The joint research team of Boreas Cryogenics and SITP, led by Dr. Haizheng Dang, has achieved the lowest temperature of 1.36 K ever reported for the hybrid cryocoolers operating at 1–2 K. In this hybrid cryocooler system, the throttle cryocooler operates at 2–4 K, where 4He as the circulating working medium is liquefied. The capacity and quality of helium liquefaction directly determine the performance of the hybrid cryocooler, which has been a technical problem in the research of the hybrid cryocooler system. Through thermodynamic simulations and optimizations of the throttle orifice and the entire throttling process, the joint team achieved a maximum liquefaction rate of 93.80% for 4He, eliminating the primary obstacle to further improving the overall cooling capacity of hybrid cryocoolers. The related work was recently published in Energy, an international journal in the energy field.
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Fig. 1. Optimization model.
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Fig. 2. Temperature and velocity profiles for orifices with varying thicknesses and diameters.
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Fig. 3. Optimization results.
