斯特林型两级脉管制冷机的研制

介绍了斯特林型两级脉管制冷机的研发过程,设计并制造了1台采用对置的动磁式直线压缩机驱动的两级脉管制冷机.对制冷机系统进行了初步的试运行,试验表明直线压缩机可以正常工作,在充气压力1.6MPa、工作频率30Hz、输入电功率220W时,产生1.3左右的压比,由该压机驱动的二级脉管制冷机,第一级和第二级分别获得124K和45K的低温.     

一种气动弹簧内置结构的斯特林制冷机设计

设计了一台100 W/77 K的分置式大冷量斯特林制冷机,其中气动弹簧组内置于空心排出器中,缩小了膨胀机的轴向尺寸。热端膨胀腔与压缩腔之间通过辐射状分布的分离式"明渠"结构通气槽连通,降低了加工难度。压缩机为对置式双气浮活塞结构,最大输入功率2 kW。介绍了该制冷机的热力设计和动力设计,给出了参数设计结果,最后分析了压缩机各类损失对制冷效率的影响。模拟结果表明,在1 064 W的PV功下,制冷机77 K可以获得104 W制冷量,当压缩机效率大于85%,热端温度20℃时,电功消耗小于1 252 W,比卡诺效率大于23%。     

热桥传热特性对热耦合二级Stirling型脉管制冷机性能的影响

级间热桥的传热特性对于热耦合型多级脉管制冷机的制冷温度和制冷效率均具有重要影响。采用铜丝编织带和铜箔连接的3种热桥进行对比实验，研究了热桥的传热特性对热耦合二级Stirling型脉管制冷机性能的影响。采用改进后的热桥，以氦气作为工质，在总输入电功率为400W，以及优化的工作频率和充气压力条件下，热耦合二级Stirling型脉管制冷机实现了12．96K的无负荷制冷温度，并可同时在23．1K和100．8K分别提供0．4W和6W的制冷量。     

6W@80K气动分置式斯特林制冷机轻量化设计和性能优化

介绍了一台由中国科学院上海技术物理研究所研制的6 W@80 K气动分置式斯特林制冷机样机,主要包括压缩机的轻量化设计和整机制冷性能的优化。该制冷机包括动磁式直线压缩机和气动膨胀机,制冷机整机质量为5.5 kg。压缩机采用两个对置布置的动磁式直线电机驱动,板弹簧支撑和无摩擦的间隙密封技术。经过对直线压缩机的结构优化,在6 W@80 K的制冷性能下,压缩机的输入电功从原来的163 W降低到106 W。     

13.5K两级气耦合型高频脉冲管制冷机实验研究

高频脉冲管制冷机由于冷端无运动部件、振动小、寿命长等优点,广泛运用于低温物理实验、航空航天等领域。通过介绍一种两级气耦合高频脉冲管制冷机,在该脉冲管的第一级中,采用了双向进气和多路旁通作为调相机构,为获取更好的调相效果,第二级脉冲管的惯性管和气库被置于第一级的冷头处。为了进一步调节第二级脉冲管中压力波质量流的相位差,将压缩机的气流引入二级脉冲管热端作为第二级脉冲管的双向进气。该制冷机在充气压力1.7 MPa,输入电功250 W的工况下,可以获得13.5 K的无负荷制冷温度,0.6 W@30 K的制冷量。文章对该制冷机实验结果进行了总结。     

分离型二级脉管制冷机的实验研究--Ⅱ:液氦温区二级脉管制冷机

研制1台新型液氦温区分离型二级脉管制冷机,该制冷机由2台独立的脉管制冷机组成,一级回热器冷端和二级回热器中部通过热桥相连,从根本上弥补了传统直接耦合型多级脉管制冷机级间干扰的不足.采用双压缩机双旋转阀驱动该二级脉管制冷机,第二级最低温度达到了2.5 K,在4.2 K下有508 mW制冷量,同时一级在37.5 K有15 W制冷量.第二级充气压力由1.7 MPa增大到1.85 MPa,制冷机在4.2 K下的制冷量可以达到590 mW.为了能简化结构、扩大应用,提出采用单压缩机单旋转阀驱动该分离型脉管制冷机,达到了相同的制冷性能.     

6 W@90 K星载斯特林制冷机的热环境适应性

针对某空间任务要求,分析了热试验温度取值.基于1台6 W@90 K星载斯特林制冷机,开展了常压热循环和热真空试验研究,得到了制冷机在不同温区下的制冷性能参数.从6个方面对比分析了两个试验中性能参数的变化,最后得出:环境温度对6 w制冷机性能影响较大,从50 ℃到-20℃温区,制冷温度为90 K时,冷量增大约1.4 W,功耗减小约17 W;在50至-20℃温区内,制冷机未发生结构热变形失效.该6 W型制冷机在合理设计辅助散热(卫星总体热控调节)之后,可满足空间应用时-20℃-40 ℃温区热环境适应性;压缩机和膨胀机通过良导热体连接散热,可平衡温差,便于控温.     

分离型二级脉管制冷机的实验研究第一部分20～40 K温区单级大功率脉管制冷机

为了满足液氦温区分离型二级脉管制冷机第二级预冷的需要,设计制作了1台20～40K温区单级大功率脉管制冷机.采用额定功率为6 kW的压缩机驱动该制冷机,最低制冷温度达13.8K,刷新了单级脉管制冷机最低制冷温度纪录.该制冷机在40 K可获得高达55.9 W的制冷量,基本可以满足15～40 K温区超导磁体等冷却的需要.着重分析了频率、充气压力和不同压缩机对系统制冷性能的影响,测试了长时间运行中系统性能的变化情况.     

电阻阵列冷却用脉管制冷机研制

为解决以电阻阵列器件为基础的动态红外景像产生器中的冷却问题,设计并研制了一台采用线性压缩机驱动的在223 K工作的脉管制冷机。实验结果表明:在500 W的电输入功下,制冷机的最低无负荷制冷温度为99.7 K,在232.8 K获得了181.3 W的制冷量,与理论预测制冷量189.4 W吻合良好,相对卡诺效率达到10.4%,工作对脉管制冷机在普冷温区的应用是一次有益的探索。     

1.6kg小型同轴脉冲管制冷机实验研究

小型脉冲管制冷机在空间以及军事领域有广泛的应用前景,通过提高制冷机的工作频率可减小制冷机的体积与质量。研制了1台重1.6 kg的脉冲管制冷机并进行了实验优化。采用实验室研制的小型直线压缩机驱动,惯性管气库、双向进气作为调相机构,在输入电功45 W,冷端温度80 K时可获得2.12 W的制冷量,相对卡诺效率13.0%。由于运行频率高,冷指尺寸小,冷指降温时间短,2 min降温到80 K,并且冷头温度受重力影响较小。     

120 K～150 K温区混合工质内复叠节流制冷机的实验研究

混合工质节流制冷机在许多方面获得越来越广泛的应用,本文提出了利用内复叠节流制冷系统获得120K－150K温区的制冷方安分析了它的应用前景,建立了相应的单级油润滑制冷压缩驱动的实验系统。无热负荷时最低温度达到112K,在130K时获得了60W的制冷量,135K时获得了74W的制冷量。     

Two-stage high frequency pulse tube cooler for refrigeration at 25 K

A two-stage Stirling-type U-shape pulse tube cryocooler driven by a 10 kW-class linear compressor was designed, built and tested. A special feature of the cold head is the absence of a heat exchanger at the cold end of the first-stage, since the intended application requires no cooling power at this intermediate temperature. Simulations where done using Sage-software to find optimum operating conditions and cold head geometry. Flow-impedance matching was required to connect the compressor designed for 60 Hz operation to the 40 Hz cold head. A cooling power of 12.9 W at 25 K with an electrical input power of 4.6 kW has been achieved up to now. The lowest temperature reached is 13.7 K.     

Model for transient behavior of pulse tube cryocooler

This article describes an investigation of the transient behavior of a small (2.0 W at 85 K) pulse tube cryocooler operating at 120 Hz with an average pressure of 3.5 MPa, capable of relatively fast cool-down from ambient to about 60 K. In a series of experiments, the cold end temperature was measured as a function of time in a complete cool-down and subsequent warm-up cycle, with no heat load and different quantities of excess mass at the cold end. A transient heat transfer model was developed, that considers the effects of the cooling power extracted at the cold end and that of the heat gain at the warm end on the cool-down time. The heat gain factor was calculated from warm-up data, and found to be approximately the same for all experiments. Using the same model with cool-down data enables a determination of both the gross and net cooling power as functions of time, but more importantly – as functions of the cold end temperature. An expression was derived for the cold end temperature as a function of time for any amount of excess mass, including zero. The cool-down time of the “lean” cryocooler (with no excess mass) was found to be less than 50 s.This cool-down/warm-up method for evaluating the cooling power of a cryocooler seems simpler than steady-state experiments with a heater simulating load at the cold end. Use of the heat transfer model with data from one or two good experiments conducted in the above manner, can yield both the gross and net cooling powers of a cryocooler as functions of the cold end temperature, and allow the determination of cool-down time with any amount of excess thermal mass. While the net cooling power during cool-down differs somewhat from that under steady-state operation, the former can serve as a good measure for the latter.     

A cryogen-free Vuilleumier type pulse tube cryocooler operating below 10 K

Vuilleumier (VM) type pulse tube cryocooler (PTC) utilizes the thermal compressor to drive the low temperature stage PTC. This paper presents the latest experimental results of a cryogen-free VM type PTC that operates in the temperature range below 10 K. Stirling type pre-coolers instead of liquid nitrogen provide the cooling power for the thermal compressor. Compared with previous configuration, the thermal compressor was improved with a higher output pressure ratio, and lead and HoCu₂ spheres were packed within the regenerator for the low temperature stage PTC for a better match with targeted cold end temperature. A lowest no-load temperature of 7.58 K was obtained with a pressure ratio of 1.23, a working frequency of 3 Hz and an average pressure of 1.63 MPa. The experimental results show good consistency in terms of lowest temperature with the simulation under the same working condition.     

15 K two-stage Stirling-type pulse-tube cryocooler

A two-stage pulse-tube cryocooler driven by a linear compressor was designed, manufactured and tested. The compressor is a moving-magnet type and dual-opposed-piston configuration, in which a plate spring is used. The two-stage cold head is a gas-separating thermal-link configuration. The phase shifter of each stage of the cryocooler can be double-inlet or inertance-tube type. Experiments have been carried out. The linear compressor can provide a pressure ratio of 1.3-1.5. Under the conditions of 1.2 MPa charging pressure and 32 Hz frequency, the second stage of the cryocooler reached a lowest temperature of 14.2 K, and the corresponding cooling temperature of the first stage is 93.3 K.     

CFD modeling and experimental verification of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler operating at 90–170 Hz

This paper presents the CFD modeling and experimental verifications of oscillating flow and heat transfer processes in the micro coaxial Stirling-type pulse tube cryocooler (MCSPTC) operating at 90–170 Hz. It uses neither double-inlet nor multi-bypass while the inertance tube with a gas reservoir becomes the only phase-shifter. The effects of the frequency on flow and heat transfer processes in the pulse tube are investigated, which indicates that a low enough frequency would lead to a strong mixing between warm and cold fluids, thereby significantly deteriorating the cooling performance, whereas a high enough frequency would produce the downward sloping streams flowing from the warm end to the axis and almost puncturing the gas displacer from the warm end, thereby creating larger temperature gradients in radial directions and thus undermining the cooling performance. The influence of the pulse tube length on the temperature and velocity when the frequencies are much higher than the optimal one are also discussed. A MCSPTC with an overall mass of 1.1 kg is worked out and tested. With an input electric power of 59 W and operating at 144 Hz, it achieves a no-load temperature of 61.4 K and a cooling capacity of 1.0 W at 77 K. The changing tendencies of tested results are in good agreement with the simulations. The above studies will help to thoroughly understand the underlying mechanism of the inertance MCSPTC operating at very high frequencies.     

1W／80K双活塞对置直线驱动斯特林制冷林的研究

介绍一种1W／80K双活塞对置直线驱动斯特林制冷机，它具有振动小，结构紧凑，噪音低，可靠性高等特点。该机在80K时制冷量为1．3W，降温时间小于3.5min（350J热负载）。     

Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2.     

两级同轴型脉管制冷机回热器与脉管壁换热影响的模拟与实验

针对同轴型结构的两级脉管制冷机,采用热力学方法分析了回热器与脉管壁间换热作用对制冷机性能的影响。发现当脉管内热量通过壁面传向回热器时,脉管冷端焓流将增大,进而提升脉管冷指的制冷量。对设计的一台两级同轴型高频脉管冷指进行了数值模拟。模拟结果表明相同结构参数及输入下,引入回热器与脉管壁间的径向换热作用,低温级制冷量由原先的0.55 W@30 K提升至1.39 W@30 K,而对高温级的影响却小到可以忽略。