>> On hot days or when the engine is working hard the car may overheat without
>> a thermostat. The water pump pumps water through the radiator at a rate
>> corresponding to the engine speed. The longer the water is in contact with
>> the radiator surface, the more heat can be transfered. Without the
>> restriction of the thermostat slowing down the coolent flow the coolent
>> just may not have enough contact time to transfer much heat.
>Are there any thermodynamics instructors out there? I had thought that
>it *IS* important to run with a thermostat for the above
>reasons, but running the water through the cooling system
>more quickly *does* cause the engine to run more cool.
I don't know if I'd call myself a thermodynamic instructor, but it was a part
of my
engineering curiculum. <g>
You're on the right track. Faster fluid flows through a heat transfer medium
result
in lower temperatures. People get the strange notion that pushing the water
through
means it can't transfer heat. Yet at the same time understand that pushing
more air
through it means a cooler radiator. It works the same with the water.
Barring turbulance problems, the faster the fluid flow, the smaller the
required
radiator. It is theoretically possible to use a radiator the size of a floppy
disk
if you could get laminar fluid flow fast enough through the entire system.
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