液氢温区两级全同轴型脉管制冷机  

A completely co-axial two-stage pulse tube cooler working at liquid hydrogen temperatures

作　　者：庞晓敏 戴巍[2] 马素霞[1] 王晓涛[2] Xiaomin Pang;Wei Dai;Suxia Ma;Xiaotao Wang(College of Electrical and Power Engineering,Taiyuan University of Technology,Taiyuan 030024,China;Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]太原理工大学电气与动力工程学院,太原030024 [2]中国科学院理化技术研究所,北京100190

出　　处：《科学通报》2021年第20期2629-2634,共6页Chinese Science Bulletin

基　　金：中国博士后科学基金(2019M661061);国家自然科学基金(5197061222)资助。

摘　　要：同轴型脉管制冷机因其结构紧凑的优势在空间探测等领域具有重要应用潜力.然而,同轴布置的两部件(如回热器和脉管)仅依靠不锈钢薄壁间隔,相同轴向位置时温度不一致会造成二者之间的径向热交换,影响整机制冷性能.本文基于液氢温区两级脉管制冷机,针对不同结构冷指中存在的径向换热进行分析,发现两级全同轴型冷指不仅能够大幅提高冷指紧凑性,而且经由低温级脉管壁面的径向换热能够有效改善其温度分布,降低低温级脉管损失,提高膨胀效率,进而提高制冷性能.相比于无径向换热的两级冷指(U型或直线型冷指),全同轴型冷指在20 K时的制冷量提高了50%以上.设计研制了一台液氢温区全同轴型两级脉管制冷机,在20 K时可获得1.2 W冷量,以声功计相对卡诺效率达到7.34%.Pulse tube coolers,which work at liquid hydrogen temperature,are widely used in applications such as cooling infrared sensors and superconducting devices because of the advantage of no moving parts at low temperatures.Pulse tube coolers can be divided into three types according to their shape:In-line type,U-type,and co-axial type.In-line type and U-type pulse tube coolers separate the regenerator and the pulse tube,both of which are only connected through the cold end heat exchanger.For co-axial pulse tube coolers,the regenerator normally has an annular cross section surrounding the pulse tube.They are becoming increasingly popular in practice for their compactness,but the thermal contact between the regenerator and the pulse tube may affect the system performance.Few studies have been conducted on the influence of radial thermal contact,most of which are based on a single-stage pulse tube cooler and deviate from an actual co-axial type pulse tube model.For pulse tube coolers working at liquid hydrogen or a low temperature,two-stage cold heads are commonly used.In this study,theoretical analyses are conducted on the basis of a two-stage gas-coupled pulse tube cooler to investigate the influence of radial heat transfer.Based on the simulations,a completely co-axial two-stage pulse tube cooler is set up and experimental studies are carried out.Four models(corresponding to different shapes of cold heads)are constructed to theoretically analyze the mechanism based on the Sage software.Without radial thermal contact(corresponding to a two-stage U-type cold head),the temperature distributions along the pulse tubes are nonlinear,especially the 2 nd stage pulse tube due to the large temperature span.Corresponding to the position of the 1 st cold end,the temperature of the 2 nd stage pulse tube is high to230 K;at the same axial location,the temperature difference between the 2 nd stage regenerator and the pulse tube is approximately 190 K.Radial heat transfer on the 2 nd stage pulse tube(corresponding to 1 st stage U-type

关 键 词：两级脉管制冷机 同轴型 径向换热 温度梯度 膨胀效率 

分 类 号：TB651[一般工业技术—制冷工程]