Fred the Red Shirt wrote:
On Nov 27, 7:26 am, Robatoy wrote:
...

I was going to try to equate this with the reason why when you
increase the waterflow through your car's radiator by taking out the
thermostat, your engine will overheat. The water HAS to spend time in
the rad to be able to give up its heat. So the thermostat slows down
the waterflow. Conventional thinking would suggest that by increasing
the waterflow, it should cool better. (There are a few caveats in
there too, so everybody keep their shirts on.)

That is the first I ever heard of that.

The higher the flow rate the higher the Reynolds number and
therefor the higher the convective heat-transfer coefficient.
You may get less heat transferred per gram of water flowing
through the radiator, but not in inverse proportion to the
rate at which grams of water flow through. IOW you might
get only 75% of the heat loss per gram of water but will
have twice as many grams of water flowing through.

Yes, it's simply wrong in general. If one didn't get additional cooling
capacity when the thermostat opened as compared to when it is closed,
there would be insufficient cooling capacity to prevent overheating at
almost any operating condition.

Whatever "caveats" were suggested to counteract that would have to be
extreme, indeed...

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