Radiator (AirFlow) Resistance Article

[Omega65]

Overclockers.com: Radiator (AirFlow) Resistance Article (http://www.overclockers.com/articles755/)

excerpts...

As the radiators' system resistance curves show, it takes a LOT of pressure to get a LOT of airflow through these radiators. Mounting a 92 cfm fan on a radiator does not mean you'll get anywhere near 92 cfm through it - more like 50-60%.
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CONCLUSIONS

One aspect of picking a radiator for a watercooling system is the amount of airflow through it. The "denser" the radiator, the less air gets through. In addition, a radiator with a plenum for the fan is more likely to yield better flow than directly mounting a fan on its fins.

[WuGgaRoO]

i hate to sound like a newbie but...whats a plenum?

[Superducky55]

Wow, i was just wondering the same thing.

Main Entry: ple·num
Pronunciation: 'ple-n&m, 'plE-
Function: noun
b : an air-filled space in a structure; especially : one that receives air from a blower for distribution (as in a ventilation system)


Never heard of it. :D
Nice article though, good link :cool:

[mmonnin]

A funnel of some sort? So the air HAS to go thru the radiator?

[shwaip]

my guess:

The fan is elevated slightly off the radiator. In the article, the BE cooling one does not, and the fan will be mounted very close to the fins, while the other two have a slight air gap in between the fan and the fins.

[WuGgaRoO]

ooooo... that makes sense!!

[leishi85]

plenum is the same as a shroud i'm guessing

[GHoosdum]

In this case, yes it is.

[aznblueeboi]

that sounds like a shroud to me too

[muddocktor]

They are definitely talking about a shroud. Why do you think a car has a shroud around the fan? If you don't think it makes a difference, try removing the fan shroud on your car and go get in some bumper to bumper traffic and watch your temps.:D

[shwaip]

muddocktor said
They are definitely talking about a shroud. Why do you think a car has a shroud around the fan? If you don't think it makes a difference, try removing the fan shroud on your car and go get in some bumper to bumper traffic and watch your temps.:D

that's what i thought too, until i read the def. from the dictionary and this:


Then it hit me - the Swiftech and Black Ice radiators use a plenum and the BE Cooling does not - the fan was mounted right on top of its fins. This caused interference with the fan blades, thereby lessening flow compared to the other two radiators.

[muddocktor]

Same difference, they are just using a built on plenum/shroud on the Swifty and Black Ice radiators. If you look at the pic of the 3 radiators, you will notice that the sides are closed in and the mounts for the fan are raised off the surface of the fins. I guess you could say that a plenum is a built on shroud whereas a shroud is a bolt on plenum.:D

The shroud I use on my watercooled dually effectively acts the very same as the way the plenums on the Swifty and Black Ice radiators do in that it seals the area between the radiator and the fan for more effective airflow and mounts the fan away from the radiator fins for less turbulence, hense better airflow.

[MarkTAW]

In architecture, the plenum is the area above the ceiling where all the ducting and wiring goes. I know this because in a previous life I worked for a company that made industrial lighting fixtures.

Google Glossary has more accurate & thorough explanations than mine:

http://labs.google.com/glossary?q=plenum

Google Glossary is your friend. =)