What is the air Delta-T on a rad?

[Gooserider]

Quick and dirty question... I know an exact answer isn't possible without more precise info, but I'm just after a rough guess.

Assume a WC system with a fairly high coolant flow volume, processors running dual stock AMD CPU's, (No OC, no pelts or radical heating / cooling stuff) There might also be blocks on the hard drives, NB, GPU, etc. I estimate the total heat load to be on the order of 200-250 watts.

Given a good typical airflow through a heater core type rad, IF the intake air is at ambient room temp, what is the temp of the air on the OUTPUT side. IOW, what is the expected Delta-T for air going through a WC rad???

I.E.:

 
  AIR IN  => => |R| => AIR OUT
  TEMP IS => => |A| => TEMP IS
 75*F / 24*C => |D| => ?? WHAT ??

I can't remember the source, but I think I recall seeing somewhere that it was only a degree or two increase, if that. Is this reccollection correct?

Thanks,
Gooserider

[bigben2k]

If you don't mind a bit of math:
http://forums.procooling.com/vbb/sho...0461#post80461

You should be able to adapt the formulae, if you use the right constant (same?), and recalculate the mass.

I'd expect a 1/4 of a degree difference, off hand.

[Cathar]

Yep, at equilibrium the radiator is dissipating X watts, being the wattage of the CPU plus the pump.

Work out the mass of the air-flow through the radiator per second, then the thermal capacity of that air (per second), and then divide the wattage by the thermal capacity to arrive at the ∆T of the air from intake to exhaust.

[Les]

An example of the sums:-

(previously posted http://forums.procooling.com/vbb/sho...5&pagenumber=4

[Gooserider]

It isn't that I'm afraid of it, but more that I don't know what numbers to plug in...

I haven't chosen the exact heater core I'll be using yet, just that it will be the biggest that I can find which will fit in an 11" tall by 8" wide space... I thought I had a pretty good idea, but I was recently thrown for a possible loop when someone said that the sizes in the HC database were just for the cooling surfaces, and didn't include the tanks. (Is that true?, if so, how does one guess at the overall size given the cooling surface size?)

Beyond the idea that they'll be the quietest 120mm fans I can find with decent airflow, I haven't picked the fans either. (come to think of it, I might even see if there is a bigger fan I can use...)

0bviously if I'm unsure of the exact hardware, I won't have exact numbers for it. However I feel comfortable in saying that what I'll choose will give me average or better results, just don't know how to calculate them exactly.

However, between BB2K's 1/4 degree estimate, and Les' graph posting of the Chevette core showing only a 4* rise with really bad airflow, going rapidly to under 1* as the airflow goes up, I think my 1-2* assumption is pretty safe. For my purposes, I don't need 'Joe Grade Accuracy' (TM) just a ball park number.

Thanks again for the help...
Gooserider