深低温回热式制冷机高效运行机理及最低制冷温度研究

Regenerative cryocoolers (< 20 K) are widely used in space exploration, Hydrogen/Helium liquefaction and superconductor cooling. “Miyin Project” was proposed and approved by China in 2019, the project plans to build a large infrared telescope to search terrestrial planets. In order to minimize the noise and improve SNR (signal to noise ratio), low temperature cooling with features of high efficiency, high reliability and long life-time is essential to cool the detectors of the telescope below 10 K. According to the roadmap of JWST telescope, it can be concluded that regenerative cryocooler and J-T cryocooler with precooling are the best choice of the cooling system of “Miyin Project”.. Based on the requirements of deep space exploration of China, this proposal focus on the two contradictions in the regenerative cryocoolers at low temperatures. The first is the efficiency at high frequency condition would be higher than that at low frequency, but the experimental study shows a contrary result. The second is the no-load cooling temperature in the experiment is lower than the theoretical prediction with ideal assumptions. The proposal aims to solve two challenges that prevent the regenerative cryocoolers working at low temperatures efficiently, the mechanism of high efficient cooling of low temperature regenerators and no-load cooling temperature of regenerative cooling. Theoretical analysis combing with experimental study and simulation are used to study the following 3 main problems: (1) Production of losses and optimization of high efficiency regenerators at low temperature. (2) Fabrication and experimental testing of novel high efficiency regenerative martials at low temperature. (3) No-load cooling temperature at real working conditions. This study will future reveal the mechanism of the regenerative cooling, determine the working conditions for high efficiency cooling at low temperature, solve the contradiction of no-load cooling temperature, and also provide some kind of help for the implementation of nation’s deep space missions.

深低温区(< 20 K)回热式制冷机在空间探测、氢/氦液化、低温超导等领域具有重要应用。为寻找系外类地行星，我国启动了“觅音计划”大型空间项目，该项目工作在深低温的红外望远镜对低温系统提出了效率高、可靠性高及寿命长等要求，回热式制冷机或由其预冷的J-T节流制冷机是“觅音计划”低温制冷系统的必选方案。本项目面向国家深空探测战略需求，基于高低频回热制冷效率困境和回热式制冷最低制冷温度矛盾，针对深低温回热器高效工作机理和最低制冷温度两个关键科学问题，采用理论分析、模拟计算和实验测试相结合的方法，主要开展：(1)深低温高效回热器损失机理及优化；(2)深低温新型高效回热填料制造与性能测试；(3)回热式制冷机实际工况下最低制冷温度三个方面的研究，从而明确深低温回热式制冷高效运行所需的工作条件，破解回热式制冷实际工况下最低制冷温度优于理想工况的困局，为我国深空探测望远镜项目的顺利实施贡献绵薄之力。

深低温区(< 20 K)回热式制冷机在空间探测、氢/氦液化、低温超导等领域具有重要应用。为寻找系外类地行星，我国启动了“觅音计划”大型空间项目，该项目工作在深低温的红外望远镜对低温系统提出了效率高、可靠性高及寿命长等要求，回热式制冷机或由其预冷的J-T节流制冷机是“觅音计划”低温制冷系统的必选方案。本项目面向国家深空探测战略需求，基于高低频回热制冷效率困境和回热式制冷最低制冷温度矛盾，针对深低温回热器高效工作机理和最低制冷温度两个关键科学问题，采用理论分析、模拟计算和实验测试相结合的方法，首先开展了基于非热平衡的回热式制冷机最低制冷温度与深低温回热器损失机理研究，指明了单级斯特林脉管制冷机的最低制冷温度。在此基础上拓展了回热式制冷动态声-力-电耦合方法，并成功指导多款高性能制冷机的研发。最后基于低温制冷机在低温液体存储方面进行应用探索，提出了一种绝热材料真空度表征方法，并建立了高精度液氢存储热力行为预测模型。三方面的研究工作明确了深低温回热式制冷高效运行所需的工作条件，破解回热式制冷实际工况下最低制冷温度优于理想工况的困局，为我国深空探测望远镜项目的顺利实施贡献绵薄之力。