• 8 K多级脉管制冷机预冷及中间温度对性能的影响研究

    Study on the Influence of Precooling and Intermediate Temperature on the Performance of an 8 K Multi-stage Pulse Tube Cryocooler

    • 工作在8 K的斯特林型多级脉管制冷机在空间探测,如太赫兹探测等方面具有优势。对于斯特林型脉管制冷机来说,合适的回热器温度分布对制冷性能有着重要的影响,回热器温度分布的变化会影响㶲损失从而影响制冷机性能。论文在一台8 K脉管制冷机中开展了回热器温度分布对制冷机性能影响的理论与实验研究。仿真结果表明,当中间换热器温度(T1)不变时,高温段回热器(REG1)内㶲损失随预冷温度(Tpre)的增加而增大;当预冷温度从63 K增加至78 K时,REG1内总㶲损失从37.91 W增加至42.25 W,低温段回热器(REG2)内㶲损失则基本不变;当Tpre不变时,T1升高会导致REG1内㶲损失减小,而REG2内㶲损失则增大。同时,随着T1升高脉管2(PT2)热端的阻抗幅值与相位均减小。实验结果表明,当Tpre升高时,中间换热器上可取得的冷量(Q1)减小,当预冷温度从63.2 K增加至73.5 K时,Q1从0.56 W减小至0.19 W,而冷端换热器可取得的冷量(Q2)基本不变;当T1升高时,Q1增大而Q2则减小。当Tpre为70 K,T1为23.35 K时,制冷机可在8 K取得74 mW冷量(输入功为349.5 W)。

       

      Abstract: Stirling-type multi-stage pulse tube cryocoolers operating at 8 K possess obvious advantages in space exploration applications such as terahertz detection. For Stirling-type pulse tube cryocoolers, the appropriate regenerator temperature distribution exerts a significant influence on cooling performance. Because the change of temperature distribution will affect the exergy loss in the regenerator. In this paper, systematic theoretical and experimental studies on the effect of regenerator temperature distribution on the performance of an 8 K pulse tube cryocooler were conducted. Simulation results indicate that: when the temperature of the intermediate heat exchanger (T1) remains constant, the exergy loss in the high-temperature section regenerator (REG1) increases with the rise of the precooling temperature (Tpre), when the precooling temperature increases from 63 K to 78 K, the total exergy loss in REG1 rises from 37.91 W to 42.25 W, while the exergy loss in the low-temperature section regenerator (REG2) remains basically unchanged; when Tpre is constant, an increase in T1 leads to a decrease in exergy loss in REG1, but an increase in exergy loss in REG2. Meanwhile, as T1 increases, both the amplitude and phase of the impedance at the hot end of Pulse Tube 2 (PT2) decrease. Changes in exergy loss within the regenerator can affect cooling performance. Experimental results show that when Tpre increases, the cooling capacity obtainable at the intermediate heat exchanger (Q1)decreases, When the precooling temperature increases from 63.2 K to 73.5 K, Q1 decreases from 0.56 W to 0.19 W, while the cooling capacity obtainable at the cold-end heat exchanger(Q2) remains basically unchanged; when T1 increases, Q1 increases while Q2 decreases. When T0 is 70 K and T1 is 23.35 K, the cryocooler can achieve a cooling capacity of 74 mW at 8 K (with an input power of 349.5 W).

       

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