Quote:
Originally posted by airspirit
Oh, and Ben, you can pretty much count on the fact that the slower the flow through the rad, the more heat is wicked away.
There are a few rules that apply to this that go into calculating the sweet spot.
1) The longer the fluid is in the rad, the more heat is xferred (until temp is normalized between coolant/air). This is just plain common sense.
2) The higher the dT bewwen the coolant/air, the faster the heat will xfer. Again, this is simple thermodynamics.
3) The wildcard is the rate that heat is xferred into the coolant. This is your hot processor cooking your block.
To calculate the sweet spot, you have to balance the rate that heat enters the system with the rad's capability to exhaust that heat. Since different systems enter different amounts of heat to the coolant, there is no way to really give a firm sweet spot to the rad, especially since flow speed affects both the rad and block in inverse proportions. Also, the temp of both your coolant and the surrounding air play a large part in efficiency. You can take a crappy rad and stick it in a block of ice and it'll work great, if you catch my drift.
That hopefully made some sense, and I'm sure one of the EngMonkeys will provide a formula, but rad performance is specific to each system.
|
I understand and agree with what you said.
The best explanation that I've been able to figure out is that if the flow rate is high in the rad, then it is turbulent, therefore can dissipate more heat, but that's countered by the heat that the rad's restrictions induce to the water (not very significant, but enough to skew a few numbers).
Did you see the radiator roundup at OC?