Abstract: A refrigeration system includes a low temperature (LT) compressor, a medium temperature (MT) compressor having a suction side fluidly coupled with a discharge side of the LT compressor, a low temperature evaporator, and a medium temperature evaporator. Refrigerant from the low temperature evaporator is returned to a suction side of the LT compressor and refrigerant from the medium temperature evaporator is returned to a connection point downstream of the discharge side of the LT compressor and upstream of the suction side of the MT compressor. The refrigeration system performs a defrost cycle by directing warm refrigerant from the suction side of the MT compressor to pass through the low temperature evaporator in a reverse direction. The warm refrigerant is drawn from a position downstream of the connection point and upstream of the suction side of the MT compressor and returned to the suction side of the LT compressor.

Abstract: A method for defrosting an evaporator of a refrigeration system includes providing a refrigeration system including a low temperature (LT) compressor, a medium temperature (MT) compressor, a low temperature evaporator, and a medium temperature evaporator. The method includes initiating a defrost cycle for the refrigeration system by closing a return valve to shut off refrigerant return to the LT compressor from an outlet of the low temperature evaporator and opening a defrost supply valve to define a fluid flow path between a suction side of the MT compressor and an outlet of the low temperature evaporator. The method includes operating the LT compressor and the MT compressor such that warm refrigerant from the suction side of the MT compressor is provided through the low temperature evaporator and returned to a suction side of the LT compressor through a hot gas tank.

Abstract: A method for defrosting an evaporator of a refrigeration system includes providing a refrigeration system including a low temperature (LT) compressor, a medium temperature (MT) compressor, a low temperature evaporator, and a medium temperature evaporator. The method includes initiating a defrost cycle for the refrigeration system by closing a return valve to shut off refrigerant return to the LT compressor from an outlet of the low temperature evaporator and opening a defrost supply valve to define a fluid flow path between a suction side of the MT compressor and an outlet of the low temperature evaporator. The method includes operating the LT compressor and the MT compressor such that warm refrigerant from the suction side of the MT compressor is provided through the low temperature evaporator and returned to a suction side of the LT compressor through a hot gas tank.