>As an experiment, heat up some water to near boiling and pour it through a
>piece of copper pipe at different flow rates. Compare heat transfer with
>your hand while blowing air across it.
>
>I'll wager your hand gets hotter (more heat transfer) the lower the flow
>rate WRT a ~constant airflow (car idling or creeping in traffic). Proving
in
>this case what women already know; that slower for longer periods of
>contact are better for achieving the desired results. :^))
And you lose that wager!
As the water gets to the end of the copper pipe (radiator), it is cool and
thus not transferring much heat to the air. With the rapidly flowing water,
you must catch it, reheat it and send it though the pipe again - to keep the
engine analogy. Since the rapidly flowing water is still hot at the end of
the pipe, it is still transferring heat. It is not an adequate test to pour
a gallon through slowly and compare that to a gallon poured through quickly.
You must run the test for the same time period.
Slow moving water will transfer a greater percentage of it's stored heat per
cycle through the radiator, but fast moving water makes more cycles per
minute. Since the Rate of heat transfer is a function of temperature
difference (hot water vs air), hot water transfers more heat per minute
than cool. You want the water at the bottom of the radiator to be hot for
maximum dissipation of heat.
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