A cryogenic refrigerator includes a pulse tube cryocooler including a pulse tube, and a pulse tube cryocooler rotating mechanism that rotatably supports the pulse tube cryocooler allowing it to be changed from a cooling posture to a heating posture. When the pulse tube cryocooler is in the cooling posture, an inclination angle formed between a vertical line and a center axis of the pulse tube is a first angle, and when the pulse tube cryocooler is in the heating posture, the inclination angle is a second angle. In a case where the inclination angle formed when a cold end of the pulse tube faces vertically downward is defined as zero degrees and the inclination angle formed when the cold end of the pulse tube faces vertically upward is defined as 180 degrees, the second angle is larger than the first angle.

A cryogenic refrigerator includes a pulse tube cryocooler including a pulse tube, and a pulse tube cryocooler rotating mechanism that rotatably supports the pulse tube cryocooler allowing it to be changed from a cooling posture to a heating posture. When the pulse tube cryocooler is in the cooling posture, an inclination angle formed between a vertical line and a center axis of the pulse tube is a first angle, and when the pulse tube cryocooler is in the heating posture, the inclination angle is a second angle. In a case where the inclination angle formed when a cold end of the pulse tube faces vertically downward is defined as zero degrees and the inclination angle formed when the cold end of the pulse tube faces vertically upward is defined as 180 degrees, the second angle is larger than the first angle.

The present invention discloses a hydrogen or helium throttling liquefaction system using direct current (DC) flow from the cold and hot ends of the regenerative cryocoolers, which belongs to the technical field of refrigeration and cryogenics. It includes a regenerative cryocooler module, a hot-end DC flow module, a cold-end DC flow module, a throttling liquefaction module, and a gas-phase circulation module. The modules are interconnected to form a closed loop for the flow of hydrogen or helium working fluid. DC flow is introduced from the cold and hot ends of the regenerative cryocooler through the DC flow pipelines and DC flow valves. The hot-end DC flow exchanges heat with the reflowing low-temperature working fluid and is cooled down. After that, it mixes with the cold-end DC flow and enters the throttling liquefaction module to generate liquid phase through throttling and liquefaction. After the liquid phase has output cooling capacity, it flows through the gas-phase circulation module and then enters the back-pressure chamber of the compressor to complete the cycle. Compared with the existing small-scale hydrogen and helium liquefaction technology using regenerative cryocoolers, the present invention has the advantages of simple structure, easy installation, high heat transfer efficiency and liquefaction efficiency of the system.