Typically, vapor/liquid equilibrium data is determined and used to predict what lubricant viscosity is required for a given compressor design. Miscibility of the lubricant and the refrigerator liquid phase often plays a key role in the return of lubricant to the compressor. This impacts compressor reliability and efficiency."
Dunaevsky further elaborates on the effect of oil/refrigerant miscibility and system performance. He says, "Overall, the degree of miscibility is an important characteristic and must be considered in the connection with the design of a refrigeration system and its components. For any given refrigerant, the percentage that can be dissolved into the lubricant depends on four factors: (1.) degree of miscibility of the refrigerant, (2.) pressure of the refrigerant vapor, (3.) temperature of the lubricating oil and (4.) length of time the two are in contact."
He continues, "The percentage of the refrigerant that can be dissolved in oil increases considerably as the temperature of the oil decreases and the pressure of the refrigerant vapor increases. If during a short time, a large quantity of refrigerant vaporizes under the right conditions, then severe oil foaming will result leading to its migration out of the compressor thus endangering its operation."
refrigerantR404A are shown in Figure 6. R404A is a hydroflurocarbon (HFC)-based refrigerant that is a blend of three refrigerants organizations that either cannot comply or choose to not follow the environmental regulations will be fined by the EPA. On top of regulatory fines, companies may experience a financial loss when they are required to buy carbon credits to meet the cap requirements.