Pro/Forums - View Single Post - Cooling Technologies Explained Discussion

Joe · 03-25-2002, 02:08 PM

With an article of that size and depth there are bound to be some slip ups

"quote:
--------------------------------------------------------------------------------
The Coolant in all cases has picked up ~90% of the heat from the heat source.
--------------------------------------------------------------------------------
How do you arrive at the figure for this and parasitic heat loss? Are they guesstimates or calculation-backed? "

Half guestimation and half educated guess

I discussed this topic at length with a few geeks from different places. One is a thermals geek who works at GM working on Engine block design, mainly coolant paths. He had some interesting numbers about car engines and how much heat they loose to the surrounding air compared to what goes through the radiator. For a car engine its around 15% by their calculations at a certain temp Delta from the ambient ( don’t know what that delta number was). After we talked and discussed the thermal densities and the environment that the cooling system runs in we came to a round about number of 5 - 10%. The fact is the parasitic loss is there, the EXACT number is almost impossible to figure out with testing gear most geeks have access to. Also it will change by how cool or hot the ambient air is, and air flow, and a billion other factors.

"quote:
--------------------------------------------------------------------------------
In water cooling I would venture a guess that a good deal of heat is lost in the hoses, reservoir, and any places its in contact with a case side or something.
--------------------------------------------------------------------------------
Sorry, nitpicking again, but didn't you previously establish this as being 10% of heat from source? "

Yep! the extra 2 lines of text didn’t take to long to download I hope.....

"quote:
--------------------------------------------------------------------------------
So with that said the Radiator on a H2O rig moves a lot of the heat but has a much easier job of it since there is a much higher mass between it and the core to loose heat at different stages.
--------------------------------------------------------------------------------
If so much heat is lost along the way, why do you need a radiator in the first place? If 10% is lost along the way, there is still 90% for the radiator to dissipate. It may be somewhat easier, but I think much is stretching it a bit far. "

Well compared to how many places a HSF has to loose heat... You need to look at the bigger picture in the writing not one sentence at a time.

"quote:
--------------------------------------------------------------------------------
The water coming back from a radiator on a H2O rig really may not be much cooler than the incoming coolant into the radiator. This is a factor of how effective the radiator is for the volume/speed/type of coolant you are moving through it. Of course the closer to ambient the better.
--------------------------------------------------------------------------------
I think it's important to note at this point that the difference in temperature across the radiator itself is going to be actually rather small. Water in the entire loop should ideally be at as similar a temperature at possible, as that is the temperature at which heat loss in the radiator(and along the way) exactly matches heat gain in the waterblock."

Isn’t that what I said... Just not as over worded?

"quote:
--------------------------------------------------------------------------------
Pump: Pumps don’t mind warm coolant, and introduce a few watts of heat themselves to the coolant, so its good to have it BEFORE the heat exchanger.
--------------------------------------------------------------------------------
This is a point I always like to contend. Its not that water will suddenly jump a few degrees between before and after the pump. It's that the pump adds another heat source to the water, raising the temperature the water has to be at to dissipate the heat. I lay before you a challenge, measure the water temperature before and after your pump. Is it even perceivably different? I'll venture as far as saying no.
What does this mean? It doesn't really matter where the pump is, the deltaT across it is negligible. It's not a sudden rise in temperature across it, it's the added heat that it contributes that raises the equilibrium temperature. This implies that the pump can pretty much go anywhere. "

Maybe you missed a line that I wrote:
"Just as with any other cooling, the movement of the coolant is vital to how well the entire system works. This is a topic that many people differ on, and some claim it makes no difference in reality for our cooling systems. That may be true, but if you are designing a cooling system, why not do it right?"

the difference may be VERY SMALL... But why would you spend that much money and time on a cooling system just to design it half assed?

Yes there are some nice grammar issues in this one

I got some fixes to do tonight on it hehehe

It wasnt meant to teach old dogs many new tricks, it was meant to act as a base level for people to see what technology does what and where they may be able to use it. glad overall you liked it!

03-25-2002, 02:08 PM	#26
Joe The Pro/Life Support System Join Date: Dec 1999 Location: Denver, CO Posts: 4,041	With an article of that size and depth there are bound to be some slip ups "quote: -------------------------------------------------------------------------------- The Coolant in all cases has picked up ~90% of the heat from the heat source. -------------------------------------------------------------------------------- How do you arrive at the figure for this and parasitic heat loss? Are they guesstimates or calculation-backed? " Half guestimation and half educated guess I discussed this topic at length with a few geeks from different places. One is a thermals geek who works at GM working on Engine block design, mainly coolant paths. He had some interesting numbers about car engines and how much heat they loose to the surrounding air compared to what goes through the radiator. For a car engine its around 15% by their calculations at a certain temp Delta from the ambient ( don’t know what that delta number was). After we talked and discussed the thermal densities and the environment that the cooling system runs in we came to a round about number of 5 - 10%. The fact is the parasitic loss is there, the EXACT number is almost impossible to figure out with testing gear most geeks have access to. Also it will change by how cool or hot the ambient air is, and air flow, and a billion other factors. "quote: -------------------------------------------------------------------------------- In water cooling I would venture a guess that a good deal of heat is lost in the hoses, reservoir, and any places its in contact with a case side or something. -------------------------------------------------------------------------------- Sorry, nitpicking again, but didn't you previously establish this as being 10% of heat from source? " Yep! the extra 2 lines of text didn’t take to long to download I hope..... "quote: -------------------------------------------------------------------------------- So with that said the Radiator on a H2O rig moves a lot of the heat but has a much easier job of it since there is a much higher mass between it and the core to loose heat at different stages. -------------------------------------------------------------------------------- If so much heat is lost along the way, why do you need a radiator in the first place? If 10% is lost along the way, there is still 90% for the radiator to dissipate. It may be somewhat easier, but I think much is stretching it a bit far. " Well compared to how many places a HSF has to loose heat... You need to look at the bigger picture in the writing not one sentence at a time. "quote: -------------------------------------------------------------------------------- The water coming back from a radiator on a H2O rig really may not be much cooler than the incoming coolant into the radiator. This is a factor of how effective the radiator is for the volume/speed/type of coolant you are moving through it. Of course the closer to ambient the better. -------------------------------------------------------------------------------- I think it's important to note at this point that the difference in temperature across the radiator itself is going to be actually rather small. Water in the entire loop should ideally be at as similar a temperature at possible, as that is the temperature at which heat loss in the radiator(and along the way) exactly matches heat gain in the waterblock." Isn’t that what I said... Just not as over worded? "quote: -------------------------------------------------------------------------------- Pump: Pumps don’t mind warm coolant, and introduce a few watts of heat themselves to the coolant, so its good to have it BEFORE the heat exchanger. -------------------------------------------------------------------------------- This is a point I always like to contend. Its not that water will suddenly jump a few degrees between before and after the pump. It's that the pump adds another heat source to the water, raising the temperature the water has to be at to dissipate the heat. I lay before you a challenge, measure the water temperature before and after your pump. Is it even perceivably different? I'll venture as far as saying no. What does this mean? It doesn't really matter where the pump is, the deltaT across it is negligible. It's not a sudden rise in temperature across it, it's the added heat that it contributes that raises the equilibrium temperature. This implies that the pump can pretty much go anywhere. " Maybe you missed a line that I wrote: "Just as with any other cooling, the movement of the coolant is vital to how well the entire system works. This is a topic that many people differ on, and some claim it makes no difference in reality for our cooling systems. That may be true, but if you are designing a cooling system, why not do it right?" the difference may be VERY SMALL... But why would you spend that much money and time on a cooling system just to design it half assed? Yes there are some nice grammar issues in this one I got some fixes to do tonight on it hehehe It wasnt meant to teach old dogs many new tricks, it was meant to act as a base level for people to see what technology does what and where they may be able to use it. glad overall you liked it! __________________ Joe - I only take this hat off for one thing... ProCooling archive curator and dusty skeleton.