In a refrigerant compressor for refrigeration plants, comprising a compressor unit driven by a drive unit, wherein at least one of these units is provided with a control unit which is controllable by means of a delivery rate control system in order to control the refrigerant compressor at different delivery rates, wherein an external delivery rate setpoint value is communicated to the delivery rate control system, in order to prevent critical operating states, it is proposed that the delivery rate control system acquires, by means of a sensor, a compressor reference temperature of the compressor unit, that the delivery rate control system ascertains an operating state value group for the acquisition of an operating state of the refrigerant compressor and, taking account of specified reference values, if the value of the ascertained operating state value group based upon the compressor reference temperature permits a critical operating state of the refrigerant compressor, specifies a delivery rate which has as its result an operation of the refrigerant compressor outside of the critical operating states.

A rotary compressor system includes a compressor housing that includes a compressor motor that draws in fluid from a suction side. The fluid is compressed within a compression chamber and discharged through a discharge side. The compression chamber is disposed between the suction side and the discharge side. An overload-protection switch is electrically coupled in series with the compressor motor and is adapted to cut power to the compressor motor responsive to an overload event. A solenoid valve is fluidly coupled between the compression chamber and a location upstream of the suction side and is electrically coupled in series with the overload-protection switch. An interruption of electrical current to the compressor motor also interrupts electrical current to the solenoid valve, which opens the solenoid valve to equalize pressure between the suction side and the discharge side.

A refrigerant system includes a compressor configured to pressurize a refrigerant fluid. The compressor includes a sump portion. A heater is situated to heat at least the sump portion. A controller is configured to selectively operate the heater to apply heat to at least the sump portion while the compressor is off and continue operating the heater when the compressor turns on until a temperature of the compressor or a temperature of fluid discharged from the compressor satisfies at least one criterion.

A refrigeration cycle apparatus in which a refrigerant having potential for disproportionation reaction circulates a first refrigerant flow path connected between a discharge side of the compressor and the condenser; a second refrigerant flow path connected between the condenser and the expansion valve; a third refrigerant flow path connected between the expansion valve and a suction side of the compressor; a jetting unit; a pressure measuring unit; and a temperature measuring unit. The jetting unit is configured to jet the refrigerant drawn from the second refrigerant flow path or the third refrigerant flow path to at least one of the compressor, the first refrigerant flow path and the second refrigerant flow path when at least one of a measured value of the pressure measuring unit and a measured value of the temperature measuring unit exceeds an allowed value.

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.

The present disclosure provides a system and a method for monitoring an operation of a vapor compression cycle. The method comprises collecting digital representation of observed variables of the operation of the vapor compression cycle over multiple instances of time and executing a constrained ensemble Kalman smoother for each instance of time to estimate the state variables of the vapor compression cycle for each instance of time. The constrained ensemble Kalman smoother updates the state variables over a sequence of time instances within a smoothing window by solving a series of constrained optimization problems in a range of a covariance, for which constraints are enforced for every variable in the smoothing window for every instance of the constrained optimization problems. The method further comprises outputting, based on the estimates of the state variables, estimates of variables of the vapor compression cycle at each instance of time.

A system and method of controlling temperature of a medium by refrigerant vaporization, the system including a container, at least one a refrigerant reservoir having at least one reservoir section that includes a wall with an exterior surface structured to be thermally coupled with a volume of the medium in the container and to provide a volume of medium thermal coverage in the container, a vapor pressure apparatus to provide regulation of refrigerant vapor pressure in the at least one refrigerant reservoir, whereby the refrigerant reservoir forms a vapor space in each of the at least one reservoir section in response to receiving refrigerant and to the vapor pressure apparatus regulation of vapor pressure above the refrigerant to enable refrigerant vaporization at or near a selected temperature of the volume of medium in the container that is thermally coupled to the respective reservoir section.

A system may include a compressor, a first passageway, a valve and a control module. The compressor includes a compression mechanism operable to compress a working fluid. The first passageway is in fluid communication with an oil sump of the compressor and the compression mechanism. The valve is disposed along the first passageway and movable between an open position allowing lubricant from the oil sump to flow to the compression mechanism and a closed position restricting lubricant from the oil sump from flowing to the compression mechanism. The control module is in communication with the valve and configured to move the valve between the closed position and the open position based on an operating parameter indicative of a temperature of the compression mechanism.

A refrigeration cycle apparatus according to the present invention performs cooling by circulation of refrigerant. The refrigeration cycle apparatus includes an evaporator, a condenser, a pump, a compressor, and a controller. The evaporator is arranged in a first space. The condenser is arranged in a second space. The pump is configured to compress refrigerant from the condenser and output the refrigerant to the evaporator. The compressor is configured to compress refrigerant from the evaporator and output the refrigerant to the condenser. The controller is configured to control the pump and the compressor to cool the first space. The controller is configured to turn on the pump after turn-on of the compressor while a temperature of the first space is higher than a temperature of the second space.

A refrigeration cycle apparatus includes a refrigerant circuit, a controller, a bypass pipe, a refrigerant cooler, a second expansion device, and a controller temperature sensor. In a case where a temperature measured by the controller temperature sensor is lower than or equal to a set temperature in a state where an opening degree of the second expansion device is controlled to an instruction opening degree that is lower than or equal to a set opening degree, the controller is configured to perform foreign substance release control where the controller is configured to increase the opening degree of the second expansion device and then is configured to return the opening degree of the second expansion device to the instruction opening degree.