X-Message-Number: 2076
Date: 07 Apr 93 14:51:59 EDT
From: "Steven B. Harris" <>
Subject: CRYONICS Last Thermopile Use..

Dear Cryonet:

   Before we toss the thermopile idea completely, I suppose I
should point out that there is still one possible design to
consider which makes use of them:  If we can get a 50 C dif-
ferential from them easily, as advertised, it might be possible
to obtain -135 C temps in one thermoelectric stage, starting from
a mechanically produced -79 C.  The latter temp, which is dry ice
temp, is the most commonly available temperature for ultracold
freezers commercially, and such freezer systems are extremely
common in research and should by now be maximally inexpensive for
the temp gradient and power needed.  A cold room, then, might run
at -79, with each patient pod (and ethyl chloride) further cooled
by Peltier devices to -135.  Failure of the mechanical -79
refrigerator then could always be backed up by easily and
universally available dry ice, and electrical failure could (as
in other designs) be backed up by a diesel generators.

                                      Steve

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