PA 160 Question

[Bigredhog]

Im going to upgrade the radiator in my V2000 case to the PA 160 and I plan to run it with one fan. My gut tells me one fan should be in a pulling configuration but since the PA 160 isnt your standard off the shelf heatercore would this be my best bet? Im running a D-TeK Mag pump with a whitewater CPU block. My temps are very good but I want to put this smaller rad I have in the wifes comp. (yea she wants water cooling too LOL)

Thanks

[jaydee]

Have nothing to substantiate my opinion but I would also put it in pull position. It seems to me it is a little more efficient. Just speculation but it seems to me when it is in the push position air gets backed up and slows the fan down because of the added pressure. In the pull position air doesn't get backed up so there shouldn't be an added pressure to slow it down. Mostly just a theory though.

[Long Haired Git]

Somewhere I recall something along the lines that air flow from a fan needs 9 to 15 fan hub diameters to form even flow over the entire surface area of the radiator (shadow of the fan hub and corners and all that).
Due the fact air will come from everywhere to fill a low pressure area, then a sucking fan only needs to be only one or two fan hub diameters away for the same effect, and even a single fan hub diameter is a good 80/20 solution.
That said, most fans prefer to push against pressure rather than suck against it.
But that doesn't matter, because unless you have a Cathar-like radiator box, you won't have the room to effective use pushing fans.

[bobo5195]

Theory would suggest that it doesnt matter (air does not get backed up unless its over mach one, infact below mach 0.3 its essentially incompresible which is nice). I would just test and see.

Any kind of fan clearance would help. The primary turbulence noise from a fan is caused by the central hub support hubs interacting with the fan. Hence fans should never have an even number of blades and support struts. By putting a big radiator by a fan your distrupting its airflow and causing this smae effect with it. I think support beam fan theoretical models for dBA are included in some of the BTX information on formfactors.org.

9-15 diameters sounds awfully high to me. This sounds alot like the time it takes a flow to gain a fully developed duct profile which is not what we are after. I cant think of any good rule off the top of my head but a "common sense" guess would probably be good. At home i have a derivation of a theoretical model of turbulence for a grid that might give a good approximation i'll see what that says

More sciency explanation of the model above
its a model of the turbulence produced by a square grid accordign to the K-e viscosity turbulence model. This is the basis of alot of the models for cfd. Its fairly exact so should give a good punt guess (5% if it was an exact model of the flow) for spacing for air flow coming through the rad to the fan. Assuming that it works for the reverse case (fan to rad) is more tricky. Since the outlet profile of the fan can be guessed you could discreatise that profile for each hole and do it like that taking the maximum turbulence distance.

[Bigredhog]

I'll plan to start in a pull configuration since the PA160 fins arent as dense and airlow is not as restricted. I would think by pulling and creating lower pressure within the shroud I would get air flowing more evenly over the entire radiator surface as opposed to pushing and having my airflow basically passing through the radiator in a smaller area of the radiators surface. As long as I can maintain the temps I have now Ill be content. At the moment Im getting 5 degrees above ambient at idle and 9-11 degrees under load according to MBM on a 4800X2.

[Long Haired Git]

bobo5195, I am a regurgitator not a science dude. I also recall an angle of 15 degrees being the max for flow to spread out. Perhaps a better rule would be some derivative then of the fan radius and and the angle of 15 degrees ?

[Les]

Originally Posted by bobo5195

... I would just test and see. ....

The only data available on this site is pHaestus's(link
From this I am unable to draw any conclusion{link)

[jaydee]

Originally Posted by Les

The only data available on this site is pHaestus's(link
From this I am unable to draw any conclusion{link)

From what little that tells us it might be down to which is quieter than which performs better? Seems to me pull is quieter. Anyone else notice the same?

[Etacovda]

has someone got a ratshack db meter floating around - not overly hard to turn the fan over and take some db tests?

[bobo5195]

ah more numbers to make my head hurt. My notes on grid turbulence similarly caused to much nonsense and last night i was up to another side project.

I’m talk about distance not degrees LHG. Fan radial flow causing the angle is wasted work (i think) either way its less important as the flow will hit the wall and settle. The 10 diameters encompasses just about any entrance flow.

Those results are too close to call. From my mixed up head i would say.
1) Moving the fan away from a rad reduces noise by providing cleaner air and less interaction between the radiator and the fan. Main effect.
2) Thermodynamically it doesn’t matter which way around the fan is. The fan is still creating a pressure differential. There is a caveat that the created pressure differential is not large enough to change the properties of the fluid. Highly unlikely.
3) For push the walls of the shroud recover air pressure as it converts radial flow to axial flow, although there are losses in the gap. Clearly no shroud and a gap is nonsensical. A special case that never happens in practice as a gap and no shroud is stupid.
4) For pull the gap and shroud (no shroud and gap is again nonsensical) the gap allows air to settle providing cleaner air to the fan. As comment 4.
5) For push having the fan close to the radiator increases head losses as air still has a rotational component that is lost when it enters the rad in push configuration (all velocity components not normal to the rad are doing anything; obviously depending on the radiator design. Some recovery does occur in the rad but settleing in free air is better). Important effect similar to 4 and 5 spaces above.
6) pulling through the rad the radiator itself may act as a lamina flow guide provided turbulence caused by the grid would be dissipated this will help. Stretching reasoning a little but I think still a valid point.
7) increasing the fan distance from the grid prevents variation in output from the fan effecting the rad. For example fan output is going to be higher at the outer edges (av m/s per m^2) as the fan blades are spinning relatively faster. By having a gap fan flow is more uniform giving a better flow. Comes with 5 and essentially the same thing.
8) The shroud may damp fan noise.

In short shroud good for noise and a little performance as there is less variation in the flow and less chance of interactions between the fan and the rad. Pull better as radiator creates lamina flow for the fan. I would recommend try it and see on your own comp if possible.

[csimon]

can you post pics of the pa160 mounted inside of the v2000 please?

[nikhsub1]

According to Cathar, with the PA series rads he actually found them to perform better in push rather than pull. Link here: http://www.xtremesystems.org/forums/...12#post1081012

[BillA]

my comparative data always favored the fan pushing (with a 1/4" min shroud)
not measured for noise differences (a bit difficult)

[bobo5195]

oh well thought experiments are a load of tosh anyway. Ill go with the emperical data.

Could be something to do with air pressure and water vapour fraction n stuff but my head cant go around it for a moment. Any help? (denser air has more water vapour in it, water vapour has alot of heat capacity, so denser air is better for cooling, dense push air is better; or i am i miss remembering stuff?)

[Bigredhog]

Well I guess Im going to go with the PA 160, a DDC pump a Storm WB and a DD maze 4 on my 7800 GTX/OC to put in my V2000 case. Ill move my D-Tek mag and Pro120 rad over to the wifes comp, this setup has been keeping my 4800X2 at 5c above ambient and around 10-12c above ambient at load. My only reservation is if the DDC can perform as well with this setup. Noise wise Id rather have the DDC versus a D5 so I guess Ill give it a go and see. Any thoughts are appreciated if someone has anything to add or owns the same setup. If it doesnt cut the mustard guess there will be a DDC up for sale. Should be fun to try out and will also try the rad in both push then pull configuration to see if there are any differences. I generally run mild overclocks but would like it somewhat quiet as well.

[Bigredhog]

Originally Posted by csimon

can you post pics of the pa160 mounted inside of the v2000 please?

Here ya go http://i19.photobucket.com/albums/b161/sdkevin/RAD9.jpg

BTW this is not my computer this was just posted elsewhere.

[Marci]

[Ruiner]

It's almost cheating to fit it in a refrigerator sized case like that.

Try working on this:

Resetting the CMOS is not fun.

[Marci]

I can beat that... I've done the LianLi PC60 don't forget

[bobkoure]

Originally Posted by nikhsub1

According to Cathar, with the PA series rads he actually found them to perform better in push rather than pull.

IMHO, it's a matter of what you mean by "perform better".
FWIW, I did some trial and error with low noise fans and a (then pretty typical) 6"x6"x2" heater core and found that pull was more "efficient" in the sense of perceived-noise-for-temp-delta. The PA160 is enough different that my results mean nothing - but for the lesson that you need to qualify what exactly you mean by "efficient" or "perform better".

[Marci]

Perform as in resultant c/w as in performance. Push resulted in lower c/w than pull.

[BillA]

"but for the lesson that you need to qualify what exactly you mean by "efficient" or "perform better"."

yet you used a ear also, no ?

"Push resulted in lower c/w than pull."
my exp as well, one could include the fan mfgrs also

if the strut related noise is the greater portion, flipping it (on a shroud) contributes what ?
not saying there is no difference, just sorting through the 'fineness' of an ear managing such

[bobkoure]

Originally Posted by unregistered

yet you used a ear also, no ?

Yep - I'd been trying to make my ears happy - and only later realized that it was interesting data for other folks even though I didn't have real sound measuring gear (yes I have a sound meter - no it doesn't go nearly low enough and no I don't have an anechoic chamber - but I did do these "tests" late at night in winter with a blanket of snow on the ground, so little background noise).

I would suggest that once you have enough cooling to support whatever kind of overclocking you want (which might be no overclocking, or even underclocking - see SPCR), then you've got "enough" c/w and it's time to twiddle some other variables. For me, the next highest one is noise. For someone else it might be "absolute best c/w", cost, mounting issues, etc. ...

[BillA]

agree completely re noise
in fact for me noise predominates

[Long Haired Git]

When I realised how well my system performed with the fans off, my whole paradigm changed. Bliss...