Abstract: A refrigerant system including a compressor, an oil separator, an oil solenoid valve, a condenser, an evaporator, a bypass pipe, and a bypass solenoid valve is disclosed. The oil separator is connected to an output end of the compressor. The oil solenoid valve is disposed between the oil cooler and the compressor. The condenser is connected to the oil separator. The evaporator is connected to the condenser. The bypass pipe has a first end and a second end opposite to the first end. The first end is connected between the oil separator and the condenser, and the second end is connected between the evaporator and an input end of the compressor. The bypass solenoid valve is disposed on the bypass pipe. A controlling method for the refrigerant system is also disclosed.

Abstract: A two-stage refrigerant compressor and an operation method thereof are disclosed. The two-stage refrigerant compressor (10) includes: a housing (1); a first compressor module (2) having first screw rods (21) and a first motor (22) driving the first screw rods (21) to rotate; a second compressor module (3) having second screw rods (31) and a second motor (32) driving the second screw rods (31) to rotate; an adjustment mechanism (4) having a first slide valve (41) and a second slide valve (42); a middle pressure sensor (51) configured to acquire a current middle pressure; and a processor configured to receive data of the current middle pressure, control rotating speeds of the first motor (22) and the second motor (32), and control locations of the first slide valve (41) and the second slide valve (42).

Abstract: A fluid machine and its operating method are provided. The fluid machine (10) includes a main body (1), a screw set (2), a capacity adjustment mechanism (3), an intermediate pressure sensor (5), and a controller (6). The main body (1) includes a low-pressure chamber (11), an intermediate-pressure chamber (12), and a high-pressure chamber (13). The screw set (2) includes a pair of first screws (21) in the low-pressure chamber (11) and a pair of second screws (22) in the high-pressure chamber (13). The capacity adjustment mechanism (4) includes a first slide valve (41) disposed corresponding to the first screws (21) and a second slide valve (42) disposed corresponding to the second screws (22). The intermediate pressure sensor (5) is placed in the intermediate-pressure chamber (12) for obtaining its interior pressure. The controller (6) drives movement of the first slide valve (41) and the second slide valve (42).