Particularly recommended for screw compressors operating with HFO (or HFC / HFO blends), the higher viscosity of Mobil EAL Arctic 170 ensures good protection against compressor wear despite the lower viscosity induced by higher solubility. At the same time, good miscibility of the oil with refrigerants improves or maintains evaporator performance for improved efficiency and refrigeration production. Mobil EAL Arctic 170 meets the needs of many commercial applications (heating, ventilation, air conditioning), commercial refrigeration (food preservation, transport) and industrial (food processing, freezing) applications.
What refrigerants can Mobil EAL Arctic 170 be used with?
A POE oil with a viscosity of 170 cSt at 40°C, it is particularly suitable for pure HFOs such as R-1234yf, R-1234ze or R-1233zd. It can also be selected to work with HFC / HFO blends, such as R-455A or R-454C.
How do you adapt the viscosity of the oil to the condensation temperature?
This is the purpose of the VPT (Viscosity, Pressure, Temperature) or Daniel curve. During the compression phase, the oil used to cool and lubricate the screws is subjected to high pressure and gas dissolves in it. The VPT curve can be used to determine the percentage of gas dissolved in the oil as a function of the discharge temperature, bearing in mind that the solubility of the refrigerant is virtually independent of the viscosity of the oil.
What should I do if I don’t have the corresponding VPT curve?
It is possible to extrapolate a curve with a refrigerant from the VPT curve of that refrigerant with the same oil of a different grade. For example, the VPT curve for R-1234ze and the viscosity of Mobil EAL Arctic 170 can be extrapolated from the VPT curve for R-1234ze and Mobil EAL Arctic 100.
Example: if we take the curve opposite, at a discharge pressure of 10 bar, for a condensation temperature of 50°C and a discharge temperature of 80°C, the plot gives a concentration of 20% R-1234ze in EAL Arctic 100 oil.
At 80°C, the actual viscosity of Mobil EAL Arctic 100 will be ~4 cSt, and therefore too low to provide wear protection for compressor bearings. A minimum viscosity of 7 to 12 cSt is required by compressor manufacturers, which would mean cooling the oil to 55°C or even 35°C. A higher oil viscosity is therefore recommended.
Cooling Mobil EAL Arctic 170 to 55°C gives a viscosity of 12 cSt, demonstrating that this oil is particularly well suited to screw compressors running on R-1234ze.
Stages of extrapolation
*Data calculated from values available on the technical data sheet