Atomizer coil temps...

[JakeStew]

I'm trying to figure out what temps atomizer coils operate at. I've tried searching and I'll post anything I find in this thread, but I'm hoping you experts here can tell me the real deal about coil temps.

Most of what I've found is a bit shakey. I've seen a lot of voltage resistance calculations here, so perhaps someone can enlighten me with some resistance/voltage/wattage vs temperature calculations or experimental data.

I've got a non-contact infrared thermometer, but I don't really want to destroy an atomizer and I think the measurement spot size on my infrared is too large to focus on just the coil anyways.

If anyone can share what they know with me or point me to a tread or other info source I'd really appreciate it. Thanks in advance!


-Jake

 

[NanoVapor]

ask the manufacturers.

Or buy/borrow a heat probe and test it yourself!

 

[Dave Rickey]

This page has a lot of data on Nichrome wire properties, but the temperature/amperage chart is for a free-standing wire. The atomizer are coiled around little tufts of silica (fiberglass) wicking, which are soaked in liquid. Most eCig atomizers appear to be 38 gauge.

Free-running, any of them are capable of reaching melting or vaporization temperature, but the usual point of failure is the solder joints (which have much lower melting temps). I strongly suspect there's something different about the construction of 510 coils that allows them to run so much hotter so reliably, I expect the answer is either how they are mounted in the ceramic cups, or that the wire is somehow thicker on the ends (I can think of a couple of ways to do that, the easiest is folding the wire back on itself and arc-welding it into a single conductor).

Getting reliable in-operation heat measurements would be tricky, and probably beyond the means of home equipment. Maybe a university lab.

--Dave

 

[JakeStew]

So from what I'm seeing there apparently isn't much consensus on coil temps. I've seen 200C quoted in a few places, but when I raise an aluminum block to 200C for a burn test the e-juice just slowly boils away and it really doesn't seem anything like what happens in the atomizer.

I'm really curious what the actual operating temp is going to be. I guess one way to estimate it is to continuously raise the temperature of a test block and see what it takes to get nearly instant vaporization of a drop.

I've tried glass microscope slides heated with a flame, but temperature control is pretty poor and the slides too often shatter or crack when that drop of e-liquid hits them.

I guess I'll keep playing with block temp until I get something that seems similar to atomizing. It's going to be well over 200C though probably.

One reason I'm interested in this is because I noticed a lot of differences in burn test results depending on how quickly the liquid is heated. Too slow and you get a goopy mess. If the coils worked at that temp they would be toast after just a couple ml of juice ran through them.

With higher temps the juice atomizes much more cleanly and the higher boiling fractions seem to get carried into the vapor due to the speed of vaporization.

I bet some people here have some ideas on this, so please post even if it's just speculation.


-Jake

 

[ZeroNullity]

Each atomizer has a slightly different temperature based on input voltage/current (wattage). It will very based on number of coils/length, gauge, material ratio (based on nichrome/steel content) Many factors can play a important role in the production of vapor including vapor pressure, wicking, heat dissipation. The amount of liquid your trying to vaporize is key.. and why spreading out the liquid using a wick type system is most efficient in small scale systems.

Key ingredient in most e-liquid is propylene glycol.

Boiling Point:
188.2C (370F)
Melting Point:
-59C (-74F)
Vapor Density (Air=1):
2.6
Vapor Pressure (mm Hg):
0.129 @ 25C (77F)
Evaporation Rate (BuAc=1):
0.01

Carbon dioxide and carbon monoxide may form when heated to decomposition. Aldehydes or lactic, pyruvic or acetic acids may also be formed.

 

[JakeStew]

I think the reason 200C is talked about is because it's around the BP of VG. So as long as the coil is supplied with liquid it can't really ever get over 200C.

What I've found is that with an aluminum block and a glass slide you need about a 292C block temperature to heat the slide to the point it will vaporize 1 drop in 10 sec.

Setting the parameters for 10 sec vaporization of 1 drop seems to be a reasonable way to standardize the results. Obviously an atomizer vaporizes a much smaller amount of liquid much faster.

Any hotter and the drops will jump around and the slides will shatter more frequently, any cooler and it takes too long to vaporize the drop and won't represent real-world atomizing results.