new rad... comments?

[Postal Dude]

jus got this rad from where my dad works. Its an oil cooler for motorsport racing. 240mm x 80mm looks like 1/4" ID which aint great. But lots of surface area. Any comments on how this would perform with 3x 80mm fans (stealth, delta or tornado)

 

[Arcygenical]

Woah, that thing looks beautiful! Is it shiny in real life like the pic makes it out to be? I'm not too sure, but it looks like you might be able to attach larger barbs to the thing, as the inlet ports appear to be screwed in? Performance wise, I'm not too sure, but I bet it depends on the metal it's made from. Please try this, I'd be really interestd to see how it looks/performs!

**EDIT** If you dont mind me asking, how much did that set you back? do you know the manufacturer and model #?

 

[Postal Dude]

Yes it it that beautiful in real life. And its light as a feather. I dont kno the manufacturer part # im afraid. it came from www.titan-lite.com its an oil cooler off there. It failed its 90PSI pressure test. but was fine upto about 70PSI so it will have no bother with what i want it for. cus it failed that test i got it for free. Yes you can change barb sizes. currently the inlet and outlet are 3/8" with enough room to fit 3/4"!!

 

[BillA]

retest, pressure leaks do not reseal after failure

 

[Postal Dude]

been done. its cool. Jus need to invest in a decent pump/block combo now

 

[boof]

I assume you are alluding to the ubiquitous RBX+D5 combo.

 

[Postal Dude]

Definatly the D5 for sure. FOr now tho im trying to look for a decent AL water block. the rad is entirely AL and i dont want any corrosion to bother me. i kno this will hurt performance somewhat. But it shouldnt do too much bother

On another note. What would i need to be running in the loop to stop corrosion. Would redlines water wetter be enough to stop galvanisation? This small rad iv got at the moment is the smallest in the line. Bigger sizes are coming available to me all the time. A good strong pump and water block and interchangable rad. Most of them are AL pipe tho. Need some serious anti corrosion stuff. Suggestions please

 

[zer0signal667]

been done. its cool. Jus need to invest in a decent pump/block combo now

With what fluid is the testing performed? Water will permeate where oil will not, I'd be careful if the test was done with oil. But, I'm guessing it was probably air pressure...

Anyway, that thing looks great, awesome score

 

[Postal Dude]

yeah it was done with air pressure not oil or water. Much smaller molecules and VERY strict testing methods. I think its designed to World Touring Cars or sumthin so they very particular with testing.

 

[rodsfree]

It'll probably do real well!
Great score.....
If you run across any more - (hint, hint)

Check the passages from one end to the other..... If the total combined area of the passages is greater than 1/2" then you'll be ok.

The larger passages allow the water to slow down and spend some time in the radiator - instead of just zipping right through.

 

[zer0signal667]

It'll probably do real well!
Great score.....
If you run across any more - (hint, hint)

Check the passages from one end to the other..... If the total combined area of the passages is greater than 1/2" then you'll be ok.

The larger passages allow the water to slow down and spend some time in the radiator - instead of just zipping right through.

Larger passages would create less resistance to flow, allowing greater volumetric flowrates. Fluid velocity (which is not the same as flowrate), on the other hand, may decrease. Lowering your flow in the radiator is not desirable, as heat transfer increases with flow.

edit: just noticed the quote in your sig- I just happen to be an engineer I don't want an argument though, just trying to make a common misconception less common

 

[Demon_of_The_Fall]

Yeah I've seen that idea of "letting the water hang around in the radiator" so that it can cool better posted a lot of times here lately. It just does not make any sense at all...

 

[rodsfree]

Yeah I've seen that idea of "letting the water hang around in the radiator" so that it can cool better posted a lot of times here lately. It just does not make any sense at all...

The idea is based on the fact that temperture equations have a time component in them.
Thermal transfer coeficients are degree per inch per second.
This is how and why a passive radiator like the Zalman Resorator works so well.

When you go to active cooling - i.e. with a fan - it's not as important. Because the volume of air passing through the radiator will remove the small amount of heat that a PC can produce rather quickly.

Go up to a 250 ton cooling tower for an industrial refridgeration system - and we want the fluid to hang around in the radiator and reservoir as long as possible. Thats also why we have reservoirs that hold 5-10 times the amount of fluid that's in the rest of the system. And why we never create a single loop to cool a system with multiple heat loads.

We go reservoir -> pump -> radiator -> manifold -> single line to each heat source that returns to the reservoir. This also allows us to control our flow - thus tailor our cooling potential for each heat load. And on some systems we'll have a dedicated reservoir cooling loop that just cycles fluid from the reservoir through a radiator and back into the reservoir.

I've even seen systems that have 2 reservoirs with a radiator between them.....
One is the HOT return reservoir and then the fluid is ran through a radiator or even an evaporative cooling tower into a cold staging reservoir before it starts it's cooling cycle again.

So....

It's not that the idea doesn't work.... it's incorporated into all of the radiators that are being used by the community today. People just don't see it working.


The cross-sectional area of the oval passages between the 2 tanks of your radiator is greater that the inlet or exit cross-sectional area. This is true for heater cores, car radiators, and the ones built just for water cooling. The one cooling design that you don't see being used is the one like a car's transmission cooler. It's a single 3/8" or 1/2" tube that's bent into a serpentine pattern and has a bunch of fins that the tube runs through.

They were tried in the early days of water cooling and people found that they don't work as well as an heater core does, even though the fluid moves through them very quickly, and they also don't have as much fin surface area to radiate heat from.

So, now a bunch of people are going to start jumping up and down and telling me that I don't know my ass from a hole in the ground and yata, yata, yata.

Let the flames begin.....
Then go tear apart an old radiator and measure the total area of the oval cross tubes against the area of the inlet and figure the velocity(Q) drop and then you tell me if the water hangs around in the radiator.

BTW.....
Part of what I do for a living is cool stuff - that's a lot hotter than a PC.
I've got 2 each 10,000 gallon reservoirs with machine cutting coolant in them and each tank has 2 125HP pumps on them and we've got 3 200ton chillers cooling the cutting fluid down to room temperture. Without the chillers on - the pumps alone, put enough mechanical energy into 20,000 gallons to raise the temps to 125deg F.
And that is just the biggest of 4 coolant systems that I've got running.

So - when one of you guys get a pc cooling system up to 20,000 gallons - let me know

 

[rodsfree]

Larger passages would create less resistance to flow, allowing greater volumetric flowrates. Fluid velocity (which is not the same as flowrate), on the other hand, may decrease. Lowering your flow in the radiator is not desirable, as heat transfer increases with flow.

edit: just noticed the quote in your sig- I just happen to be an engineer I don't want an argument though, just trying to make a common misconception less common

OK....
Pull out Mark's Mechanical Engineers Hand Book and you tell me why each of the thermal equations have a time component (sec) in them?

For PC's the volume of fluid vs the volume of air being pushed through the radiator overcomes the need for the time component. Since we don't have a huge heat load.

Plus, Your current radiators are designed to cause a drop in fluid velocity. Take it apart and do the measurements. I'll wait.

If you want one that doesn't cause a velocity drop.... then use a B&M transmission cooler.

But, damn.... everybody that's tried them found out that they don't work that well - must be because that velocity drop thing..... the B&M uses a same size, single tube in a serpentine pattern - so, no velocity drop. Plus, they suffer from a very laminar flow, the fluid has to cool itself by conduction with itself..... the fluid at the wall of the tube is moving very slowly with respect to the overall fluid flow. So, heat goes from tube wall, to slow moving fluid, to faster moving fluid - pure conduction.

What you are thinking of is the turbulent flow induced in the cpu blocks. Which will present a cool molecule of water to the thermal interface and cause a transfer of heat more quickly than just conduction could.

But we don't have turbulent flow in a radiator - you couldn't design one that could be easily built. Inducing trubulent flow requires right angles, fins in the flow that are orientated 90 degrees to the direction of flow, sharp turns, rough surfaces, and all manner of hard to manufacture things that would drive the cost of your radiator though the roof.

Thoughts?

 

[zer0signal667]

Like I said, I don't want an argument - it is beyond the scope of this thread. Sorry to have riled you up...

 

[DFI Daishi]

What you are thinking of is the turbulent flow induced in the cpu blocks. Which will present a cool molecule of water to the thermal interface and cause a transfer of heat more quickly than just conduction could.

But we don't have turbulent flow in a radiator - you couldn't design one that could be easily built. Inducing trubulent flow requires right angles, fins in the flow that are orientated 90 degrees to the direction of flow, sharp turns, rough surfaces, and all manner of hard to manufacture things that would drive the cost of your radiator though the roof.

Thoughts?

there is turbulent flow induced in rads via internal fins in the coolant stream.

whatever math you care to drag into the discussion......engineers also like well controlled tests to validate their designs, yeah? maybe some nice performance curves as well?

http://www.overclockers.com/articles778/

have a read. reduced flow restriction and increased flow rate only help matters with a watercooling rad.

 

[rodsfree]

Like I said, I don't want an argument - it is beyond the scope of this thread. Sorry to have riled you up...

Didn't rile me up.....
Just expressing my point of view, based on my experience with really large cooling systems.

Sorry if I sounded that way.

 

[rodsfree]

there is turbulent flow induced in rads via internal fins in the coolant stream.

whatever math you care to drag into the discussion......engineers also like well controlled tests to validate their designs, yeah? maybe some nice performance curves as well?

http://www.overclockers.com/articles778/

have a read. reduced flow restriction and increased flow rate only help matters with a watercooling rad.

Here is a quote from the article that you referenced.... look at the bold type.

The four curves each show the radiator’s heat dissipation at a specific backpressure, which is also a specific air flow rate for that individual radiator. Of note is the changing relationship between the liquid and air sides; at low to moderate air flow rates the dissipation increases only slightly with the flow rate, while at a high air flow rate there is also a marked increase in cooling capability.

“For the common respective flow rates, the convection heat transfer for air is the limiting parameter for a liquid to air heat exchanger. This is why there are fins (to increase convection heat transfer) on the air side and not on the liquid side for these heat exchangers. For low air flow rates, the thermal resistance of the air side is much more important than the fluid side (except for low fluid flow rates). Increasing the fluid flow rate leads to an improvement for the convection heat transfer, thus a lower thermal resistance, of the fluid side but this is negligible as compared to the air side thermal resistance. Improving the air side convection heat transfer, in other words the air flow rate, leads to a better global improvement.” *

I repeat..... there is no turbulent flow in a PC water cooling radiator.
There is trubulant flow in the CPU block - right angle changes of direction at high flow rates induce turbulance.

Cut open your radiator and measure the cross-section of the oval tubes. Then measure the cross-section of your 1/2" inlet tube = .196 sq.in. From (A=pi*r^2) anything greater than that will cause a Q drop and eliminate turbulent flow.

Cut one open and show me a picture of the fins. They should be INSIDE the OVAL TUBE to cause turbulant flow..... Plus, they should be perpendicular to the direction of flow to cause turbulance...... Nobody makes a radiator core like that.

Go to this site http://www.harvesting.com/radiator/index.html and you'll see how a common radiator core is built. Look at the pictures. The Flat tubes are clear of obstructions that would cause turbulance and there are a great many of them. Add up all that area and it'll be a lot greater than the area of the inlet tube for the radiator that they are building.

 

[DFI Daishi]

i really wish that the pics still worked.......http://www.hardforum.com/showthread.php?t=901181&highlight=heatercore+cut

i don't know which rads use them and which don't. at least some have internal fins.

 

[zer0signal667]

Turbulent flow can occur in a straight, cylindrical pipe given the right conditions *cough*Reynolds' Number*cough*

Just some food for thought.

 

[plywood99]

Turbulent flow can occur in a straight, cylindrical pipe given the right conditions *cough*Reynolds' Number*cough*

Just some food for thought.

Lol.

But, damn.... everybody that's tried them found out that they don't work that well - must be because that velocity drop thing..... the B&M uses a same size, single tube in a serpentine pattern - so, no velocity drop. Plus, they suffer from a very laminar flow, the fluid has to cool itself by conduction with itself..... the fluid at the wall of the tube is moving very slowly with respect to the overall fluid flow. So, heat goes from tube wall, to slow moving fluid, to faster moving fluid - pure conduction.

I think you are forgetting about flow resistance, so yes, there is a very noticeable velocity drop. That single serpentine tube will add quite a bit of resistance to the flow of water.

So to answer the question, no the velocity drop in the heatercore style rad is not the reason for better cooling. Mainly has to do with surface area...

 

[rodsfree]

So to answer the question, no the velocity drop in the heatercore style rad is not the reason for better cooling. Mainly has to do with surface area...

Which you can't get unless you increase the total surface INSIDE the radiator.
Which means you increase the cross-sectional size available for fluid flow.
Which will cause a velocity drop.

QED


The two work hand in hand.

 

[rodsfree]

I think you are forgetting about flow resistance, so yes, there is a very noticeable velocity drop. That single serpentine tube will add quite a bit of resistance to the flow of water.

So the flow resistance in a serpentine radiator is greater than the flow resistance in the several feet of same size tube that leads to the radiator.

That style of radiator won't add any more reisistance than adding a few more feet of tube.
Unless you count the Reynolds differences between tygon and copper..... which is insignicant.

 

[zer0signal667]

Which you can't get unless you increase the total surface INSIDE the radiator.
Which means you increase the cross-sectional size available for fluid flow.
Which will cause a velocity drop.

QED


The two work hand in hand.

It is very easy to manipulate cross-section area and surface area independently of one another. You're creating generalized cause-and-effect relationships which do not exist.

 

[Postal Dude]

Ermmm. This thread has gone SLIGHTLY off topic. Im sure this is all very interesting. But i cant see it helping my cause.

Which is the better anti corrosion agent, zerex or water wetter?

How is my rad likely to perform?

 

[rodsfree]

It is very easy to manipulate cross-section area and surface area independently of one another. You're creating generalized cause-and-effect relationships which do not exist.

The diffuclutly lies when you try to manipulate the surface area of the inside of a tank - like the one on the end of a radiator - or tube. Using current standard manufacturing processes for this type of radiator.

The only other way to increase the surface area INSIDE of a radiator is by using some type of metallic insert. i.e. a "fin". That would have to be brazed to the inner walls of the core (brazed because a mechanical connection is required to conduct heat to the tubes and fins). Which no current manufacturer of the core style radiator does. Because the cost of doing so - manufacturing cost - wouldn't be worth the return - improvement in heat transfer. Just buy a bigger radiator - it cost less.

This is exactly why you have 1 - 2 - 3 - & 4 core radiators in the performance automotive market. More cooling ability needed and you can't change the length and width of a car's radiator - then change the thickness - add another core layer - increase the surface area and the cross sectional size - which reduces the coolant velocity inside the radiator.


Now, answer me this, If we don't want the coolant to hang around for a decent period of time in the radiator - why do we keep buying bigger and bigger radiators for computers that have approximately the same heat load?

I've seen mod sites that use small car radiators with dual 12 INCH fans on them for their water cooling setups. For a single PC!!!

And how many radiators have you seen that can mount 3 X 120mm fans? This thing is bigger than the heater core in my old 1968 Catalina.

 

[rodsfree]

Ermmm. This thread has gone SLIGHTLY off topic. Im sure this is all very interesting. But i cant see it helping my cause.

Which is the better anti corrosion agent, zerex or water wetter?

How is my rad likely to perform?

Your radiator will perform at least as well an a similiar sized radiator built for water cooling - probably better concidering that the manufacturer of yours builds higher quality components than the mass produced cores used for water cooling and heater cores.

Anti-corrosion agents - take your pick - they all work by doing the same thing - reducing galvanic response between 2 dis-similiar metals in solution. Zerex has been around longer and has more experience, concidering that they make automotive coolant. And there are 3-5 or more different types of metals in a car's coolant system. But any high quality additive should work well.

If you want to monitor your system for galvanic reactions - which cause corrosion. Get a DVM and hook one lead to ground and immerse the other in your reservoir. Any voltage showing on the DVM means that you've got a galvanic reaction happening. Higher voltages mean that it's getting worse.


Sorry for hijaking your thread.....
I'm done now.

 

[plywood99]

It is very easy to manipulate cross-section area and surface area independently of one another. You're creating generalized cause-and-effect relationships which do not exist.

QFT...