R134a
(I) Physical properties
R134a (tetrafluoroethane) is the earliest HFC refrigerant to be widely used. Its ODP is 0, GWP=1430, and it is a typical high GWP refrigerant. R134a is colorless, odorless, non-flammable, non-toxic, and chemically stable. Its boiling point is -26.1℃, critical temperature is 101.1℃, and saturated vapor pressure is similar to R12, making it easy to replace in the original R12 system. R134a has good electrical insulation and can be used for direct cooling of the motor of the refrigerator. However, it has a certain hygroscopicity for water, and the water content of the system needs to be strictly controlled.
(II) Main applications
R134a is mainly used in automotive air conditioners. Because its thermal performance is similar to that of R12, the original R12 automotive air conditioner only needs a slight modification to smoothly transition to R134a. At present, automotive air conditioners around the world have basically achieved R134a replacement. R134a is also widely used in household refrigerators. After it replaced the original R12 refrigerant, the coefficient of performance (COP) of the refrigeration system decreased slightly, but by improving the efficiency of the compressor and the performance of the heat exchanger, the refrigeration capacity and energy efficiency can be improved. In addition, R134a is also used for medium and high temperature refrigeration and industrial chillers in commercial refrigeration.
R407C
(I) Physical properties
R407C is compounded by R32/R125/R134a in a mass ratio of 23/25/52. Unlike R410A, it is a non-azeotropic mixture, and the temperature slip during the phase change process reaches 5~7℃. This characteristic makes the evaporator outlet superheated, which is conducive to improving the heat exchange efficiency, but also puts higher requirements on the system control. The ODP of R407C is 0, GWP=1774, and the saturated pressure at room temperature is equivalent to R22, which is easy to transform and replace the R22 system. Its volumetric refrigeration capacity is slightly lower than that of R22, the compressor exhaust temperature is moderate, and conventional mineral oil can be used.
(II) Main applications
R407C is mainly used for industrial and commercial refrigeration. It has similar physical properties to R22 and is suitable as a transitional substitute for R22 systems. In large cold storage, quick freezing equipment, refrigerated containers and other fields, the original R22 units can be switched to R407C, and only slight adjustments to the expansion valve and controller are required to obtain a similar cooling capacity and energy efficiency as R22. Some original R22 chillers and heat pump units can also be switched to R407C after replacing the compressor lubricant.
