A heat pump system includes a compressor, usage side heat exchanger, heat source side heat exchanger, expansion mechanism, main refrigerant flow control device switchable between cooling and heating modes, gas reheat heat exchanger connected in the refrigerant circuit, a fan disposed to direct an airflow across the usage side heat exchanger and the gas reheat heat exchanger into a target space, and a secondary refrigerant flow control device switchable between first and second modes. Refrigerant flows from the discharge line to the main refrigerant flow control device in the heating mode and the cooling mode in the first mode. Refrigerant flows from the discharge line to the gas reheat heat exchanger in a gas reheat mode and then flows to the main refrigerant flow control device in the second mode. A flow of the heat transfer medium to the heat source side heat exchanger is adjustable.

A heat pump system includes a compressor, a usage side heat exchanger, a heat source side heat exchanger, an expansion mechanism, a main refrigerant flow control device switchable between cooling and heating modes, a gas reheat heat exchanger, a fan, and a secondary refrigerant flow control device switchable between first, second, and third modes. Refrigerant flows from the compressor discharge line to the main refrigerant flow control device in the first mode. Refrigerant flows from discharge line to gas reheat heat exchanger and then main refrigerant flow control device in the second mode. Refrigerant flows both from discharge line to gas reheat heat exchanger and then main refrigerant flow control device, and from discharge line to main refrigerant flow control device without flowing through the gas reheat heat exchanger in the third mode. Refrigerant may flow to the usage side and hot gas reheat heat exchanger in the heating mode.

A refrigeration system includes a high-pressure side with a gas cooler configured, while the refrigeration system is powered by a main power supply and is operating to provide refrigeration, to cool refrigerant on the high-pressure side. The refrigeration system includes a low-pressure side with one or more evaporators. The refrigeration system includes an auxiliary compressor coupled to a backup power supply. An input of the auxiliary compressor is coupled to fluid conduit of the low-pressure side, and an output of the auxiliary compressor is coupled to fluid conduit of the high-pressure side. A controller is communicatively coupled to the auxiliary compressor. After determining that the main power supply is unavailable, the controller causes the auxiliary compressor to turn on to move refrigerant from the low-pressure side to the high-pressure side.

Methods and systems for recuperated superheat return are provided. A coolant is supplied in a vapor state to a compressor. The coolant compressed by the compressor is cooled with a gas cooler. The coolant cooled by the gas cooler is supplied to an inlet of a high pressure side of a recuperator. The coolant from an outlet of the high pressure side of the recuperator is supplied to a portion of a coolant circuit. The coolant is supplied back from the portion of the coolant circuit to an inlet of a low pressure side of the recuperator. The coolant in the low pressure side of the recuperator is heated with thermal energy transferred by the recuperator from the coolant in the high pressure side of the recuperator. The coolant in the vapor state from an outlet of the low pressure side of the recuperator is supplied to the compressor.

An air conditioning apparatus uses R32 as a refrigerant, and includes a compressor, a condenser, an expansion mechanism, an evaporator, an intermediate injection channel, a suction injection channel, a switching mechanism, a branch flow channel, first and second injection opening adjustable valves, an injection heat exchanger, a refrigerant storage tank, a bypass channel, and a control part. The switching mechanism switches between an intermediate injection condition in which refrigerant flows in the intermediate injection channel, and a suction injection condition in which refrigerant flows in the suction injection channel. The branch flow channel branches from a main refrigerant channel which joins the condenser and the evaporator, and guides the refrigerant to the intermediate injection channel and the suction injection channel. The bypass channel guides a gas component of the refrigerant accumulated inside the refrigerant storage tank to the intermediate injection channel and the suction injection channel.

A refrigeration system includes a high-pressure side with a gas cooler configured, while the refrigeration system is powered by a main power supply and is operating to provide refrigeration, to cool refrigerant on the high-pressure side. The refrigeration system includes a low-pressure side with one or more evaporators. The refrigeration system includes an auxiliary compressor coupled to a backup power supply. An input of the auxiliary compressor is coupled to fluid conduit of the low-pressure side, and an output of the auxiliary compressor is coupled to fluid conduit of the high-pressure side. A controller is communicatively coupled to the auxiliary compressor. After determining that the main power supply is unavailable, the controller causes the auxiliary compressor to turn on to move refrigerant from the low-pressure side to the high-pressure side.

A pressure control device for controlling a compressor includes a pressure sensor configured to measure pressure of a pressure line and a processing circuit. The processing circuit is configured to receive the measured pressure of the pressure line from the pressure sensor and control the compressor based on a set-point and the measured pressure. The pressure control device includes a mechanical switch sensitive to the pressure of the pressure line and configured to move between an open position and a closed position responsive to the pressure of the pressure line. Movement of the mechanical switch into one of the open position or the closed position causes the compressor to turn off and overrides the control of the compressor by the processing circuit.

Motor drive device (30) includes brushless DC motor (5) that drives a load and speed controller (8) that decides a PWM ON ratio for performing PWM control on brushless DC motor (5). The motor drive device further includes PWM ON ratio increasing-reducing unit (9) that increases/reduces the PWM ON ratio in accordance with a driving speed of brushless DC motor (5) and drive unit (10) that performs PWM control for driving brushless DC motor (5) in accordance with the PWM ON ratio decided by PWM ON ratio increasing-reducing unit (9). PWM ON ratio increasing-reducing unit (9) sets the PWM ON ratio to a ratio equal to or lower than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed of brushless DC motor (5) is lower than a predetermined speed, and sets the PWM ON ratio to a ratio equal to or higher than the PWM ON ratio decided by speed controller (8) in an interval in which the driving speed is higher than the predetermined speed.

A refrigeration apparatus uses R32 as a refrigerant, and includes a compressor, a condenser, an expansion mechanism, an evaporator, an intermediate injection channel and a suction injection channel. The intermediate injection channel guides a part of the refrigerant flowing from the condenser toward the evaporator to the compressor, causing the refrigerant to merge with intermediate-pressure refrigerant of the compressor. The suction injection channel guides a part of the refrigerant flowing from the condenser toward the evaporator to the suction passage, causing the refrigerant to merge with low-pressure refrigerant sucked into the compressor.

A heat pump system may be selectively operated in a defrost mode or cycle. The system includes an energy recovery module that receives and conditions air in a regeneration air channel. A pre-processing module is positioned downstream of the energy recovery module. The pre-processing module receives and heats air from the energy recovery module. A regeneration air heat exchanger is positioned downstream of the pre-processing module. The regeneration air heat exchanger receives and conditions air from the pre-processing module. The pre-processing module heats the air from the energy recovery module to increase an efficiency of the regeneration air heat exchanger. During the defrost mode, a loop of regeneration air may be recirculated between the supply air channel and the regeneration air channel in order to defrost the regeneration air heat exchanger.