【Ten Years of Great Progress in Chemical Engineering Technology】Major breakthroughs were achieved in large-scale cryogenic refrigeration technology at minus 271°C from 2014 to 2021

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After decades of effort and five to six years of hard work, the Chinese people, with their full passion, have finally reached a new limit for large-scale refrigeration equipment at minus 271°C. The **major scientific research equipment development project titled ‘Development of a Large-scale Cryogenic Refrigeration System for the Temperature Range from Liquid Helium to Superfluid Helium’**, undertaken by the Institute of Physical Chemistry, Chinese Academy of Sciences, passed the acceptance and achievement evaluation on April 15, 2021, at the Langfang site of the institute. The expert group believes that the project as a whole has reached an internationally advanced level, with the high-stability centrifugal cold compressor technology and the megawatt-class helium-injected screw compressor technology reaching an internationally leading level. 　　Industry experts say that the successful acceptance of this project marks a breakthrough for China, as it has now broken free from foreign technological monopolies. The country now possesses the capability to develop large-scale cryogenic refrigeration equipment capable of producing kilowatt-level cooling at a temperature of 4.2 K (approximately minus 269°C), as well as hundred-watt-level cooling at a temperature of 2 K (approximately minus 271°C). Thus, China’s large-scale cryogenic refrigeration technology has reached the international forefront. 　　Researchers at the Institute of Physics and Chemistry told reporters that refrigeration technology is divided into two main categories: conventional refrigeration and cryogenic refrigeration. The former has a cooling temperature of 120K or above (about minus 153°C), and is used for cooling in household appliances; the latter has a cooling temperature below 120K, and is an essential supporting technology for conducting cutting-edge scientific research as well as for the development of high-tech industries and manufacturing sectors such as chemicals and steel. Oxygen, nitrogen, and other gases required for chemical production are mainly obtained through low-temperature refrigeration liquefaction techniques followed by low-temperature distillation; natural gas, as a clean fossil fuel, is also obtained to a significant extent via low-temperature liquefaction refrigeration technology. Large-scale cryogenic refrigeration equipment for the transition from liquid helium to superfluid helium temperatures forms the basis for fields such as aerospace, hydrogen energy, helium resources, and **large scientific facilities**. For many years, China has relied entirely on imports for its large-scale low-temperature refrigeration equipment, while the key components as well as specialized refrigeration equipment for specific applications have been subject to export bans by foreign countries. 　　 Ten years of rapid development in chemical engineering technology; praise for the prosperous and strong China. This is just a starting point to encourage more participation from everyone – with you here, Haichuan becomes even better. We welcome everyone to join in the forum discussions. It’s hot in July, so be careful to prevent fires. ---------------------------------------------- Relying on decades of expertise in low-temperature technology, and under the guidance of Academicians Hong Chaosheng and Zhou Yuan, as well as through the relentless efforts of many researchers in this field, the Institute has, after over five years of research, developed large-scale helium refrigerators with performance specifications of 2500W@4.5K and 500W@2K, based on refrigerators that operate at liquid hydrogen temperatures of 20K (about minus 253°C). The successful development of this equipment can not only meet the urgent needs in fields such as large-scale scientific projects, aerospace engineering, and helium resource development, but also promote the advancement of cutting-edge technologies in related areas. 　　It is reported that the project has achieved a series of breakthroughs in core technologies, including the development of an overall design framework and control techniques for large-scale low-temperature refrigeration systems, series-based helium turbine expander technologies using gas bearings, large-scale ultra-cold helium negative-pressure heat exchangers, large-scale, high-efficiency helium oil-injected screw compressors, highly stable centrifugal cold compressors, as well as integration and commissioning techniques for large and complex low-temperature refrigeration systems. 　　In terms of application and result transformation, the project team has established a model of \"researching, applying, and transforming simultaneously\". Project achievements — Hundred-watt-class large-scale refrigerators have been applied in the liquefied natural gas flash vapor helium extraction project in Yanchi, Ningxia, initially establishing a technical pathway for the development of helium resources in China. This device has also been successfully applied in various fields such as linear accelerators and South Korea’s KSTAR nuclear fusion research facility, earning widespread recognition and contributing to the development of related industries. The successful implementation of this project has also spurred rapid development in China’s industries related to high-end helium screw compressors, cryogenic heat exchangers, and cryogenic valves. It has enhanced the core competitiveness of a number of high-tech manufacturing enterprises, enabling relevant technologies to evolve from non-existent or low-end levels to more advanced ones. As a result, a well-developed cryogenic industry cluster with clear divisions of labor has taken shape in China, allowing cold-related equipment to experience rapid growth.