A heat source unit constitutes a refrigeration apparatus by being connected to a utilization-side unit. The heat source unit includes a low-stage compression element, a high-stage compression element, and a heat exchanger. The low-stage compression element has a discharge pipe provided with a pressure switchgear. The high-stage compression element compresses a refrigerant discharged from the low-stage compression element. When the low-stage compression element is paused in response to activation of the pressure switchgear, the high-stage compression element operates while the low-stage compression element is kept paused.

The invention provides an air conditioner control method and device and an air conditioner. The air conditioner control device acquires a current temperature of a chilled water of a unit at a preset period; determine a target load of the unit, a target temperature of a chilled water and a target temperature of a cooling water based on a temperature of the chilled water set by a user and the current temperature of the chilled water; determine an evaporating parameter and a condensing parameter of the unit based on the target load of the unit, the target temperature of the chilled water and the target temperature of the cooling water; and determine operation parameters of a compressor based on the target load of the unit, the evaporation parameter and the condensation parameter. Therefore, the unit can operate based on the operation parameters.

A method for controlling the power-on or power-off of an air conditioner is provided. The method includes the following steps: determining whether a variable capacity compressor of the air conditioner is in a standby single-cylinder operation state before starting the air conditioner, where the variable capacity compressor is configured to be switchable between a single-cylinder operation state and a dual-cylinder operation state; if so, starting the air conditioner; if not, switching the variable capacity compressor to the standby single-cylinder operation state, and then starting the air conditioner. With this control method, regardless of whether the air conditioner is shut down because the power supply of the unit is cut off or because a power-off signal is received, the air conditioner can be started in a single-cylinder operation state in the next startup, so that the operation state of the cylinder is always determined when starting the air conditioner.

A refrigeration cycle device includes a compressor to compress refrigerant, a suction-side detector to detect a pressure of the refrigerant to be suctioned into the compressor, a discharge-side detector to detect a pressure of the refrigerant discharged from the compressor, and controlling circuitry that controls the compressor. When the ratio of a second pressure value detected by the discharge-side detector to a first pressure value detected by the suction-side detector is not between a predetermined upper limit and a predetermined lower limit, the controlling circuitry controls the compressor such that the ratio falls between the predetermined upper limit and the predetermined lower limit.

The present invention provides a cooling system including a vaporizer (1) which is configured to absorb heat due to a liquid-phase refrigerant R being vaporized, a condenser (2) which is configured to discharge heat due to a refrigerant (R) in a gaseous phase state being liquefied, a resistance body (8) which is provided in a middle of a pipe passage (3) ranging from the vaporizer (1) to the condenser (2) and is configured to apply a resistance to the refrigerant (R), state detection sensors (9) which are provided in the pipe passage (3) on an upstream side and a downstream side of the resistance body (8) and are configured to detect a state of the refrigerant (R) flowing through each side inside the pipe passage (3), and a flow rate control means (C) which is configured to detect the presence of droplets in the refrigerant R flowing through the pipe passage (3) on the basis of a difference between detection values of the state detection sensors (9) which are detected on the upstream side and the downstream side of the resistance body (8), and controls a flow rate of the refrigerant (R) on the basis of detection results.

A refrigeration cycle device includes a compressor to compress refrigerant, a suction-side detector to detect a pressure of the refrigerant to be suctioned into the compressor, a discharge-side detector to detect a pressure of the refrigerant discharged from the compressor, and a control device having a function of controlling the compressor when the ratio of a second pressure value detected by the discharge-side detector to a first pressure value detected by the suction-side detector is not between a predetermined upper limit and a predetermined lower limit, such that the ratio falls between the upper limit and the lower limit.

A cooling system includes an evaporator, connected through fluid lines to a first condenser, a second condenser, a compressor, and a thermal expansion valve. One or more valves are arranged in the fluid lines. The one or more valves operated to, in a first mode, circulate fluid between the evaporator the first condenser; in a second mode, circulate the fluid between a) the evaporator and the first condenser, and b) the evaporator, the second condenser, and the thermal expansion valve, and; in a third mode, circulate the fluid between a) the evaporator and the first condenser, and c) the evaporator, the compressor, the second condenser, and the thermal expansion valve.

The present disclosure concerns a device and a method for chiller station management for providing chilled water to a load (30), a computer storage medium and a chiller station. The method for chiller station management includes: determining whether a chiller (10) with a low load exists in a chiller station and determining whether to allow to shut down one chiller (10) in the chiller station, when a certain chiller (10) in the chiller station transmits a surge risk signal; if yes, shutting down one chiller (10) in the chiller station to increase loads of other chillers (10); and if no, raising a chiller (10) outlet water temperature in the chiller station and/or lowering a cooling tower (20) outlet water temperature in the chiller station. The device and method for chiller station management according to the present disclosure provide a surge protection at a chiller station level, thereby effectively avoiding occurrence of surge in the chiller, and improving the efficiency and operation stability of the chiller station.

Systems and methods are provided for controlling compressor systems to ensure sufficient pressure differentials to provide cooling. A compressor system includes a compressor, a suction pressure sensor at a suction of the compressor, a discharge pressure sensor, a condenser, an expansion device, a liquid line, a liquid line pressure sensor, an evaporator, a condenser blower and a controller. The method includes determining a pressure target based on an intermediate pressure within the compressor and a threshold cooling differential pressure value, determining a pressure ratio setpoint based on the pressure target and a liquid line pressure measured by the liquid line pressure sensor, controlling the condenser blower to operate based on the determined pressure ratio setpoint, determining a subcooling setpoint based on the pressure target and the liquid line pressure in the compressor system, and controlling the expansion device to operate based on the subcooling setpoint.

A screw compressor includes a compressor housing defining a working chamber, the housing including a plurality of bores; a first rotor having helical threads, the first rotor being housed in a first of the plurality of bores; a second rotor having helical threads intermeshing with the helical threads of the first rotor, the second rotor being housed in a second of the plurality of bores; an inlet port that receives a fluid to be compressed; an outlet port that receives a compressed fluid; and an intermediate discharge port disposed between the compression chamber and the outlet port, the intermediate discharge port including a sealing member and a biasing mechanism, fluid flow being prevented between the compression chamber and the intermediate discharge port when in a flow-blocked state, and fluid flow being enabled from the compression chamber through the intermediate discharge port when in a flow-permitted state.