Well it's raining & I'm bored so I thought I'd jump in to this discussion again with my latest thoughts. I have some boats with high flow rates & some with slow rates & I'd really like to learn more about what's most effective. I'm not sold on the french fry experiment application logic to water-cooled boat electronics ( and what a waste of a good french fry) ! What, at least in my thinking, is most important is the transfer rate between the heat source and the cooling medium which is critically tied to the contact time between these two.
Here's my lab experiments ( perform these at your own risk) :
Test 1:
Run your finger over a hot motor [ say 165 degrees] in one second total. How hot is your finger ?
Then do the same thing but take five seconds to do the same. Hotter finger, right ?
My take is that the longer the cooling medium (your finger) is in contact with the object to be cooled, the more heat transfer from the object to be cooled.
Test 2 : Build a ten foot by five foot bed of hot coals.
Walk (very !) quickly over them. I'm sure you've seen this done on some TV show or something. Feet maybe warm.
Now take ten seconds to do the same. Feet VERY HOT !
Again, the point I'm proposing is that the longer the cooling medium is in contact with the object to be cooled, the more heat extraction takes place.
QED
Now go eat some french fries
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