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

CEC 2007 - Abstracts
C2-E-02 Hybrid Regenerator for Compact Stirling
Cryocooler Design aspectes of a compact hybrid
regenerator for pulse tube cryocooler application
B.T. Kuzhiveli, National Inst. of Technology Calicut.
A study has been conducted to find out the optimum configuration of
regenerators to be used for miniature cryocoolers. Mesh sizes starting
with 200 up to 400 with an interval of 50 have been sampled and
performance estimation has been made. The study has been extended
to determine the performance of a hybrid regenerator and its
suitability to use in a cryocooler which can produce 5W at 80 K. A
methodology has been developed to arrive at the appropriate mesh
size and number of mesh to be used in the hybrid regenerator to go
hand in hand with the available mass. Results are presented in the
form of design charts for quick reference which could be helpful in
the design of miniature regenerators.
C2-E-03 Dynamic characteristics of oscillating flow
regenerators
H.L. Chen, L.W. Yang, J.H. Cai, J.T. Liang, Y. Zhou,
Technical Institute of Physics and Chemistry, CAS.
Regenerator is the most important component in a pulse-tube
cryocooler. Because of oscillating flow, heat transfer and flow
resistance in the regenerator are complex, and phase shifts between
parameters affect the cooling performance evidently. Regenerator
research is a fundamental work for cryocoolers. Experiments are
performed to test regenerators of different size filled with different
mesh number screens. Two fine hot-wire anemometers are used to
measure the instantaneous velocities at the inlet and outlet of the
regenerators, and the pressure waves are measured by piezoelectric
pressure transducers at the same positions. The responding frequency
of the measuring system is high enough.
In the past, we have performed experiments to study the oscillating
flow at around 50Hz.In this paper, the system is driven by a
thermoacoustic engine which generates a pressure wave at 300Hz.
The two kinds of results are compared and analyzed.
C2-E-04 Analysis of Cryogenic Regenerator for Magnetic
Refrigerator Applications
B.T. Kuzhiveli, National Institute of Technology
Calicut; R. Chahine, T.K Bose, Institut de recherche
sur l’hydrogène, Université du Québec; C.B. Zimm,
Astronautics Corporation of America.
Magnetic refrigeration uses the temperature and field dependence of
the entropy of specific magnetic materials to accomplish cooling.
Because of the high efficiency of the magnetization and
demagnetization processes and also because of the potential for
excellent heat transfer between solid magnetic material and fluids,
magnetic refrigerators may promise to have higher efficiency than
existing gas cycle refrigerators. Many ground based and space borne
applications could benefit significantly from the cost savings implied
by efficiency. This paper deals with a basic computational model
which could predict the temperature drop caused by the regenerator
effect. It solves partial differential equations that describe fluid flow
combined with heat transfer between fluid and solid regenerator
particles. Temperature changes are calculated for discrete material
segments at a number of time intervals over a complete operation
cycle. A numerical step-by-step procedure to solve the differential
equations describing the regenerative heat exchanger is set out and a
computer program has been made to predict performance of the
regenerator.
C2-E-05 Second-Law Analysis and Optimization of
Regenerators Using REGEN 3.2
A.J. Lopez, The Univ. of Nex Mexcio; Sandia Nat`l
Laboratories; C. Dodson, A. Razani, The Univ. of New
Mexico; Air Force Research Lab..
In most Stirling and pulse tube refrigerators the regenerative heat
exchanger is the major contributor to the irreversibility of the
refrigerators. Exergy analysis is a convenient method to quantify the
losses in regenerators. NIST Code REGEN 3.2 provides a powerful
tool to quantify exergy flow in the regenerators to evaluate the exergy
destruction (irreversibility) due to heat transfer and fluid friction. The
effect of important parameters, with emphasis on the phase shift
between the pressure and the mass flow rate at the cold side of
regenerator, on the exergetic efficiency and the important components
of exergy destruction in the regenerator is presented. The efficiency
of the regenerator based on exergy analysis is compared to other
methods of evaluating regenerator performance. The ability of the
code to quantify the exergy flow and destruction at low temperatures
where the ideal gas assumption is not applicable is discussed.
C2-E-06 Longitudinal Hydraulic Resistance Parameters
of Cryocooler and Stirling Regenerators in Steady Flow
W.M. Clearman, S.M. Ghiaasiaan, P.V. Desai, G.W.
Woodruff School of Mechanical Engineering Georgia
Institute of Technology.
The results of an ongoing research program aimed at the measurement
and correlation of anisotropic hydrodynamic parameters of widelyused
cryocooler regenerator fillers are presented. The hydrodynamic
parameters associated with steady, longitudinal flow are addressed in
this paper. An experimental apparatus consisting of a cylindrical test
section packed with regenerator fillers is used for the measurement of
axial permeability and Forchheimer coefficients, with pure helium as
the working fluid. The regenerator fillers that are tested include
stainless steel 400-mesh screens with 69.2% and 62% porosity,
stainless steel 325-mesh screens with 69.2% and 62% porosity,
stainless steel 400-mesh sintered filler with 62% porosity, and
stainless steel sintered foam metal with 56% porosity. The test section
is subjected to a steady flow of helium at one end, and is open to the
atmosphere at the other end. The instrumentation includes pressure
transducers and a high-precision flow meter. For each filler material,
time histories of local pressures at inlet to the regenerator are
measured under steady flow conditions over a wide range of flow
rates. A CFD assisted methodology is then used for the analysis and
interpretation of the measured data. The permeability and
Forchheimer parameter values obtained in this way are then correlated
in terms of the relevant dimensionless parameters.
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