The Kigali Amendment, effective since 2019, included 18 HFC substances with high Global Warming Potential (GWP) in its regulatory list. These include compounds such as R134a, R32, R125, R152, and R410A.

According to the requirements, starting in 2024, China's production and consumption of HFCs will be frozen.
In 2023, China introduced two key policies: the List of Recommended Substitutesfor Ozone-Depleting Substances and the 2024 Total Hydrofluorocarbon (HFC) Quota Setting and Allocation Plan. These policies play a vital role in the green and low-carbon transformation of the refrigeration and related industries.
On December 29, 2023, the State Council officially issued the Decision on Amending the Regulations on the Management of Ozone-Depleting Substances, which has been in effect since March 1, 2024.
A newly released draft of China's national plan to implement the Montreal Protocol on Substances that Deplete the Ozone Layer (2024-2030) stipulates that, starting January 1, 2030, the use of refrigerants with a GWP greater than 150 will be prohibited in newly approved M1 class vehicle air conditioning systems. The plan also promotes the R&D and application of natural refrigerants such as CO2 (R744) and propane (R290) in electric vehicle thermal systems.
Refrigerant substitution is urgent – how should we choose?

Since 2018, SONGZ has been conducting research on R744 (CO2) and R290 (propane) refrigerants. SONGZ's CO2 heat pump air conditioner is now ready for mass production. This air conditioner operates between -20°C and 50°C, providing both cooling and heating capacities sufficient for a 12-meter bus. Its heating capacity and energy efficiency surpass those of R407C and R410A refrigeration systems. Additionally, it integrates a battery thermal management system, with cooling performance that meets the water temperature and heat exchange requirements for CATL and BYD batteries. The air conditioner is also EMARK certified. In 2022, the first mass-produced CO2 heat pump air conditioner was officially rolled off the production line and exported to Karsan in Turkey. The installation and commissioning on vehicles were completed smoothly, earning high recognition from the customer. The product was showcased at the IAA Mobility in Hannover, Germany, and featured in a European roadshow.

CO2 Air Conditioner

Due to the flammable and explosive nature of the R290 refrigerant, SONGZ has conducted performance tests on prototypes using a secondary circuit to prevent the refrigerant from entering the cabin.

R290 Air Conditioner

The performance tests for the R1234yf, R454C, and R474A refrigerants, along with the material compatibility tests, have been completed. Currently, studies on the reliability and stability of components and systems are ongoing.

The theoretical analysis for DL-N1 and R479A has been completed and is awaiting testing.

A comparative analysis of the advantages and disadvantages of new refrigerants

Based on the research on the new refrigerants above, SONGZ recommends the following replacements for the refrigerants currently used in bus air conditioners:

Some of the replacement refrigerants are suitable for GWP < 700, while others are suitable for GWP < 150, depending on customer needs. Based on compressor compatibility and cost, we currently recommend R454C for export products (requiring GWP < 150). Once the DL-N1 refrigerant code from the Zhejiang Research Institute of Chemical Industry is approved, it can be used in export products, providing both performance and cost advantages.