In a message dated 10/21/2005 6:14:28 PM Central Standard Time,
tr3driver@comcast.net writes:
> Doesn't even have to be the same. Lower flow won't necessarily lower
> cooling, unless the flow becomes low enough to significantly lower the
> outlet temperature from the radiator. How much heat the radiator removes
> depends only on temperature gradient, it's not directly affected by how much
> water flows through it.
>
Huh?
Pardon me but the job of the radiator is to remove heat. Since this is an
inline process the performance of a radiator is measured in BTU/Hour (or
Kilocalories per hour). A BTU is the amount of heat energy it takes to change
one
pound of water one degree Fahrenheit. This can be measured in the temperature
change inlet tot outlet. But the other part of the equation is the rate of
heat flow. So the amount of heat dissipated by the radiator is a function of
both the temperature differential AND the flow through the radiator.
But back to the original discussion about bypasses, the thermostat will
regulate the amount of coolant admitted to the radiator. Since it is a closed
loop
system (the thermostat will open and close in response to the coolant
temperature) it will admit enough coolant to the radiator to maintain its
preset
temperature. It does not matter if the excess pump capacity bypasses the
radiator
back to the engine or if this capacity just deadheads at the thermostat.
(Small amounts of bypass circulation being preferred to prevent hotspots in the
head notwithstanding.)
This works just fine until the condition is met where the thermostat is full
open and yet there is inadequate cooling because a portion of the coolant is
bypassing the radiator when it could be passing through the radiator imparting
some of its heat to the airstream. This is where the skirted thermostat (or a
flow restriction in the bypass) becomes beneficial.
Dave
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