Thermal and Chemical Stability of HFOs

With the growing concern over global warming and the signing and ratification by many countries of the Kyoto Protocol, new refrigerants with low global warming potential (GWP) such as hydrofluoroolefins HFO-1234yf and HFO-1234ze with GWP under 10 have been proposed as replacements for hydrochlorofluorocarbons (HCFC) and hydrofluorocarbons (HFC). The long-term reliability of air-conditioning and refrigeration systems of the past fifty years depends on the thermal stability of the refrigerant/lubricant working fluids and their compatibility with the materials of construction of the compressor. This paper focuses on the thermal and chemical stability of the refrigerant/lubricant working fluids.

Refrigerants HFO-1234yf, HFO-1234ze and a mixture of HFO-1234yf and R-32 (50/50 by weight) were tested with two POE oils (a mixed acid and a branched acid POE), and one PVE oil. Using the fluoride ion concentrations after aging as indicators of refrigerant decomposition and Total Acid Numbers (TAN) as indicators of lubricant decomposition, the stabilities of the different refrigerant/lubricant mixtures (when aged at 175oC for 14 days in sealed tubes) were compared.

Citation: ASHRAE/NIST Ref Conf



Product Code(s): D-ANRC12-14