A refrigeration unit and methods of operating a refrigeration unit for an HVACR system are disclosed. The refrigeration unit includes a refrigerant circuit, including a compressor, a condenser, an expansion device, and an evaporator fluidly connected. The condenser includes a condenser portion and a subcooler portion. A single receiver tank is fluidly connected to an output of the condenser portion and an input of the subcooler portion. A restrictor is fluidly connected to the receiver tank. The restrictor can induce a pressure drop in a working fluid flowing from the subcooler portion.

A header includes a plurality of branch tubes and a header manifold. If refrigerant flowing into the header manifold forms a pattern of annular flow or churn flow, tips of the branch tubes inserted into the header manifold pass through a liquid-phase portion having a thickness [m] and reach a gas-phase portion. The thickness [m] of the liquid-phase portion is defined as =G(1x)D/(4.sub.LU.sub.LS), where G is a flow speed [kg/(m.sup.2s)] of the refrigerant, x is a quality of the refrigerant, D is an inside diameter [m] of the header manifold, .sub.L is a liquid density [kg/m.sup.3] of the refrigerant, U.sub.LS is a reference apparent liquid speed [m/s] that is a maximum value within a range of variation in an apparent gas speed of the refrigerant flowing into a flow space of the header manifold. The reference apparent liquid speed U.sub.LS [m/s] is defined as G(1x)/.sub.L.

An apparatus includes a first compressor, a first load, a second compressor, a second load, a first heat exchanger, and a second heat exchanger. The first compressor compresses a first refrigerant. The first load uses the first refrigerant to remove heat from a space proximate the first load. The first load sends the first refrigerant to the first compressor. The second compressor compresses a second refrigerant. The second load uses the second refrigerant to remove heat from a space proximate the second load. The second load sends the second refrigerant to the second compressor. The first heat exchanger receives the first refrigerant from the first compressor. The first heat exchanger transfers heat from the first refrigerant to a fluid. The second heat exchanger receives the second refrigerant from the second compressor. The second heat exchanger transfers heat from the fluid to the second refrigerant.

A refrigeration system includes a refrigeration circuit and a coolant circuit separate from the refrigeration circuit. The refrigerant circuit includes a gas cooler/condenser, a receiver, and an evaporator. The coolant circuit includes a heat exchanger configured to transfer heat from a refrigerant circulating within the refrigeration circuit into a coolant circulating within the coolant circuit, a heat sink configured to remove heat from the coolant circulating within the coolant circuit, and a magnetocaloric conditioning unit configured to transfer heat from the coolant within a first fluid conduit of the coolant circuit into the coolant within a second fluid conduit of the coolant circuit. The first fluid conduit connects an outlet of the heat exchanger to an inlet of the heat sink, whereas the second fluid conduit connects an outlet of the heat sink to an inlet of the heat exchanger.

A heat exchanger includes a plurality of heat transfer tubes, a liquid header distributor, and a gas header distributor. The heat transfer tubes include U-shaped bent portions. The heat exchanger includes a heat exchanger core. A relationship between the liquid header distributor and the plurality of heat transfer tubes is established such that 9?? is satisfied, where Lh [m] is the length of the liquid header distributor, Lb [m] is the length of the shortest one of the heat transfer tubes, and ? is the ratio of the length Lb of the shortest heat transfer tube to the length Lh of the liquid header distributor and is expressed by ?=Lb/Lh.

An apparatus includes a compressor, a load, a heat exchanger, and a heater. The compressor compresses a refrigerant. The load uses the refrigerant to remove heat from a space proximate the load. The load sends the refrigerant to the compressor. The heat exchanger receives the refrigerant from the compressor. The heat exchanger transfers heat from a fluid to the refrigerant. The heat exchanger discharges the refrigerant to the compressor. The heater adds heat to the fluid.

An evaporator for a cooling system has a slab coil having a plurality of refrigerant circuits with each refrigerant circuit being a fin-and-tube assembly that extends across the slab coil. At least one of the refrigerant circuits has a mini-slab circuit extender that has a fin-and-tube assembly that extends across only a portion of the fin-and-tube assembly of that refrigerant circuit and is disposed in front of that portion of the fin-and-tube assembly of that refrigerant circuit.

Some embodiments of the present disclosure provide a heat exchanger, including: at least three heat exchange tube groups, herein the heat exchange tube groups are communicated in sequence, and at least two heat exchange tube groups are superposed mutually along a direction in which a heat exchange airflow flows, a medium sequentially flows through each heat exchange tube group and forms a U-shaped trajectory; an intermediate adapter portion, herein at least two heat exchange tube groups are communicated with each other by means of the intermediate adapter portion, the intermediate adapter portion includes at least two adapters and an adapter tube communicated with the two adjacent adapters, herein the adapter is composed of a first plate and a second plate, the adapter tube is an extrusion-formed flat tube, and a width direction of the adapter tube is perpendicular to a width direction of the heat exchange tube groups.

The present invention maintains a compact evaporator size in a centrifugal chiller utilizing a low pressure refrigerant used at a maximum pressure of less than 0.2 MPaG while avoiding efficiency losses and equipment damage that result from carryover of liquid state refrigerant to the turbo compressor side. This evaporator is equipped with a pressure vessel into which a condensed refrigerant is introduced, a refrigerant inlet which is provided to the bottom portion of the pressure vessel, a refrigerant outlet which is provided to the top portion of the pressure vessel, a heat transfer pipe group which passes through the interior of the pressure vessel, circulates liquid to be chilled through the interior thereof, and exchanges heat between the liquid to be chilled and the refrigerant, and a demister which is disposed between the refrigerant outlet and the heat transfer pipe group in the interior of the pressure vessel and carries out vapor-liquid separation of the refrigerant, a dividing section (for example, a plurality of notches) being provided between the periphery of the demister and the inner peripheral surface of the pressure vessel. The dividing section is provided to a side of the demister along the lengthwise direction.

A heat exchanger comprises double-plated material with good heat conductivity and endurance in the shape of drum with convex wall or cylinder or rectangular shape having inlet(s) for first fluid to be cooled to flow into space between the double layer and out through outlet(s). A plurality of heat exchangers are connected through an inlet tubing where first fluid flows into each heat exchanger and flows out through a connecting outlet tubing. Heat exchange is made between the first fluid and large volume of second fluid the heat exchanger immersed in, where the term fluid covering all types of liquids and gases. The present design efficiently allows heat exchange while clogging is avoided. Installation of elements within heat exchanger to cause change in direction of flow of first fluid increases rate of heat transfer. The disclosed heat exchanger is used as condenser in air-conditioner either in building or in vehicle.