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Recently, Shanghai Boreas Cryogenics Co., Ltd. has been granted two Chinese invention patents in the field of dilution refrigerators.

 

This invention discloses an external cold trap for the dilution refrigerator. It includes a liquid nitrogen tank with a purification chamber inside. The purification chamber, from top to bottom, comprises a separation unit, a purification unit, and a pre-cooling unit. A sealed top cover is provided on the top of the purification chamber, with an inlet pipe, an outlet pipe, and a maintenance channel. This invention increases the heat exchange efficiency of the airflow and reduces the cooling time by adding a pre-cooling unit and a separation unit to the lower and upper parts of the purification unit, respectively, made of activated carbon, thereby improving purification efficiency. Simultaneously, the separation unit and copper mesh filter form a self-purification device, avoiding the self-contamination effect of the cold trap. This ensures long-term stable operation of the throttling process and the stability of the dilution refrigerator during repeated long-term operation, significantly extending the maintenance cycle of the dilution refrigerator. This has a very positive significance for the practical application of the dilution refrigerators.

 

 

2. A Throttling Heat Exchanger for Dilution Refrigerators and Its Manufacturing Method
 

This invention discloses a throttling heat exchanger for the dilution refrigerator and its manufacturing method, specifically relating to the fields of cryogenic engineering. The invention includes an outer corrugated tube and an inner core of the heat exchanger housed within the inner cavity of the outer corrugated tube. The outer corrugated tube comprises a low-pressure outlet connecting pipe and a low-pressure inlet connecting pipe fixed at the top and bottom ends of the heat exchanger, and is configured as a spiral corrugated tube. This invention achieves enhanced convective heat transfer of high and low-pressure fluids in a confined space through a combination of a spiral corrugated outer tube and a spiral inner tube. Furthermore, by introducing a throttling orifice into the heat exchanger, the orifice is fully pre-cooled during the stable phase of the dilution refrigeration system, thus integrating the throttling orifice and the throttling heat exchanger. The design of varying orifice diameters before and after throttling better matches the changes in the physical properties of helium at extremely low temperatures. This invention has significant implications for optimizing the pre-cooling process and the throttling process of the throttling heat exchanger, as well as for improving the performance of the dilution refrigerator.
 

 

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