Continuous effort is made on Gifford-McMahon cryocoolers (GMC) to amplify its refrigeration power, so they can be used to cool the cryopumps, high Tc magnets and development of efficient small-scale hydrogen liquefiers, etc. The fluidic-driven GMC is considered to be more reliable and prominent candidate than the mechanically-driven GMC due to its structural simplicity and reliability. Nonetheless, cooling mechanism of the fluidic-driven GMC is complicated, as the displacer motion inside the displacer cylinder is simultaneously controlled by the pressure difference between drive chamber and compression/expansion chamber. Different paths of displacer can be traced inside the displacer cylinder for different drive-chamber discharging process, hence, pressure–volume power of compression and expansion chambers, and refrigeration power changes. A theoretical study is conducted in present paper to visualize the influence of drive-chamber discharging process on the thermodynamic characteristics of fluidic-driven GMC for the first time. Thermodynamic cycles are drawn at the expansion chamber of the fluidic-driven GMC for different values of drive-chamber discharging process for two types of valve timing arrangements. Energy and work loss behaviors in different components of the GMC are also analysed. Adequate experimental investigations have also been carried out on a fluidic-driven displacer type GMC to verify the simulation results.

中文翻译：

---

驱动室排放过程对流体驱动的 Gifford-McMahon 低温冷却器的非线性置换器动力学和热力学过程的影响

Gifford-McMahon 低温冷却器（GMC）不断努力放大其制冷功率，因此它们可用于冷却低温泵、高 Tc 磁体和开发高效的小型氢液化器等。流体驱动的 GMC 被认为由于其结构简单性和可靠性，它比机械驱动的 GMC 更可靠、更突出。尽管如此，流体驱动的 GMC 的冷却机制很复杂，因为置换器气缸内的置换器运动同时受驱动室和压缩/膨胀室之间的压差控制。对于不同的驱动室排放过程，可以在置换器气缸内追踪不同的置换器路径，因此，压缩和膨胀室的压力体积功率和制冷功率发生变化。本文首次进行了理论研究，以可视化驱动室放电过程对流体驱动 GMC 热力学特性的影响。热力学循环在流体驱动 GMC 的膨胀室绘制，用于两种类型的气门正时布置的驱动室排放过程的不同值。还分析了 GMC 不同组件的能量和工作损失行为。还对流体驱动置换器型 GMC 进行了充分的实验研究，以验证模拟结果。热力学循环在流体驱动 GMC 的膨胀室绘制，用于两种类型的气门正时布置的驱动室排放过程的不同值。还分析了 GMC 不同组件的能量和工作损失行为。还对流体驱动置换器型 GMC 进行了充分的实验研究，以验证模拟结果。热力学循环在流体驱动 GMC 的膨胀室绘制，用于两种类型的气门正时布置的驱动室排放过程的不同值。还分析了 GMC 不同组件的能量和工作损失行为。还对流体驱动置换器型 GMC 进行了充分的实验研究，以验证模拟结果。