The evaporative tower water cooling for pc


Work in progress, some things can't be said are propely english :P

As many other interent stories everything started while googling around. I was looking at some of those uber overclocked computers and I though "Yeah sweet, but how much it is noisy!". Problem of overclocked computers is that if you are not one of those very rich guys around that can buy hi technology advanced systems like compressor coolers, azotum thingis and those stravagances, you are stick to buy a HUGE fan, that is rather noisy and transform your pc in a home radiator.

I allready have problems with my pc beeing too hot and noisy, I can't sleep with it turend on. I wanted really to fix this, because running some servicies like httpd and ftpd can be useful for some of your friends. So I looked around for something that can cool a lot, cost a few and was discrete.

The answer just stumbled to my feets. An evaporative tower. Those things are used nowdays to cool down the nucleus of nuclear plants and are quite effective if you can provvide enougth water. For a nuclear plant, it's easy, just build it near a river, for a homemade system it revealed more triky...

You can now think that those are silent, water slowly flow near the thing to cold and stop. Yeah ok, if you have a river in your home. Problem is that we need to design a closed system that stock the water in some reservoir, let it cool down, and then reuse it. This means you don't need anymore a continuos flow of water but you can use what is in your reservoir. Yeah you will consume it in the process, but why?

The answer is easy, water evaporates. It allways evaporates even at negative temperatures (Celsius grades) what the themperatute change is how much water evaporats in a given time. It allwasy evaporated because what count is the difference of quatity of water in the air and in the water itself. Air can hold a certain amount of water, that's the perchentage they give when you look weather bulletin or that you hear around during summer when they talk about "percived temperature". When air has 100% of water no more water will evaporate. We will not focus on what happends in extreme condition, since those rules are not perfectly valid allways, what they give is a really good idea of what happends.

So why water evaporation should be benefical to us? Another easy answer, evaporation is an endotermic process, that mean that to evaporate water need energy and it takes it from the water itself, making so it a little bit colder. So more water evaporates more heat it bring away both in the form of hot vapor and in the form of energy necessary to change it state from water to vapor.

We discovered that water need to be in contact with air, so air can bring away some of it, so we can guess that more surface of the water we put in contact with air, more water it will bring away. To augment the surface we can provvide or a big static exchange surface or... What happends when you take a hot shower in your bathroom? After some minutes the air fill up with vapor!! The air has bringed away lot of water. We can use a shower head!

Mmm a problem from before come to my mind... We wanted a silent system and when you take a shower it's not exactly so quiet. Now go in your bathroom and open the water, it makes that damn noise... But what if you put hands under it and gently let the water flow down. It's quite! WOW! So we just need to find a way to gently acompain the water that comes out from the shower head to the underlying reservoir and the joke is done.

Getting the necessary material

What we need is:

My first idea to get that material was to go to some big bricolage center we have here in Italy. They are rather expensive but many things can be found easily and bought immediately.

I headed immediately to "Brico" one of such big places, just outside the city and I got the shower head for 10 euros, a WC tube as reservoir with some "mods" to make it longer, closed on one side and Y shape. Those type of reservoir was expensive since each small "mod" had fixed price of 9.99 euros and the big "mod" had price of 19.99 for a total of 50 euros. I bought a "super long tube extension" that make the reservoir more than 1 meter tall, geeez that was cool!

The fan was another easy get, but I was luck to find one so nice! And so cheap! I bought it in a small independent shop inside the complex of the "Brico" center 4.99 euros!! I bought some to stock...

For the pump I gone in an animals shop, they for sure sell pumps for aquarium and such. I entred in the shop and asked for a pump. "How many liters is your aquarium?" - " I don't have an aquarium!" - "So, do your aquarium allready have a biological filter?" - "Hey, you deaf! I have no aquarium! I need that pump for cooling my pc" - "So you don't have a filter, do you want one included with the pump?" - "H E A R M E: show me the pumps you have and I will choose alone". I choose a pump with no filter, hoping to be able to change the whole water of my reservoir often, it costed me 29.99 euros (all those stupid prices..). It has 1500 liters/hour and a good prevalence diagram nice thing is that it's very silent, during nigth you can barely hear it if you less than 1 meter from it, farter it's just too silent.

NOTE: What is a prevalence diagram? A pump is not just a thing that move an ammount of water from one place to another, the method used to move the water is quite important. Leaving out noise levels for now, since all the pumps we can use in this case are more or less few noisy, the most used method to archive high loads of water wihtout having a bad prevalence is using "rotating fan" that ""compress"" the water (terrible thing to say, really, but gives the idea to "no science mans"). But what happends if it meet some form of resistance? You can for example put your finger and tap the out tube or you can have to pump the water from the bottom of the valley to the top of a mountain! We can now think that the pump will have some more stress if the water have to go in a place higher from where it is now. So the flow of water will decrease along with how much "resistance" the water have during it's travel. Those include both height (due to gravity) and pressure drops (due to high turns or obstructions). Common aquarium pumps have normally a linear proportional law, so we can expect half of the flow at a delta H (height difference from pump level and water exit level) that is half of the maximum. This anyway can change totally from one pump to other (your common bike tires pump indeed have a total different law).

For rubber tubes and anything related to rubber I luckly have not far from my home a nice place called "Moroni Gomma" they sell any type of rubber, gum or related things (phonoabsorbers...)

Now the real problem, where to buy a bar of copper to build the water block? On the net all americans just say "I gone to local hardware shop...", what the heck is an hardware shop!? I'm a poor italian! Here we buy anything allready built and they bring it to your home directly too. Where to buy copper in a not industrial quantity? Luck is a thing did not missed. I was looking for some laboraroty that let me use their instruments (perofessional turret drill, solder...) and I noticed, no farther than 50 meters away from my home, such a looking place named "Garavaglia", so I steped in ask asked. They pointed me to another near shop they call "The drugstore", because the propietor sell metal as it was candy and they advided me that candies can be expensive. After 5 minutes of walking i reached this other place, no insigna, no big entrance just a common shop door with a small showing of some old metal pices like an old metal "alladin" style lamp. I steped in.

Once in the place it immediatly looked strange, it was a small room with metal everywhere, iron, alluminum, pipes and another lot of disordered stocked things. The shop dealer was a nice 70-years old granny, that asked me: "What thou neeed, young brave guy?", after some step back I firmly answered "Copper!" she replied "So you seeeking for The Coopper.. eheheh", now I was convinced that this palce cannot be true and that this was all a dream so I took courage and gone near the granny showing my scatch about the water block, explaining the dimensions of the piece I needed, she for a moment looked me intensly and then gently stated "Follow meeee" before disapperaing back to a small door. Following her sentence I took the door too. Woah! Impressive we was in a really huge space 4 store high and say really wide! Metal was again everywhere, imprssive quantites of it! Long bars, tubes and blocks!!! Of every color and of every form! She was wating for me and as I gone near her she started to walk again. We reached a set of shelves, every level had different sizes of copper bars, she searched my dimension and took out from the shelf a 2 mether long copper bar, and passed it to me! As I took it I risked to make it fall to ground, Hey that was heavy!!! And the granny managed it as it was a feather.. it was 16Kg!! After cutting it she sold me that 4Kg bar of copper for 60 euros!!! That's a lot.. luck for us we use a few of it, since we can get 10 blocks from it, it's only 6 euros each. Affontable.

NOTE: The copper was raw and not top quality, Later on working on it I discovered it was a bit "mangled" internaly, full of internal tensions and so very hard to work propely. Luck for me I have studied metals at university course and I can state that quality of copper does really a few difference in heat transfers, since higly pure copper is easly reached with an inexpensive process, so the purity difference from a bad copper and the best impurities-free copper is probbaly much less than 5%, we can aproximate heat transefer of 2 mixed materials as the weigthed media (based on quantities) of the two.

The palce is a family run shop, the father get the cash and the son talk to clients, they have 2 employeers that are "jack of all trades", they normaly deal (build and repair) faucets so have great confidency with metal and water. I showed them my water block scatch and after some explaining to the "jack" guy he firmly stated "Easy, we can do that!" so I had just found someone that will do the work for me! I mean, yes I'm good to drill things, but this guy drill things all the day and he build faucets that are _not_ supposed to lose a single drop of water so if this guy help me with my water block it will be 100% safe!! Really a sure deal.
The copper bar The copper pipes Work tools The fan
Bathroom testing Some testing in the bathroom The system in action The system in action
A nice closeup System look duting nigth The copper bar Without the shower head
At night Shower head closeup Shower head closeup Shower head closeup
Shower head closeup The glass to lap the wb Scientific termometers to misure the efficency Scientific termometers to misure the efficency
Lapping paper Anti-noise system The water block The water block lapping side
The other side of the water block Water block, closeup Water block, closeup Water block, closeup
Pipe blocking system Tube/pipe attachs The lapping paper
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