My cooling set up...

[Random Nonsense]

Hi guys.... bought all the ingredients for an evaporator tower today.... pump is 750 litres per hour..... i thought it would be plenty but flow doesnt look good even when at just over half rated lift..... it pumps 2 litres in 45 seconds at about 90 CM above water level.... i think i need more but then i came up with an idea.... if i have high airflow through the tower.... it will be the equivilent of making a bigger drop! so im thinking about a 30 inch lift, with say 90 CFM flow through the tower?

How does that sound?

[Áedán]

Originally posted by Random Nonsense
Hi guys.... bought all the ingredients for an evaporator tower today.... pump is 750 litres per hour..... i thought it would be plenty but flow doesnt look good even when at just over half rated lift..... it pumps 2 litres in 45 seconds at about 90 CM above water level.... i think i need more but then i came up with an idea.... if i have high airflow through the tower.... it will be the equivilent of making a bigger drop! so im thinking about a 30 inch lift, with say 90 CFM flow through the tower?

How does that sound?

2 litres in 45 seconds with a 90cm lift? That's 160lph. As you're talking 30inch (76.2cm) lift, you should see more throughput, assuming your piping isn't causing restrictions.

The biggest problem with higher airflow is that more water will be blown out the top of the tower. At a certain point, you'll find that the airflow overcomes gravity, and most of your water travels upwards instead of downwards...

AidanII

[Random Nonsense]

Yeh i know! its WAY under its rated flow! and thats WITHOUT a showerhead! ARGH! i think i'll take it back and spend the £10 extra for 1000 litres per hour

[Áedán]

Originally posted by Random Nonsense
Yeh i know! its WAY under its rated flow! and thats WITHOUT a showerhead! ARGH! i think i'll take it back and spend the £10 extra for 1000 litres per hour

There's two factors to deciding which pump you want. There's the throughput, pretty obviously indicating how fast the pump can pump water. Then there's the pressure that the pump can generate. If the 1000lph pump generates the same pressure, then it'll run out of steam in exactly the same way!

The flow rate indicated will be pretty unachievable if you have any lift, and if you use any piping. Most of the aquarium type pumps are not designed to operate into much of a lift, as the typical aquarium/pond doesn't have much of a lift! You need to find out how the pump will operate into the lift you require - some manufacturers will provide graphs you can read flow/back pressure off. Kaitain's probably got more of a feel for this than myself!

When I finally get round to building my cooling system, I'm going to attempt a completely closed loop system. That way I don't have to worry about lift, instead only worrying about the internal flow resistance!

AidanII

[Random Nonsense]

well it can lift to 1.3 metres.... so i was expecting a lower flow rate at 90CM but this was kinda silly! im sure it will work though, and if it wont i'll take it back and get my money back

[dimmreaper]

A diaphragm pump would be much better suited to the task IMHO. I've got an old diaphragm pump out of a respirator in my "lab", and with a few modifications to the valving system it pumps water great, with lots and lots of head and up to 18PSI. Big downside is that it's quite loud for everyday use, probably around 55-60dba.

[Random Nonsense]

and it would pulsate dimm.... i REALLY dont want that with direct to die water.... pressure waves could blow the block off the CPU.... not good

[dimmreaper]

Originally posted by Random Nonsense
and it would pulsate dimm.... i REALLY dont want that with direct to die water.... pressure waves could blow the block off the CPU.... not good

Not really, the pump has a 1/4HP 4500RPM electric motor, and a real small stroke on the crank. It pulsates, but 75 times a second. Pressure waves wouldn't be intense enough to hurt anything. I'd be more consernded about having a sufficient route for water to exit the block with the 18PSI of possible static pressure.

[Colin]

FWIW, the Mag 7 I use does about 1/2 gallon per minute going through the old Maze 2.2 and a 69" bong cooler.

[irsquirt]

One thing you could try is to copy part of the design of industrial cooling towers.

Normally there is a "pack" in the middle of the tower which normally consists of plastic beads or rings or something similar (with lots of holes in). The water falls from the nozzles onto the pack, runs over that & then falls into the reservoir.

The idea is that it reduces noise splash noise (because the water isn't falling into the reservoir from the same height) and improves efficiency because there is more surface area for the evaporation to take place on.

If you glued a piece of plastic filter into the cooler you could put whatever kind of pack you wanted on top.

Because its running more efficiently, you could drop the airflow and still get the same cooling effect.

Another point is that you won't need a shower head - the evaporation now takes place on the pack, so getting a fine spray isn't important. How about putting some microbore greenhouse hose on top of the pack & feeding the water through that?

[Kaitain]

Hi guys.... bought all the ingredients for an evaporator tower today.... pump is 750 litres per hour..... i thought it would be plenty but flow doesnt look good even when at just over half rated lift..... it pumps 2 litres in 45 seconds at about 90 CM above water level.... i think i need more but then i came up with an idea.... if i have high airflow through the tower.... it will be the equivilent of making a bigger drop! so im thinking about a 30 inch lift, with say 90 CFM flow through the tower?

Erk! Erm, I think I know what's going on...

What I think you've got is a centrifugal pump. These pumps have high flowrates and can generate quite reasonable head pressure. Quite resistant to having crud in the water, too.

To use a centrifugal pump, you ideally want it to be the lowest point in your water circuit: these pumps cannot suck water - it just cavitates and knackers the inside of your pump. When they give a rated lift, it's the head pressure at the outlet. I'm guessing that you've put the pump at the top of a lift, and are expecting it to lift water from a reservoir 90cm below.

Swap it round so that it's on a level with (or even below) your reservoir, and you should start to see a bit better flowrate. Centrifugal pumps operate most efficiently with no reservoir pressure, pushing against a back pressure. In terms of pressure vs flow, they are most efficient at somewhere between 60% - 75% of their design spec.

If it's already at the lowest point in your circuit, then your pump's malfunctioning.

If you need it to suck the water up 90cm, you have the wrong type of pump - for that you'll be better with either a reciprocating pump (piston-type pump) or a diaphragm pump. Both are, unfortunately, noisy.

[Random Nonsense]

its all sorted, kaitain i got it as low as i can, i was aware of centrifugal pump probs...... its all fine now! i think maybe the pump wasnt really "bedded in" as it were... now its fine! got a couple pics below!

I tested it in bath, as i dont have any hose barbs yet to attach the pump to the reservoir..... it cools pretty well even without any airflow! water was warm to touch and spilled out of the tower where the fan should be, MUCH cooler

[Random Nonsense]

and another

[Áedán]

Originally posted by Random Nonsense
I tested it in bath, as i dont have any hose barbs yet to attach the pump to the reservoir..... it cools pretty well even without any airflow! water was warm to touch and spilled out of the tower where the fan should be, MUCH cooler

Man, you REALLY need to get that bathroom finished! Stop playing with the cooling tower and slap some paint up there!

AidanII

[Random Nonsense]

Originally posted by AidanII


Man, you REALLY need to get that bathroom finished! Stop playing with the cooling tower and slap some paint up there!

AidanII

hehehe i aint in charge of stuff like that! its my dad's job... 10 years and counting for the bathroom!

[Kaitain]

Looks good (all except for the bathroom decor ).

Just thought that you may have had an air bubble in the pump. Centrifugal pumps shouldn't have to be primed, but invariably do! It probably went away of its own accord

Quick ideas on the design of your tower:

* For that diameter tube, 30" should provide a fairly reasonable updraught once the water temperature reaches its highest, so you may not need much forced airflow.

* Industrial scale cooling towers have a wooden trellis/scaffold inside them. This is to increase the surface area of the water in contact with the air (it's all about mixing ). You might find setting up a little trellis inside your tube really useful.

Looks like a fun experiment

[Random Nonsense]

i'll see how it performs as is.... with a fan.... with a trellis.... and maybe with a platform holding a load of beads or something

[Random Nonsense]

i may be using a quad pelt set up..... 4 pelts on one giant coldplate, or 2 stacks of 2 on a giant cold plate.... if i did this i'd also get a DD super cube to help the tower as i think 4 72 watt pelts would overload it. I would go with bigger pelts but they are a pain to power.

as to waterblock/waterblocks i assume DD maze 2 is still the mutts nuts? thing is how the hell could i attach 4 onto the "hotplate" i'll be using on the pelts? AS epoxy? as i dont think i can clamp them very easily on a copper plate that size

[mrpcman]

Originally posted by Random Nonsense
i may be using a quad pelt set up..... 4 pelts on one giant coldplate, or 2 stacks of 2 on a giant cold plate.... if i did this i'd also get a DD super cube to help the tower as i think 4 72 watt pelts would overload it. I would go with bigger pelts but they are a pain to power.

as to waterblock/waterblocks i assume DD maze 2 is still the mutts nuts? thing is how the hell could i attach 4 onto the "hotplate" i'll be using on the pelts? AS epoxy? as i dont think i can clamp them very easily on a copper plate that size

I have the maze 2-2 with a coldplate built in capable of handling two peliters. It's pretty sweet.

[dimmreaper]

Stacking peltiers with equal Qmaxes is not just stupid, it's dangerous. The second peltier in the stage needs to be at least 2.5 times as large to even work without endangering the CPU to hellish temperatures. Having the second peltier in the stage offer 3-4 times the Qmax is preferable. I could go it to the long boring details of this, but basically this must be so because the second TEC not only removes the heat pumped by the first TEC, but also the heat generated from the first TEC using electricity.

Staging TECs when done properly can offer huge DeltaT's, but it is extremely inefficient, especially under the type of load a CPU generates. Concentrate on increasing the Qmax of a single stage configuration, this will Increase the real world DeltaT(the "DeltaT" figure the TEC manufacturers supply you with is a zero load DeltaT).