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

[gdeal]

This is the most impressive vape science thread in existence. Cheers! To add to the pursuit of the ultimate vape:

gdeal, I'd like to hear your thoughts on pressure. It is my understanding that because vapor is not a gas but a liquid in a gaseous state, it can be compressed back into liquid by pressure alone without cooling. If this is correct, then might that be the key factor in producing thicker vapor? And in the current model doesn't the draw create a slight drop in pressure inside the plant? The draw imparts vacuum force and encounters resistance at the air inlet.

Pardon my amateurish science, trying to close some enormous rifts in my understanding.

I think I understand where you are going on this. We create a lower pressure high energy environment inside the atty. The energized VG/PG vapor then exits the atty into a relatively higher pressure environment but loses energy. This change is state causes the vapor to cool faster and produce greater vapor density. So to increase vapor density, we can either increase energy and/or decrease pressure inside the atty or increase pressure and cooling outside the atty. Given the relatively simplistic mechanics of our atomizers, it may difficult or expensive to change these parameters (except for increasing power to the coil). But I am open to ideas!

The other factor that effects evaporation is airflow. Assuming we have a good wick for delivery of ejuice, increasing airflow over a higher power coil can and will increase density by itself. I think this is a more practical approach and probable one of the reasons why you see all those shirtless guys in dim lighting blowing "clouds" on youtube. (just kidding...)

I get why/how they are doing it, but really with my current setups and how I vape that would take away from my vape experience. With lower ohm/thicker wire/ribbon, and #500/Ceramic/Bamboo/Hemp, wick etc.. I get a solid full density warm satisfying vape. I tend to take a slower drag, not a power hit, so I need to balance the variables a bit differently.

This subject is a bit OT, but a good question in anycase. I am sure that others with more expertise can provide better insight here.

 

[Skepticide]

I made an illustration of how I'm seeing it and the formation of an idea:

And then there's this bit that I find most intriguing:

A vapour (British spelling) or vapor (see spelling differences) is a substance in the gas phase at a temperature lower than its critical point. This means that the vapour can be condensed to a liquid or to a solid by increasing its pressure without reducing the temperature.

So the theory is that by creating a pressurized vapor plant, you can alter the density of the vapor by adjusting psi. There would also likely be greater heat retention, producing dense AND warm vapor.

I'm also left with a burning inquiry about the vapor composition. As the gas condenses, are the droplets getting bigger? If so, that means more of it will adhere to your mouth and throat as you inhale, making you taste more of the substance (and receive more nicotine). Such a fog might require special juice blends.

 

[thedesbois]

Skepticide, what I understand about your diagrams makes me think this: I have a ZAU with a larger than usual air intake (airy draw). I didn't like that when using a normal size drip tip. So I ordered a custom drip tip with a smaller air hole. What I think is that it makes for a situation similar to the no. 2 diagram you made.

I don't know if it fits the science behind what you're saying. But I do notice a huge difference between a normal size drip tip and the tight draw one.

Am I understanding this correctly?

 

[asdaq]

Nice to see some talk about pressure. I have found my optimum intake to be 1.5mm with an outlet size of 2mm. There is a downtube on the outlet that is offset so that it draws from behind the wick and serves to prevent any liquid from escaping. In combination these restrictions make the draw not too airy, but if the inlet is smaller it is much too tight, and if the outlet is smaller than the inlet vapor is much lower as well.

Skepticide, I think your second diagram is over the limit and what one should aim for is forward pressure in the chamber.

 

[mob1900]

Been following your article on for months and it's proven true especially using the Ribbon Kanthals, the wide surface of the ribbon kanthal gave more intense heat than a normal Kanthal A-1 of the same resistance/wattage/voltage. I think Ribbon Kanthal needs a better/new measurement system to gauge its performance or maybe we just need raise the bar for its class alone.

 

[Skepticide]

The low and high pressure zones in the diagram represent the chamber, that zigzag thing is supposed to represent the coil.

Instead of drawing air through the vapor plant, the air is pushed in with external pressure and vapor is pushed out through a narrow valve. This raises the psi inside the chamber where vapor is produced, theoretically condensing it as it is squeezed through. This is more or a less a complete reversal, vapor is pushed instead of pulled.

If such a thing is feasible, your PV would spew clouds out of the mouthpiece.

 

[gdeal]

The low and high pressure zones in the diagram represent the chamber, that zigzag thing is supposed to represent the coil.

Instead of drawing air through the vapor plant, the air is pushed in with external pressure and vapor is pushed out through a narrow valve. This raises the psi inside the chamber where vapor is produced, theoretically condensing it as it is squeezed through. This is more or a less a complete reversal, vapor is pushed instead of pulled.

If such a thing is feasible, your PV would spew clouds out of the mouthpiece.

It is feasible, here is a demonstration. Not sure if its at the PSI your thinking about. The velocity of the stream coming out seems like it may be a bit more than what you would be able to inhale.

 

[gdeal]

Been following your article on for months and it's proven true especially using the Ribbon Kanthals, the wide surface of the ribbon kanthal gave more intense heat than a normal Kanthal A-1 of the same resistance/wattage/voltage. I think Ribbon Kanthal needs a better/new measurement system to gauge its performance or maybe we just need raise the bar for its class alone.

There are a number of variables that can effect the vape. We could focus solely on Watt Density (the amount of power delivered to a surface area), however, it may not tell the whole story. But for discussion purposes, we can get some thinking on the table here.

If we compare 30g round A-1 with .5mm x .1 mm ribbon (both have about the same resistance per mm/inch), the ribbon has 50% more surface area, so watt density will be about 50% greater for round wire.

At 10 watts - round will have .25 watts/mm and ribbon will have .16 watts/mm
At 15 watts - round wlll have .375 watts/mm and ribbon will have .25 watts/mm

Since ribbon has a greater heated surface area exposed to air flow it should produce more vapor. But given the relative watt densities you will need more power to get that vapor. So if you have an optimal wire temp for a certain type/flavor ejuice and want to maintain the same flavor profile (ie cooler for mints, fruits, etc or hotter for Tobaccos, etc.) you theoretically could increase the vapor production with ribbon and not change the taste profile of the juice.

For example, if we hold all variables constant except power and wire type, the same flavor profile could be achieved with 30g at 10 watts and 15 watts with ribbon, but with more vapor. Of course your vape will overall be warmer, but the vaporization temp at the wire level should give you the same flavor.

I am sorta mixing watt density and wire temp which may not be the correct way to explain the cooling effect of air flow over surface areas, but it seems to align with personal experiences. Thoughts?

 

[Skepticide]

It is feasible, here is a demonstration. Not sure if its at the PSI your thinking about. The velocity of the stream coming out seems like it may be a bit more than what you would be able to inhale.

Well I had no particular amount of pressure in mind, just the underlying concept. Interesting demo too, but it doesn't seem to be compressing the vapor at all, possibly due to design. I noticed that it was creating a sort of vortex in the chamber (and splattering a lot of juice lol), wondering if a more linear air flow and a diffuser would solve this.

 

[thedesbois]

Nice to see some talk about pressure. I have found my optimum intake to be 1.5mm with an outlet size of 2mm. There is a downtube on the outlet that is offset so that it draws from behind the wick and serves to prevent any liquid from escaping. In combination these restrictions make the draw not too airy, but if the inlet is smaller it is much too tight, and if the outlet is smaller than the inlet vapor is much lower as well.

Skepticide, I think your second diagram is over the limit and what one should aim for is forward pressure in the chamber.

Very interesting sir! But could you help my confused mind vs the picture? Maybe a picture of the setup or diagram? I don't get your atomizer.

Thanks

 

[Tintreach]

I'm so glad this got brought up. It's been in the back of my head since tinkering with attys was the coil temp. Makes sense and have been thinking about doing some super tight windings. As much as I like SS it's too inconsistent (for me at least).

As for the airflow issue. This all needs to be treated like a combustible engin intake and exhaust. With all the variables of air intake, intake flow, wicking, juice viscosity, boiling to atomizing temps of the juice.

I have yet to see an atty that you and fully regulate your air mixture an exhaust flow. We can dial in the heat within reason but with. When it comes to low ohm attys and high wattage I think of it like drag racing. Dump as much fuel into the the motor as fast as you can and go as fast as you can. Fun but inefficient on fuel.

I think there is something to be explored in bottom feeds as well. The whole wicking process going up seems to be a big bottle neck for juice delivery. You are working agains gravity and wick material and only relying on vacuum and heat to get it up there. With a bottom feed gravity and fluid pressure work for you.

Is still go back to motorcycles 101. Air, spark and fuel.

 

[cadcoke5]

I made an illustration of how I'm seeing it and the formation of an idea:

I do not disagree with your concept of how air pressure will be affected by the geometries you are showing. But, there is also another principal that may be involved; in pneumatics there is something called "Bernoulli's Principle". Basically, it states that when there is an airflow restriction in a line, the pressure drops. It is certainly counter intuitive, but it is a well established and observed phenomenon. Here is a Wikipedia article on this.

Bernoulli's principle - Wikipedia, the free encyclopedia

Here is my own simplistic illustration.



One of the weird things of this principal is that after going through the restriction, the air pressure INCREASES from what it was inside the restriction. So, if you are seeking to lower the air pressure, you might consider restricting the airflow at the coil itself. For cartomizers, I suspect that since the air is flowing through the center of the absorbent material, it is possible that the coil itself reduces the diameter of the open air flow, and so causes the airflow to drop in pressure a bit.

Now, I also think that if you measure the air pressure before and after the restriction, you will see that there is higher pressure before the restriction than after it.

Skepticide, There is one statement I should comment on. It was the statement that the air density changes. When air flows well below its "mach number" (i.e. the speed of sound), we can generally treat it like it is an incompressable liquid, as long as the flow rate is the same, and we aren't adding or removing heat. But, in this case, we are certainly adding heat from the coil. So that may play a part.

Perhaps the real answers will come through the same thing that made the Wright Brothers such a success with the airplane. They invented the first wind-tunnel to test wing designs. So, gdea's work is where the answers really lay. I don't know if we can really make a good video to see how things work inside, because the clear surface quickly gets opaque. I suspect the best answers will come by trying various shapes, and measuring the output. Has anyone made a good fog analyzer and standard yet? I think I will start a new thread on this subject.

Joe Dunfee

 

[Skepticide]

in pneumatics there is something called "Bernoulli's Principle".
View attachment 201137

Good find, definitely broadens our understanding!

One of the weird things of this principal is that after going through the restriction, the air pressure INCREASES from what it was inside the restriction. So, if you are seeking to lower the air pressure, you might consider restricting the airflow at the coil itself.

Well we are actually seeking to increase the air pressure inside the vapor plant (the chamber where the coil is), not lower it. My hypothesis is that vapor produced in a high pressure environment will condense quickly.

Now, I also think that if you measure the air pressure before and after the restriction, you will see that there is higher pressure before the restriction than after it.

This is essentially true, but don't think of the coil as a restriction. Inside the chamber, pressure will always be the highest at the entry point where it is being forced in. This is feeding air directly to the coil and emitting vapor, which then flows away from the coil toward the low pressure point - the exit hole.

Skepticide, There is one statement I should comment on. It was the statement that the air density changes. When air flows well below its "mach number" (i.e. the speed of sound), we can generally treat it like it is an incompressable liquid, as long as the flow rate is the same, and we aren't adding or removing heat. But, in this case, we are certainly adding heat from the coil. So that may play a part.

I'm not sure I know which statement you're referring to, but that's ok The accumulating heat will no doubt add to the pressure inside, so that would definitely have to factor in when regulating.

I don't know if we can really make a good video to see how things work inside, because the clear surface quickly gets opaque. I suspect the best answers will come by trying various shapes, and measuring the output. Has anyone made a good fog analyzer and standard yet?

I imagine you could actually use the opacity of the chamber to gauge the vapor output. A laser pointer and lux meter just might do the trick.

 

[cadcoke5]

I imagine you could actually use the opacity of the chamber to gauge the vapor output. A laser pointer and lux meter just might do the trick.

Sorry, I didn't start a new tread in regards to measuring output, like I said I would. I will be moving from PA to TN later this week, and so will not really be able to put any effort into this.

I think the method you described will be insufficient. First, the exact power output of the laser varies from unit to unit, and from the same unit over time. I imagine there has to be a way to monitor the actual output of the laser in real time, to compare to the reading at the sensors.

The theatrical industry has had foggers for decades, but has yet to come up with a standard to describing the output of the machines. The main way to differentiate between different theatrical foggers is its wattage. In general, the higher the wattage, the more fog you get. But, manufacturers like PeaSouper tout that their foggers produce a finer particle size, and thus more opacity for the output from their machines. So, wattage is not the only factor, but it seems to be the only method available to compare between units.

Ideally, we would want a way for someone to describe the output of their atomizer, so someone else can compare to their own atomizer output. Both the measurement terms, and a way to calibrate the measuring device are needed.

I think there are two separate measurement issues, particle size and particle distribution. The total amount of "juice" vaporized is related as well. Note that some of the "juice" ends up as true gas, because it has evaporated. It has been stated elsewhere that particle size affects how deeply particles are inhaled into the lungs. The smaller particles going deeper, and causing a more rapid absolution of Nicotine, which is more like the smoke from a cigarette. For my own purposes, I am only concerned with how opaque the output is, so your simple laser measurement may be quite useful. But, for E-cigs, I imagine both particle size and distribution density is important.

Regarding using a laser, here is a clip from Particle Size Analyser, CD Spectropolarimeter, Rheometer

Laser diffraction is the one of the most widely used particle sizing techniques and has become the standard method in many industries for characterization and control. This type of particle size analyser relies on the fact that particles passing through a laser beam will scatter light at an angle that is directly related to their size. When particle size decreases, the observed scattering angle increases logarithmically. Scattering intensity is also subject to particle size, diminishing with particle volume. What this means is that large particles scatter light at narrow angles with high intensity while small particles scatter at wider angles with low intensity.
​

Here is a link to a great, brief article about detecting fog. Optical sensors

But, I have not come across information about making anything yourself.

Joe Dunfee

 

[cadcoke5]

I just came across an article about the creation of a fog/cloud measurement device for weather purposes. I imagine a similar device would be adaptable for e-cig smoke measurement if the smoke were put into a known volume.

http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA395148

Joe Dunfee

 

[100%VG]

Hello Everyone,

Off Topic, but have you noticed this up top, in the yellow ECF Banner field?

Please would you take a few moments to complete our 2013 ECF Survey?

 

[Skepticide]

The laser pointer method is a crude measuring stick, but it is a fairly cheap one. You wouldn't shine the pointer right at the sensor, but angled perpendicular so that way you are measuring the ambient light emitted when the fog diffuses the beam. Battery drain I'm sure would throw off results as you say, but for this particular application we don't really need amazing precision.

 

[DrSeuss]

Hi fellow vapers,

This is an interesting debate. I would really like to add my 2 cents. Please bear with me.

Let us assume in an ideal world 100% of the work done by a heating coil is put into vaporising fluid, the coil should never be capable of overshooting the desired temperature as all the energy is absorbed by the fluid as it vaporises. This means the maximum temperature a coil should achieve is 188.2 degrees C the vaporisation temperature of Propylene Glycol (approximately the temperature measured in the video linked to earlier). All the energy in the coil goes into just heating fluid from room temperature to vaporisation temperature. No losses, again, this is a hypothetical scenario.

Now, this only holds true as an assumption if, the wick is suitably efficient to provide a continuous level of fluid. The kanthal wire will never get hotter than this critical vaporisation temperature. We know that this isn't actually true in the real world, what tends to happen, is that the wick is not sufficiently effective at supplying fluid to cool the coil and therefore allows the coil to overshoot in temperature and burn the fluid This is obviously undesirable as it causes that burnt taste from the sugars in the fluid. This is most likely to happen with high power densities due to lower coil to wick contact areas.

Where wire diameter is likely to play a key role, is (as correctly asserted) is in the amount of contact area with the wick. By increasing contact area, the efficiency of the whole system will increase as overall power density decreases, since you are spreading the energy over a larger area. Where it will have a negative effect, if you have a larger contact area, you have a greater thermal inertia (the coil has to heat a larger volume of fluid up to vaporisation temperature). This thermal inertia results in slower response times to both changes in airflow and initial heat up. This does not take into account parasitic effects of the coil mounting assembly (and general environmental losses)

What you really want to overcome all these issues, is the ability to monitor when inhalation is taking place, attempt to quantify the airflow and then adjust the amount of heat going into the coil through a proper control loop. So, as you start vaping, lots of power to get up to temperature quickly and give you a nice instant response, then quickly tail off to avoid overshoot of the coil temperature, varying based on the rate of inhalation. I believe Raidy was working on a system to do just that. I am sad he no longer feels able to share his designs, but understand his reasoning.

So, sorry for the essay. I shall go back to lurking.

 

[gdeal]

DrSeuss. Very well stated.

Just as side note, I believe there was some discussion a while back in one of the threads on incorporating a two stage power throttle mechanism into a mod. I cant remember who was pursuing it, perhaps BJ43 remembers?

Also, there is some worked being done by Scubabatdan on placing a conductive porous thin film heating element on ceramic wick. This may help with the thermal inertia issue as well.

 

[BJ43]

DrSeuss. Very well stated.

Just as side note, I believe there was some discussion a while back in one of the threads on incorporating a two stage power throttle mechanism into a mod. I cant remember who was pursuing it, perhaps BJ43 remembers?

Also, there is some worked being done by Scubabatdan on placing a conductive porous thin film heating element on ceramic wick. This may help with the thermal inertia issue as well.

I remember the theme but not the person. I do feel that the rage going on with all these sub ohm coils needs some study, if a coil gets red while you vape, you are smoking not vaping. Studies have been done on the chemical composition of our vaping, but burnt juice (smoke) can have a completely different chemical composition and could be as harmful as an analog. Tried a 3 wrap 28g .7 ohm on a mechanical, give me a break, that is definitely not vaping. Wire temp has to be kept high enough for good vaper, but below a temp that could chemically effect the composition of the juice and form harmful gasses. Hope to see the day our units have a thermostat...