Defrost refrigeration system

A defrost refrigeration system of the type having a main refrigeration circuit in which a refrigerant absorbs heat from an evaporator stage and releases heat in a condensation stage, with a compression stage sequentially between the evaporation stage and the condensation stage during a refrigeration cycle, said defrost refrigeration system comprising:

• at least a first compressor and a second compressor serially positioned with respect to one another such that refrigerant going through the compression stage in the refrigeration cycle passes sequentially through the first compressor and the second compressor;
• a first line extending from an exit of one of the first compressor and the second compressor of the compression stage, and in fluid communication with the evaporator stage in a defrost cycle and adapted to receive a defrost portion of refrigerant compressed in the compression stage;
• and
• valves for switching at least one evaporator between the refrigeration cycle and the defrost cycle, by stopping/allowing a flow of refrigerant from the condensation stage to at least one evaporator of the evaporation stage in the refrigeration cycle, and for allowing/stopping a flow of said defrost portion of refrigerant to defrost the at least one evaporator in the defrost cycle.