As international refrigerant regulations are strengthened to achieve carbon neutrality, a cooling technology using water with an environmental pollution index of zero as a refrigerant has been developed for the first time in Korea. This technology is economical as it is cheaper than existing chemical refrigerants, and it is expected to contribute to the realization of carbon neutrality as it can be applied as an eco-friendly refrigerant to air conditioners and industrial cooling units in the future.

Kim Jeong-cheol, a senior researcher at the Heat Pump Research Center of the Korea Institute of Machinery and Materials (President Ryu Seok-hyeon) under the Ministry of Science and ICT, announced on the 25th that he had developed the first core technology for an eco-friendly water refrigerant cooling system that can cool or transfer heat using water as a refrigerant.

The system developed this time uses water as a refrigerant instead of the existing chemical refrigerants, and is expected to be eco-friendly and inexpensive, significantly reducing refrigerant costs and increasing efficiency in maintenance and operating costs.

This technology was developed only in advanced countries such as Germany and Japan, but this time, we have developed the original technology for the first time in Korea, which has enabled us to secure national competitiveness.

Unlike existing compressors that use synthetic refrigerants, the Korea Mechanical and Electrical Engineering Research Institute has developed centrifugal compressors, evaporators, and condensers that can use water as a refrigerant.

When using water as a refrigerant, the inside of the evaporator must be maintained at 7℃ or lower, the inside of the condenser must be maintained at 35℃ or higher, and the inside of the cooling system must be in a vacuum state.

Additionally, because the surface tension of water is large, the heat transfer tubes are selected and arranged differently from those in synthetic refrigerant systems to suit the structure of the evaporator and condenser.

This system is designed to accommodate the compressible properties of water, maximizing the benefits of water in the cooling process while maintaining existing system functionality.

Environmentally friendly refrigerants such as ammonia and propane are often flammable or toxic, so if they must be used, separate safety facilities must be installed in the cooling device in accordance with the High Pressure Gas Safety Management Act.

On the other hand, water is non-toxic and non-flammable, so there is no need for separate safety facilities. There are advantages.

Due to tightening environmental regulations, refrigerants currently in use on the market will either be phased out entirely or their use reduced by up to 80% by 2045, depending on the refrigerant type. Furthermore, eco-friendly synthetic refrigerants currently being sold for development are expensive, and the companies that produce them monopolize the market. Therefore, alternatives are needed.

The newly developed cooling system utilizes water as a refrigerant, which is up to 100 times cheaper than conventional refrigerants, thereby reducing cooling system maintenance costs. Furthermore, using water as a refrigerant allows it to efficiently absorb and release heat, achieving the same cooling effect as conventional refrigerants while reducing energy consumption, potentially leading to lower electricity bills.

Kim Jeong-cheol, a senior researcher at the Korea Institute of Machinery and Materials, said, “This is the first case of developing an industrial chiller and heat pump system that uses water as a refrigerant in Korea, which was developed mainly in some advanced countries.” He added, “In line with the international trend of continuously demanding the development of eco-friendly chiller and heat pump technologies related to new refrigerant regulations, we will work to systematically develop related technologies in Korea and achieve commercialization.”

This research was conducted with the support of the Ministry of Trade, Industry and Energy's 'Development of 350kW-class natural refrigerant (R-718) application compression refrigeration technology' project.