Refrigeration system with superheating, sub-cooling and refrigerant charge level control

A refrigeration system, comprising:

• a refrigerant reservoir;
• a compressor to compress a refrigerant;
• a condenser disposed downstream of the compressor to condense the refrigerant;
• an evaporator disposed downstream of the condenser to vaporize the refrigerant;
• refrigerant lines fluidly connecting the compressor, the condenser and the evaporator in series to form a refrigerant circuit for circulating the refrigerant;
• at least one sensor configured to measure a temperature of the refrigerant and a pressure of the refrigerant in the refrigerant circuit;
• and
• a controller communicatively coupled to the at least one sensor and configured to:
• determine a sub-cooling level or super-heating level based on the temperature or the pressure measured by the at least one sensor;
• determine a refrigerant charge level based at least in part on the sub-cooling level or the super-heating level;
• determine whether the refrigerant charge level is below a predetermined refrigerant charge level;
• and
• in accordance with a determination that the refrigerant charge level is below the predetermined refrigerant charge level, selectively inject additional refrigerant from the refrigerant reservoir to the refrigerant circuit, thereby raising the refrigerant charge level to at least the predetermined refrigerant charge level.