A team at The Korea Institute of Energy Research (KIER) has developed a cooling system that uses air as a refrigerant. This new technology eliminates the need for harmful cooling chemicals – such as freon gas, and hydrofluorocarbons (HFCs) – that contribute to global warming.
“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.
Most cooling systems in use today utilize a method called the vapor compression cycle, which cools things by evaporating a liquid refrigerant, which then absorbs heat. Though easy to use, it relies on refrigerants, such as chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), both potent greenhouse gasses.
KIER’s 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.
To accomplish 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. The device was successfully integrated into an air refrigeration system, allowing it to reach temperatures as low as -60 degrees Celsius. The new cooling system using the compander could cool air to -60 degrees Celsius (-76°F) in just one hour, and – in theory – could 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.
The researchers admit that this system is complex to design and build, which is why it hasn’t been used in refrigeration systems before. For example, the compander needs to be built to highly specific specifications, as it spins extremely fast.