CEC Abstracts in PDF format (as of 7/3/07) - CEC-ICMC 2013

CEC 2007 - Abstracts
C1-M-10 Development of a Cryogenic Gate Valve with
Robust Sealing
W.H. Hatfield, Sierra Lobo, Inc.; J.P. Sass, NASA
KSC.
A soft-seat cryogenic gate valve has been designed, fabricated, and
demonstrated by the Cryogenics Test Laboratory at the Kennedy
Space Center (KSC), featuring a robust sealing technology and a high
Cv flow characteristic. The robust seat design incorporates a novel
retracting seat-retaining disk to prevent soft-seat abrasive wear and
damage on the valve body hard seat. Advanced materials were
incorporated into the design, including porous sponge
polytetrafluoroethylene (PTFE) for the seat material and titanium
nitride coating for the 316 stainless-steel surfaces that are subject to
wearing or galling. The valve is suitable for applications from
ambient temperature down to liquid nitrogen temperature (77 K), with
a seat leakage rate of less than 1 sccm per inch of valve diameter. The
very low seat leakage, throttling capability, and high Cv flow
characteristic of the valve make it suitable for block valve applications
on standard to very large cryogenic storage tanks.
C1-M-11 Atmospheric Pressure Effects on Cryogenic
Storage Tank Boiloff
J.P. Sass, C.R. Fortier, NASA KSC.
The Cryogenics Test Laboratory at the Kennedy Space Center
routinely uses cryostat test hardware to evaluate comparative and
absolute thermal conductivities of a wide array of insulation systems.
The test method is based on measurement of the flow rate of gas
evolved as a result of evaporative boiloff of a cryogenic liquid. The
gas flow rate typically stabilizes after a couple of hours to a couple of
days, depending upon the test setup. The stable flow rate value is then
used to calculate the thermal conductivity for the insulation system
being tested. The latest set of identical cryostats, 1000-L spherical
tanks, exhibited different behavior. On a macro level, the flow rate
did stabilize after a couple of days; however, the stable flow rate was
oscillatory, with peak-to-peak amplitude of up to 25% of the nominal
value and a consistent period. The source of the oscillation has been
traced to variations in atmospheric pressure caused by atmospheric
tides similar to oceanic tides. This paper will present analysis of this
phenomenon, including a calculation that explains why other cryostats
are not affected by it.
C1-M-12 Cryocooler Prognostic Health Management
System
B. Penswick, Sest, Inc.; A. Shaw, Sest, Inc; C.
Dodson, T. Roberts, Air Force Research Laboratory.
High performance sensors are playing an increasingly important role
in all aspects of all critical DoD missions. There is a family of sensors
that operate with improved sensitivities if cooled to very low
(cryogenic) temperatures. For these sensors a healthy and reliable
mechanical refrigeration system (cryocooler) is required. The ability
to accurately predict the “health” or remaining useful life of the
cryocooler has significant benefits from the viewpoint of insuring that
mission critical functions can be carried out with a high probability of
success. The proposed paper provides an overview and approaches
used for the development of a Cryocooler Prognostic Health
Management System capable of assessing the cryocooler “health”
from the viewpoint of the level of performance degradation and/or the
potential for near term failure. Additionally, it quantifies the reliable
remaining useful life of the cryocooler. While the proposed system is
focused on the specific application to linear drive cryocoolers,
especially for DoD, many of the attributes of the system can be
applied to other specialized system hardware in both commercial and
U.S. Government agency for situations where it is critical that all
aspects of the hardware “health” and “remaining useful life” be fully
understood. Several benefits of the health monitoring system are also
described in the paper.
C1-N Large Scale Refrigerators and
Liquefiers - I
C1-N-01 The on-site status of the KSTAR helium
refrigeration system
H.-S. Chang, D.S. Park, J.J. Joo, K.W. Cho, Y.S.
Kim, J.S. Bak, National Fusion Research Center;
H.M. Kim, M.C. Cho, I.K. Kwon, Samsung
Engineering and Construction Corporation; E. Fauve,
J.-M. Bernhardt, P. Dauguet, J. Beauvisage, F.
Andrieu, Air Liquide - Advanced Technologies
Division; G.M. Gistau Baguer, Consultant - Biviers.
Since the first “Cryogenic System Design Description” of the KSTAR
helium refrigeration system (HRS) had been carried out in year 2000,
many modifications and changes have been applied due to both
system optimization and improved knowledge of the cold component
of KSTAR. The present specification of the KSTAR HRS had been
fixed during the “Design Clarification Meeting”, beginning of year
2005. Consequent manufacturing of main equipments, such as
compressor station (C/S), cold box (C/B), and distribution box (D/B)
was completed by or under the supervision of Air Liquide (AL) DTA
by the end of 2006. The major components of the C/S are 2 low and 2
high pressure compressor units and an oil removal system. The
cooling power of the C/B at 4.5 K equivalent is 9 kW which is
extracted by 6 AL turbo expanders. The D/B is a valve box housing
49 cryogenic valves, 2 supercritical helium circulators, 1 cold
compressor, and 7 heat exchangers immersed in a 4 m3 liquid helium
storage. The installation and commissioning of the KSTAR HRS is
planned to be executed in year 2007.
In this proceeding, we will introduce the on-site installation and
commissioning status of the KSTAR HRS. In addition, the final
specification and design features of the HRS and the cooling schemes
of the KSTAR cold components, which consist of superconducting
(SC) magnets and corresponding structures, SC bus-lines, current
leads, and thermal shields, will be presented.
C1-N-02 The JT60SA Cryoplant Current Design Status
D. Henry, P. Reynaud, J.-Y. Journeaux, J.-L.
Maréchal, D. Balaguer, Ch. Roux, Département de
Recherche sur la Fusion Contrôlée, Association ; F.
Michel, P. Rousset, Département de Recherche
Fondamentale sur la Matière Condensée,
CEA/Grenoble, F-38000 Grenoble France.
In the framework on the ITER Broader Approach, CEA is carrying
out the procurement of the Cryogenic System to the JA-EU Satellite
Tokamak JT60SA, which should be operated in Japan at JAEA, Naka
since 2014. According to the Conceptual Design Review Report,
JT60SA is to operate for periods of at least 6 months per years, with
major shutdown periods in between for maintenance and further
upgrades installation. For this operation scenario, the cryoplant and
the cryodistribution have to cope with different heat loads which
depend on the different JT60SA operating states. The cryoplant
consists of two 4.5 K refrigerators and one 80 K helium loop coupled
with an LN2 Pre-Cooler. These cryogenic subsystems have to operate
simultaneously in order to remove the heat loads from the magnet, 80
K shields, divertor cryopumps and Pellet Injection System.
The first part of this study based on the Process Flow Diagram (PFD),
presents the current design status of the JT60SA cryogenic system.
The second part is dedicated to the analysis of the cryoplant normal
operation modes including the regeneration mode of the divertor
cryopumps.
Thanks to this analysis, the architecture of the present PFD is
proposed in order to meet the technical specifications of the cryoplant
with the JT60SA operation requirements.
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