Hot gas defrost using medium temperature discharge gas

A method of operating a refrigeration system, the method comprising:

• operating a first evaporator of a plurality of evaporators in a refrigeration mode;
• determining that operation of the first evaporator in a defrost mode is indicated;
• and
• after determining that operation of the first evaporator in the defrost mode is indicated, causing the first evaporator to operate in the defrost mode by adjusting a three-way valve positioned downstream from one or more medium temperature compressors of the refrigeration system to direct a portion of refrigerant compressed by the one or more medium temperature compressors to the first evaporator.

A controller of a refrigeration system, the controller comprising:

• an input/output interface communicatively coupled to a three-way valve positioned downstream from the one or more medium temperature compressors, the three-way valve configured to receive refrigerant compressed by one or more medium temperature compressors, wherein the three-way valve is operable to direct flow of the received compressed refrigerant to one or both of a gas cooler and one or more of the evaporators of the plurality of evaporators based on an operation mode of the plurality of evaporators;
• and
• a processor configured to:
• determine that operation of a first evaporator of a plurality of evaporators of the refrigeration system in a defrost mode is indicated;
• and
• after determining that operation of the first evaporator in the defrost mode is indicated, cause the first evaporator to operate in the defrost mode by adjusting the three-way valve to direct a portion of the received compressed refrigerant to the first evaporator.