Notes with links to drawings
for a JT-heat exchanger (finned tube-in-shell) for 4.5 K to 2.2 K
precooling of the supply to a 2 K fill valve in test facilities.
Tom Peterson
The JT heat exchanger evolved over several generations of the same
general design:
1. Design originated with Stand 5 at the Magnet Test Facility in
the 1980's
2. Then the two vertical test cryostats for SRF testing at DESY
in the early 1990's (2782-MD-314172)
3. A modified larger (2-layer) version for the TTF feedbox for
DESY in 1994 (1650-ME-250550)
4. The vertical magnet test facility (VMTF) JT-HX (back to the
smaller 1-layer design)
5. Test stand 4 at MTF in the late 1990's (1670-MD-304851,
drawings linked below)
6. Vertical SRF dewar at MTF
7. Others assembled by AD for A0 SRF and Meson SRF test
facilities
The following are links to the TIF drawings of the Stand 4 JT heat
exchanger, which was the last version that I personally revised
and procured.
JT-HX assembly drawing
(31 MB TIF file)
Heat exchanger outer shell
(31 MB TIF file)
Heat exchanger mandrel
(7 MB TIF file)
The mandrel material changed in various designs. My experience
with large chunks of teflon being cold shocked was not good -- they can
crack due to thermal stresses. UHMW polyethelene was good.
A stainless mandrel has also been tried but the fear is some convective
heat transfer inside a hollow madrel, even with flow-through
blocked. Polyethelene ended up being my choice here.
Heat exchanger nozzle (4 MB TIF file)
Temperature sensor feedthru (15 MB TIF file)
last revision: 12 June 2008
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