Coil measured temp profile over time

[Mikla]

Not sure this is the best place to post this, but:

I decided to take some quick measurements of what my coils were doing when I vaped. So I hooked up a temp sensor (Type K thermocouple ). I placed it inside the coil sandwiched between the coil and the cotton (centered between ends of the coil).

This first plot is with the top off the rda and button held for ~6 seconds:

Vapor started somewhere around 250F. The slow cool down ramp I attribute to the juice in the cotton being heated and holding on to that heat. What it does mean is if the energy is applied again, the ramp up will start from a higher value which should lead to faster vapor as there is no juice preheat required.

Which leads to the second plot. This was the same build. But this time with the cap on and air flow holes wide open. I vaped on this in a normal fashion with about 2 second pulls:

This plot matches the experience I had. The first to pulls were pretty standard and expected.

• The first pull gave me a moderate amount of cool vapor.
• The second pull gave me what I would say is a typical amount of vapor and I could feel it starting to get warm.
• The 3rd and 4th pulls were very warm and heated up real quick. The 4th pull was almost burning
• The 5th pull was a failed attempt since I was hesitant to draw and burn myself

What I take from this is that after the 2nd pull the juice in the cotton so hot that it does not take much energy to vaporize it and keep the vapor going.

Most of this is pretty intuitive, but it was interesting to me to see some numbers behind it.

I'll do some additional tests when I have some time.

 

[Mikla]

As an FYI here is a vid of the coil giving off vapor in slow motion:

 

[93gc40]

The METAL of the coil and Atty are what hold the heat and determine ramp up and down time, for the most part. the more metal the coil contains the slower it will heat and cool. The juice will cool the coil more than it will hold heat in the coil.

 

[Mikla]

Thanks! Excellent clarification and I agree, the coil material plays a big part in the ramp times. But, IMHO, the point I was trying make was the juice in the cotton is definitely heated and aids in the coil holding heat. Here is another chart showing the ramp of the bare coil and the "juiced" coil.

As you mentioned, the juice helps to cool the coil at first, but it appears as the coil starts approaching the temperature of the juice in the cotton the cooling quickly slows down.

The chart has some minor corrections for temp (~30 F) and time shifted for alignment

As a side note. I believe the two primary sources of cooling are convection of the coil (and a little with the hot wet cotton) and conduction through the cotton to the juice pool. Conduction out the leads to the Atty would be minimal (though probably not insignificant) and radiation would probably be insignificant.

If I get some time, I'll compare a few different coil builds to see what I get.

 

[vapdivrr]

Pretty neat deal here, look forward to more.

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