Watts do not matter. Its all about wire temp. Read on

[jjkillian]

Glad you guys responded with some ideas. I was thinking about it off and on throughout last night.

My initial thought is that I should be reading the coil from the bottom to avoid the vapor all together. This can be done by mounting an IR window to something and make that the "atomizer base". From there I am lost as to what to do to mount the atomizer. We need to be able to create pressure. I can monitor the pressure with a micro manometer and a pitot tube. I have access to both. Ideally I want to be able to hook up a fan to the outlet (where the drip tip inserts) of the atomizer. The micro manometer I have also controls a device called a blower door. This fan is big and sickly powerful, but I can control it pretty accurately with the manometer. I just need to build something that takes it from 36" down to whatever on the tubing. I can just attach a nipple to the drip tip insert on the atomizer. I do not necessarily have to go from 36" down. There are holes that are approx 1" across on these plates that go in to the fan inlet in order to control airflow for clean room testing. This part shouldnt be hard. The only thing I need is a standard draw. Any of you guys have manometers that can read pascals? If so, take the pitot tube and attach it to an added hole to an atomizer or anything that can simulate an atomozier cap, then take some pulls and log the readings.

Now for the test rig. I need something I can quickly add and remove coils from. Needs to have approx the same air volume as an atty chamber and somehow allows me to attach the atomizer to an IR window. I am wondering if I can just come up with something that when the "draw" is introduced it will just suck it to the IR window? Like some sort of silicon layer at the bottom of the atomizer or a small rubber doughnut that has a groove for the atomizer to sit in.

 

[Alexander Mundy]

Sorry, nothing fancy here just hillbilly engineering as far as manometers go. I built a flow bench for porting racing heads one time out of various bits from the garage and used a mass air flow meter from a car with a homemade incline manometer and calibrated it with a friends flow bench and plates. I don't know that I could home make an incline tube to do the kind of small readings you are looking for due to viscosity and I have no way of calibrating it now anyway except for a water column but I wouldn't think that would be precise enough. I am an electrical contractor so I have no need for such equipment but my cousin owns a heat & air company so I will see if he has anything that precise.

 

[StrappedKaos]

on a side note mr. mundy. if you have any info on how you built the flow bench I would be extremely grateful.... I fabricate manifolds and would love a simplistic meter I can build out of all my old tinker stuff. Thanks in advance. Strapped

 

[Alexander Mundy]

on a side note mr. mundy. if you have any info on how you built the flow bench I would be extremely grateful.... I fabricate manifolds and would love a simplistic meter I can build out of all my old tinker stuff. Thanks in advance. Strapped

You need to measure the mass of air and the depression (vacuum) from which you can derive the flow rate.
Mass can be measured with a MAF from a car IF you can build the interface and IF you have the manufactures formula or chart for interpretation.
I used a MAF which gave a frequency dependent on mass and read that with one of the frequency counters I had for ham gear.
Some MAF's give a voltage that could be read with a digital multimeter.
You can build a simple incline water column but you need to calibrate it against something.
You also need a vacuum source that has a high flow rate.
I happened to have at that time a 3 stage axial saved from an industrial machine.
You also need a way to control the flow which can be as simple as a large plumbing valve.

That said, IMO you really need to run or at least see one being used with the operator explaining it.
Also you need to be aware of what ranges of flow you want to optimize for and a way to measure velocity inside at corners etc.
Hogging out for maximum flow can kill critical velocity at certain points and make a really nice looking but dog of a head or manifold unless it is a top fueler.
Smaller is better in some cases and inside and outside radius of bends can really create some dead spots and a flow bench can't tell you that.

Sorry, got way off topic there.

 

[Mad Scientist]

I'm determined to try the embedded thermocouple idea. For the other old timers out there, the quick and dirty plan is to dig out my old Tek 7854 and use a 7A13 differential amp vertical plugin (1 mV per division sensitivity and ridiculously high CMRR) direct to the thermocouple wires. No cold junction compensation. Horizontal sweep speed of .5 sec per division. This should allow a photo of the time/temp curve over 5 seconds as the 7854 can easily digitize a single sweep at that speed.

Any comments on the plan appreciated before I spend a lot of time on it.

 

[theb0b]

I've just read this thread from the beginning and loved it!

I'd like to modify the title to "Watts don't matter. Its all about getting the juice up to vaporization temperature and keeping it there!"

An ideal situation.

Imagine a straight wire immersed in juice. As you apply power (Watts) to that wire, it heats up, and the juice around it heats up. That heat spreads out into the juice. Imagine a cross section of that wire suspended vertically in juice, the juice heats up concentrically, in an expanding ring.

Imagine there are 2 parallel wires. As they warm up, the concentric rings cross. If we can arrange the distance between the wires to the correct distance apart, so that just as the juice vaporizes, the expanding circle of heat from the other wire intersects, the juice will vaporize at the coolest wire temperature, heated by both wires.

Now we need to imagine that the parallel wires are different turns in the same coil. The coil has the correct diameter and pitch so that the circles of expanding heat, reach the temperature of vaporization near the center of the coil.

I think that applying the same amount of Watts, to coils of different gauge wire, will produce the same amount of vapor, as long as the pitch and diameter of the coils are optimum for that gauge.

I'd like to see straight wire tests in juice to see the heat conductivity to calculate the coil dimensions. I think that a table for PG, VG and 25:75 and 50:50 would give enough information to extrapolate.

There will be a fudge factor for soft wicks. I'd guess that silicon verses cotton wicks would have different porosity and different heat conduction characteristics.

Genesis style mesh wicks would be another story all together.

I think that a lot of the discrepancy in the measurement of VW mods, is because a coil is an inductor, and the PWM output is AC. But I may be totally wrong!

 

[Mad Scientist]

I did an initial experiment with a thermocouple embedded in an atomizer. It does appear to support my hypothesis that the atomizer, any atomizer, plateaus at phase change temp. It was also fun to try.

Here's the link.
http://www.e-cigarette-forum.com/fo...-time-curve-inside-atomizer.html#post11175823

 

[edyle]

That's right, it's really the TEMPERATURE that's important.

Right now we talk about variable voltage, but future products will refer to temperature.
There will even be a prime temperature! Right now we talk about manually 'priming' which really translates into warming up some eliquid to a suitable temperature

 

[Mad Scientist]

That's right, it's really the TEMPERATURE that's important.

Right now we talk about variable voltage, but future products will refer to temperature.
There will even be a prime temperature! Right now we talk about manually 'priming' which really translates into warming up some eliquid to a suitable temperature

Well, I disagree. It's all about the volume of juice brought to phase change temp over time. The temp itself is a constant. I'll soon devise a precise method to measure juice volume vaporized. I can (and did) measure temperature. I can also measure weight to very small differences.

 

[pdib]

Well, I disagree. It's all about the volume of juice brought to phase change temp over time. The temp itself is a constant. I'll soon devise a precise method to measure juice volume vaporized. I can (and did) measure temperature. I can also measure weight to very small differences.

yeppers. With wire mass, surface area (distribution), efficient use of the heat generated, and amperage asked for and delivered.

Thanks for doing that work, Mad! It's great to have that temp. plateau factor as a fixed point in all these variables.

 

[Mad Scientist]

yeppers. With wire mass, surface area (distribution), efficient use of the heat generated, and amperage asked for and delivered.

Thanks for doing that work, Mad! It's great to have that temp. plateau factor as a fixed point in all these variables.

I'm at the point where I think all of the involved variables result in volume of juice vaporized per unit of time (all the above you mention and also airflow). The remaining wild card I can't yet factor in is warmth of the vapor generated. In any event, when I can measure volume of juice vaporized as a function of time, we can change the various variables one at a time to see how they each contribute to atomizer performance during a vape. It may be a few weeks to gather the things I need and build the measuring fixture that will weigh a functioning atomizer to a hundredth of a gram in real time, but we'll get there.

If anyone can think of an easier measure than weight, let me know. Weight is a little bit of a challenge because of the need to connect stuff to the object being weighed.

 

[pdib]

Yeah, I was just reiterating, or listing off the factors that comprise volume of juice vaporized.

Well, probably too many factors involved; but another way to measure it, is the result. The quantity of juice vaporized in X amount of time will occlude the light of, say a laser to varying degree, based on the density of the cloud. (i.e. vaporize atomizer inside a plexi cube, say one cubic foot in size.) Something tells me I'm stealing this idea. . . . . . .. . Did P.Busardo do this? Yeah, I think he did.

 

[pdib]

And I think that the warmth of the vapor generated is completely about airmix. (Secondary, tho are factors affecting airmix, like a warm atty reduces the effectiveness of a given volume of air passing through it.)

 

[MikeWhy]

It is definitely very interesting but if anyone can draw useful conclusions from this, I'd be interested to know what they are.

The proximity of average as well as high and low temps to the boiling point of PG is certainly suggestive of just how much vaporizing is or isn't happening.

Conclusive? Meh. Phase change and latent heat dominates the thermodynamics. As though we needed a government grant to figure that part out.

 

[Kilo23]

Well luckily I have a lab in my basement better than anything the government has, J/K this seems like a hard topic to go either way.

 

[MikeWhy]

I had no intention of shutting down the lively discussion.

The high temp in jk's scans, in the very core of the short wrap, is right at the boiling point of VG. I think this is as conclusive as measurements go.

The next step is to read the temperature distribution on a longer coil, more wraps, see if more of the coil stays in the range for PG, closer to 400@F. (Or maybe those scans were made on a juice heavy in VG. I don't recall if that had been said.)

I think we're close to conclusion. Just one more good read on a longer micro coil with a PG/VG mix.

 

[Mad Scientist]

The proximity of average as well as high and low temps to the boiling point of PG is certainly suggestive of just how much vaporizing is or isn't happening.

Conclusive? Meh. Phase change and latent heat dominates the thermodynamics. As though we needed a government grant to figure that part out.

The proximity of the temp of a dry coil to the boiling point of pure PG doesn't suggest much to me except the coil is real hot in open air.

The energy absorbed by phase change is what controls, as you seem to say in your second paragraph. The exact boiling points of PG and VG are also sort of irrelevant because they change dramatically in their aqueous forms. For example: http://www.lyondellbasell.com/techlit/techlit/2519.pdf

The heat of a dry coil is suggestive of the power applied to it, which is wattage. Not much else. Various designs are more efficient than others in generating localized heating. As long as the heat is transferred to enough liquid, it won't burn, but if transferred to too much liquid, it won't vaporize. Different coil shapes perform better at finding that sweet spot envelope for a wet wick.

The title of the thread was its all about wire temp and we know it's not. I applaud the efforts to measure the temp of a dry coil, but I don't see the point.

 

[MikeWhy]

Wet, he shows the temps ranging from 540 to 420, boiling for VG to within 10% above PG's, respectively. This says the wick is feeding well enough to keep the coil wet. Heat of vaporization kept the coil from exceeding that peak temperature.

Dry, black body radiation is the poor man's thermograph. My 0.624 ohm,1.5 mm 26 ga. micro coil glows lemon yellow in about a half second. (4-wire milliohm meter, $159 and US based shipping from an eBay seller through Amazon.)

 

[Mad Scientist]

Wet, he shows the temps ranging from 540 to 420, boiling for VG to within 10% above PG's, respectively. This says the wick is feeding well enough to keep the coil wet. Heat of vaporization kept the coil from exceeding that peak temperature.

Dry, black body radiation is the poor man's thermograph. My 0.624 ohm,1.5 mm 26 ga. micro coil glows lemon yellow in about a half second. (4-wire milliohm meter, $159 and US based shipping from an eBay seller through Amazon.)

Maybe we are looking at two different things? The wick is dry in that experiment. No heat of phase change transferred.

For your coil, the thing is you could make any coil do what you describe by supplying sufficient power but it doesn't describe what makes an atomizer actually function as an atomizer.

 

[MikeWhy]

We have to be. He posted images of both. The wet one, I agree, is the one of interest.