New air-based refrigeration system achieves -76°F, no harmful gases used

Most of the current refrigeration systems rely on harmful refrigerants that contribute to global warming.

Now, the Korea Institute of Energy Research (KIER) has developed a cooling system that uses air as a refrigerant.

This refrigeration technology eliminates the need for harmful cooling chemicals such as Freon gas, and hydrofluorocarbons (HFCs). This is the first time an air cooling system has been developed in Korea, according to a press release.

“Due to environmental regulations, refrigeration systems that primarily use refrigerants with a high global warming potential are rapidly transitioning to the use of eco-friendly refrigerants,” said Dr. Beom Joon Lee, the lead researcher.

Air-based cooling system

Most traditional cooling systems use a method called the vapor compression cycle. This method cools things by evaporating a liquid refrigerant, which then absorbs heat.

This standard technique is easy to use, but it relies on refrigerants, such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). These are potent greenhouse gases, which trap heat in the atmosphere, causing global warming.

The new eco-friendly system works by compressing air and then going through a series of heat exchange and expansion processes. This allows it to produce a low-temperature gas without the need for liquid refrigerants.

For this, the team developed a “compander” device that can operate at very high speeds. The compander is a single, four-sided rotor that performs both compression and expansion functions.

This device was successfully integrated into an air refrigeration system, allowing it to reach temperatures as low as -60 degrees Celsius.

Moreover, the new cooling system follows a cycle called the reverse-Brayton cycle.

“This system compresses a gas and then goes through heat exchange and expansion to produce a low-temperature gas, enabling cooling without the need for liquid refrigerants,” the press release explained.

-76°F in just one hour

The developers highlight that this system is complex to design and build, which is why it hasn’t been used in refrigeration systems before.

The compander needs to be very precise as it spins extremely fast. For example, the gaps between parts must be smaller than 0.1 millimeters.

The researchers created a new system that combined a compressor, expander, and motor onto a single shaft. Interestingly, the new cooling system using the compander could cool air to -60 degrees Celsius (-76°F) in just one hour.

In theory, it can reach temperatures as low as -100 degrees Celsius (-148°F). At that temperature, its efficiency is expected to be over 50% better than traditional vapor compression systems.

“We are currently working on improving the system’s performance to enable the production of cold temperatures below -100 degrees Celsius. We anticipate that this technology will be applied in fields that require ultra-low temperatures, such as semiconductor processes, pharmaceuticals, and biotechnology,” Lee said in the press release .

The European Union has recently implemented stricter regulations on fluorinated greenhouse gases (F-gases). These regulations will phase out the sale of products containing F-gases starting in 2025 and tighten restrictions on their use in various processes.

This poses a significant challenge for countries like Korea, which rely heavily on F-gases in key export industries such as air conditioners, automobiles, and semiconductors. As a result, there is an urgent need to develop alternative technologies that do not rely on F-gases.

This new technology may come to the rescue of the Korean cooling industry. Moreover, it has the potential to be applied in a wide range of industries that require ultra-low temperatures.