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

CEC 2007 - Abstracts
C3-K-06 Cost-Efficient Storage of Cryogens
J.E. Fesmire, J.P. Sass, D.L. Morris, NASA KSC; Z.F.
Nagy, S.D. Augustynowicz, Sierra Lobo, Inc.; S.J.
Sojourner, ASRC Aerospace.
NASA’s critical cryogenic infrastructure that supports launch vehicle
operations and propulsion testing is reaching an age where major
refurbishment will soon be required. A key element of this
infrastructure is the insulation in large double-walled cryogenic
storage tanks, for which perlite has been the insulation material of
choice for decades. New materials are now available that can provide
improved thermal and mechanical performance. An internal research
and development project investigated the application of new bulk-fill
insulation materials and associated technology upgrades to advance
the overall efficiency of cryogenic storage tanks. Technical, safety
and affordability data were produced to support NASA program
decisions on the benefits and risks of using the alternative insulation
materials, including glass microspheres and aerogel beads. Work was
divided into three areas: material testing (thermal conductivity and
physical characterization), tank demonstration testing (liquid nitrogen
and liquid hydrogen), and system studies (thermal modeling,
economic analysis, and insulation changeout). The research work
presents a more cost-effective solution for large-scale cryogenic
storage worldwide, new cryogenic test equipment and methods, and a
pathway for mass-efficient storage and transfer of cryogens on the
Moon and Mars.
Funding was provided by the NASA Space Operations Mission
Directorate under the Internal Research and Development project
New Materials and Technologies for Cost-Efficient Storage and
Transfer of Cryogens.
C3-L Accelerator Cryogenics
C3-L-01 Cooldown of the first sector of the Large Hadron
Collider: comparison between mathematical model and
measurements
L. Liu, Chinese Academy of Sciences; G. Riddone, L.
Tavian, CERN.
The first LHC sector (3.3-km long) will be cooled down for the first
time from room temperature to 1.8 K at the beginning of the year
2007. For this cool-down, the mass-flow distribution of each cell has
been optimized using a mathematical model developed to establish
reference set-points. In this paper, the measured evolution of
temperatures, pressures, mass-flow rates of helium in each cell of the
machine as well as in the cryogenic distribution line will be presented
and compared with the simulation results obtained from the previous
mathematical model. Possible discrepancies between measurements
and calculation will be also analyzed for improving the mathematical
model.
C3-L-02 Commissioning the cryogenic system of the first
LHC sectors
F. Millet, S. Claudet, G. Ferlin, P. Gomes, S. Junker,
G. Riddone, M. Soubiran, L. Tavian, B. Vullierme, U.
Wagner, CERN; L. Ronayette, L. Serio, CNRS.
The LHC machine, composed of eight sectors with superconducting
magnets and cavities requires a complex cryogenic system providing
high cooling capacities (equivalent to 18 kW at 4.5 K and 2.4 kW at
1.8 K per sector produced in large cold boxes and distributed via 3.3-
km cryogenic transfer lines). After individual reception tests of the
cryogenic subsystems (cryogen storages, refrigerators, cryogenic
transfer lines and distribution boxes) performed since 2000, the
commissioning of the cryogenic system of the first LHC sectors is
under way since November 2006.
After a brief description of the LHC cryogenic system and its
specificities, the commissioning will be reported detailing the
preparation phase (pressure and leak tests, conditioning and flushing),
the cool-down or warm-up sequences including the handling of
cryogenic fluids and finally the powering phase of magnets and
cavities. Preliminary conclusions of the commissioning of the first
LHC sectors will be drawn with the review of the critical points
solved or still pending. Finally this paper will report on the first
operation experience of the LHC cryogenic system in perspective of
the commissioning of the remaining LHC sectors and the beam
injection test.
C3-L-03 Validation and Performance of the LHC
Cryogenic System Through Commissioning of the First
Sectors
L. Serio, CERN.
The cryogenic system for the Large Hadron Collider accelerator is
presently in its final phase of commissioning at nominal operating
conditions. The refrigeration capacity for the LHC is produced using
eight large cryogenic plants and eight 1.8 K refrigeration units
installed on five technical sites. Machine cryogenic equipments are
installed in a 26.7 km circumference ring deep underground tunnel
and are maintained at their nominal operating conditions via a
distribution system consisting of transfer lines, cold interconnection
boxes at each technical site and a cryogenic distribution line.
The functional analysis of the whole system during all operating
conditions was established and validated during the first sectors tests
in order to maximize the system availability and minimize the
operation cost. The analysis, operating modes, main failure scenarios,
results and performances of the cryogenic system are presented.
C3-L-04 Thermal test of the cryogenic distribution line of
the first complete sector of the Large Hadron Collider
K. Brodzinski, S. Claudet, J. Fydrych, F. Millet, G.
Riddone, L. Serio, M. Strychalski, L. Tavian, CERN;
M. Chorowski, Wroclaw University of Technology.
The first of the eight sectors of the Large Hadron Collider (LHC) has
been completely installed in the underground tunnel and connected to
its cryogenic distribution line (QRL). The QRL will distribute the
gaseous and supercritical helium along the 3.3-km long sector. In the
so-called service modules the supercritical helium is sub-cooled and
then expanded to produce saturated 1.8 K superfluid helium This
helium is used as cryogenic refrigerant for the accelerator
superconducting magnets already immersed in a superfluid helium
bath at 1.9 K.
One of the next milestones, after the successful thermo-mechanical
validation of the QRL alone, carried out in 2005, is the hardware
commissioning of first complete sector of the LHC. One of the main
issues of this commissioning is the heat inleak measurements to the
different circuits located in the QRL as well as in the LHC machine.
The paper describes the applied heat inleak measurement
methodology, its accuracy and error estimation, as well as presents the
main results of the measured heat inleaks at the different temperature
levels. The measured heat inleaks will be also compared to the results
obtained from the test of the QRL alone.
C3-M Pulse Tube Theory and Models
C3-M-01 Performance Limits of 3He in Pulse Tube
Cryocoolers
P. Kittel, Consultant.
The enthalpy, entropy, and exergy flows of the real gas effects of 4He
in ideal pulse tube cryocoolers have been described previously.
Huang, et. al, have recently developed a computer program for the
thermophysical properties of 3He. This paper uses this model to
describe how the thermodynamic flows are affected by real gas
phenomena of 3He in ideal pulse tube cryocoolers.
Frequently such descriptions take an energy-centric view,
concentrating on the first law of thermodynamics, the conservation of
energy. This approach can result in a complex description of the
cooler in terms of energy and enthalpy flows.
An alternative is to take an entropy-centric approach. Closely related
to this is the exergy-centric approach. These descriptions concentrate
on the second law of thermodynamics, the generation of entropy or
the destruction of exergy.
Both the energy-centric and exergy/entropy-centric approaches make
use of both the laws of thermodynamics and both approaches give
equivalent descriptions of a cryocooler. However, the latter approach
can be more useful as it can yield a simpler description, one that
emphasizes loss mechanisms.
This paper applies the second law approach to pulse tube cryocoolers.
The non-ideal gas effects of 3He in Pulse Tube cryocoolers are
discussed and compared to similar effects from 4He.
This work was funded through University Affiliated Research Center
(UARC) Subcontract P0228861. The UARC is managed by the
University of California, Santa Cruz under NASA Ames Research
Center Contract NAS2-03144.
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