The present invention is provided with: a turbo compressor that compresses a refrigerant; a condenser that condenses the refrigerant compressed by the turbo compressor; an expansion valve that expands a liquid refrigerant introduced from the condenser; an evaporator that evaporates the refrigerant expanded by the expansion valve; an oil tank that stores a lubricating oil supplied to the turbo compressor; a pressure equalizing pipe that connects the oil tank and the evaporator; and a control unit that controls start-up. The control unit calculates the amount of a refrigerant eluded into the lubricating oil in the oil tank at the time of start-up, and reduces a pressure reduction speed in the oil tank by limiting the opening operation of an IGV when the refrigerant elution amount per prescribed time exceeds a prescribed value.

An air compressor includes a tank unit that stores compressed air, a motor unit that generates compressed air to be stored in the tank unit, a pressure detection unit that detects a pressure value in the tank unit, and a control unit that drives the motor unit when a pressure value in the tank unit detected by the pressure detection unit is equal to or less than a motor start pressure value, and stops the motor unit when the pressure value in the tank unit detected by the pressure detection unit is equal to or greater than a motor stop pressure value. The control unit changes at least either of the motor start pressure value or the motor stop pressure value every time when a predetermined time passed.

An exemplary heat pump (10) includes: a compressor (16A, 16B) that discharges refrigerant; an oil separator (30) that separates oil from the refrigerant discharged from the compressor; an oil return channel (80) that returns the oil separated by the oil separator to the compressor; a pressure sensor (86A, 86B) that detects a pressure in the oil return channel; a first pressure loss member (84A, 84B) and a second pressure loss member (88A, 88B) disposed in portions of the oil return channel at an oil separator side and a compressor side relative to the pressure sensor; and a control device that increases an output of the compressor in a case where a pressure detected by the pressure sensor exceeds a suction pressure of the compressor and less than a discharge pressure of the compressor.

A refrigeration cycle (1) comprises in the direction of flow of a circulating refrigerant: a compressor unit (2); an oil separation device (4) which is configured for separating oil from an refrigerant-oil-mixture leaving the compressor unit (2); at least one gas cooler/condenser (6); and at least one evaporator (10) having an expansion device (8) connected upstream thereof. The oil separation device (4, 5) comprises: a refrigerant inlet line connected to the compressor unit (2), the refrigerant inlet line having at least a first portion (12) with a first diameter (d1); a refrigerant conduit arranged downstream of and connected to the refrigerant inlet line, the refrigerant conduit having at least a second portion (14) with a second diameter (d2), which is larger than the first diameter (d1); a refrigerant outlet line arranged downstream of and connected to the refrigerant conduit, the refrigerant outlet line having at least a third portion (16) with a third diameter (d3), which is smaller than the second diameter (d2); and an oil suction line (20) having an inlet portion (22) which opens into the second portion (14) and is configured for sucking oil from the second portion (16). The third portion (16) having the third diameter (d2) extends into the second portion (14) forming an oil separation pocket (18) between the outer diameter of the third portion (16) and the inner diameter of the second portion (14).

An air compressor includes a tank unit that stores compressed air, a motor unit that generates compressed air to be stored in the tank unit, a pressure detection unit that detects a pressure value in the tank unit, and a control unit that drives the motor unit when a pressure value in the tank unit detected by the pressure detection unit is equal to or less than a motor start pressure value, and stops the motor unit when the pressure value in the tank unit detected by the pressure detection unit is equal to or greater than a motor stop pressure value. The control unit changes at least either of the motor start pressure value or the motor stop pressure value every time when a predetermined time passed.

Systems and methods for a vapor compression system including primary actuators, secondary actuators, primary sensors that provide a primary set of system outputs, and secondary sensors that provide a secondary set of system outputs. A primary controller receives the primary set of system outputs, and produces a primary set of control inputs for the primary actuators, to regulate one or more zone temperatures to set-points and to regulate one or more critical process variables to set-points. A secondary controller receives the secondary set of system outputs, and produces a secondary set of control inputs, to minimize an overall system power consumption. The secondary inputs may include set-points to the primary controller. The primary outputs may include estimates of critical process variables that are used as inputs to the secondary controller.

In a method for operating a compressor (22) having an inlet (26) and an outlet (28), the method includes: running the compressor to compress a fluid; shutting down (422) the compressor; determining (420) a condition-dependent threshold restart pressure difference (threshold) across the compressor; relieving the pressure-difference to reach the threshold; and, after the threshold is reached, restarting (434) the compressor.

A method for controlling a valve arrangement (10) interconnecting at least one oil separator (8) and an oil receiver (9) in a vapour compression system (1) is disclosed. A pressure difference between a pressure prevailing inside the oil separator(s) (8) and a pressure prevailing inside the oil receiver (9) is obtained. Then a duration for an open time of an open/close sequence of the valve arrangement (10) is derived, based on the obtained pressure difference, and the valve arrangement (10) is controlled in accordance with the derived duration of an open time. The supply of oil to the oil receiver (9) can be accurately controlled, regardless of the operating conditions.

In order to provide a control unit which can cooperate with a great variety of operating units and/or status acquisition units, it is proposed that the control unit comprises a base module which has at least one processor and at least one memory store for the required program code for operating the processor and terminals for operating units carrying out basic functions and/or status acquisition units and that the processor and the program code stored in the memory store are configured such that therewith additional functions of an additional module connectable to the base module are also executable.

A refrigeration system, a fault diagnosis system and a fault diagnosis method for the refrigeration system, a controller and a storage medium. The fault diagnosis method includes: receiving a fault alarm sent by an associated refrigeration system, and acquiring a fault cause list associated with the fault alarm; determining whether to run a fault diagnosis system associated with the fault alarm; and when the fault diagnosis system associated with the fault alarm is run, checking the associated refrigeration system sequentially according to the fault cause list, and acquiring a fault cause and a repair means list associated with the fault cause.