Oh NO! the dreaded radiator thread!!!!
Last spring we "definitively" decided that the higher the flow rate
through a radiator were under ideal (theoretical) conditions
the better. (More is better).
Unfortunately, we do not have ideal conditions, and turbulent
flow "somehow" reduces heat transfer. Some turbulence is OK
since it mixes the coolant near the radiator wall, but I guess too
much is a bad thing.
You are right that higher flow rates do not allow a certain volume of
coolant to release all its heat in its passage through the radiator since
it spends too little time there, but remember that the total amount of
energy
transferred to the radiator is proportional to the difference in
temperature
between the coolant and the radiator. You will maximize your energy (heat)
lost to the radiator by replacing the slightly cooled coolant with fresh
hot stuff right out of the engine. Yes, inlet to outlet, the radiator has
less temperature drop, but the whole engine and radiator runs at a
lower temperature by having the best possible heat exchange when runnning
at higher flow rates.
-Tony
Message text written by INTERNET:triumphs-owner@autox.team.net
>Date: Tue, 27 Jul 1999 13:57:32 -0700
From: Joe Curry <spitlist@gte.net>
Subject: Re: Coolant flow restriction explained !
Randall,
While I don't dispute the referenced passage, I think there is a bit (if
not a lot) of truth to this story you have been hearing. Here is my
explanation of the dynamics of what happens.
In order for the heated water to be cooled, it has to transfer its
energy to the heat sinks (cooling fins) in the radiator coils. If it is
flowing too rapidly through the radiator, the amount of energy that is
absorbed by the fins is minimized, and reduces the effectiveness of the
radiator.
On the other hand, restricting the flow to a certain extent will cause
the water to stay in the engine too long and pick up more heat than is
dissipated by the radiator. The trick is to find that magic point where
the water flows at just the right speed to dissipate just enough heat to
keep the engine at the desired temperature. That is why the thermostats
are temperature rated to open at a desired temperature.
Of course this is dependent on a number of things:
Ambient temperature (look at all the trucks in the wintertime that have
the entire radiator covered with vinyl to keep the temperature up)
The particular design of the cooling system (some work much better than
others)
How old the car is (as referenced, older cars typically used a lower
pressure system)
The condition of the cooling system and the engine.
WARNING: DISCLAIMER AHEAD!
Any correlation between the above description and reality is purely
coincidental.
Regards,
Joe
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