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

CEC 2007 - Abstracts
C2-P-04 Cryogenic design of the ALUHEAT project
I. Hiltunen, A. Korpela, R. Mikkonen, J. Lehtonen,
Tampere University of Technology; M. Runde,
SINTEF Energy Research; N. Magnusson, SINTEF
Energy Research ; G. Kalkowski, Fraunhofer IOF.
In this paper, the cryostat design of the ALUHEAT project that aims
to build a cryogen-free superconducting induction heater is presented
in detail. Designing of the cryostat involves heat loss calculations,
mechanical analysis and the optimization of current leads and cooling
conditions. The system consists of two separate cryostats between of
which the billet to be heated is located. Exceptionally short distance
between the magnet and the cryostat wall, the large forces between the
magnets in separate cryostats, and the rotation of the billet create
application specific requirements that must be taken into account.
Finite element analysis is used to design the cryostat to withstand both
the vacuum and magnetic forces.
Finally, the thermal interface, the radiation shield and the magnet
support are designed and all components assembled into the complete
system.
C2-P-05 Introduction of the 35kV/90MVA Saturated Iron
Core Type Superconducting Fault Current Limiter
Y. Xin, W.Z. Gong, X.Y. Niu, B. Tian, Z.J. Cao, H.X.
Xi, Y. Yang, J.Y. Zhang, X,M. Hu, H. Hong, A.L. Ren,
Z.L. Chen, H.H. Li, B. Hou, X.C. Yang, Innopower
Superconductor Cable Co..
A 35kV/90MVA prototype saturated iron core type superconducting
fault current limiter was developed and installed in a transmission
network for testing and trial operation. This prototype is of many
unique features, such as actively de-magnetizing the iron core when a
fault takes place to enhance the limiting capacity, additional circuit for
protecting the dc current supply and other components in the dc bias
side, and a new concept in iron core design. These innovations
overcome the shortcomings that the long-established design of a
saturated iron core type superconducting fault current limiting device
has, making this type of current limiter more reliable and efficient.
For the 35kV/90MVA system, we plan to carry out a live-grid trial
operation at Puji Substation of China Southern Power Grid for a long
period of time. In this presentation, we will report the technical
details of the system and the testing results we have got up to date.
C2-P-06 Modular concept for the cryopackaging design.
V.V. Borzenets, SLAC; I.V. Borzenets, Duke Univ.
Cryocooled devices and assemblies always involve two interfaces: the
cryogenic interface which provides the required low temperatures, and
the electronic interface which essentially provides the function of your
device. A problem with all current systems is that these two interfaces
are linked together. That means that in order to do any component
replacement or electronics maintenance, the entire system has to be
shut down and taken apart. This introduces extensive delays during
system assembly and usage. More over, this rules out a system with
easily interchangeable electronic components.
We propose a concept of modular packaging that will completely
decouple the cryogenic/temperature control interface with the
electronic interface. This will result in the ability to quickly remove
and replace one interface without the need to shut down or
disassemble the other. This means that the system will not only have
reduced servicing time, but that the system will have the capability to
do “cold swaps”. Conceptually, this would be achieved by having a
separate vacuum space for the cryogenic interface as well as for each
detachable electronic interface block. The thermal contact for all low
temperature stages of the cryocooler with the electronics package will
be achieved via properly matched thermal metal to metal contacts.
Wednesday, 07/18/07 Oral
5:00pm - 6:00pm
C2-R JT Coolers (Non-Aerospace)
C2-R-01 Fast Cool-Down J-T Cryocooler to 88K
N. Tzabar, I. Lifshits, A. Kaplansky, Rafael Ltd..
Fast cool-down is usually implemented with J-T cryocoolers which
also enable low-cost and small-scale systems. In this paper, we
describe an analysis for achieving cool-down time of a few seconds to
88K, using Argon as the main coolant, and at least 3 minutes of steady
state cooling. It appears that according to system demands, cost
reduction, reliability, and manufacturing considerations the use of
Argon as a single coolant is more beneficial than precooling with
another coolant, such as Krypton. The results were successfully
verified against experimental data.
C2-R-02 Vibration Characterization and Reduction of a
Joule-Thomson Cryocooler for a SQUID-Based Metal
Detection System
G.J. De Groot, CSIRO Industrial Physics, M.A.
SANTIN, CSIRO Industrial Physics & Federal
University of Santa Catarina, T. THIJSSEN, CSIRO
Industrial Physics & University of Twente.
Very sensitive high-temperature SQUID (Superconducting Quantum
Interference Device) magnetometers are used for the detection of very
small metal contaminants in food and other products. When the
SQUIDs are cooled with liquid nitrogen, a detection sensitivity of 500
nAm2 in a 150 × 150 mm2 orifice is obtained [1]. However, when a
commercial Joule-Thompson cryocooler was used, the sensitivity was
reduced by a factor of 5 due to spurious magnetic signals [2].
In this study the emphasis is on understanding noise that may be
created due to mechanical vibrations in the cryocooler cold head. The
natural frequencies of the cryocooler cold head are modelled and two
mechanisms of noise generation are considered and analysed.
Calculations show that the noise created by vibrating dipoles in the
cold head may create noise of 1 pT up to 20 pT in the frequency range
of 10 to 50 Hz. The vibration characteristics of several parts of the
cryocooler cold head assembly were determined with a laser
vibrometer, a fluxgate magnetometer and through finite element
simulations. Two natural frequencies of approximately 21 and 49 Hz
are particularly noticeable and are also observed in the SQUID noise.
Anti-vibration measures are introduced to reduce external vibrations.
Many thanks go out to Marcel Bick, David Tilbrook, Keith Leslie,
Barry Martin, Lawrence Dickinson, Prem Narang and Emma Mitchell
for their support and insights.
C2-R-03 Performance of a precooled J-T refrigerator
operating with refrigerant mixtures
C.T. Sairam, G. Venkatarathnam, Indian Institute of
Technology Madras.
Single stage J-T refrigerators operating with refrigerant mixtures are
under development worldwide. Precooled J-T refrigerators operating
with refrigerant mixtures were studies by Alexeev et.al for operation
in 90-100 K temperature range [1-2].
In this paper we present the results obtained by us in a two stage J-T
refrigerator. Mixtures of propane and ethane are used in the first stage,
and mixtures of neon,nitrogen,methane, ethane and propane in the
second stage. The refrigerator was tested in the temperature range 69-
85 K. A heat load of 9W was met at a temperature of 77K with a
power input of 1.4 kW. A heat load of 50W was met at a temperature
of 100K with a power input of 1.1-1.3 kW. The performance of the
refrigerator with different mixtures in the precooling stage and the
main stage are described in this paper.
References
1.Alexeev, A., Ch. Haberstroh and H. Quack (1998) Further
development of a mixed gas Joule-Thomson refrigerator. Advances in
Cryogenic Engineering, 43B, 1667-1675.
2.Alexeev, A., Ch. Haberstroh and H. Quack (1999) Mixed Gas J-T
Cryocooler with Precooling stage. Cryocoolers 10, 475-479.
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