> I am amused by the lack of knowledge of heat flow out there in
> net-land. Heat flow is exponential with exposure time. That
> means that if x calories was loss when y gallons spent s seconds
> in the radiator, then the square root of x calories would be loss
> by y gallons if it spent s/2 seconds in the same radiator.
I am amused by the simplified models that people try to use to
model systems that are not much like the model.
Saying that heat flow is exponential with exposure time ignores
the basic fact that the air flow over the radiator is what removes
heat from a radiator - the transfer of the heat from the radiator
to the air depends on the relative temperatures of the air and the
outside of the radiator, and NOT on the flow rate of the coolant
(except indirectly). The reason that a higher flow rate of coolant
may improve the cooling is that more total heat is entering the
radiator, so more of the radiator may come up to the temperature
of the coolant. Normally, radiators are hot at the top, and cooler at
the bottom. If the flow of coolant goes up, you'll have a radiator that
is hot at the top AND the bottom, and it will transfer more heat to the
air as a result. This is the only way that heat can actually leave the
system, since the coolant is closed loop (residual heat in the coolant
leaving the radiator will eventually come back in at the top).
> The opions express in British Car Digest #942 by Scott Fisher and
> John R. Lupien are two more data points on my anti-Lucas theory.
> ALL of the major electrical problems with all of my British cars
> were due to incompent repairs made by previous owners. I follow
> the manuals and have never had a serious problem with Lucas
> electrical parts.
> Martin Frankford
I can't tell if this is intended to be a slam or high praise.
The manuals surely don't indicate that running without a thermostat
is a "Good Idea", but the manuals don't really have much to say about
any number of modifications that can be made to our vehicles that
will significantly improve (or harm) the ways that they work.
If you are happy to just leave your car alone, perform the recommended
5,000 mile oil change and alternator lube, and take what you get,
that's fine, but some folks are NEVER happy to take what they get,
and want to make changes. In these cases, it is useful to know what
one can do that is harmful and what is likely to help, and why.
--
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John R. Lupien
lupienj@wal.hp.com
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