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Measuring Air Temperature of E-mesh Options
 
CloudyDays
#1 Posted : 3/11/2023 4:26:12 AM
I have been curious to know how much the air & vapor are heated during vaping with the e-mesh. To measure this I used the same setup described here and inserted a thermocouple into the air stream just above the drip tip.

The short answer: with 12 W of heat, the air ranges from 40 C to 80 C depending on the draw rate.

Details
The first two pictures below shows the setup.

Mod box: Aegis Mini, set to 12 W
Atomizer: Wotofo Profile 1.5 equipped with SS e-mesh, holes half open
Two Type K thermocouples, one in the room, one in the air tube
No spice, air flow only

The data were collected with an Arduino microcontroller at a rate of about 6 reading per second. That seemed fast enough to capture the quick rise time.

I drew air through the system at four flow rates, as measured by the ball flow meter. I did this until my lungs were 80% to 90% full, then stopped. The fire button was pressed just after I started the draw and released just as the draw ended.

The first chart shows the air temperature versus time. The temperature rises very quickly (in 1 to 2 seconds), then falls almost as quickly once the power is off. I noticed the mesh would also heat up the atomizer body. I didn't want to wait for it to return to room temperature, so drew in cool air a few times to cool the atomizer. That's what the dips in the plot are.

As expected, the faster you draw in the air, the cooler the air is. With my lung capacity (see this post), a 10 second draw is around 8 or 9 liters per minute. So for my setup, at 12 W, the air temperature will be about 60 C.

The next chart shows these four heat up curves overlaid on top of one another. At the faster draw rates, my lungs filled up faster, so the pulse is of shorter duration. The other thing to note is the temperature is rising throughout the draw, even though the flow is steady.

The third chart is a blow up of the second one, highlighting when the power comes on and off.

An interesting side question is how much of the 12 W is carried away by the air? We know the e-mesh will lose heat by conduction through the terminals, convection to the air and radiation to the atomizer body, but how much to each? I estimate the radiative losses are no more than 0.5 W. The convective losses can be calculated using the flow rate and the heat capacity of air. For the four flow rates I get these values:

Flow Convective Loss
6 lpm 6.9 W
8 lpm 6.2 W
12 lpm 6.3 W
15 lpm 6.8 W

Roughly half the 12 W is carried away by the air while much of the rest is conducted through the terminals holding the mesh.

Next I would like to measure the mesh temperature directly. But so far I haven't been able to get a thermocouple in consistent contact with it.
CloudyDays attached the following image(s):
Fig1_Setup.jpg (2,712kb) downloaded 18 time(s).
Fig2_Setup.jpg (1,159kb) downloaded 18 time(s).
Fig3.jpg (61kb) downloaded 18 time(s).
Fig4.jpg (60kb) downloaded 18 time(s).
Fig5.jpg (64kb) downloaded 18 time(s).
 
 
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