High-speed defrost refrigeration system

A method for defrosting evaporators in a refrigeration system of the type having a cooling refrigerant circulating sequentially between a compression stage, a condensing stage, an expansion stage and an evaporation stage to then return to the compression stage, comprising:

• i) stopping a suction of the cooling refrigerant in a first evaporator of the evaporation stage;
• ii) directing defrost refrigerant from the compression stage to the first evaporator so as to defrost the first evaporator;
• iii) directing the defrost refrigerant from the first evaporator upstream of the expansion stage;
• and
• iv) mixing the cooling refrigerant exiting from the condensing stage with the defrost refrigerant by controlling a cooling refrigerant pressure downstream of the condensing stage;
• and
• v) exposing the mixture of cooling refrigerant and defrost refrigerant to a heat exchanger to remove excess gas from the mixture;
• vi) directing all of the mixture to the expansion stage;
• whereby a second evaporator of the evaporation stage is cooled with the mixture of cooling refrigerant from the condensing stage with the defrost refrigerant.

A method for installing a defrost system in a refrigeration system of the type having a cooling refrigerant circulating sequentially during a refrigeration cycle between a compression stage, a condensing stage, an expansion stage and an evaporation stage to then return to the compression stage, comprising:

• providing a valve to stop a suction of cooling refrigerant in at least a first evaporator of the evaporation stage;
• positioning a first line feeding the first evaporator with defrost refrigerant from the compression stage in a defrost cycle;
• positioning a second line between the first evaporator and a main line between the condensing stage and the expansion stage to direct the defrost refrigerant from the first evaporator to the main line to feed at least a second evaporator in the refrigeration cycle;
• providing a pressure reducing device in the main line to reduce the pressure of the cooling refrigerant for a subsequent mixing with the defrost refrigerant from the second line in the refrigeration cycle;
• and
• providing a sub-cooling system f or liquefying all of the mixture of cooling refrigerant and defrost refrigerant.