X-Message-Number: 2138
Date: Wed, 21 Apr 93 10:23:48 CDT
From: Brian Wowk <>
Subject: CRYONICS Ballast Comments

Perry Metzger:
 
> Here is a wacky idea -- possibly a bad one, but who knows.
> Presumably, a mixture of water and cryoprotectants such as the
> ones we use on patients would have a "knee" EXACTLY where we want
> it -- at the glass transition point for the patients!
 
        Unfortunately (or perhaps fortunately) there is no phase 
change (crystalization) at the the glass transition point, and hence 
no energy absorption.  As far as heat flow is concerned, the glass 
transition is a non-event
 
 
Tim Freeman:
 
> I wonder to what extent the ice will sublime from inside the buckets
> and redeposit itself on the outside of the buckets?
 
        The vapor pressure of water is negligible at -130'C.  I expect 
that the same goes for ethanol, which at this temperature is far below 
its boiling point.
 
        The biggest ice buildup problem is going to be from moist 
outside air that finds its way into the room.  Most of this ice will 
deposit itself on the heat exchangers, which may have to be removed 
and defrosted from time to time.  This is another reason to have two 
independent heat exchangers.
 
                                                --- Brian Wowk  

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