Rotary heat exchangers can include a ride-along compressor, at least a portion of which can be rotated along with the heat exchanger. By rotating at least a portion of the compressor along with the heat exchanger, a sealed fluid circuit containing a two-phase working fluid can be provided. A rotary heat pump or heat engine can include an evaporator and a condenser in the form of back-to-back centrifugal fans. The centrifugal fan blades or other portions of the evaporator and condenser may include internal cavities where the working fluid undergoes a phase change.

A climate-control system may include a compressor, a condenser, an evaporator, a first sensor, a second sensor, a third sensor, and a control module. The compressor may include a motor and a compression mechanism. The condenser receives compressed working fluid from the compressor. The evaporator is in fluid communication with the compressor and disposed downstream of the condenser and upstream of the compressor. The first sensor may detect an electrical operating parameter of the motor. The second sensor may detect a discharge temperature of working fluid discharged by the compression mechanism. The third sensor may detect a suction temperature of working fluid between the evaporator and the compression mechanism. The control module is in communication with the first, second and third sensors and may determine whether a refrigerant floodback condition is occurring in the compressor based on data received from the first, second and third sensors.

Methods, systems, and apparatuses are described to help manage oil return such as in a chiller system of a HVAC system. A refrigerant/oil mixture can be directed out of the evaporator into an oil return heat exchanger that is configured to help vaporize a refrigerant portion of the refrigerant/oil mixture. Superheat refrigerant vapor can be directed from a condenser into the oil return heat exchanger as the heat energy to vaporize the refrigerant portion in the refrigerant/oil mixture. The oil return heat exchanger can be positioned lower than the evaporator so that gravity can help the refrigerant/oil mixture to flow into the oil return heat exchanger.

An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

An embodiment of method used to control operation of a screw compressor of a refrigeration system may include receiving status signals regarding operation of the screw compressor of the refrigeration system. The method may further include determining an operating point of the screw compressor based upon the received status signals, and selecting a torque profile for the screw compressor based upon the operating point. The method may also include driving the screw compressor per the selected torque profile. Refrigeration systems and compressor systems suitable for implementing the method are also presented.

A refrigeration apparatus, including a main circuit for a loop circulation of a main flow of refrigerant, the main circuit including a compressor, a condenser, an expansion valve and an evaporator. The refrigeration apparatus comprises a lubrication branch, for deriving a lubrication flow from the main flow for feeding the compressor for lubrication. The main circuit includes a low-temperature part, consisting in the evaporator, the compressor inlet, and any part of the main circuit between the evaporator and the compressor inlet. The lubrication branch further includes a subcooling heat exchanger, which is configured for enabling an exchange of heat between the lubrication flow circulating through the lubrication branch and the main flow of refrigerant circulating through the low-temperature part, so that the lubrication flow may be cooled by the main flow of refrigerant circulating through the low-temperature part, within the subcooling heat exchanger.

A freezing device including a compressor that compresses sucked refrigerant using a compression mechanism and discharges compressed refrigerant includes a compressor, an inverter, and a controller. The compressor includes a motor, a low pressure unit, a compression space, a high pressure unit, a communication flow path, and a flow control valve. The inverter drives or stops the motor. The controller controls the inverter and the flow control valve. The controller performs, in stop control in which an operation of the compressor is stopped, braking control in which driving of the compression mechanism is prevented or suppressed, and pressure equalization control in which pressure in the high pressure unit is equalized with pressure in the low pressure unit.

Rotary heat exchangers can include a ride-along compressor, at least a portion of which can be rotated along with the heat exchanger. By rotating at least a portion of the compressor along with the heat exchanger, a sealed fluid circuit containing a two-phase working fluid can be provided. A rotary heat pump or heat engine can include an evaporator and a condenser in the form of back-to-back centrifugal fans. The centrifugal fan blades or other portions of the evaporator and condenser may include internal cavities where the working fluid undergoes a phase change.

Rotary heat exchangers can include a ride-along compressor, at least a portion of which can be rotated along with the heat exchanger. By rotating at least a portion of the compressor along with the heat exchanger, a sealed fluid circuit containing a two-phase working fluid can be provided. A rotary heat pump or heat engine can include an evaporator and a condenser in the form of back-to-back centrifugal fans. The centrifugal fan blades or other portions of the evaporator and condenser may include internal cavities where the working fluid undergoes a phase change.

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.