"Using Air as a 'Refrigerant'... Expected Applications in Semiconductor Processes and More"

A refrigeration technology that can use air as a refrigerant to replace chlorofluorocarbon gases and hydrofluorocarbons (HFCs), which are identified as the main culprits of global warming, has been developed for the first time in Korea. This technology is expected to be used for semiconductor processes and the storage of bio and pharmaceutical products.

The Korea Institute of Energy Research (hereinafter KIER) announced on the 22nd that it has developed an integrated ultra-high-speed compander for air refrigeration and succeeded in developing an air cooling system for the first time in Korea.

The research team is verifying the performance and related data of an air-based cooling system. Provided by Korea Institute of Energy Research

Using the system developed by KIER, it is possible to create a temperature environment of minus 60 degrees Celsius by utilizing air as a refrigerant. This is significant in that it can replace fluorinated greenhouse gases (F-gases) that were previously used as refrigerants.

The European Union’s “Fluorinated Greenhouse Gas Regulation Amendment,” which came into effect in March, includes provisions to gradually ban the sale of products containing fluorinated greenhouse gases starting next year and to strengthen regulations on processes using these gases.

Existing refrigeration and cooling systems mainly use vapor compression cycle methods. The vapor compression cycle method cools by absorbing heat as the liquid refrigerant evaporates, and due to its simple structure and design, it has been widely used in various fields. However, the use of fluorinated greenhouse gases, which accelerate global warming, as refrigerants has been considered a major drawback.

Above all, fluorinated greenhouse gases are used in Korea’s major export products such as air conditioners, automobiles, and semiconductor processes, creating a need for technology to replace them in accordance with the “Fluorinated Greenhouse Gas Regulation Amendment.”

In response, KIER has focused on implementing an “inverse-Brayton cycle cooling system” that uses air as a refrigerant. Unlike the conventional method of evaporating liquid, this system compresses gas and produces low-temperature gas through heat exchange and expansion, enabling cooling without liquid refrigerants.

However, the difficulty of designing and manufacturing such a system is very high, and it had not been applied to actual refrigeration systems. This is because the equipment rotates at ultra-high speeds during the cooling process, requiring precise design of gaps between devices including compressors and expanders, and shaft displacement to within 0.1 mm.

(From left) Wang Eun-seok, Dr. Jo Jong-jae, Dr. Lee Beom-jun, Dr. Shin Hyung-gi, Dr. Lee Gil-bong. Photo by Korea Institute of Energy Research

However, KIER devised a compander system that connects the compressor, expander, and motor on a single shaft to implement the inverse-Brayton cycle system, resolving these issues.

They also applied advanced turbomachinery design technologies such as aerodynamic design technology that allows the compressor and expander connected on a single shaft to operate at their highest efficiency, and shaft system design that enables stable operation even at ultra-high rotational speeds.

The cooling system applying the developed compander succeeded in cooling air to below minus 60 degrees Celsius within one hour, and especially when generating cold energy below minus 50 degrees Celsius, it was evaluated to have higher refrigeration efficiency than existing vapor compression systems.

KIER explained that theoretically, cooling down to minus 100 degrees Celsius is possible, and at that temperature, refrigeration efficiency is expected to improve by more than 50% compared to vapor compression systems.

Dr. Beomjun Lee, the lead researcher, said, “With environmental regulations spreading the use of eco-friendly refrigerants in refrigeration systems, KIER is currently conducting research to improve performance to produce cold energy below minus 100 degrees Celsius. We expect that future research outcomes can be applied to semiconductor processes and pharmaceutical and bio fields that require ultra-low temperature cold energy.”

Meanwhile, this research was conducted with support from the Ministry of Science and ICT’s Climate Change Response Technology Development Project (lead researcher Beomjun Lee) and KIER’s basic project (lead researcher Hyunggi Shin).

This content was produced with the assistance of AI translation services.