The refrigerant lubricant HFO-1234yf is currently available. While R-1234yf oils can be used in R-134a systems, R-134a PAG oils cannot be used in R-1234yf systems. As such, it is important to select an appropriate oil for each system.
HFO-1234yf has a global warming potential (GWP) that is less than half of that of R-1234yf. It also has lower absolute pressure during compression which leads to better fuel economy. These factors make HFO-1234yf a more environmentally friendly choice than R-1234yf.
HFO-1234yf was developed by Honeywell International as a replacement for R-1234yf. It is known under the names Trifluoromethane Fluoroolefin (CF3CHFCHF2) and Tetrafluoroethane Fluoroolefin (C2FCFHFCF3). The substance is active against bacteria, fungi, and mildew and does not harm animals or humans. It is also non-toxic and does not contaminate ground water.
Honeywell began testing HFO-1234yf in 2005 and went on to win several patents related to its use.
Many features of R-134a and R-1234yf are comparable. R-134a is a hydrofluorocarbon (HFC) refrigerant, whereas R-1234yf is a hydrofluoro-olefin (HFO) refrigerant. They are both made up of hydrogen, fluorine, and carbon atoms. While R-134a has a GWP of 1,300, R-1234yf has a GWP of less than one. Overall, these two fluids have similar environmental impacts.
Both R-134a and R-1234yf are considered greenhouse gases under global warming theory. However, they do not affect climate in the same way. R-134a binds strongly to atmospheric moisture, which prevents it from entering the atmosphere. This means that it doesn't contribute to global warming in itself. However, because it takes several years for all of the R-134a taken up by air molecules to be released back into the atmosphere, it has some impact on climate over time.
R-1234yf does contribute to global warming since it does enter the atmosphere and remain there for an extended period of time.
According to Thomas, new fluorinated refrigerants like hFo-1234yf are compatible with Poes and PaGs. "Use with mineral oils is not currently suggested due to concerns with mutual solubility and miscibility," he says. "Ammonia has been utilized as a refrigerant since 1850," according to the brief. Modern formulations are available that include ammonium salts of fatty acids as catalysts (RX-744) or absorbents (Puraflo). These products are compatible with hFo-1234yf.
The use of ammonia as a refrigerant was limited by toxicological concerns related to its high flammability. Ammonia also has a strong odor that can be problematic for its storage and transportation. However, it is non-toxic and non-flammable, making it an attractive alternative to hydrocarbons for applications where toxicity or flammability is a concern.
Ammonia has many advantages as a refrigerant. It is non-ozone depleting, has low global warming potential, and is renewable through natural processes. It also does not contribute to acid rain or soil contamination.
Ammonia has one major disadvantage: Its boiling point is -33°C, meaning it must be compressed into a liquid at room temperature to be used in any practical capacity.
That's where hFo-1234yf comes in.
The refrigerant HFO-1234yf is one alternative. RENISO PAG 1234 is an ISO VG 46 refrigeration oil designed for use with both HFO-1234yf and R134a refrigerants. It has excellent lubricity, stability at low temperatures and is non-toxic.
Comparing this oil to R134a, it has a lower boiling point (-20°C or -4°F) and a higher viscosity (3.5 cSt at 100°F). However, it should be noted that some compressors are not capable of handling oils with higher viscosities. Also, since HFO-1234yf is a new product, it may require special attention when used in applications with which it has not yet been tested or where there is risk of damage due to high pressure or temperature.
For more information on how to select the right oil for your application, please see our article: How to Select the Right Refrigeration Oil.