In order to improve a refrigerant compressor comprising a drive motor and a compressor unit which compresses a refrigerant entering through a suction inlet and allows it to exit through a pressure outlet in such a way that it works as reliably as possible, it is proposed that the refrigerant compressor comprise a compressor monitoring system which is integrated into a compressor control system and which determines a compressor condition by means of a first condition value that corresponds to a first saturation temperature in the suction inlet and a second condition value that corresponds to a second saturation temperature in the pressure outlet, and which compares the compressor condition with permissible compressor conditions lying in a given deployment field of a deployment diagram and initiates a process of switching-off the refrigerant compressor if the compressor condition departs from the deployment field.

A refrigeration system includes compressor and a duct assembly that includes a duct frame and a sensor unit. The duct frame provides a path for evaporating refrigerant from a lubricant sump of the compressor. The sensor unit obtains temperature measurements of the refrigerant and a lubricant within the lubricant sump and heats and evaporates the refrigerant located within the duct frame of the duct assembly. A control module receives temperature measurements from the sensor unit, determines a presence of liquid refrigerant within the lubricant sump of the compressor in response to a determination that an actual temperature change does not correspond with an expected temperature change for the lubricant, and in response to a determination that the actual temperature change corresponds with the expected temperature change for the lubricant, operates the compressor.

An air conditioning apparatus includes an electric compressor, an inverter, a temperature detection element, and an ECU. The electric compressor compresses a refrigerant drawn from a refrigerant intake port and discharges the refrigerant from a refrigerant discharge port. The inverter is integrated with the electric compressor so as to be cooled by the drawn refrigerant, and operates the electric compressor according to a control signal. The temperature detection element detects a temperature of the inverter. The ECU outputs a control signal to control the inverter. The ECU performs any one or both of a control for reducing a self-cooling amount of the electric compressor and a control for increasing a self-heat generation amount of the inverter with respect to the inverter when the temperature detected by the temperature detection element is lower than a predetermined reference temperature.

A system may include first and second compressors, first and second heat exchangers, a flash tank, and first, second and third fluid paths. The first compressor may include first and second inlets. The second compressor may receive fluid from an outlet of the first compressor. The first heat exchanger may receive fluid from the second compressor. The flash tank may receive fluid from the first heat exchanger and includes a vapor outlet and a liquid outlet. The second heat exchanger may be in fluid communication with the flash tank and may receive fluid from the liquid outlet. The first fluid path extends from an outlet of the second heat exchanger to an inlet of the second compressor. The second fluid path extends from the vapor outlet to the first fluid path. The third fluid path may transmit fluid from the vapor outlet to the second inlet.

Methods are directed towards dynamically determining refrigerant film thickness at the rolling-element bearing and for dynamically controlling refrigerant film thickness at the rolling-element bearing. Further, an oil free chiller system is configured for dynamically determining refrigerant film thickness at the rolling-element bearing of the oil free chiller system, wherein the oil free chiller system is also configured for dynamically controlling refrigerant film thickness at the rolling-element bearing of the oil free chiller system.

An illustrative example refrigeration system includes a cooling apparatus, a generator that provides electrical power to the cooling apparatus, and an engine that provides power to the generator. A processor is configured to determine an ambient temperature, determine a load of the generator, determine a temperature of the generator, and determine whether the temperature of the generator exceeds a threshold, which is dependent on the ambient temperature and the load of the generator.

A controller, at least during the heating operation, controls the opening degree of a second expansion device and/or a third expansion device based on a discharge refrigerant temperature detected by a discharge refrigerant temperature detector, or a value computed using the discharge refrigerant temperature, and causes refrigerant having a quality equal to or greater than 0.9 and less than or equal to 0.99 to be suctioned into a compressor.

A refrigerant compressor for refrigeration plants having a compressor unit driven by a drive unit. At least one of the compressor and drive units has a control unit which is controllable by delivery rate control system to control the refrigerant compressor at different delivery rates. An external delivery rate setpoint value is communicated to the delivery rate control system to prevent critical operating states. The delivery rate control system is configured to acquire, via a sensor, a compressor unit reference temperature. The delivery rate control system is configured to ascertain an operating state value group to acquire an operating state of the refrigerant compressor, and specify a delivery rate for operation of the refrigerant compressor outside of the critical operating states, 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.

A control system includes processing and memory circuitry, the memory circuitry storing a temperature-based capacity control scheme for a chiller system and the processing circuitry being configured to perform the temperature-based capacity control scheme. The motor temperature-based capacity control scheme is performed as a function of a monitored temperature in a motor configured to drive a compressor of the chiller system, a first temperature threshold corresponding to the monitored temperature, and a second temperature threshold corresponding to the monitored temperature higher than the first temperature threshold.

A fluid injection control system, a fluid injection control method and a fluid circulation system including the fluid injection control system are provided. The fluid injection control system includes an injection valve, control apparatus and energy storage apparatus. The injection valve is arranged in a path along which a fluid flows into a device; the energy storage apparatus is configured to supply, in response to the control apparatus being powered off, power to the control apparatus so as to maintain an operation of the control apparatus.