液氦温区VM-PT制冷机气量分配特性

VM气耦合脉冲管制冷机(VM-PT)是一种新型的液氦温区制冷机,为探索两级气耦合复杂的机理,本文采用Sage软件构建了低温调相VM-PT制冷机的整机模拟程序,研究了运行频率、平均压力、毛细管长度以及Er3Ni填充长度等参数对两级气量分配的影响。结果表明:运行频率、平均圧力、毛细管长度以及Er3Ni填充长度均会影响两级质量流的分配,进而影响制冷机的最低温度,权衡工质的做工能力以及蓄冷器损失两方面因素,该四个参数均存在一个最佳值。搭建了实验平台并对数值模拟进行了验证。在实验中通过优化毛细管和蓄冷器,在运行频率1.6 Hz、平均压力1.4 MPa、压比1.6的情况下得到了3.86 K的无负荷制冷温度,在4.2 K可提供约10 m W的制冷量。     

脉冲管制冷机混合填充式蓄冷器的实验研究

基于脉冲管制冷机蓄冷器结构,提出了#400不锈钢丝网以及其与#300和#500组合而成的混合式蓄冷器填充方式.通过构建一单级分体式脉冲管制冷机测试平台,将#400及混合目数丝网分别填充至制冷机蓄冷器内进行整机实验,实验结果验证了低温制冷机蓄冷器冷热端分别填充高低目数丝网,可提高制冷机性能,是一种有效的蓄冷器优化方法.     

应用磁性蓄冷材料的低温制冷机试验

本文报告了应用磁性蓄冷材料提高低温制冷机效率的实验情况,在国产的二级索尔文制冷机中,用稀土化合物铒三镍(Er3Ni)取代第二级蓄冷填料铝(pb)之后,使试验样机的最低制冷温度由原来的11.5K 降低到4.2K 以下,从而在国内首次通过回热式制冷机从室温直接获得氦的液化点(4.2K)温度。     

10W/80K高频同轴脉冲管制冷机的实验性能

介绍了一款大冷量高频单级同轴脉冲管制冷机的基本结构、数值模拟和实验性能。其线性压缩机采用Redlich动磁式直线电机驱动,压缩活塞对置布置,使用板弹簧支撑和间隙密封技术,80 K温区工作时的电机效率在83%以上。膨胀机的蓄冷器和脉冲管为同轴型布置,这种结构使冷头与器件之间的耦合非常方便。使用数值软件对制冷机整机和调相部件进行数值模拟,并对模拟结果进行实验验证。对制冷机的运行频率和制冷性能进行实验研究,制冷机在210.3 W输入电功时能获得10 W/80 K的制冷性能,比卡诺效率为12.66%,运行频率为62 Hz,整机重量小于5.5 kg。     

液氦温度级的二级索尔文制冷机的研制

液氦温度(4.2K)级的二级索尔文制冷机,采用了日本产的新型磁性材料Er_3Ni作为国产二级索尔文制冷机的二级蓄冷材料,使原机的制冷温度从11.5K降到了4K以下。     

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.     

新型磁性蓄冷材料G—M制冷机的研制

对应用磁性蓄冷材料作为二级蓄冷器填料而研制的大制冷功率两级Ｇ－ Ｗ 制冷机的研究工作进行了总结,给出了理论分析及结构设计。并在一台样机进行了实验研究,通过优化制冷机结构参数和运行参数,使制冷机二级最低制冷温度达７．８ Ｋ、２０ Ｋ 时取得１４．５ Ｗ 的有效制冷量,从理论和试验上对应用磁性蓄冷材料改善Ｇ－ Ｍ 制冷机性能的有效性进行了有益的探索。     

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.     

空间环境模拟设备用G—M制冷机的研制

介绍了一台以磁性蓄冷材料Ｅｒ３Ｎｉ为第二级蓄冷器填料的大制冷功率两级Ｇ－Ｍ制冷机。该制冷机可作为空间环境模拟设备冷背景冷源，满足了辐射制冷器空间环境热模拟试验的要求。通过优化制冷机结构参数，使制冷机在转速为４０ｒ／ｍｉｎ时，二级最低制冷温度达５．５Ｋ、２０Ｋ时取得１５．４Ｗ的有效制冷量。证明了应用磁性蓄冷材料改善Ｇ－Ｍ制冷机性能的有效性。     

300 Hz脉冲管制冷机特性研究

从实验和数值计算两个方面研究了1台工作频率为300 Hz的单级脉冲管制冷机的制冷特性.实验方面,验证了平均压力、入口压比、惯性管长度以及均流化元件对其制冷性能的影响,该制冷机在平均压力为3.96 MPa、入口压比为1.21时获得了79.6 K的最低制冷温度;数值计算方面,基于线性热声理论的模拟结果与实验结果进行了比较,以验证程序的有效性.     

A novel coupled VM-PT cryocooler operating at liquid helium temperature

This paper presents experimental results on a novel two-stage gas-coupled VM-PT cryocooler, which is a one-stage VM cooler coupled a pulse tube cooler. In order to reach temperatures below the critical point of helium-4, a one-stage coaxial pulse tube cryocooler was gas-coupled on the cold end of the former VM cryocooler. The low temperature inertance tube and room temperature gas reservoir were used as phase shifters. The influence of room temperature double-inlet was first investigated, and the results showed that it added excessive heat loss. Then the inertance tube, regenerator and the length of the pulse tube were researched experimentally. Especially, the DC flow, whose function is similar to the double-orifice, was experimentally studied, and shown to contribute about 0.2 K for the no-load temperature. The minimum no-load temperature of 4.4 K was obtained with a pressure ratio near 1.5, working frequency of 2.2 Hz, and average pressure of 1.73 MPa.     

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。     

混合填充式回热器单级脉管制冷机性能研究

回热器为回热式低温制冷机的关键部件,其性能对系统的影响甚大。为探索回热器内金属丝网混合填充对回热器性能的影响,文章基于回热器模拟软件REGEN3.3仿真结果的基础上,制作了单级脉管制冷装置,采用#300SS,#400SS和#500SS的金属丝网混填了四组回热器,并在不同输入功率下进行了系统制冷性能实验。实验结果表明,较之低目数丝网填充的回热器制冷机,采用高目数丝网填充的回热器制冷机性能较优;在回热器热端填充低目数,冷端填充高目数的丝网,可提高回热器冷端压比,提高整机制冷性能。     

斯特林型两级脉管制冷机的改进

在最近研制的1台直线压缩机驱动的两极脉管制冷机的初步试验的基础上,对直线压缩机的线圈重新进行了设计和制作,解决了由于绕制圈数过多而无法输入足够电功率的问题。对冷头的热端法兰及回热器热端热交换器进行了改进,采用了微槽式水冷却器,解决了压缩热无法得到充分冷却引起的制冷机热端温度过高的问题。改进后制冷机的性能得到了显著的提高,在2.0 MPa充气压力和40 Hz频率的条件下,该制冷机获得了14.2 K的最低制冷温度。并且,第一级和第二级在97.8 K和34.9 K时,分别具有2.5 W和1 W的制冷量。     

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.     

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%.     

A single-stage GM-type pulse tube cryocooler operating at 10.6 K

In order to explore the lowest attainable refrigeration temperature and improve cooling performance at temperatures around 20 K for a single-stage G-M type pulse tube cryocooler (PTC), numerical and experimental studies were performed. The National Institute of Standards and Technology (NIST) numerical model known as REGEN was applied to the simulation of a G-M type PTC for the first time. Based on the calculation results, a single-stage G-M type PTC was designed, fabricated and tested. The performance improvement of the regenerator in the temperature range of 10-80 K was investigated. The calculations predicted a lowest temperature of 10 K. A lowest temperature of 10.6 K was achieved experimentally with an input power of 7.5 kW, which is the lowest temperature ever achieved by a single-stage PTC. Further more, the cryocooler can provide a cooling power of 20 W at 20.6 K and 39.5 W at 30 K, respectively.     

冷指尺寸对超高频微型脉冲管制冷机性能的影响分析

冷指是脉冲管制冷机的重要部件,其尺寸大小决定压缩机乃至制冷机整机的尺寸,其内部的功热转换效率和损失等会对制冷机的性能产生显著的影响.为满足脉冲管制冷机微型化的需求,必须提高制冷机频率、减小冷指尺寸,而冷指尺寸的缩小又会影响制冷机的性能.为了掌握冷指尺寸对制冷机性能的影响规律,利用SAGE软件对运行频率为130 Hz,直...     

Intermediate cooling from pulse tube and regenerator in a 4 K pulse tube cryocooler

This paper introduces intermediate cooling by thermally attaching heat exchangers on the second stage pulse tube and regenerator in a commercial 4 K pulse tube cryocooler. Due to the large enthalpy flow in the 2nd stage pulse tube and regenerator, both intermediate heat exchangers on the pulse tube and regenerator can provide cooling capacities in the temperature range of 5–15 K without or with minor effect on the performance of the 4 K stage. Extracting cooling capacity from the pulse tube or regenerator reduces the 1st stage cooling performance in the present study. The joint intermediate heat exchanger on the pulse tube and regenerator has demonstrated promising results for applications.     

The thermodynamic characteristics of a Stirling/pulse tube hybrid cryocooler

A Stirling/pulse tube hybrid cryocooler (SPC), comprised of a Stirling cryocooler as the first stage and a pulse tube cryocooler as the second stage, features the ability of shifting cooling capacity between stages by adjusting the movement of the displacer in the first stage. Such an ability allows an SPC to accommodate itself to time-varying heat loads at different temperatures, which makes it a competitive candidate in space applications. However, due to the gas coupling, there exists a significant mutual effect between stages which endows an SPC with special thermodynamic characteristics and has a significant effect on the SPC’s capability of shifting cooling capacity between stages. With the phasor analysis and the thermodynamic analysis, this paper establishes an idealized model of an SPC. The model is then used to study the effect of the second stage on the first stage and reveal the condition that an SPC is able to shift cooling capacity between stages. Also, the model is compared with a Sage numerical model and the two models are consistent on the overall trend. Though it is unable to reflect reality precisely, the idealized model can interpret the mechanism and highlight some of the essential nature of an SPC, which will eventually benefit the appropriate design of an SPC.