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

CEC 2007 - Abstracts
C2-K-03 Evolution of the standard helium liquefier and
refrigerator range designed by Air Liquide Advanced
Technology Division, France
A. Caillaud, S. Crispel, V. Grabié, F. Delcayre, G.
Aigouy, Air Liquide DTA.
The standard helium liquefier and refrigerator range, called HELIAL
and designed by Air Liquide DTA, has recently been upgraded in
order to improve the efficiency of these machines. Indeed in the multirange
of markets requiring these cryogenic systems, (international
laboratories, aerospace applications, synchrotrons, HTS
applications...), the technological solution has to provide increasingly
high performances. The new HELIAL Evolution range, equipped with
very reliable DTA turbo-expanders, will constitute a highly efficient
product for this wide application field. The optimizations, adaptations
and results of the HELIAL Evolution series, doubling the performance
for the same electrical consumption, will be presented.
C2-K-04 Cryocooler for Air Liquefaction Onboard Large
Aircraft
J.J. Breedlove, P.J. Magari, Creare Inc.; G.W. Miller,
Air Force Research Laboratory.
Creare has developed a turbo-Brayton cryocooler designed to produce
approximately 1 kW of refrigeration at 95 K. The cryocooler is
intended to provide cryogenic cooling to an air separation system
being developed for the Air Force to produce and store liquid oxygen
and liquid nitrogen onboard large aircraft. The oxygen will be used
for high-altitude breathing and medical evacuation operations, while
the nitrogen will be used to inert the ullage space inside the fuel tanks.
The cryocooler utilizes gas bearings in the turbomachines for long life
without maintenance, which is a critical requirement for this
application. The mass of a flight version of this cryocooler is
expected to be around 270 kg, while the input power is expected to be
approximately 25 kW. This paper describes the design and testing of
the laboratory demonstration cryocooler that was constructed to
demonstrate the feasibility of the approach. In the future, the
cryocooler will be integrated and tested with a distillation column
subsystem. Subsequent testing may also be performed in-flight on an
Air Force transport aircraft.
C2-K-05 Process Study of Nominal 2 K Refrigeration
Recovery
P.N. Knudsen, V. Ganni, Jefferson Lab.
There is an increased interest in the nominal 2K helium refrigeration
systems (below lambda) for test stands at the present time. This paper
presents the process parameter choices and their influence on the
system performance of various non-cold compressor configurations.
This study is intended to facilitate the adoption of this process in
conjunction with commercially available small 4.5K helium
refrigerator systems. By way of an introduction, the efficiency of
some commonly employed (but inefficient) 2 K process
configurations are analyzed. Then the analyses of three nominal 2K
refrigeration recovery process configurations utilizing a refrigeration
recovery heat exchanger are presented. The effect of the process
parameters, such as flow imbalance, heat exchanger size, supply
pressure and 4.5K plant injection location are investigated so that the
conditions yielding the maximum coefficient of performance can be
determined.
C2-K-06 Recent progress in dynamic process simulations
of cryogenic refrigerators
A. Kuendig, Linde Kryotechnik AG.
At the CEC 2005 a paper with the title “Helium refrigerator design for
pulsed heat load in Tokamaks“ was presented. That paper highlighted
the control requirements for cryogenic refrigerators to cope with the
expected load variations of future nuclear fusion reactors. First
dynamic computer simulations have been presented.
In the mean time, the computer program is enhanced and new series
of process simulations are available. The new program considers not
only the heat flows and the temperature variations within the heat
exchangers, but also the variation of mass flow and pressure drops.
The heat transfer numbers now are calculated in dependence of the
flow speed and the gas properties. PI-controllers calculate the
necessary position of specific valves for maintaining pressures,
temperatures and the rotation speed of turbines.
The value of such a program is the tracing of difficult transient
operating modes in the design phase of a refrigerator. The simulation
further is helpful for testing control programs in absence of the real
refrigerator and it enables to find optimal control parameters. Worth
mentioning that such a program is applicable for the education of
engineers and operators.
C2-K-07 Design of Subcooled Pressurized Cryogenic
Systems
G.E. McIntosh, Cryogenic Technical Services, Inc..
High temperature superconducting power lines and various beamline
targets require cooling with subcooled, non-boiling cryogens in the
pressure range from 5 to 15 Bar. In conventional closed-loop
refrigerated systems this is accomplished by using a pressurized
ballast cryogen dewar to maintain the desired pressure. Although
consumption is modest, cryogen flows continuously from the ballast
dewar and periodic replenishment is necessary. This paper describes
an innovative refrigerated system which eliminates the ballast dewar
and operates continuously without cryogen or gaseous make-up after
the initial fill.
C2-K-08 The Cost of Helium Refrigerators and Coolers
for Superconducting Devices as a Function of Cooling
Power at 4.5 K
M. A, Green, Lawrence Berkeley National
Laboratory.
This paper is written in memory of Rod Byrns of the Lawrence
Berkeley National Laboratory who died two years ago.
This paper is an update of papers written in 1991, 1997 by Rod Byrns
and this author concerning estimating the cost of refrigeration for
superconducting magnets and cavities. The actual costs of helium
refrigerators and coolers (escalated to 2007 dollars) are plotted and
compared to a correlation function. A correlation function between
cost and refrigeration at 4.5 K and 1.8 K is given. The capital cost of
larger refrigerators (greater than 50 W at 4.5 K) 1s plotted as a
function of 4.5 K cooling. The cost of small coolers is also plotted as
a function of refrigeration available at 4.5 K. An annual cost for
refrigeration can also be estimated based on the refrigeration at 4.5 K
or 1.8 K and the cost of electrical energy. A correlation function for
estimating input power to the compressors to the refrigeration
produced at 4.5 K and 1.8 K is also given.
This work was supported by the Office of Science, United States
Department of Energy, under DOE contract DE-AC02-
05CH11231.
C2-L Stirling and Pulse Tube Coolers,
Development and Testing (Aerospace)
C2-L-01 Development Of A 4.5 K Pulse Tube Cryocooler
For Superconducting Electronics
Ted Nast , Jeff Olson , Patrick Champagne , Jack
Mix, Bobby Evtimov, Eric Roth , Andre Collaco , ,
Lockheed Martin Space Co.
Lockheed Martin`s Advanced Technology Center is developing a four
stage pulse tube to provide temperatures of 4.5 K for superconducting
electronics to be used in a ground based communications system. We
have developed prior 4 stage units which have operated down to 3.8K.
The relatively high cooling loads for this program led us to a design
which reduces the input power over prior systems. The design of the
system includes a unique pulse tube approach using both Helium-3
and Helium 4 working gas in two separate compression spaces, which
leads to enhanced power efficiency. The compressor is our standard
moving magnet, clearance seal, flexure bearing system. This paper
will present the experimental data and compare it with our prediction
methods.
The system is compact, lightweight and reliable and utilizes our
aerospace cooler technology to provide unlimited lifetime. The unit is
an engineering model to demonstrate proof of concept. Follow on
production for ground based communication systems is anticipated.
This work is subcontracted from HYPRES and is funded by the Army
and the Navy
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