Quote:
Originally posted by 8-Ball
Not true.
This comes up a lot. There are a few threads discussing this. Faster flow equals greater efficiency.
It is necessary to think backwards.
You have a fixed air temp.
If the efficiency is improved, then the average water temp will be reduced. Equally, the efficiency of the waterblock will be increased, leading to a reduced delta T between the cpu and the water, which is already cooler.
However, increasing the flow will likely introduce more heat to the water through the pump. When the additional heat from increasing the flow rate exceeds the reduction in temp expected from the improved efficiency, you will reach the point of diminishing returns. Go no further.
It is a common misconception that water needs to spend time in the radiator for optimum performance. You need to try and detach yourself entirely from the flowing coolant and just imagine that there is heat coming in and heat going out. Changing the flow rate effects the efficiency of the heat exchangers carrying out these steps.
Hope this makes sense. (I think I get better at explaining it each time I give it a go, though there may still be mistakes.)
8-ball
|
I don't think this is correct. I know of other instances involving automobile cooling systems where increasing the flow rate has lead to overheating of the engine because the radiator couldn't cool the water fast enough.
It is not a misconception that water needs to spend time in the radiator for optimum performance. The reason people may think this is because they are confusing heat transfer rates with what we ultimately want the radiator to do.
The radiator works best at 0 flow. At 0 flow, the water in the radiator will be cooled down to ambient. That the coolest water we can get out of the radiator. As the flow increases, the temperature of the water, at the outlet, increases. This is exactly what we don't want. It does not matter if the heat transfer is occuring with better efficiency. The fact is that the output temperature is increasing, and that's a bad thing.
It is also a mistake to discount the cause-&-effect relationship between the waterblock and radiator. Increasing flow lowers the temperature of the water coming out of the block, and that greatly affects the performance of the radiator.
It is an absolute truth that faster flow increases the heat transfer rate. However, you cannot blindly apply this truth to an entire system. Reality is far too complex to allow that.