bypass flow passage branching at a part of the refrigerant circulating passage between the condenser and the expansion valve routing through throttle means and communicating with a rotor room within the screw compressor is provided the screw refrigerating apparatus is capable of simplifying the structure decreasing the size decreasing labor of the maintenance and the like application_number US 65397503 A description the section below describes embodiments of the present invention following drawings fig1 shows a screw refrigerating apparatus 1 according to a first embodiment of the present invention in this screw refrigerating apparatus 1 a refrigerant circulating flow passage i includes a screw compressor 11 having an unillustrated rotor room rotationally storing a pair of male and female screw rotors meshing with each other a condenser 12 an expansion valve 13 and an evaporator 14 a bypass flow passage ii branches at a part of the refrigerant circulating passage i between the condenser 12 and the expansion valve 13 routes through throttle means 15 and communicates with the rotor room anything having a throttle effect may be used for the throttle means 15 the throttle means 15 may be an orifice a fixed throttle valve or a variable throttle valve the refrigerant in the gas state sucked by the screw compressor 11 is compressed is discharged from the screw compressor 11 to the condenser 12 and releases the heat to the outside through heat exchange in the condenser 12 the refrigerant in the gas state is condensed.