• 2022-04-13
  • 4 min read


Growing needs to introduce environmentally friendly equipment

As global warming accelerates, the development of international frameworks for prevention of it such as COP26 is progressing. Under the circumstances, ESG management in private sectors becomes important and has been widely accepted around the globe as a key factor for increasing corporate value. In particular, the companies are actively addressing environmental issues (the “E” aspect of ESG) based on their social responsibilities.

Global trend of low-GWP refrigerants accelerates zero FCs and low-carbon society

The Kigali Amendment to the Vienna Convention / Montreal Protocol, which was signed in Rwanda in 2016, promised a concrete reduction in the usage amounts of specific fluorocarbons (HCFCs) and alternative fluorocarbons (HFCs). As a result, it has become necessary to gradually switch to the use of refrigerants with low GWP *¹. *¹GWP: Global Warming Potential In addition to international treaties, the establishment of refrigerant regulations based on each country's policies is also progressing. In Japan, for example, the designated product scheme will begin in 2025, and it will be essential for manufacturers to switch to low-GWP refrigerants. Moreover, government policies, private companies (primarily global companies) are also working to eliminate fluorocarbons and lower their carbon footprints based on their own guidelines.

Global refrigerant regulation trends
Global refrigerant regulation trends

CFC,HCFC,HFC:IPCC Fourth Assessment Report HFO:IPCC Fifth Assessment Report

Economics and environmental premium

Many companies are considering global environment and its protection by using appropriate facilities/equipment for the purpose. However, it is also fact that there is a certain threshold to pay for such solutions. To support such effort of companies (e.g. install appropriate facility/equipment for reducing environmental impact), the form of national policy for each country, such as subsidy systems that match the level of global warming regulations, is necessary. In terms of a supplier, we believe that it is responsible for us to develop and supply the required facility/equipment, and one of our solutions is the advanced centrifugal chillers using low-GWP refrigerants.


MHI Thermal Systems’ thinking

The need for environmental thermal solutions is increasing on a global scale. With our advanced heat source technologies to reduce CO₂ emissions, we are actively contributing to protection of the environment.

History and achievements in development of low-GWP refrigerant chillers

MHI Thermal Systems has always been sensitive to the environmental issues. We have been pioneering advanced technology ahead of other air-conditioning manufacturers, and developing and introducing state-of-the-art chillers utilizing low-GWP (HFO-type) refrigerants to the market since the 2000s. Specifically, we launched centrifugal chillers utilizing HFO-1233zd (GWP=1) in 2015, and another utilizing HFO-1234ze (E) (GWP<1) in 2017.

Low-GWP refrigerant chillers
 Low-GWP refrigerant chillers

Centrifugal chillers using previous HFC refrigerant have been replaced with a full range of units with new refrigerants. New chillers range from 150Rt to 5000Rt, which provide a full lineup of centrifugal chillers with low-GWP refrigerants for all customer needs. We are continuing to develop new products in the shortest possible development intervals and supplying them to the customers.

Performance history of MTH chiller
Performance history of MTH chiller

Development concept for low-GWP refrigerant chillers

For selecting refrigerants to be used, in addition to “low GWP” feature, “Safety” and “Availability” nature are also considered. For our design concept and as prominent technological approach, we have precisely considered and solved the concerned challenges e.g. low-pressure refrigerants need larger volume of compressors and heat exchangers than high pressure refrigerants, so the size of chiller tends to be larger in a normal design. MHI Thermal Systems therefore minimizes the shape of compressors and heat exchangers using its proprietary CFD analysis techniques to achieve a compact design. At the same time, we achieved that performance is equivalent to that of chillers using conventional refrigerants.

Future initiatives for low-GWP refrigerant chillers

It is also necessary to provide customers with our supports for the chillers delivered in the past in terms of environment. For example, we are also planning to exchange refrigerants for those chillers. In Japan, where refrigerant regulations are ahead of those in other countries, exchanging refrigerants cannot be performed easily under current laws. For this reason, we have been consulting with relevant organizations, and cooperates to formulate guidelines and advance the development of legislation. We will continue to contribute to global environmental conservation by focusing on the development of high-performance centrifugal chillers utilizing refrigerants with even lower GWP; and facilitate the changeover to new refrigerants and improvements in performance using cutting-edge technologies cultivated by the MHI Group so far.


  • MHI Thermal Systems’ centrifugal chillers using low-GWP refrigerants have been taking care of environment and offer the higher efficiency based on long track record of success and extensive knowledge, in order to satisfy customer needs in terms of both environmental and economic aspects.
  • As with our conventional refrigerant chillers, we are working to improve not only the performance on rated capacity but also that for partial loads. We continue making technical considerations to enable customers to reduce their total energy consumption.
A man is carefully gazing a chiller
A man is carefully gazing a chiller

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