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 heating system including a condenser and an evaporator. A compressor is along a refrigerant line and is configured to compress refrigerant flowing to the condenser. A first valve is along the refrigerant line between the compressor and the condenser. A controller is configured to partially close the first valve when a measured temperature is below a threshold to increase discharge pressure of refrigerant compressed by the compressor and increase heat dissipation of the condenser.

An air conditioner is provided. The air conditioner includes a heat pump cycle channel in which a compressor, an outdoor heat exchanger, an expansion valve, and an indoor heat exchanger are connected with one another in sequence. A resistance channel is disposed between an outlet of the compressor and the outdoor heat exchanger to increase pressure of refrigerant flowing from the outlet to the outdoor heat exchanger.

A condenser (404) configured to condense gas phase refrigerant to liquid phase refrigerant. The condenser (404) includes a gas header (408) configured to receive gas phase refrigerant, a liquid header (410) disposed opposite the gas header, the liquid header (410) separated into at least two sections, each section of the at least two sections having a port, and parallel tubes (406) extending between the gas header (408) and the liquid header (410).

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.

An absorption heat pump having a generator, a heat source to heat the generator to drive coolant vapor out of solution, a condenser for cooling the coolant vapor and an expansion valve that expand the coolant fluid as well as an evaporator for at least partial evaporation of the expanded coolant fluid against a medium which is connected to at least one absorber which absorbs the expanded coolant fluid. A hot gas line which branches off from a line for coolant vapor upstream of the condenser and is fluid-connected to the evaporator such that it bypasses the condenser and the expansion valve, a defrosting valve being provided in the hot gas line, by means of which the flow of coolant vapor through the hot gas line can be controlled. The absorption heat pump is operated in a cyclic circulation process.

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 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 valve 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 valve in the second mode. Refrigerant flows both from discharge line to gas reheat heat exchanger and then main refrigerant flow control valve, and from discharge line to main refrigerant flow control valve without flowing through the gas reheat heat exchanger in the third mode. Refrigerant flows to the usage side and hot gas reheat heat exchanger in the heating mode.

A heating system including a condenser and an evaporator. A compressor is along a refrigerant line and is configured to compress refrigerant flowing to the condenser. A first valve is along the refrigerant line between the compressor and the condenser. A controller is configured to partially close the first valve when a measured temperature is below a threshold to increase discharge pressure of refrigerant compressed by the compressor and increase heat dissipation of the condenser.

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.