Technical

[VIVAP2]

I observed that when I am exhaling air from my nose on the back of my wrist, the hit of blown air is warm.
When exhaling a "good" intake", the hit of vapor felt is cold.

There is an endothermic reaction going on. Experts, I am asking for technical details.

 

[VIVAP2]

Oops, there is a technical thread made specifically for these type of questions. Should have searched it before writing. Move over my Thread if mods think it more relevant.

Ooops again.

 

[VIVAP2]

No, the technical thread is concerning designs of e-cigs. Who has enough knowledge to answer that question?
It may take a week or more for me to find it myself.

 

[CityLights]

Wow, your right! it is cooler!

 

[denali_41]

perhaps because you blow it out faster through the mouth then the nose,,thats my findings

 

[ChellyNelly]

I've found this too, the vapor is always very cool. I'd like to know too.

 

[wood]

ive pondered this for years

 

[Concat]

I believe PG acts as a coolant. That is, it rapidly transfers heat. When you blow the vapor out, it cools down almost immediately, and when it contacts your skin, it sucks the heat out of you skin faster than air.

Keep in mind air is actually a terrible conductor of heat. It's probably as simple as the conductive nature of vaporized PG vs air.

 

[DaveP]

The water in the vapor begins to evaporate when it hits air, cooling your skin through that evaporation.

Try dampening the back of your hand and then blowing on it. The same thing will happen. You can also breathe on your hand close to your mouth and then hold it out in open air. The same cooling effect will occur. The technical term is evaporative cooling. It's the same thing that happens with a swamp cooler.

 

[Concat]

I don't think there's much water in ejuice tho, is there? I guess it depends on the juice... Plus when you exhale, you aren't spraying your skin with water droplets. It's already vapor so there's no evaporative cooling going on. If anything, it condenses... like when you fog up a window.

Just thinking aloud really.

 

[Blaisun]

yes but PG is a Humectant, which means that it absorbs moisture or water.... so my theory is that the cool feeling is the pg absorbing the moisture from the surface of your skin when it "blows" by, simulating the evaporative cooling sensation...

I dont know for a fact, but thats my theory

 

[VIVAP2]

Here is a hint of a theory after spending few hours here and there reading about enthalpy change* in dissolution for the last 3 days. I still can't explain exactly what is going with that phenomena.

E-liquids are made of 80%+ glycols blend. The backbone of glycols are surrounded by hydroxy groups. These will strongly attract water moisture in our body by hydrogen bonding.

I would assume water molecules are mostly in the form of liquid on the surface of our lungs. When it passes from its liquid form to vapor, attaching to the vapor mist** of highly concentrated glycols, the water is changing in phase from liquid to vapor.

More of scientific minded ecf members thoughts required.

* My hint of a theory doesn't have anything to do with enthalpy change but more to phase state change of water. Although, there must be some of enthalpy change of dissolution occuring.

** the boiling point of PG is 188°C and PG is the lowest molecular weight glycol in the blend. So don't tell me there was a phase change in e-liquid to its vapor form. I know for a fact that attomizers aren't heating up the liquid to that level. Yeah, what is the average boiling point of e-liquid?

Next scientific question will be.:

How much money have I saved from using e-cig by not having to open the door twice to go smoke outside during the winter on an average outdoor temperature of -5°C knowing that the house temperature is maintained at 20°C?

 

[kanadiankat]

Next scientific question will be.:

How much money have I saved from using e-cig by not having to open the door twice to go smoke outside during the winter on an average outdoor temperature of -5°C knowing that the house temperature is maintained at 20°C?

Less than if you lived in Alberta (where average temp outside in winter is -20 to -30 and I keep my domicile at +24). ....

Guess Mexicans, Texans and Californians don`t really save as much on ecigs!

Viva La Canada! (burrrrr)

 

[Ms. Creant]

yes but PG is a Humectant, which means that it absorbs moisture or water.... so my theory is that the cool feeling is the pg absorbing the moisture from the surface of your skin when it "blows" by, simulating the evaporative cooling sensation...

I dont know for a fact, but thats my theory

That sounds like a good theory. Just for shiggles and gits I used my infrared thermometer and checked the skin temp before and after as well as with plain breath. Temperature went down with vape and went up with plain breath. Also did the same experiment on the countertop temp went up in both cases.

 

[Ms. Creant]

Here is a hint of a theory after spending few hours here and there reading about enthalpy change* in dissolution for the last 3 days. I still can't explain exactly what is going with that phenomena.

E-liquids are made of 80%+ glycols blend. The backbone of glycols are surrounded by hydroxy groups. These will strongly attract water moisture in our body by hydrogen bonding.

I would assume water molecules are mostly in the form of liquid on the surface of our lungs. When it passes from its liquid form to vapor, attaching to the vapor mist** of highly concentrated glycols, the water is changing in phase from liquid to vapor.

More of scientific minded ecf members thoughts required.

* My hint of a theory doesn't have anything to do with enthalpy change but more to phase state change of water. Although, there must be some of enthalpy change of dissolution occuring.

** the boiling point of PG is 188°C and PG is the lowest molecular weight glycol in the blend. So don't tell me there was a phase change in e-liquid to its vapor form. I know for a fact that attomizers aren't heating up the liquid to that level. Yeah, what is the average boiling point of e-liquid?
Next scientific question will be.:

How much money have I saved from using e-cig by not having to open the door twice to go smoke outside during the winter on an average outdoor temperature of -5°C knowing that the house temperature is maintained at 20°C?

I'm reasonably sure that red hot metal coils are easily 1500 F / 800 C and up. I don't follow your comment, really. How else could we be 'vaping' something that 'was' a liquid and is now a vapor?

 

[VIVAP2]

[...] I used my infrared thermometer and checked the skin temp before and after as well as with plain breath. Temperature went down with vape and went up with plain breath. Also did the same experiment on the countertop temp went up in both cases.

Could you please, for the sake of science, repeat the experiment with inhaled vapor and non-inhaled vapor?
It seems like the optimal coolest vapor is got by holding for about three seconds.
Let us know !