A little info.. about a diffrent kind of cooling system RE: Why pressure in coolant system?

["Avi Meron" <avi@cosmoslink.net>]

Very good, brother Dave...........there are engines that are designed to use
that principal solely for cooling the engine (no antifreeze no water pump),
as the water enters the engine it heats up and turned to steam, the steam
rises up and as it gets to the cooler part of the engine it condenses back
to water and the cycle starts all over............
Avi

-----Original Message-----
From:	owner-quattro@coimbra.ans.net [mailto:owner-quattro@coimbra.ans.net]
On Behalf Of Dave Head
Sent:	Thursday, September 03, 1998 3:26 AM
To:	frankbauer@thevine.net
Cc:	quattro@coimbra.ans.net
Subject:	Re: Why pressure in coolant system?

At 03:40 PM 9/2/98 -0800, you wrote:
>mike sez:
>>Can someone tell me why coolant systems are made to develop & maintain
>>pressure in them?
>
>water boils at 212dF.
>add some coolant and the boiling temp rises.
>put the mixture under pressure and it rises further.
>it is cleaner and more efficient to operate the engine when coolant
>temps are in the 230dF range, so they use tricks to get the coolant mix
>to operate at the higher temps without boiling over.
>(also, the heat transfer is practically nonexistent wherever boiling
>occurs since the liquid phase isn't touching the hot metal.)
>

Actually, during the nucleate boiling phase the heat transfer capability is
at its highest. Them little steam bubbles carry away mucho thermal flux
into the cooler center of the channel. It's what happens afterwards that
ain't pretty...
When the boiling completely covers the surface (departure from nucleate
boiling) a 'rapid reduction in heat transfer capability' occurs (of course
we're talking 2000# pressure and 800 degree plate temps). Zirk hyriding is
next...

(creeping nukism here...)


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                                   EMCM(SW) Dave Head
87 5KCStq 241K miles                1.85 or so... bar
    qcusa #3442           Oviedo, Florida     plate: STLTHTQ
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