Control system for a vapor compression system

A vapor compression system, comprising:

• a compressor configured to circulate a refrigerant through a refrigerant loop;
• a lubrication circuit comprising a cooler configured to receive a mixture of a lubricant and the refrigerant from a sump, wherein the cooler is configured to absorb thermal energy from the mixture received from the sump, and wherein the cooler comprises an inlet fluidly coupled to the sump and an outlet fluidly coupled to the compressor;
• and
• a controller comprising a memory and a processor, wherein the processor is configured to:
• receive a signal indicative of a temperature of the mixture at the outlet of the cooler;
• receive inputs indicative of properties of the lubricant, properties of the refrigerant, or both;
• determine a viscosity value of the mixture based on the signal;
• determine a threshold range based on the properties of the lubricant, the properties of the refrigerant, or both;
• and
• output a control signal in response to the viscosity value exceeding the threshold range.

A vapor compression system, comprising:

• a compressor configured to circulate a refrigerant through a refrigerant loop;
• a sump configured to receive a mixture of lubricant and the refrigerant from the compressor;
• a cooler configured to receive the mixture from the sump, wherein the cooler is configured to absorb thermal energy from the mixture, and wherein the cooler comprises an inlet fluidly coupled to the sump and an outlet fluidly coupled to the compressor;
• and
• a controller comprising a memory and a processor, wherein the processor is configured to:
• receive a first signal indicative of a temperature of the mixture within the sump;
• receive a second signal indicative of a pressure of the mixture within the sump;
• receive a third signal indicative of a temperature of the mixture at the outlet of the cooler;
• determine a relative amount of the refrigerant in the mixture based on the first signal and the second signal;
• determine a viscosity value of the mixture based on the third signal;
• output a first control signal in response to the relative amount of the refrigerant in the mixture exceeding a first threshold value;
• and
• output a second control signal in response to the viscosity value exceeding a first threshold range.