In line with the Korean government’s recent efforts to achieve the goal of “going carbon neutral by 2050,” the energy transition from fossil fuels to new and renewable sources of energy has been gaining speed. In this context, the joint research team led by Principal Researcher Young Kim of the Korea Institute of Machinery and Materials (KIMM), an institute under the jurisdiction of the Ministry of Science and ICT, and professors Min-sung Kim and Dong-kyu Kim of Chung-Ang University has successfully developed an environment-friendly refrigerant compressor using an electrochemical method instead of a mechanical method.

 In contrast to conventional refrigerants containing HFCs (hydrofluorocarbons) that destroy the ozone layer and cause global warning, environment-friendly refrigerants (ammonia, R1234yf, etc.) have very small environmental impacts. In accordance with the Kigali Amendment to the Montreal Protocol, advanced nations in Europe as well as the United States and Japan are in the process of transitioning to eco-friendly refrigerants until the complete phase-out of the use of HFCs in 2024. Using environment-friendly refrigerants can help to prevent environmental pollution and contribute to sustainable development.

 Meanwhile, mechanical compressors have several limitations such as problems with durability of parts due to rapid rotation, contamination of refrigerants caused by lubricants, and loud noise. As electrochemical compressors have no moving parts and do not require the use of lubricants, they can help to overcome the shortcomings of conventional mechanical compressors. Additionally, a constant flow rate can be provided at various pressure ratios with electrochemical compressors, and the high efficiency thereof can help to significantly increase the COP (coefficient of performance) of the heat pump.

 To maximize the energy-saving effect of the rooftop greenhouse, the research team developed a “optimized smart farm operating solution” capable of controlling every aspect of the system such as air conditioning, LED, and hydroponics system in accordance with external weather conditions, and plans to demonstrate this solution through the demonstrated rooftop greenhouse.

 The joint research team has secured the core technologies necessary for producing the environment-friendly electrochemical refrigerant compressor and for designing the system thereof, and has successfully implemented the test run. With the newly developed environment-friendly electrochemical refrigerant compressor, the desired flow rate and pressure can be obtained by stacking.

Unlike conventional mechanical compressing, an electrochemical compressor compresses refrigerants through the movement of ions by charging the ion exchange membrane with DC (direct current) voltage, while using hydrogen as the carrier gas. Additionally, it also allows for isothermal compression by applying a multi-layer freezing technology where cells are accumulated in a stack configuration. To date, the refrigerants that have been successfully compressed are ammonia, a natural refrigerant, and R1234yf, an eco-friendly refrigerant. The joint research team designed cells capable of operating solidly even under repeated high-pressure conditions and also demonstrated a leak-free design to prevent the leakage of refrigerants at high pressure. Moreover, by designing a channel capable of producing high performance even at high voltage, the joint research team has succeeded in maximizing the compression efficiency of the electrochemical compressor.

 The electrochemical compressor is capable of offering the desired compression ratio regardless of the size thereof, and can provide a stable flow rate in accordance with the compression ratio, and has excellent efficiency. Therefore, it can be used not only for constructing high-efficiency plants and heat pumps but also for building small-scale systems. In particular, as an electrochemical ammonia compressor can be used for compressing ammonia even when the ammonia acts as a hydrogen carrier, it can also be used for constructing hydrogen infrastructure.

 Dr. Young Kim of the KIMM’s Department of Thermal Energy Solutions was quoted as saying, “The eco-friendly electrochemical refrigerant compressor is highly efficient and requires a small footprint, which makes it economically attractive.” Dr. Kim added, “We are planning to develop a heat pump system using this technology to contribute to the achievement of the goal of going carbon neutral by 2050.”

 Meanwhile, this research was conducted with the support of the project for the “development of a chemical absorption-type heat pump using an electrochemical compressor” led by the Korea Institute of Energy Technology Evaluation and Planning of the Ministry of Trade, Industry and Energy.