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Originally Posted by pdf27
This is the bit that confuses me. If I understand correctly, you're using the cooling fluid from the system to pre-heat the air. This warmer air then cools some fluid - and this is where I get confused. What are you doing with the cooled fluid?
Also, I think the "low humidity" part is a bit of a red herring as far as cooling goes. The net heat you are dumping to atmosphere will basically be the mass flow rate of water multiplied by the latent heat of evaporation of the water (about 2.5 MJ/Kg at room temperature). The potential efficiency improvement in this system is that you will be able to dump more heat per unit volume of air, as warmer air is able to carry more water. There will be a pretty insignificant change in the total water consumption (a quick look at my steam tables suggests that the latent heat of evaporation of water decreases as temperature increases).
Was going to post more, but too tired...
Let us know if it works - sounds an interesting concept  |
Wow thanks for the replies! Sorry I haven't replied, I tore down my rig in anticipation (no tubing yet
) anyway - I've been rewiring, reformatting etc.
Ok, firstly let me say again, this idea was patented by a German company, and apparently it is very effective. Things to use for more indepth info would be to Google "2 stage evaporative cooler" "direct/indirect" etc.
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Originally Posted by lolito_fr
I think you may be missing something. As evaporation by itself can't bring air (or water) below dew point, aren't you going to need a phase change unit (dehumidifier basically) to pre-dry the air?
As I see it, this is what you are trying to do with the first coil in pipe #1. But the water in this pipe is only cooled by evaporation, so it won't be cold enough (IMHO) to allow any condensation to happen.
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The stage #1 isn't really to condense the air, as in a dehumidifier. It's just using some free thermal energy to precool the liquid somewhat. Basically the first tube is what everyone using closed loop watercooled systems with radiators has. Ambient (if lucky) to warm (or even hot in some cases - pun intended) air blowing across a radiator/heater core. Now imagine if you will that same radiator inside a shroud covered by wet pads. Now add a light flow of water across the surface of the radiator it's self. Now if we were only cooling the air - we could put another wet pad and let the cooled air leave the shroud through it. It should be below wet bulb. So what they are doing is using a heat exchanger, then an evaporative cooler. Both of these are potentially very energy efficient as you know so they don't really require high speed fans or pelts or compressors. But they also don't reach the extreme temps, either.
As for the 2 stage,
Here is a picture illustrating the basic unit they manufacture.
And again
I realize this has more than likely been kicked around and I
seriously doubt I have stumbled across anything new.....but it makes sense to me and while a cooling tower is really efficient at cooling, there's so much humidity not to mention water loss.
I'm simply trying to combine a heat exchanger and cooling tower
and evaporative cooler lol into one little package. :shrug:
The 1st solid idea I had was described in my 1st post. In a sense it was like taking approx. 20' of 1/2" copper tubing, and about a foot from each end start bending the copper into tight coils (that would fit inside a 4" pipe) until you have two coils - connected with a few inches between them. Place both of these into 2 seperate tubes and on the 1st mount a fan blowing air through. There would have to be a crossover path for the air as I mentioned, and the air would cross into the 2nd tube & blow upward where it would pass through a wetted mat. Immediately after it would encounter the 2nd coil (which has water flowing lightly down it btw) and out past the coil & "drip pan."
This is a (very) crude picture of my 1st idea.
Of course the blue=water - red & light blue=air flow - light gray=case - gray-fan - dark gray=main system pump.
I've since changed the plan because I want to put the entire thing into my case.
(Right now I have nothing on my PC, I really want to put in 3dmax and think about it a little more before I cut any thing, so unfortunately all I have is paint tonight lol.)
First some misc. stuff I've found. I bet you guys already have all this...
If I remember most homes have a RH% lower than 30% (w/ HVAC) and my home stays @ 72*f which puts it off of that chart if it is at all accurate.
An illustration of a simple heat exchanger:
High quality examples of commercial exchangers:
Here is a very primitive sketch of my latest brain "storming" lol. I will try to further explain so some of you more informed/experienced/educated/all the above can give input(?)
Damn I've written an essay!
Ok...some of this self-explanatory but anyway here' goes:
1.) fan - exhausted air
2.)drip pan (pan with holes for water to drip through (*note* showerhead not necessary, water doesn't have to be "fine")
3.)a water block
lol
4.)1/2" tubing (preferably no 90* unlike sketch)
5.)These have an actual "name" though I don't know it. Let's call them air deflectors.
I'm pretty sure their placement is important on air flow....
6.)1/2" tubing
7.)Wet mat
8.)Air vents/holes/openings whatever for hot air intake inside case
9.)catch pan (w/ overflow btw) water drips from top through holes and into heat exchanger, onto wet mat material, whatevers left falls here and runs off back into loop.
10.)1/4" pipe or tubing (I worry that this will be a problem because it controls overflow and can be easily fouled - "crudded up") this tubing runs from a refillable resevoir outside of case and needs only a really small aquarium pump. I want just a steady stream of water....
11.)Main pump (DannerMag 3 in my case)(yes, pun intended lol)
12.)main system (closed loop) resevoir.
Ok now I think that's probably enough breaking of the laws of grammar & physics for one night.
Hopefully my material will be here soon, though now I'm thinking it's too big for something like above. :shrug:
Yes I will continue to take pictures along the way and document all I can. I am excited to start.
~Robert