Radiator Cap

[Tom Cloud]

>Too fast and you don't take ANY heat from the metal and you over heat.  You
>are correct, delta-T is required for cooling, but there is a finite time
>period the liquid must be in contact with the metal for optimum
>thermodynamic transfer of heat to take place.

sorry, this is over-simplification -- and just not true !!  If you flow
coolant across a surface -- and the coolant stays in contact with the
surface -- the amount of heat removed is a function of delta-T  PERIOD !!
Therefore, the faster the coolant flow (remember, it has to stay in contact)
the higher the delta-T .... ergo, the more heat removed.  Where does this
stuff about it having to stick around for a certain period of time come
from?  The Wizard of Oz???  Certainly, the faster the coolant flows past,
the less heat each unit of coolant absorbs -- i.e. the coolant won't get as
hot -- but that's the point, isn't it??  ... to keep the "coolant" cool!

Now, in a closed system, where the coolant T0 (temp at entry to the
heat source) is not constant but rather a function of a secondary heat
exchanger (the radiator), another factor enters -- the variation in T0
(the beginning coolant temp as it enters the block).

I think I buy the cavitation thing  ....  it allows me to keep my
hard-headed reasoning  ;-)  .... the disclaimer I've been making all
along is that the coolant ** HAS TO STAY IN CONTACT WITH THE HEAT
SOURCE **.  So, with the demon, "cavitation", I can smugly allow
those less informed than me am think that faster is worser -- cause
it just could be.  Now, faster is not the same as "more" -- and we
can all agree that "more" is better, can't we?  And by this, I mean
more volume.  This may not be possible without extensive redesign
of the cooling system -- if you want to keep the velocity the same.

Ah, well, now that I've shanghaied the diy-efi list for a couple of
days, I think I'll go nurse my carpal tunnel wrists  ;-)

Seriously (er, cirrusly) guys, thanks for all the input.  I can
honestly that I've not changed my mind one whit, but I have
been enlightened  ;-)




Tom Cloud

     Madness takes its toll   .....   please have exact change