An exemplary heat pump includes: an accumulator that separates liquid refrigerant from gas refrigerant returning to a compressor; a refrigerant suction channel connecting the compressor to the accumulator; a refrigerant return channel that returns liquid refrigerant in the accumulator to the refrigerant suction channel; a first valve disposed on the refrigerant return channel; a temperature sensor that detects a temperature of refrigerant in the refrigerant suction channel; a second valve that reduces a pressure of a part of liquid refrigerant flowing between the first and second heat exchangers; a refrigerant evaporator that gasifies, by using waste heat of an engine, the liquid refrigerant whose pressure has been reduced; a gas refrigerant supply channel through which the gasified refrigerant is supplied to the accumulator; and a control device that, while the first valve is open, controls an opening of the second valve based on the temperature detected by the temperature sensor.

An appliance air/water handling system includes a rotating drum, airflow and fluid paths for directing process air and fluid, respectively, therethrough. First and second heat exchangers are in direct engagement with the airflow and fluid paths, respectively. A reversible refrigerant circuit delivers refrigerant through the first and second heat exchangers to alternatively define washing and drying conditions. In the washing condition the first heat exchanger cools the process air into cooled process air, and the second heat exchanger heats the fluid to define a heated fluid that is directed into the drum. In the drying condition the first heat exchanger heats the process air to define heated process air that is directed through the drum and through a third heat exchanger, and the second heat exchanger cools the fluid to define a cooled fluid that is directed to the third heat exchanger intersect with the heated process air.

A multi-stacked heat exchanger comprises a first heat exchanger and a second heat exchanger. A first end of the first heat exchanger receives a first fluid in a first conduit flowing in a first direction within a plane. A first end of the second heat exchanger receives the first fluid from the first heat exchanger in a second direction flowing opposite to the first direction within the plane. A flow of a second fluid is communicated through the second heat exchanger and then through the first heat exchanger, in a second direction orthogonal to the first direction. The second fluid is in thermal communication with the first fluid in the second heat exchanger and then in the first heat exchanger. By doubling the flowed first fluid back upon itself, embodiments achieve counterflow between the first fluid and second fluid within a compact space.

An air conditioning system can be toggled between a heating mode, in which heat is withdrawn from a source (e.g., a geothermal source) and deposited into a conditioned space (e.g., a building), and a cooling mode, in which heat is withdrawn from the conditioned space and deposited into the source. The air conditioning system uses a combination of efficiency-enhancing technologies, including injection of superheated vapor into the system's compressor from an economizer circuit, adjustable compressor speed, the use of one or coaxial heat exchangers and the use of electronic expansion valves that are continuously adjustable from a fully closed to various open positions. A controller may be used to control the system for optimal performance in both the heating and cooling modes, such as by disabling the economizer circuit and vapor injection when the system is in the cooling mode.

A vapor compression system (20; 120; 220; 320) has: first (22A; 122A; 222A) and second (22B; 122B; 222B) compressors; first (40) and second (46) heat exchangers; and one or more expansion devices (52; 52A, 52B). Means (32A, 32B; 32A, 32B, 126A, 126B; 32A, 32B, 232A, 232B) are provided for switching the system between operation in first and second modes using the respective first and second compressors. In the first mode: the first compressor compresses refrigerant; the compressed refrigerant is cooled in the first heat exchanger; the cooled refrigerant is expanded in at least one of the one or more expansion devices; and the expanded refrigerant absorbs heat in the second heat exchanger. In the second mode: the second compressor compresses refrigerant; the compressed refrigerant is cooled in the second heat exchanger; the cooled refrigerant is expanded in at least one of the one or more expansion devices; and the expanded refrigerant absorbs heat in the first heat exchanger.

A central air conditioning and heat pump system includes a main heat exchange system and a cooling arrangement. The main heat exchange system includes a compressor, a first heat exchanger, a second heat exchanger. The cooling arrangement includes a cooling tower and a condensing unit. When the central air conditioning and heat pump system is selectively operated in an air conditioning mode, refrigerant may be cooled both by water and ambient air in the condensing unit and the second heat exchanger respectively.

The invention is directed to systems and methods for providing a domestic hot water (DHW) priority refrigeration circuit in a heating ventilation and air conditioning (HVAC) system including a storage tank, source heat exchanger (HXR), DHW HXR, load HXR, compressor, reversing valve, and DHW circulating pump, the method including: receiving at the DHW heat exchanger hot gas discharged from the compressor; determining if the DHW storage tank is below a set point temperature, and if so: activating the DHW circulating pump providing water from DHW HXR to the storage tank; condensing hot gas refrigerant by the DHW HXR to a warm liquid, traveling to the reversing valve, where if the HVAC system is in a heating mode, the reversing valve directs it to the load HXR and if the HVAC circuit is in a cooling mood the reversing valve directs it to the source HXR.

An air source or water sourced packaged self-contained heat pump unit comprises indoor and outdoor sections. Heat exchangers present in these sections transfer heat between the indoor building space and the outdoor ambient. The heat exchangers are connected to form a closed loop and a compressor present in the loop pressurizes the refrigerant. A refrigerant charge control system present controls the charge of refrigerant in the main refrigerant system during heating and cooling modes. A hot-gas heat exchanger is added to the indoor section of the unit downstream of the indoor heat exchanger with respect to the airflow. Valves are used to bypass the flow of refrigerant from the compressor to the hot-gas heat exchanger during regular heating and cooling modes. In the hot-gas reheat mode, the compressed refrigerant is first directed to the hot gas heat exchanger which reheats the air to decrease the relative humidity. The charge control system is active during the hot gas reheat cycle to control the charge of refrigerant in the system.

A supplemental heat-providing system is provided for heating a refrigerant. The system includes an outdoor unit that can act as a heat pump located outside a building and configured to use the refrigerant to condition an indoor space inside the building; a hot water heater located in the building and connected to one or more points of use in the building, the hot water heater being configured to heat water and provide the water to the one or more points of use; a water-refrigerant heat exchanger containing a refrigerant pathway and a water pathway, configured to pass the refrigerant from the outdoor unit through the refrigerant pathway, to pass the water from the hot water heater through the water pathway, and to exchange heat from the water to the refrigerant; and a water pump configured to selectively pump the water from the hot water heater through water pathway.

Systems and methods for heating and cooling a vehicle using a heat pump are disclosed herein. In one embodiment, a system for heating and cooling the vehicle includes a heat pump having: a compressor located in an engine compartment of the vehicle, and an evaporator located in a sleeper or a cab of the vehicle. The system also includes a controller for selecting a cooling mode or a heating mode for the heat pump. In one embodiment, the system includes a clutch for engaging the compressor with a transmission of the vehicle.