Second law based modeling to optimum design of high capacity pulse tube refrigerators

The objective of the present work is to analyze the performance of the regenerator of pulse tube refrigerators. Hydrodynamic and thermal behavior of the regenerator is investigated in this respect. To consider the system performance, a system of conservation equations including two energy equations for the regenerator as a porous media is employed. The present model considers one dimensional periodic unsteady compressible flow in the regenerator. The conservation equations are transformed by implementing the volumetric average scheme. Method of harmonic approximation is employed to derive an analytical solution. To explore the system performance, net energy flow and entropy generation minimization technique is applied in order to calculate the regenerator first and second law efficiencies. The effect of geometry and operating key parameters on the regenerator performance are considered as well.

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Performance Analysis and Optimization of High Capacity Pulse Tube Refrigerator

ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, Volume 1 ◽

10.1115/esda2010-24863 ◽

2010 ◽

Author(s):

Amir R. Ghahremani ◽

F. Roshanghalb ◽

R. Jahanbakhshi ◽

M. H. Saidi ◽

S. Kazemzadeh Hannani

Keyword(s):

High Capacity ◽

Cooling Capacity ◽

Cooling Power ◽

Operating Parameters ◽

Geometrical Parameters ◽

Average Charge ◽

Pulse Tube ◽

Pulse Tube Refrigerator ◽

Aspect Ratios ◽

Pulse Tube Refrigerators

High capacity pulse tube refrigerator (HCPTR) is a new generation of cryocoolers tailored to provide more than 250 W of cooling power at cryogenic temperatures. The most important characteristics of HCPTR when compared with other types of pulse tube refrigerators are a powerful pressure wave generator, and an accurate design. In this paper the influence of geometrical and operating parameters on the performance of a double inlet pulse tube refrigerator (DIPTR) is studied. The DIPTR is modeled applying the nodal analysis technique, using mass, momentum and energy conservation equations. The model is able to compute instantaneous flow field throughout the system and calculate cooling capacity and COP. The model is validated with the existing experimental data. To perform the optimized mode of operation, the influence of both geometrical and operating parameters on cooling capacity and COP is investigated. The key geometrical parameters considered in this paper are aspect ratios of regenerator and tube section, length ratio of regenerator and tube, and type of screen mesh. The main operating parameters considered are average charge pressure, and position of opening of orifice and bypass. As a result of this optimization a new configuration of HCPTR is proposed. This configuration provides 300 W at 80 K cold end temperature with a frequency of 50 Hz and COP of 0.054.

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Experimental Investigation and Modeling of Inertance Tubes

Journal of Fluids Engineering ◽

10.1115/1.1989369 ◽

2005 ◽

Vol 127 (5) ◽

pp. 1029-1037 ◽

Cited By ~ 6

Author(s):

L. O. Schunk ◽

G. F. Nellis ◽

J. M. Pfotenhauer

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Acoustic Power ◽

Operating Conditions ◽

Thermodynamic Efficiency ◽

Pulse Tube ◽

Design Charts ◽

Wide Range ◽

Pulse Tube Refrigerators

Growing interest in larger scale pulse tubes has focused attention on optimizing their thermodynamic efficiency. For Stirling-type pulse tubes, the performance is governed by the phase difference between the pressure and mass flow, a characteristic that can be conveniently adjusted through the use of inertance tubes. In this paper we present a model in which the inertance tube is divided into a large number of increments; each increment is represented by a resistance, compliance, and inertance. This model can include local variations along the inertance tube and is capable of predicting pressure, mass flow rate, and the phase between these quantities at any location in the inertance tube as well as in the attached reservoir. The model is verified through careful comparison with those quantities that can be easily and reliably measured; these include the pressure variations along the length of the inertance tube and the mass flow rate into the reservoir. These experimental quantities are shown to be in good agreement with the model’s predictions over a wide range of operating conditions. Design charts are subsequently generated using the model and are presented for various operating conditions in order to facilitate the design of inertance tubes for pulse tube refrigerators. These design charts enable the pulse tube designer to select an inertance tube geometry that achieves a desired phase shift for a given level of acoustic power.

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