Advice on water cooled PC *spawn*

[Mize]

So B heats up the air enough that it doesn't do much over A. This is why air velocity is more important - faster moving air means cooler air in contact with the radiator fins.

AFAIK, stacked HSF designs are to increase air velocity with minimal noise increase. If you can create a stacked radiator that results in higher airflow through both radiators you have a winner, but air pressure is a bit different with high-fin-density radiators compared to the relatively low density of HSFs. Stacked radiators would be equivalent to just a much thicker radiator, thermodynamically, so you just need fans that can create enough pressure to get high airflow through the double radiator.

 

[lanek]

Martin have do all the tests, and they cant be contested .. 2 rads sandwiched,thisis a no go .. I think he have test absoluletely all the configuration possible for it, but the result of the tests are clear.. no
way, this dont work.... the air exchange of the first rad used in the second rad is like use higher temp for entry the rad, result the water temp is higher, and the system will equilibrate it, resulting in an higher temperature of the water on final..

For make it work you will need a negative delta T between the water and air on the rad number 1 ...

 

[Grall]

If you arrange the fans and hoses like I mentioned it's not possible for temps to go higher than when using just one radiator. At worst it'd be exactly the same, but as total radiator surface area is larger and there's additional air turbulence involved that reduces laminar flow (which is bad in a cooler), I'd think there'd be at least a slight difference. Maybe not a cost-effective difference, but it should at least be there. Your Martin buddy must have screwed something up, it's the only explanation.

 

[Mize]

If you arrange the fans and hoses like I mentioned it's not possible for temps to go higher than when using just one radiator. At worst it'd be exactly the same, but as total radiator surface area is larger and there's additional air turbulence involved that reduces laminar flow (which is bad in a cooler), I'd think there'd be at least a slight difference. Maybe not a cost-effective difference, but it should at least be there. Your Martin buddy must have screwed something up, it's the only explanation.

Uh, sorry Grall, but you're incorrect.
You're assuming that the fans can move air through two radiators at a comparable velocity as through one. This simply isn't true. Radiators are fare more constrictive than HSFs and all that turbulence you mention - which is generally good - creates back-pressure that greatly reduces the flow created by fans.

I can't emphasize airflow enough here.

We can all agree that a radiator in a vacuum is near useless other than dissipating a small amount of heat through IR radiation (no air to which it can transfer the heat).

I think we can also all agree that air that is the same temperature as the water serves no use either.

Now let's talk about moving air at a lower temperature. The rate at which heat can be dumped from the radiator into the air is determined, in part, by the temperature difference between the water and the air. This difference is essentially a thermal gradient much like a hill - heat "rolls down the hill" to the colder side. The warmer my air is, the slower the heat transfer.

Anything that increases the dormancy of the air inside the radiator will decrease the rate at which heat is transfered because the air becomes hotter.

So if you want to double the thickness of your radiator or double the fin density or put two radiators together then you'd better switch your fans for those that can produce dramatically higher pressure such that the dormancy doesn't change.

 

[Grall]

All factors would have to be reasonably similar of course or any comparison becomes meaningless. That includes airflow, etc. I assumed you guys were with me on this.

Btw, if one was to stack rads, I'd want fans sandwiched in the middle as well as fans taking in air on top of the stack. High static pressure units, of course...

 

[Mize]

Well things just got a lot noisier then

 

[aaronspink]

All factors would have to be reasonably similar of course or any comparison becomes meaningless. That includes airflow, etc. I assumed you guys were with me on this.

Btw, if one was to stack rads, I'd want fans sandwiched in the middle as well as fans taking in air on top of the stack. High static pressure units, of course...

Stacked radiators MIGHT work if you were using some of the "quiet" rad designs, but then you would probably be better off just buying one of the normal rad designs in that case. Basically, HWLabs already makes 3 different lines of radiators that pretty much satisfy all your possible needs.