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RoboTech · 03-05-2003, 07:28 AM

I agree with Skulemate...

Actually there is a shread of truth to having "the water stay in the radiator longer" but it can't be accomplished by reducing flow rate. A big misconception is that by slowing the water down - it gives it more time to dissipate heat in the radiator (and some even believe to pick up heat in a waterblock). This just isn't so as illustrated by one of the basic laws of thermo that states heat transfer is directly proportional to mass flow rate. So increasing system flow will increase heat transfer in both the rad and waterblock. Obviously there are a LOT of other things going on in the system that contribute to overall efficiency. Like converting high flow to high velocity in the waterblock - usually a good thing...

Back to the shread of truth comment - IF you increase the size of the radiator (or put two radiators in parallel) then you can maintain a relatively high overall system flow but decrease the velocity of water thru the rads. So really it is the larger surface area, lower velocity (less flow resistance) and not "more time spent" that results in better heat transfer.

Just my $.02 worth...

03-05-2003, 07:28 AM	#20
RoboTech Cooling Savant Join Date: Sep 2002 Location: Cincinnati, OH Posts: 229	I agree with Skulemate... Actually there is a shread of truth to having "the water stay in the radiator longer" but it can't be accomplished by reducing flow rate. A big misconception is that by slowing the water down - it gives it more time to dissipate heat in the radiator (and some even believe to pick up heat in a waterblock). This just isn't so as illustrated by one of the basic laws of thermo that states heat transfer is directly proportional to mass flow rate. So increasing system flow will increase heat transfer in both the rad and waterblock. Obviously there are a LOT of other things going on in the system that contribute to overall efficiency. Like converting high flow to high velocity in the waterblock - usually a good thing... Back to the shread of truth comment - IF you increase the size of the radiator (or put two radiators in parallel) then you can maintain a relatively high overall system flow but decrease the velocity of water thru the rads. So really it is the larger surface area, lower velocity (less flow resistance) and not "more time spent" that results in better heat transfer. Just my $.02 worth...