the appropriate wattage to achieve the target temperature? The mod would have to know the gauge, but it can read the resistance so if it internally knew gauge ratio to resistance and compared that against a known temperature table, and the mod downregulated to the wattage output in the table, could you achieve temperature control that way? That would give you the ability to temperature regulate without reading the coil resistance.

Please poke holes in this, there are greater minds on this board than mine.

Jay

P.S. Here is the mathematical basis on which I am suggesting the idea:

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html#c1

 

[Israfil]

The real issue, in my mind, is that as juice wicks to the coil and is vaporized it has a cooling effect. Combine that with draw speed, draw volume, atomizer chamber size, gunk level, and all the other variables and it just becomes too difficult to calculate temperature on the fly without simply adding a temperature probe IN the atty.

 

[WattWick]

If it's based on calculations - not temperature probes - it's just a more gimmicky VV/VW mod. Or...? Essentially you tell it to apply "more power" or "less power". As pointed out above, with liquid and air cooling, you can't simply calculate wire heat by power input alone.

The one and only benefit I see to temperature controlled wire is that it should (in theory) stop firing once the wick starts drying out. Or...? Sort of the rice cooker of the vaping world.

 

[dr g]

The one and only benefit I see to temperature controlled wire is that it should (in theory) stop firing once the wick starts drying out. Or...? Sort of the rice cooker of the vaping world.

In practice it does just that. Complete elimination of dry hits. There are other benefits as well.

 

[Firecrow]

In practice it does just that. Complete elimination of dry hits. There are other benefits as well.

Those are the benefits I am looking for. While I am going to upgrade both my ZNA30 (if they offer it - dont see why not) and my VS rDNA, but, I was thinking if you had a device that did not have temperature control, but does have down regulation, one could reference the chart on your build and at least set an upper limit. You would get dynamic regulation with feedback from the coil, but you could operate more "safely", ie: further from the ranges that result in burnt wicks or nasty chemical decompositions that occur at the higher temps with e-liquids.

 

[schuff]

The sad part is evolv moves at a decrepit pace and the world of innovation passes it by. The day before evolv announced the DNA40 products were released for beta by other chip manufacturers that did everything the DNA40.

Now evolv says they want the DNA40 full production in December but there is already two lined up to produce devices with the yihi SX350 V250 in December. The SX350 V250 utilizes temperature control but also adds bluetooth, touch sensor, 250 watts and software / gui updates.

Box mod makers everywhere recently have been leaning towards using the yihi chips to make their own mods where the choice use to be either a raptor DC/DC convertor or DNA30 a year ago. Have we not come to the point yet where American mod makers such as Hana, protovapor, house of hybrids etc. stop supporting evolv and their ridiculous chip prices and put together the best hardware with the best software.

 

[WattWick]

Edit: This post is full of bull. I stand corrected. Original post below the line. Don't believe any of it

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In practice it does just that. Complete elimination of dry hits. There are other benefits as well.

Certainly not lecturing you lol. I'm sure you're aware this would take temperature probes and not just some calculating mod chip.

I'd go as far as to call it false marketing to claim that a mod can have any direct control of an attys wire temperature all by itself. Without probes, it's not temperature control. It's temperature guesstimation.

 

[rusirius]

Certainly not lecturing you lol. I'm sure you're aware this would take temperature probes and not just some calculating mod chip.

I'd go as far as to call it false marketing to claim that a mod can have any direct control of an attys wire temperature all by itself. Without probes, it's not temperature control. It's temperature guesstimation.

Not at all... The reason Evolv uses Nickel instead of kanthal for their temperature protection is because nickel has a very high temperature coefficient of resistivity. In other words, it's resistance changes a lot more as it's temperature increases versus other conductors. All conductors have their resistance change as their temperature increases. Typically the resistance goes up as their temperature increases. (insulators do the opposite, their resistance typically decreases as temperature goes up) Anyway, the point is, this is EXACTLY what the DNA40 does... When an atomizer is connected (i.e. unheated) it measures the resistance of the coil... When firing it constantly monitors the resistance of the coil... In this way it knows exactly how many degrees the temp of the coil has raised. I believe their margin of error is around +/-10 degrees F. Which is very small given temperature ranges of 300-600 degrees that most would run at. No temperature probes are needed, simply measuring how much the resistance of the wire has increased.

 

[WattWick]

Aaaha! That makes sense. I've been horribly mistaken once again

Thanks for the insight!

 

[DoubleEwe]

I don't think it could eliminate the dry hits entirely, but it would reduce them and their intensity. The regulated coil temperature would still be hot enough to burn/char cotton if dry, but it just would not get as high as with a standard mod dry hit.


Am I correct in assuming that it is possible to get the same regulated temperature effect with Kanthal by increasing the sensitivity of the on-board resistance meter?

 

[rusirius]

I don't think it could eliminate the dry hits entirely, but it would reduce them and their intensity. The regulated coil temperature would still be hot enough to burn/char cotton if dry, but it just would not get as high as with a standard mod dry hit.


Am I correct in assuming that it is possible to get the same regulated temperature effect with Kanthal by increasing the sensitivity of the on-board resistance meter?

Believe it or not, but it should (and from what I've heard from actual users DOES) in fact completely eliminate any and all dry hits... You figure cotton has a charing point of 550 degrees if memory serves me? Most users are setting there coils around the 400-430 mark.... In excess of 100 degrees less than what is required to burn/char cotton...

From what has been described (by actual users) you can literally fire a wicked coil (let's say in a dripper) and completely dry out the cotton without ever burning the cotton at all.

As for your second point, yes, it COULD be done with kanthal, but the thing is you would lose a LOT of accuracy... I don't know what the temperature coefficient of resistivity for kanthal is to be honest... and i'm too lazy to look it up.. .LOL... but let's take nichrome instead... the alpha (per degree Celsius) of nichrome is .00017. On the other hand, the alpha for Nickel is .005866. That's a huge difference... In other words, there is going to be VERY little change in kanthal over say a 600 degree temperature range... However with Nickel there is a MUCH larger shift over that same range... That means we can get much more accurate results with nickel...

Think of it like this... If I tell you that I want you to "guess" the combination to a lock that requires 3 digits... and I'm going to represent the answer with lengths of string...

If on one hand I tell you that I'm going to add .001mm for every 1 with a range up to 60... on the other hand I tell you I can instead add 1" for every 1.... Which is going to be easier for you to get the right combination? It's going to be a LOT easier to measure the length to the nearest inch and know exactly what number it represents rather than trying to measure thousands of a millimeter...

 

[DoubleEwe]

I think cotton chars at around 480F, so it is not that far off (12%), but yes, I see your point and stand corrected.

And thank you for the elaborate confirmation that Yes it can be done for Kanthal, but is unlikely to happen due to the accuracy needed.

 

[dr g]

The sad part is evolv moves at a decrepit pace and the world of innovation passes it by. The day before evolv announced the DNA40 products were released for beta by other chip manufacturers that did everything the DNA40.

Now evolv says they want the DNA40 full production in December but there is already two lined up to produce devices with the yihi SX350 V250 in December. The SX350 V250 utilizes temperature control but also adds bluetooth, touch sensor, 250 watts and software / gui updates.

Box mod makers everywhere recently have been leaning towards using the yihi chips to make their own mods where the choice use to be either a raptor DC/DC convertor or DNA30 a year ago. Have we not come to the point yet where American mod makers such as Hana, protovapor, house of hybrids etc. stop supporting evolv and their ridiculous chip prices and put together the best hardware with the best software.

A bunch of false information, coupled with cluelessness. Evolv is one of the few companies in vaping that is actually innovating, and on balance is the most innovative company in the industry. They are several steps ahead of anyone else.

Back to the OP: There's no real reason to go another direction when the temperature control we have right now is as good as it is.