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This paper reviews the recent advances in Stirling-type pulse tube cryocoolers for aerospace applications in the author's group. Due to the special environment featuring the limited power supply and adverse rejection condition, high cooler efficiencies are emphasized and thus the approaches to realize them are stressed. The cold fingers involve thr...
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Context 1
... compressors are usually divided into three main types: moving-iron, moving-coil, and moving-magnet ones. The moving-coil design, due to its distinguishing advantages such as complete elimination of radial forces, absence of open circuit axial forces and torques, proven high efficiency, enhanced producibility and high reliability, has been chosen as the principal type for space missions [1][2][3][4][5][13][14]. Figure 5 shows a schematic of the dual-opposed moving-coil linear compressor developed in the author's group. It adopts the balanced-opposed arrangement so that the self-induced vibrations are offset. ...
Context 2
... during operation, either the coil must always be in the uniform magnetic field, or a fixed magnetic field has to remain within the coil. In practice, the magnet can be magnetized in either the radial or axial direction, and the coil can be made into either short or long. Our present designs adopt the axial magnet with long coil, as shown in Fig. 5. The studies on the main components, magnet, return irons and coils are regarded to be critical to achieve reliable and efficient linear motors. The emphases about the above studies have been laid on working out compact circuit with low flux ...
Citations
... In many special application fields such as in space, the stable performance is heavily stressed, and thus in our development the possibility of employing the double-inlet bypass is completely excluded, while the inertance tubes together with a gas reservoir is used as the only phase-shifter to ensure the performance stability in a long operation time. Furthermore, many practical applications have a high demand on both the system compactness and the easy integration between the SPTC and the device to be cooled [6]. A SPTC with the coaxial arrangement has strong appeal to these applications, but one of the key problems is to enhance its cooling efficiency [7]. ...
This paper presents the CFD modeling and experimental verifications of a single-stage inertance tube coaxial Stirling-type pulse tube cryocooler operating at 30–35 K using mixed stainless steel mesh regenerator matrices without either double-inlet or multi-bypass. A two-dimensional axis-symmetric CFD model with the thermal non-equilibrium mode is developed to simulate the internal process, and the underlying mechanism of significantly reducing the regenerator losses with mixed matrices is discussed in detail based on the given six cases. The modeling also indicates that the combination of the given different mesh segments can be optimized to achieve the highest cooling efficiency or the largest exergy ratio, and then the verification experiments are conducted in which the satisfactory agreements between simulated and tested results are observed. The experiments achieve a no-load temperature of 27.2 K and the cooling power of 0.78 W at 35 K, or 0.29 W at 30 K, with an input electric power of 220 W and a reject temperature of 300 K.
... In the authors' laboratory, the double-segmented inertance tube with different inner diameters and lengths, respectively , has usually been adopted as the main type of phase shifters (Dang, 2014Dang, , 2015). Based on Eqs. ...
The match between the pulse tube cold finger (PTCF) and the linear compressor of the Stirling-type
pulse tube cryocooler plays a vital role in optimizing the compressor efficiency and in improving the
PTCF cooling performance as well. In this paper, the interaction of them has been analyzed in a
detailed way to reveal the match mechanism, and systematic investigations on the two-way matching
have been conducted. The design method of the PTCF to achieve the optimal matching for the given
compressor and the counterpart design method of the compressor to achieve the optimal matching for
the given PTCF are put forward. Specific experiments are then carried out to verify the conducted
theoretical analyses and modeling. For a given linear compressor, a new in-line PTCF which seeks to
achieve the optimal match is simulated, designed and tested. And for a given coaxial PTCF, a new
dual-opposed moving-coil linear compressor is also developed to match with it. The simulated and
experimental results are compared, and fairly good agreements are found between them in both cases.
The matched in-line cooler with the newly-designed PTCF has capacities of 4 W to 11.84 W at 80 K
with higher than 17% of Carnot efficiency and the mean motor efficiency of 81.5%, and the matched
coaxial cooler with the new-designed compressor can provide 2 W to 5.5 W at 60 K with higher than
9.6% of Carnot efficiency and the mean motor efficiency of 83%, which verify the validity of the
theoretical investigations on the optimal match and the proposed design methods.
... In the authors' laboratory, the double-segmented inertance tube with different inner diameters and lengths, respectively , has usually been adopted as the main type of phase shifters (Dang, 2014Dang, , 2015). Based on Eqs. ...
Theoretical analyses and modeling are conducted on dynamic and thermodynamic characteristics of the moving-coil linear compressor in the Stirling-type pulse tube cryocooler. Governing equations are deduced, and φ and ΔP are found to be two key parameters connecting compressor to pulse tube cold finger. An improved ECA model is developed to investigate the cold finger characteristics and their influences on φ, ΔP. Systematic simulations based on a specific case are performed to provide elaborate explanations about the theoretical analyses with the frequency varying from 30 Hz to 100 Hz at 60 K, 80 K and 100 K, respectively. The variations of four important parameters of φ, ΔP, I and θ, and the compressor thermodynamic performances and the cryocooler cooling performances, with the frequency at above temperatures are simulated and analyzed, respectively. The effects of compressor geometrical parameters on ηmotor are also simulated. The experimental verifications will be presented in Part B.
... To verify above theoretical analyses about the partial scaling method, a typical compressor (shown in Fig. 4) developed in NLIP/SITP/CAS [8] is selected to scale. This original compressor couples with a coaxial pulse tube cold finger developed in the same laboratory [18] to form a cryocooler working above 50 K [17]. Table 3shows the capacity of the original cryocooler at the typical operating temperature of 80 K. Table 4shows the theoretical and actual scaling factors of selected dimensional parameters. ...
... The mature single-stage SPTCs has already been able to cover the temperature range of 25-200 K with the capacities varying from milliwatt levels to over 30 W, and a variety of space applications are underway. The previous reviews or studies [50][51][52][53][54][55] presented by the same author laid more emphases on the coolers as a whole or on their pulse tube cold fingers, this paper will present a review of the progresses in the moving-coil dual-opposed linear compressors in National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences (NLIP/SITP/CAS). In fact, in a SPTC, the linear compressor is the only part which includes the moving mechanical component and thus plays a major role in influencing the mean-time-to-failure (MTTF) of the cryocooler. ...
Pulse tube refrigerators do not have moving parts in the cold section, and they have low vibration, high reliability, and long life. The expander in refrigerators typically has an inverted U or coaxial shape because this attains a wider absorber area, lower height, and compactness. However, the performance of a Stirling‐type pulse tube refrigerator is inferior to that of a Stirling refrigerator. Cooling characteristics of the pulse tube refrigerator greatly depend on the shape of the expander. In this study, an inertance‐type refrigerator, which uses ambient air for the working gas, was developed to examine the effect of expander shape. This refrigerator model with changeable expander operated with a Stirling cycle, and it was composed of a reciprocating compressor, after‐cooler, regenerator, absorber, pulse tube, hot‐end, and inertance tube with reservoir. The following expander shapes were tested: in‐line, L shape, L‐L shape, and coaxial shape. The effect of expander shape on cooling capacity was examined experimentally and numerically using the model pulse tube refrigerator. The results of experiments showed that the L shape expander had the highest performance and the coaxial expander had the lowest performance. In addition, the characteristics of the gas flow in each expander were confirmed by fluid dynamics analysis. A model pulse tube refrigerator using ambient air with changeable expander was newly developed. The effect of expander shape was examined experimentally for four shapes, and the cooling capacity for each was measured. The expander shapes were ranked from high to low performance in the order L shape > L‐L shape ≅ in‐line shape > coaxial shape. Then, performance analysis by a simple numerical method was carried out. In addition, the gas flow in the expanders was visualized using CFD analysis.
Based on the structures and design equations of widely-used moving-coil linear compressor for pulse tube cryocoolers, the paper analyzes the theories of scaling laws and summarizes the principles for practical applications. The paper further puts forward the theories of partial scaling laws for moving-coil linear compressors, and have made the systematic theoretical and experimental investigations.
This paper reviews the recent advances in high efficiency pulse tube
cryocoolers (PTCs) in SITP/CAS for space-borne infrared applications.
Due to the special aerospace environment where the power supply is
limited and the rejection condition is adverse, the high cooler
efficiency is especially emphasized. A brief history of the PTC and the
last 30-year worldwide quest for highly reliable and efficient PTCs has
been provided as a background. Then our efforts to achieve high
efficiency coolers are discussed. Three typical geometrical
arrangements, U-type, coaxial and in-line, are all involved, while the
latter two are stressed on. Some typical development programs are
introduced and a brief overview of the relevant data package is
presented. To date, the no-load temperature reaches 25 K, and the
typical cooling capacities of 0.9W@40K, 4.5W@60K, 8.0W@80K and 12W@95K
have been achieved, respectively. For the mature coaxial coolers, the
typical relative Carnot efficiencies of 2.8%, 9.4%, 14.4% and 15.7% has
been achieved at 40 K, 60 K, 80 K and 95 K, respectively. For the
newly-developed high efficiency in-line PTCs, the corresponding values
are 2.9%, 9.6%, 16.2% and 17.8%, respectively. The acquired high
efficiencies have made them enabling cryocoolers for the aimed space
applications. The batch production of the main components has been
realized and the typical EM machines have been worked out.
