【作者】 闫磊；

【导师】 陈安斌；

【作者基本信息】 哈尔滨工业大学 ， 制冷与低温工程， 2007， 硕士

【摘要】 脉管制冷机作为一种新型低温制冷机,由于低温端没有运动部件,因此与传统G-M制冷机和斯特林制冷机相比,具有结构简单、成本低、可靠性高、机械振动和电磁噪声低等突出优点。随着脉管制冷机性能的逐渐提高,在各种应用场合显示出了很强的竞争力,应用范围涉及航空航天、军事、低温电子学、低温医学、气体液化等诸多领域。本文在回顾脉冲管制冷机的发展历史和最新研究进展的基础上,对两级脉冲管制冷机进行了如下具体研究工作:首先,对两级脉管制冷机实际制冷量进行计算。参照G-M制冷机运用分离计算法对实验样机第二级理论制冷量进行了计算,并分析计算了各项不可逆损失,最后得出第二级在4.2K的实际制冷量。其次,运用Fluent对二级回热器进行数值模拟。建立了二级回热器的物理和计算模型,给出了多孔介质主要参数的计算方法,模拟得出两种不同填料组合下回热器的温度及比热分布。引入参数ξ表示蓄冷器中氦气和填料的比热容之比,根据ξ值沿回热器长度方向的分布情况判断填料组合的蓄冷效果,ξ值越接近1蓄冷效果越好。模拟的结果用以确定二级回热器填料的配比。最后,两级脉管制冷机实验台的组成介绍和制冷机性能测试。实验使用针阀调节小孔和双向进气开度,得到了制冷机降温曲线以及针阀调节的最佳阀门开度曲线,并分析了双向进气开度对冷头温度波动的影响。对实验中的现象从机理和计算两个方面进行分析,总结出目前制冷机存在的问题以及进一步提高制冷机性能的措施。更多还原

【Abstract】 As a new type of refrigerator, pulse tube refrigerator has no moving parts in the low temperature region compared with G-M and Stirling refrigerators, which gives it a lot of advantages such as simple structure, low cost, high reliability, low mechanical vibration and electromagnetism noise, etc. Along with its gradually improvement of performance, pulse tube refrigerator shows great competitive abilities in many application fields, including space, military, cryo-electronics, cryo-medicine, gas liquefaction, etc. In this paper, research on the two-stage pulse tube refrigerator which works at 4K is carried out based on the development history of pulse tube refrigerator and latest researches Detailed work is as follows:Firstly, calculation of the actual refrigeration capacity of the second stage at 4K is done. Consulting the separate theoretical refrigeration capacity computational methods of G-M refrigerator, the theoretical refrigeration capacity and various types of irreversible losses of the second stage are calculated, so the actual refrigeration capacity is obtained by subtracting theoretical refrigeration capacity by all loses. Based on the calculation, the actual refrigeration capacity of the second stage at 4K is determined.Secondly, CFD software Fluent has been applied for the numerical simulation of the second stage regenerator. The physical and computational models of the second stage regenerator are established and the calculation methods of the parameters which are important to the porous zone are given. Through the results of the simulation, the temperature and volumetric specific heat distributions of the second stage regenerator are obtained. Parameterξis introduced to prescribe the ratio of volumetric specific heat of helium and regenerative materials. Theoretically, the value ofξshould be close to 1, which means the effect of the arrangement of the regenerative materials is good. The result of the simulation is used to determine the arrangement of the second stage regenerative materials.Lastly, the experimental setup of the two-stage pulse tube refrigerator is introduced and the performance test of the refrigeratorr is conducted. The opening of the orifice and double-inlet are adjusted by needle valves. During the experiment, the cooling-down curve of the refrigerator and the optimal opening curve of the valves are gained. The temperature fluctuation of the cold-head which is influenced by the double-inlet valve opening is analyzed. Theoretical and computational analyses of the phenomena which are found in the experiment are done. According to these analyses, the problems of the cooler are concluded and measures to figure out these problems are also put forward, so that the refrigerator could be improved.更多还原