Steam Engine Heat Flux Wattage Question

[Zevo]

Hello Vapers,

I have used this forum exclusively for my vaping information and have found almost all the answers I needed. Yet I do have a question about using Steam Engine calculator. I have read the two blogs from State O' Flux (Steam Engine: From basic use to advanced features...) it was a great article. My question comes from the 2nd part of the article where Heat Flux is explained. I was hoping to verify that I am using the calculator correctly. For the example used in the article:

"Let me offer an example. You are a mech user, and are - like most rda fans - of the opinion that thicker wire is always a good thing. You build a dual coil rda with a 28 gauge, dual parallel build at 1.0Ω. You're using an 18350 mech with an Efest "Purple" 10.5a rated battery.

So... why the hell is my vape so darn cold, or why does my wick and coil "gunk up" so quickly, you ask? Heat, or rather... a lack of it.

You may think that because your battery is rated for 10.5 amps continuous discharge, that you're getting a full 42 watts of power and your heat flux is around 186 mW/mm2, right? Nope.
Recalling Ohm's law... your resistance dictates how much current is being discharged, which in the case of a 1.0Ω net resistance and a 4.2v battery... that's only about 17 watts. Your HF is a chilly 75 mW/mm2.

To "push" your unregulated 18350 battery mod to it's maximum continuous discharge, you'd need to run at least 30 gauge wire for a 1.0Ω net resistance, dual parallel build, and preferably 31 or 32 gauge, to obtain a warmer heat flux.
Other options are a lower resistance, or build a single coil with your 28 gauge... any of these, or a combination will increase your HF temperature.
Watch the HF values change - sometimes dramatically - as you change just one variable."

So if I have a mech mod, and want to build a 1.0 ohm coil I would first go to the "Ohms Law" taband figure out the wattage being used. In this case it would be 17 Watts. Now I enter the info for the build (28 gauge, 1.0 ohm, dual coil). Do I enter the 17 Watts in the field right next to the Heat Flux label? And if I do, and I change the resistance on the build do I need to return to the "Ohms Law" calculator, recalculate the Wattage used and re-enter it the same field?


Any feedback is appreciated.

 

[Efektt]

Yes and yes. But a 1 ohm dual out of 28g is not going to vape very good on a mech. You will be throwing 8.5 watts max at each 2 ohm coil. Its not going to heat up right. I am not basing this of the steam engine... just my personal experience. Try dual 1.1 to 1.2 coils. Yo get a resistance of around .7. Use steam engine to make sure your battery can handle it.

 

[State O' Flux]

Hello Vapers,

I have used this forum exclusively for my vaping information and have found almost all the answers I needed. Yet I do have a question about using Steam Engine calculator. I have read the two blogs from State O' Flux (Steam Engine: From basic use to advanced features...) it was a great article. My question comes from the 2nd part of the article where Heat Flux is explained. I was hoping to verify that I am using the calculator correctly. For the example used in the article:

"Let me offer an example. You are a mech user, and are - like most RDA fans - of the opinion that thicker wire is always a good thing. You build a dual coil RDA with a 28 gauge, dual parallel build at 1.0Ω. You're using an 18350 mech with an Efest "Purple" 10.5a rated battery.

So... why the hell is my vape so darn cold, or why does my wick and coil "gunk up" so quickly, you ask? Heat, or rather... a lack of it.

You may think that because your battery is rated for 10.5 amps continuous discharge, that you're getting a full 42 watts of power and your heat flux is around 186 mW/mm2, right? Nope.
Recalling Ohm's law... your resistance dictates how much current is being discharged, which in the case of a 1.0Ω net resistance and a 4.2v battery... that's only about 17 watts. Your HF is a chilly 75 mW/mm2.

To "push" your unregulated 18350 battery mod to it's maximum continuous discharge, you'd need to run at least 30 gauge wire for a 1.0Ω net resistance, dual parallel build, and preferably 31 or 32 gauge, to obtain a warmer heat flux.
Other options are a lower resistance, or build a single coil with your 28 gauge... any of these, or a combination will increase your HF temperature.
Watch the HF values change - sometimes dramatically - as you change just one variable."

So if I have a mech mod, and want to build a 1.0 ohm coil I would first go to the "Ohms Law" taband figure out the wattage being used. In this case it would be 17 Watts. Now I enter the info for the build (28 gauge, 1.0 ohm, dual coil). Do I enter the 17 Watts in the field right next to the Heat Flux label? And if I do, and I change the resistance on the build do I need to return to the "Ohms Law" calculator, recalculate the Wattage used and re-enter it the same field?


Any feedback is appreciated.

With "yes and yes", Zevo... Efektt has the "what goes where / when" bit well in hand. ;-)

You want to look at the heat flux that is produced with your mech powered build at 17.6 (lets call it 18 even) watts.
Everything is fine for that resistance, right up until you build it as dual parallel coils rather than a single coil - or if duals are mandatory... in 28 gauge wire, rather than thinner wire.
It's just too thick for a dual parallel build, at that resistance/voltage determined wattage to provide a decent heat flux.

As a dual 28 gauge build, your HF is a chilly 80 mW/mm2, while as a single coil build (still with 28 gauge)... HF is a toasty 320 mW/mm2.

Although I don't particularly like wire thinner than 28... your best dual parallel build, and perhaps the best choice overall, if you don't want to go sub-ohm, would be with 31 gauge, where the HF is a still nicely warm 227 mW/mm2.

With the 28 gauge, which you seem to have on hand, you might want to consider a dual parallel build at 0.5Ω to 0.7Ω.

Values are (respective):
0.5Ω / 35 (heat flux of 311 mW/mm2)
0.6Ω / 29 (heat flux of 214 mW/mm2)
0.5Ω / 25 (heat flux of 158 mW/mm2)

And those can be fine tuned a bit to fill the HF gaps.

Anyway... remember that with DIY vaping, once you have your limits sorted out, everything within those limits are a progression. With a mech, if one gauge wire doesn't do it, try another gauge... or different resistance or build coil count to obtain the surface area and heat flux values you like.

 

[Zevo]

Thank you all for the replies. I have been building sub ohm parallel builds for a while but recently found this Steam-Engine guides me to a better vape. To summarize what I hope I understand correctly, with an unregulated mode, using Ohm's law first, I get the watts to set in the Heat Flux. Then I need to vary the gauge or number of coils to obtain the "green" vape, while keeping the wattage constant (because of unregulated mod). Now if I want to build with 26 gauge, I would have to go back and forth between Ohm's law and coil build until I find a resistance that works out good? I am sorry, I am trying to understand this a little better. So if I get my wattage based on the battery and resistance , plug in the values and it winds up too cool, I need to start over? Like this:

resistance: 0.5
bat volt: 4.0
amps: 8
watts:32

26 gauge
dual
0.5 total ohms
heat flux 32 watts
mW: 142

Too cool so now I have to start back at step 1 and change resistance to get new wattage and redo coil build with new values?

 

[State O' Flux]

Thank you all for the replies. I have been building sub ohm parallel builds for a while but recently found this Steam-Engine guides me to a better vape. To summarize what I hope I understand correctly, with an unregulated mode, using Ohm's law first, I get the watts to set in the Heat Flux. Then I need to vary the gauge or number of coils to obtain the "green" vape, while keeping the wattage constant (because of unregulated mod).
Well... yes, but the "green zone" isn't hard, fast and universal for one an all. I tend to vape at the 220~320 mW/mm2 range... while some of my friends prefer cooler or warmer than that. I seem to recall one guy, who after I crunched his - somewhat suspect - numbers, appeared to enjoy vaping in the 800 mW/mm2 range. I'm thinking short... very short draws, were that correct.

Now if I want to build with 26 gauge, I would have to go back and forth between Ohm's law and coil build until I find a resistance that works out good?

Yep. As I said, without wattage regulation, other than resistance to control wattage output (and remember that for most batteries, voltage drops fairly rapidly initially, then settles in and drops at a slower rate after around 3.8v-3.9v... so 4.2v and the associated peak wattage isn't around for long)...

Slight pause to break up an otherwise annoyingly gigantic sentence... breath...​

... the variables to control heat flux are net resistance (which sets your wattage per Ohm's law), then wire gauge and parallel coil count... these last two being the only variables within your calculated resistance / wattage settings that you can fool with, somewhat interdependently... at least to the point where your atomizer can't hold the coils in it's physical confines, or the surface area is pitifully low.

And after all that... don't forget you want low heat capacity and leg loss values too.

I am sorry, I am trying to understand this a little better. So if I get my wattage based on the battery and resistance , plug in the values and it winds up too cool, I need to start over? Like this:

resistance: 0.5
bat volt: 4.0
amps: 8
watts:32
Exactamundo!

26 gauge
dual
0.5 total ohms
heat flux 32 watts
mW: 142
'Zactly spot on!

Too cool so now I have to start back at step 1 and change resistance to get new wattage and redo coil build with new values?

Ta Da! Winner winner - chicken dinner!

 

[Zevo]

Thank you so much for your patience and understanding as I try to figure this out. I must have read your blog at 10 times. I found it very informative and right on target to explain Steam Engine as well as the regular things to look for. I think I am now well taught by the excellent information you have provided. Thanks to Efektt for the excellent suggestions on builds. I will try them out on my next build. Looking forward to more blogs like this in the future.

 

[RamShot Rowdy]

Very interesting read. I have an RDA coming, so helpful info.

 

[State O' Flux]

It's a bit late ... but I just noticed a typo in post #3. In the resistance/wattage/heat flux listing:

"With the 28 gauge, which you seem to have on hand, you might want to consider a dual parallel build at 0.5Ω to 0.7Ω.

Values are (respective):
0.5Ω / 35 (heat flux of 311 mW/mm2)
0.6Ω / 29 (heat flux of 214 mW/mm2)
0.5Ω / 25 (heat flux of 158 mW/mm2)"

It should be 0.7Ω... not 0.5Ω again. Thanks to member "215Z" for "liking" the post, bringing it to my attention. Sorry for any confusion by later readers. Cheers. ;-)