Large-capacity ultra-low temperature chiller for industrial use opens the era of “zero GWP”

The KIMM has succeeded in conducting the cooling test of a large-capacity ultra-low temperature (hereinafter referred to as ULT) Turbo-Brayton cooling system using a zero GWP refrigerant.

The research team led by Principal Researcher Junseok Ko of the Department of Energy Storage Systems of the Korea Institute of Machinery and Materials (President Seog-hyeon Ryu, hereinafter referred to as KIMM), an institute under the jurisdiction of the Ministry of Science and ICT, has developed a Turbo-Brayton cooling system using a zero GWP^* refrigerant, and has succeeded in conducting a performance test to confirm a cooling capacity of over 10kW at -100 ℃. It is the first time in Korea for the development of a large-capacity ultra-low temperature cooling technology using the Turbo-Brayton cooling system to be demonstrated through actual operation.
^{*GWP (Global Warming Potential) is an indicator used to describe the impact that a refrigerant has on global warming. Due to stronger regulations on refrigerants, acceptable levels of GWP are continuously being lowered. A “zero GWP” refrigerant refers to a refrigerant that has no influence whatsoever on global warming, and is considered as the goal that must ultimately be achieved.}

The KIMM developed the Turbo-Brayton cooling system using its own centrifugal compressor and turbo expander. The demand for large-capacity ULT chillers with a cooling temperature of -100 ℃ or lower and a cooling capacity of 10 kW or larger has recently been increasing in the semiconductor industry. Through its latest research, the KIMM has demonstrated that the Turbo-Brayton cooling technology is a powerful technology that can meet these industrial needs.

The Turbo-Brayton cooling technology is a cooling system that uses a turbo machine that rotates at ultra-high speeds of tens to hundreds of thousands of rpm. This technology has been used in limited areas such as superconducting cable cooling, cryogen sub-cooling and LNG re-liquefaction. However, in recent days, the demand for large-capacity ULT cooling technology is rapidly increasing in the semiconductor industry as it seeks to secure super-gap technologies, as well as in the bio industry where companies are striving to establish an ULT cold chain ecosystem. At the same time, the development of highly efficient cooling technologies with low GWP is required due to carbon neutrality and reinforced regulations on refrigerants. The newly developed Turbo-Brayton cooling system uses a zero GWP refrigerant that goes beyond low GWP. It is a technology that can satisfy ultra-low temperature, large capacity, and high efficiency required by industries.

Conventional vapor-compression type ULT chillers use refrigerants that have a high GWP or natural refrigerants that have a high risk of explosion. Moreover, it is difficult to increase the capacity of these chillers due to the constraints on the equipment, and it is also not easy to control the operating temperature and capacity because of the characteristics of the refrigerants and limited control methods. On the other hand, as for the Turbo-Brayton cooling technology, it is possible to control temperature and capacity over a wide range. Through the latest performance test, it was confirmed that the capacity thereof can be freely controlled within the range of 5.5 to 11 kW.

The research team of the KIMM has succeeded in developing its own centrifugal compressor and turbo expander, which are the core components of the chiller, while at the same time securing system technologies including the technology for the Turbo-Brayton cooling system which has not yet been successful in Korea.

Principal Researcher Junseok Ko of the KIMM was quoted as saying, “Through the cooling performance test, we have confirmed that the Turbo-Brayton cooling system can be used for large-capacity cooling of 10kW or larger at the ULT of -100 ℃. Within three years, we will further develop the system so that it can evolve into a form suitable for industrial chillers, and will conduct research and development so that the system can be used in the semiconductor industry and also in other industries.”

Meanwhile, this research was conducted with the support of the project for the “development of the core machinery for ultra-low temperature cooling systems used in the semiconductor manufacturing process,” one of the KIMM’s basic projects.

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The Korea Institute of Machinery and Materials (KIMM) is a non-profit government-funded research institute under the Ministry of Science and ICT. Since its foundation in 1976, KIMM is contributing to economic growth of the nation by performing R&D on key technologies in machinery and materials, conducting reliability test evaluation, and commercializing the developed products and technologies.

This research was conducted with the support of the project for the “development of the core machinery for ultra-low temperature cooling systems used in the semiconductor manufacturing process,” one of the KIMM’s basic projects.