摘要
30 K温区大冷量回热式低温制冷机在超导冷却、气体液化等领域具有广阔的应用前景.相较于其他类型的低温制冷机,斯特林制冷机具有结构紧凑、降温速率快、效率高等优势.基于理论分析和数值计算结果研制了一台大冷量二级斯特林制冷机,并对其开展了初步的实验研究.对不同工况下制冷机的压力波特性以及室温端换热器的换热特性进行研究,发现提高充气压力,压缩腔的压力振幅会提高,室温端换热器的换热量提高.提高第二级制冷温度,压缩腔的压力振幅与室温端换热器的换热量减小,且其减小速率均随制冷机第一级热负荷的增加而提高.制冷机无负荷工作时,每提高0.1 MPa充气压力,制冷机第二级制冷温度降至30 K的平均降温速率提高0.72 K/min.在2.6 MPa充气压力时,制冷机第二级可在13.24 min内降至30 K,最终无负荷制冷温度为19.83 K,此时第一级制冷温度为71.2 K.在第一级无热负荷时,该制冷机在30 K时可提供110 W制冷量,相对卡诺效率为10.96%,这是目前国内该类型低温制冷机公开报道的最高性能.
Regenerative cryocoolers with large cooling capacity at 30 K have a promising prospect in the fields of superconducting technology and gas liquefaction. Compared with other types of cryocoolers, Stirling cryocoolers have the advantages of high cooling capacity, high efficiency, fast cool-down process and compact configuration. A two-stage Stirling cryocooler with large cooling capacity driven by the crank-rod mechanism is developed based on the Sage simulation results, and the preliminary experimental results are presented. Firstly, the pressure characteristics under different working conditions are investigated. The amplitude of the pressure and the pressure ratio at the compression chamber increases as the charging pressure increases. Increasing the refrigeration temperature of the second stage results in the decrease of the pressure amplitude, and the decreasing rate increases as the heat load on the first stage increases. Then, the performance of the ambient heat exchanger is studied. As the charging pressure increases from 2.2 to 2.6 MPa, the heat rejected from the ambient heat exchanger increases from 7.57 to 9.19 k W when there are no heat loads at the two stages of the cryocooler.The heat rejected from the ambient heat exchanger increases by 400 W with every increase of 0.1 MPa of charging pressure. With the increase of the refrigeration temperature of the second stage, the heat rejected from the ambient heat exchanger decreases, and the decreasing rate increases as the heat load on the first stage increases. Furthermore, the influence of the variation of the charging pressure and heat loads at the two stages on the cooling performance is introduced. The temperature of the second-stage cold end heat exchanger drops to 30 K at a nearly constant cooling rate after the startup of the cryocooler. As the charging pressure increases from 2.2 to 2.6 MPa, the cooling rate increases from16.59 to 19.46 K/min, and the cooling rate increases by about 0.72 K/min for every increase in pressure of 0.1 MPa. Under the charging pressure of 2.6 MPa, the second stage of the cryocooler reaches a no-load refrigeration temperature of19.83 K, while the temperature of the first stage is 71.2 K. The no-load refrigeration temperature has a weak relationship with the charging pressure. As the charging pressure increases, the increasing rate of cooling capacity and COP with the refrigeration temperature increases. The cryocooler is capable of providing 110 W cooling power at 30 K with a relative Carnot efficiency of 10.96%. This is the best result ever reported in China. What is more, it is found that the cooling power at the two stages has little influence on the cooling performance of each other, which means the cooling power from the first stage can be applied in the pre-cooling process with little influence on the second stage. These results lay a solid foundation for future applications and performance improvement of the cryocooler.
作者
乔鑫
孙大明
祁云
苏峙岳
于弘元
章杰
王建中
牛小飞
Xin Qiao;Daming Sun;Yun Qi;Shiyue Su;Hongyuan Yu;Jie Zhang;Jianzhong Wang;Xiaofei Niu(Key Laboratory of Refrigeration and Cryogenic Technology of Zhejiang Province,Institute of Refrigeration and Cryogenics,Zhejiang University,Hangzhou 310027,China;Jiangsu Cryote Cryogenic Technology Co.,Ltd,Changzhou 213000,China)
出处
《科学通报》
EI
CAS
CSCD
北大核心
2020年第10期955-962,共8页
Chinese Science Bulletin
基金
国家自然科学基金(51276156,51676168)资助。
关键词
低温制冷
回热器
斯特林
超导
大冷量
cryogenic refrigeration
regenerator
Stirling
superconducting
high cooling capacity
