低于11 K的单级脉管制冷机性能研究

研究了回热器长度以及80 K以下温区不同回热材料布置形式对单级G-M型脉管制冷机性能的影响.试验研究表明,适当增加回热器长度,制冷机性能可显著提高.在此基础上对低温区回热材料进行优化,采用Er3Ni、铅丸和不锈钢丝网3层复合回热材料获得了最佳的制冷性能.采用额定输入功率为7.5 kW的压缩机驱动,脉管制冷机最低制冷温度达10.9 K,这是目前单级脉管制冷机达到的最低制冷温度.该制冷机在21 K可获得20 W制冷量.     

斯特林型高频脉冲管制冷机的实验研究

介绍了一台单级U型高频脉冲管制冷机的实验装置和实验结果.制冷机冷端无负荷最低温度达到了38.31 K,此结果为目前国内单级斯特林型高频脉冲管制冷机所达到的最低温度.当输入电功率200 W时,在50 K有0.6 W制冷量;当输入电功率为250 W时,在80 K有4.25 W的制冷量.这为40 K以下深低温,大冷量的斯特林型脉冲管制冷机的研制做出了有益的探索.通过分析压缩机运行频率对制冷机的最低温度和制冷量的影响,得出了在液氮温区针对特定的制冷温度,压缩机存在的一个最佳工作频率.在此工作频率下,压缩机和脉冲管耦合后,制冷机能够获得较高的效率.     

液氢温区单级高频多路旁通型脉冲管制冷机

为了既能降到液氢温区又能确保制冷机的温度稳定性,开展了仅采用长颈管,不使用双向进气进行调相的单级高频多路旁通型脉冲管制冷机的实验研究。首先用数值计算的方法获得了多路旁通开度是否最佳的判据。研制出的制冷机在充气压力1.73MPa,输入电功220W时,无负荷最低制冷温度能够降到23.6K,为目前所报道的在没有双向进气时单级高频脉冲管制冷机获得的最低温度。在达到稳定状态后,制冷机性能稳定,温度波动幅值小于0.1K。在220W输入电功下,能够在29.2K获得0.516W,34.3K获得1.0W的制冷量。     

具有独立气路的液氦温区G-M型二级脉管制冷机性能研究

研究了一台具有独立气体回路的液氦温区G-M型二级脉管制冷机的制冷性能.目前的实验装置由两套独立的单级双向进气型脉管系统构成,第一级冷头对第二级进气的预冷通过安装在第二级回热器中部的换热器与一级冷头之间的热联接来实现.研究表明,该制冷机采用4He为工质,分别以Leybold CP4000和RW2氦压缩机来驱动第一级和第二级,可以获得2.18 K的最低无负荷制冷温度,4.2 K提供的最大制冷量为595 mW.     

单级G-M型脉管制冷机回热器性能

为了能进一步提高单级G-M型脉管制冷机的性能,着重对80 K到300 K温区回热器的效率进行了理论和试验研究.通过对不锈钢和磷青铜丝网材料热渗透深度和热导率的分析,指出在这一温区采用不锈钢丝网的制冷性能优于磷青铜丝网.基于REGEN3.2进行的数值模拟,进一步指出适当增大不锈钢丝网目数有利于提高制冷性能,并由此指导实验取得了理想的结果.单级G-M型脉管制冷机经优化后,取得了11.1 K的最低制冷温度,是当前国内外报道的最好结果;同时该制冷机在20 K和30 K分别可获得17.8 W和40.7 W的制冷量.     

深冷文献消息(国内部分)

20 0 5 110 1　 1 2 7K 3 He二级脉管制冷机性能研究蒋　宁等　《低温工程》　 2 0 0 4　№ 5　 1～ 7在一台具有独立气体回路的液氦温区G M型二级脉管制冷机上 ,采用3He为第二级制冷工质 ,获得了 1 2 7K的最低无负荷制冷温度。与两级均采用4 He工质的情况相比 ,在相同的条件下 (相同压缩机耗功 :4 3kW 1 3kW) ,第二级采用3He为工质 ,使得该二级脉管制冷机在 4 2K的制冷量提高了 4 0 5 %。2 0 0 5 110 2　斯特林型高频脉冲管制冷机的实验研究王国平等　《低温工程》　 2 0 0 4　№ 5　 8～ 12介绍了一台单级U型高频脉冲管制冷机的…     

多路旁通型高频脉冲管制冷机及固定调相装置比较实验

研制了一台低于40 K温区的单级同轴型高频脉冲管制冷机,采用多路旁通结构,在输入功率为222 W时,其最低温度达到34.22 K,并比较了惯性管、惯性管加双向进气、惯性管加多路旁通以及惯性管加双向进气加多路旁通4种固定调相装置的差异(其中双向进气采用喷嘴结构).实验结果表明:惯性管、喷嘴、多路旁通组合方式是一种非常有效的降低制冷温度的方式,是应用深低温区单级脉冲管制冷机调相方式的最佳选择;而惯性管则是应用于较高温区大冷量的最佳的调相方式.实验还表明,多路旁通加喷嘴结构能够降低脉冲管内部的直流,有效地提高脉冲管制冷机的性能.     

20K温区GM型单级脉管制冷机初步实验

介绍了自行研制的一台GM型单级脉管制冷机,其回热器蓄冷材料采用247目磷青铜丝网和不锈钢丝网,双向进气方式采用两个方向相反的精密针阀并行布置.在输入功率仅为2kW的条件下,该制冷机获得了22.4 K的最低制冷温度,80 K温度时的制冷量为5.65 W.在长达24 h的连续运行中,该机的无负荷制冷温度波动小于0.3K.     

氦氢混合工质G-M单级脉管制冷机性能研究

对G-M型单级脉管制冷机采用氦氢混合工质在30 K温区进行实验研究,从制冷量、COP、压降特性、压缩机耗功、制冷温度的稳定性等方面进行了讨论和分析,同时给出了在最优状态下加载热负荷的温度变化情况.实验结果表明,采用适当配比的氦氢混合工质有助于提高脉管制冷性能.     

冷却高温超导磁体的大冷量单级G-M制冷机

随着高温超导磁体在电工技术方面日益广泛的应用，如高温超导限流器、高温超导变压器、高温超导储能系统等。对工作在30K～40K、并可提供50W～100W制冷量的低温制冷机提出了需求。常规的单、双级G-M制冷机产品不能满足高温超导磁体的冷却要求，本文初步得到了提高单级G-M制冷机性能、增大40K温度以下制冷量的方法，并在一台常规单级G-M制冷机上验证，获得了30W/40K制冷量的好结果，指明了研制这种大冷量G-M制冷机的方向，为成功研制冷却高温超导磁体的大冷量单级G-M制冷机走出了第一步。     

空间百瓦自由活塞斯特林发电机的实验研究

搭建了实验测试系统并对研制的百瓦自由活塞斯特林发电机进行性能优化实验,探究了板簧刚度、运行压力、外负载和冷端温度等因素对发电机输出功率、热电效率、运行频率、热端温度等输出特性的影响.结果 表明:同一工况下,配气、动力活塞板簧刚度均存在最佳值使得发电机的输出功率与热电效率最高,运行频率对前者的变化更为敏感.运行压力和外负...     

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.     

改进冷端换热器的大功率脉冲管制冷机

依据热力学非对称理论对脉冲管制冷机冷端的热力学过程进行分析,采用输出功率3 kW的压缩机在80 K时得到了35 W的制冷量,并提出了改进方案;搭建了单级低频大功率脉冲管制冷机的实验台,采用新型的填料烧结型换热器作为脉冲管的冷头.实验表明改进冷端换热器是提高脉冲管制冷机制冷效率的关键技术.     

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.     

Numerical analysis of different valve effects on the cooling performance of a two-stage GM type pulse tube cryocooler

The cooling performance of GM type pulse tube cryocoolers (PTCs) is strongly affected by the valve setting for phase shifting. In this research, the effects of different valve openings on the no-load temperatures in a two-stage GM PTC have been investigated by numerical simulation. Results show that the no-load temperature at the 1st stage mainly depends on the openings of 1st stage orifice valve, and both 1st and 2nd stage double-inlet valves. While the no-load temperature at the 2nd stage below 10 K sensitively depends on the openings of both 1st and 2nd stage orifice valves, and 2nd stage double-inlet valves. There exist several local minimum no-load temperatures at the 2nd stage under different valve openings below 7 K. The best valve setting corresponds to minimizing the cold end phase angle, making the cold end acoustic power compensate the real gas enthalpy flow with maximum degree.     

Experimental results on V-M type pulse tube refrigerator

This article mainly introduces experimental results on a new type pulse tube refrigerator named as V-M type pulse tube refrigerator. The main difference from Stirling type or G-M type pulse tube refrigerator is that thermal compressor similar to that of a V-M cryocooler is used instead of mechanical compressor. By using temperature difference between room temperature and liquid nitrogen, pressure wave with high to low pressure ratio around 1.2 is obtained. This pressure wave is used to generate cooling effect at the cold end. With a 20 K pre-cooler, this machine reaches lowest temperature 5.25 K by using helium⁴ at 0.77 Hz, 19 bar charge pressure. DC flow plays an important role in our system. It not only influences the final obtainable lowest temperature, but also is used to increase cold end cool-down speed. Total volume of the V-M type pulse tube refrigerator is around 3.3 l. However, dead volume inside rotor housing occupies about 2.8 l and can be much reduced.     

L型脉管制冷机的试验研究

介绍了文中提出的L型脉管制冷机的特点：一是采用L型脉管结构而不是通常的直型（文中称为Ⅰ型）脉管结构,降低了冷端死容积,且降低了冷头加工难度;二是在脉管热端采用双小孔阀结构取代了通常的单小孔阀结构,用来分别控制脉管热端进排气的质量流率;以四阀型脉管制冷机作为实验样机,给出了此种新型结构在有阀氦压缩机驱动下的初步性能试验,初步试验结果表明本文中的L型脉管制冷机在频率为2．5Hz,采用200目青铜丝网作为蓄冷器填料下能够达到的最低温度为67．5K。     

多目标约束下半导体制冷片几何结构参数的优化设计

研究半导体制冷片几何参数的影响,往往设置固定的制冷片冷热端温度及输入电流。本文通过固定半导体制冷片外部的冷热端换热条件及输入电压,逐一分析了制冷片多个几何参数对制冷量、COP和制冷片冷端温度的影响,对每一个影响项的物理含义都给出了详细的说明,揭示了这些参量之间存在着的耦合关系。并在此基础上,综合制冷量、COP和制冷片冷端温度3个优化目标对制冷片几何参数选取范围的约束特性,提出了基于多目标优化的几何参数选择图,该图可快速清晰地得到不同需求下最佳的pn结几何参数。如在设置的边界条件下,当冷端温度需求为280 K,制冷量为15 W时,存在几何参数的最优解,而当冷端温度需求为240 K,制冷量为100 W时,则不存在可同时满足冷端温度和制冷量需求的几何参数。     

Study on a high frequency pulse tube cryocooler capable of achieving temperatures below 4 K by helium-4

High-frequency pulse tube cryocooler (HPTC) has advantages of compact structure, low vibration, high reliability and long operation time. In this study, Theoretical analysis and experimental tests have been conducted in four aspects based on a developed 4 K HPTC. Firstly, a compressor with larger power output capability was employed and the impedance match between the cold head and the compressor was discussed. Secondly, simply using inertance tube configuration to replace the traditional inertance tube-gas reservoir structure. Then, the type and the size of the regenerator materials working at 4–20 K have been experimentally optimized. Finally, the performance of double-inlet working at as low as 20 K has also been tested for the first time for the HPTC. The present prototype achieved a no-load temperature of 3.6 K, which is the lowest temperature record ever reported for HPTC using helium-4 as working gas. A cooling power of 6 mW/4.2 K was also obtained with 250 W input power and a precooling power of 12.1 W/77 K.