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.

A refrigerating and air-conditioning apparatus that performs defrosting operation, the refrigerating and air-conditioning apparatus including: a refrigerant circuit in which a compressor, a first heat exchanger, an expansion device, a second heat exchanger, and a four-way valve are connected to each other by pipes to allow refrigerant to circulate through the refrigerant circuit; a temperature sensor configured to measure a temperature of the compressor; and a heat generation control unit configured to increase a temperature of the compressor when the heat generation control unit detects a decrease in a value measured by the temperature sensor in defrosting operation performed on the first heat exchanger.

A compressor includes: a container forming an outer shell of the compressor; a terminal portion projecting from an upper surface of the container, and configured to supply electric power to an inside of the container; a rod projecting from the upper surface of the container; a terminal cover covering the terminal portion to protect the terminal portion, and fixed to the container by the rod; and a thermal protector configured to detect a temperature of the compressor. The thermal protector is brought into contact with and fixed to a flat outer surface of the container that is formed between the terminal portion and the rod.

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.

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 refrigerant compressor according to an exemplary aspect of the present disclosure includes, among other things, a first stage and a second stage downstream of the first stage, and a cooling line configured to cool power electronics. The cooling line is configured to be switched between a first mode and a second mode. The first mode is configured to dump refrigerant between the first stage and the second stage, and the second mode is configured to dump refrigerant upstream of the first stage.

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.

A refrigeration apparatus (1) includes a main refrigerant circuit (2) including a positive displacement compressor (4), a condenser (6), an expansion valve (8), and an evaporator (10), through which a refrigerant circulates successively in a closed loop circulation, a lubrication refrigerant line (18) connected to the main refrigerant circuit (2) between the condenser (6) and the expansion valve (8) or to the condenser (6), in which circulates a portion of the refrigerant of the main refrigerant circuit (2) and connected to the compressor (4) for lubrication of the compressor (4) with the refrigerant. The lubrication refrigerant line (18) includes, upstream from the compressor (4): a throttle valve (20) adapted to vary the lubrication refrigerant flow entering the compressor (4), a downstream pressure detector (30) configured to measure refrigerant pressure (P3) downstream the throttle valve (20) and upstream the compressor (4).

Systems and methods for lubricant management of a compressor in an HVACR system are disclosed. A heat transfer circuit can utilize a working fluid to provide heating or cooling includes a compressor for compressing the working fluid and a heat source configured to increase a suction temperature of the working fluid entering the compressor. One or more lubricant rheological properties in a compressor system based on measurements taken at or near a bearing cavity of the compressor are determinable. A lubricant reservoir can be in thermal communication with a discharge flow path of the compressor. An internal heat exchanger can be disposed within a compressor for improving viscosity of the lubricant to be cycled back into the compressor. A heater can be located on a fluid line between a lubricant separator and a lubricant inlet. Condenser fans can be controlled.

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.