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Dekozn
Stranger than kindness


Registered: 04/12/06
Posts: 1,184
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Re: Themodynamic Analysis of Monotub Air Currents [Re: Tmethyl]
#21690744 - 05/17/15 02:12 PM (9 years, 7 months ago) |
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-------------------- Organized people are just to lazy to search for their stuff...
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Fog1
Apprentice


Registered: 04/04/15
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Re: Themodynamic Analysis of Monotub Air Currents [Re: Dekozn]
#21748443 - 06/01/15 01:13 PM (9 years, 7 months ago) |
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Just so much freaking information...
I am trying to figure out a how to on a mono and there are so many different ideas and ways....
Great writeup GR...
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GreenRabbit
Plutonium Pollinator



Registered: 04/28/13
Posts: 2,667
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Re: Themodynamic Analysis of Monotub Air Currents [Re: Fog1]
#21748841 - 06/01/15 02:33 PM (9 years, 7 months ago) |
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Yea it did end up being quite long..
One thing I want to mention at this point is that rectangular holes are a bitch to stuff with polyfill. It doesn't get in the corners very well so I would recommend long elliptical holes. But if you have a hole saw just use that...
Also, don't make holes too low, keep them above 4 inches so you can have a 2-3" substrate in there.
Actually, my next idea is to make 6" high subs but keep them 2-4" thinner than the tub, so it would not cover the bottom at all. Just something I want to try.Side pins like a mother-fucker...
Edited by GreenRabbit (08/04/15 12:19 AM)
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NRustler
Amorphous Noob



Registered: 07/02/15
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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22040143 - 08/03/15 10:59 PM (9 years, 5 months ago) |
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Sorry for jumping onto this thread so late, but I'm curious if changing the rectangular openings that are so hard to stuff with polyfil with a row of smaller holes might achieve the same results you were aiming to achieve. I know you were wanting to avoid using a hole-saw, but for those with access to one I think the following might work:

Four 2-in. diameter holes equals the area of one 4-in. diameter hole and they put the exiting air low to substrate, which I think has merit. Unless there there are serious issues I'm overlooking, I might try something along these lines.
Great analysis by the way, thanks for all the hard work.
NRustler
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GreenRabbit
Plutonium Pollinator



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Re: Themodynamic Analysis of Monotub Air Currents [Re: NRustler]
#22040335 - 08/04/15 12:17 AM (9 years, 5 months ago) |
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Even though your surface area is the same, it might be harder for air to flow through the smaller holes still, since air will flow faster in the center. I would expect faster airflow through the larger hole even with equivalent surface area due to the friction from the walls of the holes. (Your overall circumference is higher, therefore more surface friction.) Of course, this can all be balanced by properly stuffing the holes, so for that reason I would prefer having less holes to stuff.
To make my most recent minimono, I used a 4" diameter metal can like people around here have mentioned, except I bent the can so that the hole was in the shape of an eye. (I'll add a pic soon)
The eye shape allows for a lower air exit point compared to the round circle. The max air velocity is still in the middle, but you are able to place the entire hole an inch lower.
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insanemike

Registered: 02/23/14
Posts: 4,272
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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22040538 - 08/04/15 02:38 AM (9 years, 5 months ago) |
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Nice write up. I will definitely give this a more thorough read when I have a few minutes.
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NRustler
Amorphous Noob



Registered: 07/02/15
Posts: 23
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Re: Themodynamic Analysis of Monotub Air Currents [Re: insanemike]
#22042458 - 08/04/15 02:43 PM (9 years, 5 months ago) |
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Quote:
Even though your surface area is the same, it might be harder for air to flow through the smaller holes still, since air will flow faster in the center. I would expect faster airflow through the larger hole even with equivalent surface area due to the friction from the walls of the holes. (Your overall circumference is higher, therefore more surface friction.)
It's always something ... Thanks for pointing out the increased circumference/area ratio. My combined circumference would be double a single hole of the same area, whereas the perimeter of your rectangular hole was only about 31% greater (I'll wait until you post pics before taking the integral to find the circumference of the ellipse ).
Edited by GreenRabbit (08/04/15 02:57 PM)
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GreenRabbit
Plutonium Pollinator



Registered: 04/28/13
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Re: Themodynamic Analysis of Monotub Air Currents [Re: NRustler]
#22042521 - 08/04/15 02:58 PM (9 years, 5 months ago) |
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lol sorry didn't mean to edit your post. I switched it back, no edit has been made...
Perimeter of the ellipse is the same. I used a bent can, so it is using the same length of can that makes the circle, just in a different shape.
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NRustler
Amorphous Noob



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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22042717 - 08/04/15 03:41 PM (9 years, 5 months ago) |
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No worries - I wasn't at my computer to even notice, lol. You're right about the circumference of the ellipse; I was just joking about needing to take an integral (and not a very friendly integral, at that) to find the circumference of an ellipse. I'd actually forgotten that, but I'm sure I saw it in a calculus class long, long ago. Based on the thoroughness of your air flow analysis I'm guessing you saw a semester or two (or three or four...) of calculus and beyond at some point in time.
-------------------- NRustler
GATCAATGAGGTGGACACCAGAGGCGGGGACTTGTAAATAACACTGGGCTGTAGGAGTG
ATGGGGTTCACCTCTAATTCTAAGATGGCTAGATAATGCATCTTTCAGGGTTGTGCTTCTA
et cetera
et cetera
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yrninja
Stranger
Registered: 02/03/15
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Re: Themodynamic Analysis of Monotub Air Currents [Re: NRustler]
#22182967 - 09/03/15 12:56 PM (9 years, 4 months ago) |
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thank you for this write up. i'll have to re-read this again but still learned something through my first read
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GreenRabbit
Plutonium Pollinator



Registered: 04/28/13
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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22826725 - 01/26/16 01:08 PM (8 years, 11 months ago) |
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Added Pressure and Temperature sections and made corrections to other sections.
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insanemike
Registered: 02/23/14
Posts: 4,272
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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22828738 - 01/26/16 10:07 PM (8 years, 11 months ago) |
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I have to say, you really put a lot of hard work into this. This thread is very well organized and easy to follow. Your research and explanations of each dynamic are impeccable. Keep up the awesome work that you are doing.
Have you tested air quality yet?
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GreenRabbit
Plutonium Pollinator



Registered: 04/28/13
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Re: Themodynamic Analysis of Monotub Air Currents [Re: insanemike]
#22832014 - 01/27/16 08:38 PM (8 years, 11 months ago) |
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Quote:
insanemike said: Have you tested air quality yet?
You mean humidity? No. Analog hygros are the best way to do that, haven't ran a monotub in a while. Got jars on the way though, I'll add more pictures when that gets going.
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insanemike
Registered: 02/23/14
Posts: 4,272
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Re: Themodynamic Analysis of Monotub Air Currents [Re: GreenRabbit]
#22832062 - 01/27/16 08:53 PM (8 years, 11 months ago) |
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No. Not humidity. I'm talking ppm oxygen and co2 levels. I'm talking cellular respiration. The idea of the perfect monotub would be to get as close to atmospheric oxygen levels without drying out the growing chamber. Or to just know at what levels a typical monotub sustains and how these levels change hour by hour, day by day and over the course of the monotub run.
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eatyualive
Eat's You Alive :)



Registered: 08/17/01
Posts: 19,026
Loc: In Your Head
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Re: Themodynamic Analysis of Monotub Air Currents [Re: insanemike]
#22832366 - 01/27/16 10:13 PM (8 years, 11 months ago) |
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GreenRabbit
Plutonium Pollinator



Registered: 04/28/13
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Re: Themodynamic Analysis of Monotub Air Currents [Re: insanemike]
#22848036 - 01/31/16 07:54 PM (8 years, 11 months ago) |
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Quote:
insanemike said: No. Not humidity. I'm talking ppm oxygen and co2 levels. I'm talking cellular respiration. The idea of the perfect monotub would be to get as close to atmospheric oxygen levels without drying out the growing chamber. Or to just know at what levels a typical monotub sustains and how these levels change hour by hour, day by day and over the course of the monotub run.
Well, I would love to be able to test that, but I have no equipment for testing air quality, and I'm guessing separate detectors would be needed for each molecule. That, or a Gas Chromatography machine, which I don't have access to, and they cost about $7000 soo.. Best advice I can offer as far as air quality goes is to have as much FAE as possible (and fresh ambient air), just don't let your sub dry out. Some of the large grow rooms I have seen would have stale ambient air, but most of them have some sort of ventilation and filtration system to deal with that. For a small time grower, opening a window once a day would be fine.
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cronicr


Registered: 08/07/11
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Loc: Van Isle
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Re: Themodynamic Analysis of Monotub Air Currents (moved) [Re: GreenRabbit]
#22921698 - 02/19/16 12:17 AM (8 years, 10 months ago) |
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This thread was moved from the user's journal.
Reason:
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MajorDick
notbeingadick


Registered: 10/14/06
Posts: 1,202
Loc: Westchestertonfieldville,...
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Re: Themodynamic Analysis of Monotub Air Currents (moved) [Re: cronicr]
#22921728 - 02/19/16 12:36 AM (8 years, 10 months ago) |
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Wooooow. Nice write up.
I was thinking about rectangles too. But using ironed poly filters. Figured it would be easy to dial in by simply changing the amount the hole (slot?) is blocked with an over lapping solid door-type-thing.
Thoughts?
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GreenRabbit
Plutonium Pollinator



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Re: Themodynamic Analysis of Monotub Air Currents (moved) [Re: MajorDick]
#22921742 - 02/19/16 12:44 AM (8 years, 10 months ago) |
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You could do that.. I would recommend against rectangles though after trying them. They make stuffing the holes annoying; the corners are hard to get right.
I much prefer an eye shaped hole. Take the can you would use to make the normal round hole, and bend it into a eye shape. This will give you the lower vertical center, and is much easier to stuff evenly with polyfill. Honestly though, I doubt there is a difference between this and the standard monotub tech.
This write-up isn't meant to promote new ideas. It is a mathematical analysis and the main purpose was to refute the idea of air going in one way out the other.
However, the conclusion was that air will go in either direction, the main deciding factor being how much water is in the substrate.
If there is enough heat and humidity, air will go in through the bottom holes and out the top holes. If the tub dries out though, and the air is allowed to build CO2 without the addition of water vapor, density will increase the flow will reverse. In through top holes, out through bottom.
And as mention in the OP, if there is no stuffing in the top holes at all, this entire analysis means nothing to that specific system. Due to this, I prefer to have monotubs with minimal stuffing in the top holes, and I never have a monotub with empty top holes.
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MajorDick
notbeingadick


Registered: 10/14/06
Posts: 1,202
Loc: Westchestertonfieldville,...
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Re: Themodynamic Analysis of Monotub Air Currents (moved) [Re: GreenRabbit]
#22921755 - 02/19/16 12:52 AM (8 years, 10 months ago) |
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I think you sum it up pretty good by calling it an "air mixing chamber"
The idea with the flat ironed poly filters is too eliminate the need for stuffing all together. No reason it can't be put over any shape hole... Or array of holes....
You've really laid good ground work for experimentation and development.
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