脉管制冷机研究进展

回顾了脉管制冷的发展简史，总结了最近１０年脉管制冷研究取得的突出成就及其水平，叙述了相移原理对了解脉管制冷机理及强化制冷效应的作用，指出了脉管制冷机发展的方向。有阀脉管制冷机有可能取代常规Ｇ－Ｍ制冷机，无阀脉管制冷机将成为空间用斯特林制冷机的竞争对手。最后讨论了可达到液氦温度的多级脉管制冷机的级联方法及相关的若干重要问题。     

高性能低温制冷机--脉管制冷机研究进展

回顾了自20世纪60年代中期至今脉管制冷机的发展历史，探讨了促使脉管制冷机从实验阶段发展成为当前最高效低温制冷的各种因素，阐述了不同形式脉管及热声制冷机的工作机理，简要介绍了近年来为减少不同组件的各种损失，从而提高其效率所作的一些改进。列举了脉管制冷机还存在的主要问题和部分应用例子。目前，脉管制冷机在80K温区的效率已经达到了卡诺效率的20％，并且获得了2K的最低制冷温度。     

低于4K的三级脉管制冷机的新型结构

叙述了用以提高多级脉管制冷机的工作性能和系统简单化的新结构．为减少国热器的损失和脉管冷损，在从室温到液氦温区内工作的脉管制冷机中引入了回热管．采用这种结构的三级制冷机达到了３．６Ｋ的最低温度，４．９Ｋ时制冷量为１１９ｍＷ．给出了该脉管制冷机的实验结果和制冷性能．     

基于REGEN的100 mm长回热器脉管制冷机优化设计与实验研究

根据已有研究,回热器长度100 mm的脉管制冷机在温度低于60 K时的性能较好。将一台已有的65 mm长回热器单级同轴型脉管制冷机改造为100 mm长回热器单机同轴型脉管制冷机,分析回热器长度对脉管制冷机性能的影响。基于REGEN软件对脉管制冷机回热器进行优化设计,通过改变回热器填料、压比、冷端相位角和充气压力,研究其对回热器性能的影响。在实验中进一步探索研究输入功、频率等对制冷机的最低制冷温度和比卡诺效率的影响。实验结果表明,在充气压力2 MPa,运行频率51 Hz,输入功809 W,制冷量60 W时,冷头温度109 K,制冷机的相对卡诺效率达到12.9%。     

液化天然气温区大功率脉管制冷机模拟及实验研究

大功率脉管制冷机有望满足小型液化天然气装置的各种需求,介绍了一台大功率脉管制冷机的优化及实验结果。模拟结果表明,采用0.03 mm丝径的300目丝网能提高脉管制冷机的制冷效率,在进行了两种回热器丝网规格的对比实验之后,验证了模拟结果,通过对制冷机冷端均流器进行改进,大大提高了脉管制冷机的性能。实验结果表明,在输入功为5 501 W时,于119.7 K下获得了500 W的制冷量,其比卡诺效率为13.7%。     

有阀型小孔脉管制冷机的深入研究

为了克服第三代脉管制冷机存在的制冷温度不稳定的缺陷,本文从提高脉管制冷效率,进一步降低制冷温度的角度,对有阀型小孔脉管制冷机进行了研究。通过理论计算和实验改进,有阀型单级脉管制冷机取得了３４Ｋ的无负荷制冷温度,在８０Ｋ获得３０Ｗ以上的制冷功率,其制冷效率达到国外同类商品型有阀脉管制冷机的水平。     

基于线性压机驱动的高频同轴脉管制冷机研究

介绍了基于线性压机驱动的高频同轴脉管制冷机的特点及同轴脉管制冷机与线性压机匹配时的设计思路,通过数值计算模拟了同轴脉管制冷机制冷性能和动态参数的关系。搭建了脉管制冷机试验台并介绍了测试系统的组成,最后对所设计的高频同轴脉管制冷机进行了初步试验研究。试验结果对进一步改进脉管制冷机的设计提供了有益的参考。     

主动调相型脉管制冷机数值模拟与实验研究

设计了一台主动调相型斯特林脉管制冷机,采用线性压缩机作为脉管制冷机主动调相控制器(APC),连接于冷指热端出口。通过控制调相压缩机与驱动压缩机(PWG)间的位移相位角实现主动调相,从而调节质量流和压力波之间的相位关系,优化制冷性能。利用模拟软件进行数值模拟并进行实验研究。研究结果表明,定输入功下APC与PWG位移相位角为-110°及扫气容积比(PWG扫气容积/APC扫气容积)2.98时,无负载制冷温度最低,同时比卡诺效率最高,能够达到原惯性管型脉管制冷机同样的效率。     

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。     

脉管制冷机污染试验研究

通过强化加速试验,从运行时间、加热烘烤温度、自由气体污染和约束气体污染等方面研究了工质气体污染对脉管制冷机制冷性能的影响,试验结果表明,脉管制冷机在工作时,污染物在回热器内的重新分布以及污染回热材料是脉管制冷机产生污染效应的主要因素。结合传热及流阻等理论对试验结果进行了机理分析,其试验结论有助于脉管制冷机的空间工程化应用。     

Experimental study of a cascade pulse tube cryocooler with a displacer

Recovering the expansion power in pulse tube cryocooler is of great utility in improving cooling efficiency. Using a second-stage cooler after a primary cooler to produce extra cooling power is an effective way especially when the cooling temperature is not very low. In the configuration, the two coolers are connected by a displacer which is used as a phase shifter. In this paper, experimental investigations were conducted to study this system. Firstly, the performance of the overall system and separated cooler was respectively presented. To better understand the displacer, phase relation, mechanical resistance and displacement were then clarified. In addition, the power consumption distribution of the cascade cryocooler was discussed. Finally, both numerical and experimental comparisons were made on the displacer-type and tube-type cryocooler. The experimental results show that the displacer-type cryocooler has superior performance due to the better phase-modulation capability and less power loss. With the input electric power of 1.9 kW and cooling temperature of 130 K, the overall system achieved a cooling power of 371 W and a relative Carnot efficiency of 24.5%.     

High-efficiency 3 W/40 K single-stage pulse tube cryocooler for space application

Temperature is an extremely important parameter for space-borne infrared detectors. To develop a quantum-well infrared photodetector (QWIP), a high-efficiency Stirling-type pulse tube cryocooler (PTC) has been designed, manufactured and experimentally investigated for providing a large cooling power at 40 K cold temperature. Simulated and experimental studies were carried out to analyse the effects of low temperature on different energy flows and losses, and the performance of the PTC was improved by optimizing components and parameters such as regenerator and operating frequency. A no-load lowest temperature of 26.2 K could be reached at a frequency of 51 Hz, and the PTC could efficiently offer cooling power of 3 W at 40 K cold temperature when the input power was 225 W. The efficiency relative to the Carnot efficiency was approximately 8.4%.     

Development of high efficiency Stirling-type pulse tube cryocoolers

Thermoacoustic theory is a powerful tool to understand the working mechanism of regenerative thermodynamic systems. In this paper, a modified thermoacoustic model is employed to design three single-stage Stirling-type pulse tube cryocoolers. The first one (PTC-10) is designed with in-line configuration and the second one (CPTC-10) is designed with co-axial configuration. Both of them are able to provide about 10 W cooling power at 77 K with a relative Carnot efficiency of about 18.6%. The third one (PTC-20), designed with in-line configuration, has a twice cross section area of the PTC-10. It can provide more than 20 W cooling power at 77 K with a relative Carnot efficiency of 22%.     

Theoretical and experimental study of a gas-coupled two-stage pulse tube cooler with stepped warm displacer as the phase shifter

A compact and high efficiency cooler working at liquid hydrogen temperature has many important applications such as cooling superconductors and mid-infrared sensors. This paper presents a two-stage gas-coupled pulse tube cooler system with a completely co-axial configuration. A stepped warm displacer, working as the phase shifter for both stages, has been studied theoretically and experimentally in this paper. Comparisons with the traditional phase shifter (double inlet) are also made. Compared with the double inlet type, the stepped warm displacer has the advantages of recovering the expansion work from the pulse tube hot end (especially from the first stage) and easily realizing an appropriate phase relationship between the pressure wave and volume flow rate at the pulse tube hot end. Experiments are then carried out to investigate the performance. The pressure ratio at the compression space is maintained at 1.37, for the double inlet type, the system obtains 1.1 W cooling power at 20 K with 390 W acoustic power input and the relative Carnot efficiency is only 3.85%; while for the stepped warm displacer type, the system obtains 1.06 W cooling power at 20 K with only 224 W acoustic power input and the relative Carnot efficiency can reach 6.5%.     

Numerical analysis of stirling type pulse tube cryocoolers

A one-dimensional finite volume discretization method is proposed and is implemented as a computer program for the modeling of a family of stirling type Pulse Tube Cryocoolers (PTC). The set of unsteady, one-dimensional, viscous compressible flow equations are written in a general form such that all, porous and non-porous, sections of the PTC can be modeled with these governing equations. In present work, temperature dependency of thermo-physical properties are taken into account as well as the heat transfer between the working fluid and the solid parts, and heat conductions of the gas and solid. The simulation tool can be used to model both the inertance tube type and the orifice type cryocoolers equipped with regenerators made up of different matrix constructions. The PTC might have an arbitrary orientation with respect to the gravitational field. By using the computer program, an orifice type and an inertance tube type pulse tube cryocooler are simulated. Diameter of the orifice and length of the inertance tube are optimized in order to maximize the coefficient of performance. Furthermore, the cooling power of the two types is obtained as a function of the cooling temperature. The behavior of thermodynamic parameters of the inertance tube PTC is investigated. Mean cyclic values of the parameters are presented.     

Numerical investigation on a 300 Hz pulse tube cryocooler driven by a three-stage traveling-wave thermoacoustic heat engine

A 300 Hz pulse tube cryocooler (PTC) driven by a three-stage traveling-wave thermoacoustic heat engine (TSTHE) has been proposed and studied in this paper. In the configuration, three identical thermoacoustic heat engine units are evenly incorporated in a closed traveling-wave loop, in which three pulse tube cryocoolers are connected to the branch of each thermoacoustic heat engine. Compared with the conventional thermoacoustic heat engine which involves a traveling-wave loop and a long resonator, it has advantages of compact size and potentially high thermal efficiency. A TSTHE–PTC system was designed, optimized and studied in detail based on the thermoacoustic theory. Firstly, numerical simulation was conducted to design the system thus the optimum structure parameters of the system were obtained. With the operating condition of 4 MPa mean pressure and high working frequency, a cooling power of 7.75 W at 77 K and an overall relative Carnot efficiency of 11.78% were achieved. In order to better understand the energy conversion characteristics of the system, distributions of key parameters such as acoustic work, phase difference, dynamic pressure, volume flow rate and exergy loss were presented and discussed. Then, the coupling mechanism of the system was investigated. In addition, influence of coupling position on the system performance was further studied.     

A single-stage pulse tube cooler reached 12.6 K

A single-stage G-M type pulse tube cooler (PTC) was designed and tested to explore the lowest attainable refrigeration temperature and to further improve the cooling performance in the temperature range of 15-40 K. The magnetic material Er₃Ni was used as part of the regenerative material besides the phosphor-bronze and the lead so as to improve the efficiency of the regenerator. With an input power of 6 kW, a lowest no-load refrigeration temperature of 12.6 K was obtained, which is a new record for the single-stage PTC. The cooling capacity at 15-40 K was also significantly improved, which may extend the application of the single-stage PTC for the cooling of superconductors and cryopumps.     

A high efficiency coaxial pulse tube cryocooler operating at 60 K

In recent years, improved efficiency of pulse tube cryocoolers has been required by some space infrared detectors and special military applications. Based on this, a high efficiency single-stage coaxial pulse tube cryocooler which operates at 60 K is introduced in this paper. The cryocooler is numerically designed using SAGE, and details of the analysis are presented. The performance of the cryocooler at different input powers ranging from 100 W to 200 W is experimentally tested. Experimental results show that this cryocooler typically provides a cooling power of 7.7 W at 60 K with an input power of 200 W, and achieves a relative Carnot efficiency of around 15%. When the cooling power is around 6 W, the cryocooler achieves the best relative Carnot efficiency of around 15.9% at 60 K, which is the highest efficiency ever reported for a coaxial pulse tube cryocooler.     

大功率单级脉管制冷机回热器性能模拟与实验

为了提高单级脉管制冷机在20 K-40 K温区的制冷量,对自行设计制作的1台单级G-M型脉管制冷机采用REGEN3.3进行了计算模拟,获得了铅丸直径选择、不同温区回热器材料最佳组合等结果。在此基础上,对该台单级脉管制冷机进行了试验,实验结果表明该脉管制冷机在20.6K和29.9 K可分别获得20 W和40 W的制冷量,输入功率为7.5 kW。