Air conditioner including heat exchanger

Abstract

An air conditioner may include indoor and outdoor heat exchangers, wherein at least one of the indoor heat exchanger and the outdoor heat exchanger includes: first and second heat exchange units respectively including a first plurality and a second plurality of heat transfer tubes through which a refrigerant is flowable, and a connection unit connecting the first and the second heat exchange units in series so that refrigerant flows through the first plurality of heat transfer tubes in a first direction, then through the connection unit and then through the second plurality of heat transfer tubes in a second direction opposite the first direction, and the refrigerant that flowed through at least one heat transfer tube of the first plurality of heat transfer tubes does not mix in the connection unit with the refrigerant that flowed through other heat transfer tubes of the first plurality of heat transfer tubes.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a continuation application, under 35 U.S.C. § 111(a), of International Application PCT / KR2025 / 000803, filed Jan. 14, 2025, which claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2024-043049, filed Mar. 19, 2024 and Japanese Patent Application No. 2024-212514, filed Dec. 5, 2024, in the Japanese Intellectual Property Office, the disclosures of which are incorporated herein in their entireties by reference.TECHNICAL FIELD

[0002] The disclosure relates to an air conditioner including a heat exchanger.BACKGROUND ART

[0003] A heat exchanger may include a plurality of heat transfer tubes arranged side-by-side in an up-and-down direction and a vertical-connection header connected to one-side ends of the plurality of heat transfer tubes. A refrigerant flowing through a plurality of heat transfer tubes arranged at the lower side (a first stage), among the plurality of heat transfer tubes, flows into a plurality of heat transfer tubes arranged at the upper side (a second stage), via the vertical-connection header. Such a type of heat exchanger is disclosed in, for example, Japanese Patent Publication No. 2010-112581.

[0004] A vertical-connection header of such a heat exchanger includes a space communicating with a plurality of heat transfer tubes. A refrigerant supplied from a plurality of heat transfer tubes on an upstream side joins in a space in the vertical-connection header and then is divided and flows into a plurality of heat transfer tubes on a downstream side.DISCLOSURETechnical Solution

[0005] An air conditioner may include: an indoor heat exchanger, and an outdoor heat exchanger wherein at least one of the indoor heat exchanger and the outdoor heat exchanger may include a first heat exchange unit including a first plurality of heat transfer tubes through which refrigerant is flowable, a second heat exchange unit including a second plurality of heat transfer tubes through which the refrigerant is flowable, and a connection unit connecting the first heat exchange unit and the second heat exchange unit to each other in series so that the refrigerant flows through the first plurality of heat transfer tubes in a first direction, then through the connection unit, and then through the second plurality of heat transfer tubes in a second direction opposite the first direction, and the refrigerant that flowed through at least one heat transfer tube of the first plurality of heat transfer tubes does not mix in the connection unit with the refrigerant that flowed through other heat transfer tubes of the first plurality of heat transfer tubes.

[0006] The connection unit may connect the first heat exchange unit and the second heat exchange unit so that the refrigerant that flowed through each heat transfer tube of the first plurality of heat transfer tubes does not mix in the connection unit with the refrigerant that flowed through another heat transfer tube of the first plurality of heat transfer tubes.

[0007] The connection unit may connect the first heat exchange unit and the second heat exchange unit so that a first refrigerant flow path length that the refrigerant travels through a first heat transfer tube of the first plurality of heat transfer tubes, then through the connection unit, and then through a first heat transfer tube of the second plurality of heat transfer tubes is almost equal to a second refrigerant flow path length that the refrigerant travels through a second heat transfer tube of the first plurality of heat transfer tubes, then through the connection unit, and then through a second heat transfer tube of the second plurality of heat transfer tubes.

[0008] The connection unit may include a plurality of connection flow paths, each connection flow path of the plurality of connection flow paths having a connection flow path length, the first plurality of heat transfer tubes, the second plurality of heat transfer tubes, and the plurality of connection flow paths may respectively correspond to one another, and each connection flow path of the plurality of connection flow paths may connect, to each other, a heat transfer tube of the first plurality of heat transfer tubes and a heat transfer tube of the second plurality of heat transfer tubes, and each connection flow path length of the plurality of connection flow paths may be almost equal.

[0009] Each connection flow path of the plurality of connection flow paths may connect heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes based on heat transfer tube positions within the first heat exchange unit and the second heat exchange unit respectively, so that first heat transfer tube positions of heat transfer tubes of the first plurality of heat transfer tubes respectively correspond to second heat transfer tube positions of heat transfer tubes of the second plurality of heat transfer tubes.

[0010] The connection unit may include a plurality of connection flow paths and each connection flow path of the plurality of connection flow paths may connect, to each other, a heat transfer tube of the first plurality of heat transfer tubes and a heat transfer tube of the second plurality of heat transfer tubes, the first plurality of heat transfer tubes, the second plurality of heat transfer tubes, and the plurality of connection flow paths may respectively correspond to one another, and each connection flow path of the plurality of connection flow paths may connect heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes based on heat transfer tube positions within the first heat exchange unit and the second heat exchange unit respectively, so that first heat transfer tube positions of heat transfer tubes of the first plurality of heat transfer tubes symmetrically correspond to second heat transfer tube positions of heat transfer tubes of the second plurality of heat transfer tubes.

[0011] A number of heat transfer tubes of the first plurality of heat transfer tubes may be equal to a number of heat transfer tubes of the second plurality of heat transfer tubes, and respective lengths of heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes may be almost equal.

[0012] The air conditioner may further include at least one dummy heat transfer tube, which may be between the first heat exchange unit and the second heat exchange unit, and through which no refrigerant is flowable.

[0013] The first plurality of heat transfer tubes may be arranged side-by-side in an up- and down direction, the second plurality of heat transfer tubes may be arranged side-by-side in the up- and down direction, the second heat exchange unit is adjacent to the first heat exchange unit in the up- and down direction, the connection unit may include a vertical-switching connection unit connecting downstream-side ends of the first plurality of heat transfer tubes to upstream-side ends of the second plurality of heat transfer tubes to introduce the refrigerant that flowed through the first plurality of heat transfer tubes into the second plurality of heat transfer tubes, and the vertical-switching connection unit may include a plurality of vertical-connection flow paths configured so that heat transfer tubes of the first plurality of heat transfer tubes may individually communicate with heat transfer tubes of the second plurality of heat transfer tubes.

[0014] A number of heat transfer tubes of the first plurality of heat transfer tubes, a number of heat transfer tubes of the second plurality of heat transfer tubes, and a number of vertical-connection flow paths may be equal to one another.

[0015] The plurality of vertical-connection flow paths may connect the first plurality of heat transfer tubes to the second plurality of heat transfer tubes so that a first heat transfer tube of the first plurality of heat transfer tubes and a second heat transfer tube of the second plurality of heat transfer tubes which may individually communicate may be located at a same position in an up-and-down direction within the first heat exchange unit and the second heat exchange unit respectively, and flow-path lengths of the plurality of vertical-connection flow paths may be almost equal.

[0016] The plurality of vertical-connection flow paths may connect the first plurality of heat transfer tubes to the second plurality of heat transfer tubes so that a first heat transfer tube of the first plurality of heat transfer tubes and a second heat transfer tube of the second plurality of heat transfer tubes may be symmetric to each other in an up-and-down direction about a plane between the first heat exchange unit and the second heat exchange unit.

[0017] The at least one of the indoor heat exchanger and the outdoor heat exchanger may include: a third heat exchange unit which may include a third plurality of heat transfer tubes through which the refrigerant is flowable, which may be arranged side-by-side in an up-and-down direction, the third heat exchange unit may be arranged adjacent to the second heat exchange unit in a horizontal direction, the connection unit may include a horizontal-switching connection unit connecting downstream-side ends of the second plurality of heat transfer tubes to upstream-side ends of the third plurality of heat transfer tubes to introduce the refrigerant that flowed through the second plurality of heat transfer tubes into the third plurality of heat transfer tubes, and the horizontal-switching connection unit may include a plurality of horizontal-connection flow paths configured so that heat transfer tubes of the second plurality of heat transfer tubes may individually communicate with heat transfer tubes of the third plurality of heat transfer tubes.

[0018] The at least one of the indoor heat exchanger and the outdoor heat exchanger may be an evaporator, the first heat exchange unit and the second heat exchange unit may be on a windward side of the evaporator, and the third heat exchange unit may be on a leeward side of the evaporator.

[0019] The at least one of the indoor heat exchanger and the outdoor heat exchanger may be a condenser, the first heat exchange unit and the second heat exchange unit may be on a leeward side of the condenser, and the third heat exchange unit may be on a windward side of the condenser.DESCRIPTION OF DRAWINGS

[0020] FIG. 1 is a schematic perspective view illustrating a whole configuration of a heat exchanger according to an embodiment of the disclosure.

[0021] FIG. 2 is a schematic front view of the heat exchanger shown in FIG. 1, according to an embodiment of the disclosure.

[0022] FIG. 3 is a diagram illustrating a first row and a second row in a separated state, of the heat exchanger shown in FIG. 1, according to an embodiment of the disclosure.

[0023] FIG. 4 is a schematic enlarged view of a connection unit according to an embodiment of the disclosure.

[0024] FIG. 5 is a diagram separately illustrating a first row and a second row of a heat exchanger according to an embodiment of the disclosure.

[0025] FIG. 6 is a schematic enlarged view of a connection unit according to an embodiment of the disclosure.

[0026] FIG. 7 is a schematic configuration diagram of an embodiment of an air conditioner according to the disclosure.

[0027] FIG. 8 is a schematic perspective view of a heat exchanger according to the related art.

[0028] FIG. 9 is a diagram illustrating the flow of a refrigerant in a connection header in the heat exchanger shown in FIG. 8 according to the related art.

[0029] FIG. 10 is a schematic perspective view illustrating a whole configuration of a heat exchanger according to an embodiment of the disclosure.

[0030] FIG. 11 illustrates schematic front and rear views of the heat exchanger shown in FIG. 10.

[0031] FIG. 12 is a schematic configuration diagram of an embodiment of an air conditioner according to the disclosure.

[0032] FIG. 13A is a diagram illustrating the flow of a refrigerant when an indoor heat exchanger functions as an evaporator.

[0033] FIG. 13B is a diagram illustrating temperature changes of air and a refrigerant passing through heat exchange units in a second stage when an indoor heat exchanger functions as an evaporator.

[0034] FIG. 14A is a diagram illustrating the flow of a refrigerant when a heat exchanger, in which an inlet tube is connected to a heat exchange unit in a first row (a windward side) and an outlet tube is connected to a heat exchange unit in a second row (a leeward side), functions as an evaporator.

[0035] FIG. 14B is a diagram illustrating temperature changes of air and a refrigerant passing through the heat exchanger shown in FIG. 14A when the heat exchanger shown in FIG. 14A functions as an evaporator.

[0036] FIG. 15A is a diagram illustrating the flow of a refrigerant when an indoor heat exchanger functions as a condenser.

[0037] FIG. 15B is a diagram illustrating temperature changes of air and a refrigerant passing through the indoor heat exchanger shown in FIG. 15A when the indoor heat exchanger shown in FIG. 15A functions as a condenser.MODE FOR INVENTION

[0038] Various embodiments of the disclosure and terms used therein are not intended to limit the technical features of the disclosure to specific embodiments and should be understood as including various modifications, equivalents, and substitutes thereof.

[0039] Regarding descriptions of the drawings, like or related components may be denoted by like reference numerals.

[0040] Unless the context clearly indicates otherwise, a singular form of a noun corresponding to an item may include one item or a plurality of items.

[0041] As used herein, each of the phrases “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B, or C”, “at least one of A, B, and C”, and “at least one of A, B, or C” may include one of the items listed in the corresponding one of the phrases, or all possible combinations of the items.

[0042] The term “and / or” used herein includes a combination of a plurality of related described components or any one of the plurality of related described components.

[0043] Although the terms such as “first”, “second” and the like may be used herein to describe various components, these terms may be used only to distinguish one component from another component and do not limit the components in other aspects (for example, importance or order).

[0044] When a component (for example, a first component) is referred to as being “coupled to (or with)” or “connected to (or with)” another component (for example, a second component) together with the term “functionally” or “communicably” or without such a term, this means that the component may be connected to the other component directly (for example, in a wired manner), wirelessly, or via a third component.

[0045] The terms such as “comprises”, “comprising”, “includes”, “including”, “has”, and “having”, when used herein, specify the presence of stated features, numbers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0046] When a component is referred to as being “connected to (or with)”, “coupled to (or with)”, “supported by”, or “in contact with” another component, the component may be directly connected to (or with), coupled to (or with), supported by, or in contact with the other component, or the component may also be indirectly connected to (or with), coupled to (or with), supported by, or in contact with the other component via a third component.

[0047] When a component is referred to as being placed “on” another component, the component may be directly placed on and contact the other component, or an intervening component(s) may also be present therebetween.

[0048] An air conditioner according to various embodiments of the disclosure refers to a device configured to perform at least one of functions, such as air purification, ventilation, humidity adjustment, cooling, and heating, in an air conditioning space (hereinafter, referred to as an “indoor space”).

[0049] According to an embodiment of the disclosure, the air conditioner may include a heat pump device to perform a cooling function or a heating function. The heat pump device may include a refrigeration cycle, in which a refrigerant circulates along a compressor, a first heat exchanger, an expansion device, and a second heat exchanger. All components of the heat pump device may be embedded in one housing that forms the external appearance of the air conditioner, and a window-type air conditioner or a portable air conditioner corresponds to such an air conditioner. On the other hand, some components of the heat pump device may be separately embedded in a plurality of housings that form one air conditioner, and a wall-mounted air conditioner, a stand-type air conditioner, a system air conditioner, and the like are included in such an air conditioner.

[0050] The air conditioner including a plurality of housings may include at least one outdoor unit mounted outdoors and at least one indoor unit mounted indoors. For example, the air conditioner may be provided with a configuration in which one outdoor unit is connected to one indoor unit via a refrigerant tube. For example, the air conditioner may be provided with a configuration in which one outdoor unit is connected to two or more indoor units via a refrigerant tube. For example, the air conditioner may be provided with a configuration in which two or more outdoor units are connected to two or more indoor units via a plurality of refrigerant tubes.

[0051] The outdoor unit may be electrically connected to the indoor unit. For example, information (or a command) for controlling the air conditioner may be input via an input interface arranged on the outdoor unit or the indoor unit, and in response to a user input, the outdoor unit and the indoor unit may simultaneously or sequentially operate.

[0052] The air conditioner may include an outdoor heat exchanger arranged in the outdoor unit, an indoor heat exchanger arranged in the indoor unit, and a refrigerant tube connecting the outdoor heat exchanger and the indoor heat exchanger to each other.

[0053] The outdoor heat exchanger may perform heat exchange between a refrigerant and outdoor air by using a phase change (for example, evaporation or condensation) of the refrigerant. For example, while the refrigerant is being condensed in the outdoor heat exchanger, the refrigerant may emit heat to the outdoor air, and while the refrigerant flowing through the outdoor heat exchanger is being evaporated, the refrigerant may absorb heat from the outdoor air.

[0054] The indoor unit is arranged indoors. For example, indoor units may be classified into ceiling-type indoor units, stand-type indoor units, wall-mounted indoor units, and the like, depending on arrangement methods of indoor units. For example, ceiling-type indoor units may be classified into 4-way indoor units, 1-way indoor units, duct-type indoor units, and the like, depending on ejection methods of air.

[0055] Likewise, the indoor heat exchanger may perform heat exchange between the refrigerant and indoor air by using a phase change (for example, evaporation or condensation) of the refrigerant. For example, while the refrigerant is being evaporated in the indoor unit, the refrigerant may absorb heat from the indoor air, and as the indoor air cooled through the indoor heat exchanger that is cooled is blown, an indoor space may be cooled. In addition, while the refrigerant is being condensed in the indoor heat exchanger, the refrigerant may emit heat to the indoor air, and as the indoor air heated through the indoor heat exchanger having high temperature is blown, the indoor space may be heated.

[0056] That is, the air conditioner performs a function of cooling or heating by a phase change process of the refrigerant circulating through the outdoor heat exchanger and the indoor heat exchanger, and for such circulation of the refrigerant, the air conditioner may include a compressor configured to compress the refrigerant. The compressor may suck a refrigerant gas through a suction portion and may compress the refrigerant gas. The compressor may discharge the refrigerant gas having high temperature and high pressure through a discharge portion. The compressor may be arranged in the outdoor unit.

[0057] Via the refrigerant tube, the refrigerant may sequentially circulate through the compressor, the outdoor heat exchanger, the expansion device, and the indoor heat exchanger in the stated order or may sequentially circulate through the compressor, the indoor heat exchanger, the expansion device, and the outdoor heat exchanger in the stated order.

[0058] For example, in the air conditioner, when one outdoor unit is directly connected to one indoor unit via the refrigerant tube, the refrigerant may circulate between the one outdoor unit and the one indoor unit via the refrigerant tube.

[0059] For example, in the air conditioner, when one outdoor unit is connected to two or more indoor units via the refrigerant tube, the refrigerant may flow from the outdoor unit into a plurality of indoor units via a plurality of the refrigerant tubes that are branched. The refrigerant discharged from the plurality of indoor units may join to circulate to the outdoor unit. For example, each of the plurality of indoor units may be directly connected to one outdoor unit in parallel, via a separate refrigerant tube.

[0060] Each of the plurality of indoor units may independently operate according to an operation mode set by a user. That is, some of the plurality of indoor units may operate in a cooling mode, and simultaneously, the others may operate in a heating mode. Here, the refrigerant may flow into each indoor unit while being in a high-pressure or low-pressure state selectively according to a circulation path specified by a flow path switching valve that is described below, and then, may be ejected to circulate to the outdoor unit.

[0061] For example, in the air conditioner, when two or more outdoor units are connected to two or more indoor units via a plurality of refrigerant tubes, the refrigerant ejected from a plurality of outdoor units may join to flow through one refrigerant tube, and then, may be branched again at a certain point to flow into a plurality of indoor units.

[0062] Depending on an operational load according to the amount of operation of the plurality of indoor units, all of the plurality of outdoor units may operate, or at least some of the plurality of outdoor units may not operate. Here, the refrigerant may flow into an outdoor unit, which is selectively operated by the flow path switching valve, and may circulate. The air conditioner may include an expansion device to reduce the pressure of the refrigerant flowing into the heat exchanger. For example, the expansion device may be arranged in the indoor unit or in the outdoor unit or may be arranged in both the indoor unit and the outdoor unit.

[0063] The expansion device may reduce the temperature and pressure of the refrigerant by, for example, a throttling effect. The expansion device may include an orifice capable of reducing the cross-sectional area of a flow path. The refrigerant having passed through the orifice may have a reduced temperature and a reduced pressure.

[0064] The expansion device may be implemented by, for example, an electronic expansion valve capable of adjusting an opening ratio (a ratio of the cross-sectional area of a flow path of a valve in a partially open state with respect to the cross-sectional area of the flow path of the valve in a fully open state). The amount of the refrigerant passing through the expansion device may be controlled according to the opening ratio of the electronic expansion valve.

[0065] The air conditioner may further include a flow path switching valve arranged on a refrigerant-circulating flow path. The flow path switching valve may include, for example, a 4-way valve. The flow path switching valve may determine a circulation path of the refrigerant according to an operation mode (for example, a cooling operation or a heating operation) of the indoor unit. The flow path switching valve may be connected to the discharge portion of the compressor.

[0066] The air conditioner may include an accumulator. The accumulator may be connected to the suction portion of the compressor. The low-temperature and low-pressure refrigerant, which is evaporated in the indoor heat exchanger or the outdoor heat exchanger, may flow into the accumulator.

[0067] When the refrigerant, in which a refrigerant liquid and a refrigerant gas are mixed, flows into the accumulator, the accumulator may separate the refrigerant liquid from the refrigerant gas and may provide, to the compressor, the refrigerant gas from which the refrigerant liquid is separated.

[0068] An outdoor fan may be arranged in the vicinity of the outdoor heat exchanger. The outdoor fan may blow outdoor air to the outdoor heat exchanger to accelerate heat exchange between the refrigerant and the outdoor air.

[0069] The outdoor unit of the air conditioner may include at least one sensor. For example, the sensor of the outdoor unit may include an environment sensor. The outdoor unit sensor may be arranged at any position inside or outside the outdoor unit. For example, the outdoor unit sensor may include a temperature sensor for sensing the temperature of air around the outdoor unit, a humidity sensor for sensing the humidity of air around the outdoor unit, a refrigerant temperature sensor for sensing the refrigerant temperature of the refrigerant tube passing through the outdoor unit, or a refrigerant pressure sensor for sensing the refrigerant pressure of the refrigerant tube passing through the outdoor unit.

[0070] The outdoor unit of the air conditioner may include an outdoor-unit communication unit. The outdoor-unit communication unit may be configured to receive a control signal from a control unit of the indoor unit of the air conditioner, the control unit being described below. The outdoor unit may control operations of the compressor, the outdoor heat exchanger, the expansion device, the flow path switching valve, the accumulator, or the outdoor fan, based on the control signal received via the outdoor-unit communication unit. The outdoor unit may transmit a sensing value detected by the outdoor unit sensor to the control unit of the indoor unit.

[0071] The indoor unit of the air conditioner may include a housing, a blower configured to circulate air to the inside or outside of the housing, and an indoor heat exchanger configured to exchange heat with air flowing into the housing.

[0072] The housing may include an inlet port. Air in the indoor space may flow into the housing via the inlet port.

[0073] The indoor unit of the air conditioner may include a filter for filtering out foreign substances in air flowing into the housing via the inlet port.

[0074] The housing may include a discharge port. Air flowing in the housing may be discharged to the outside of the housing via the discharge port.

[0075] An airflow guide for guiding the direction of air discharged via the discharge port may be arranged in the housing of the indoor unit. For example, the airflow guide may include a blade located on the discharge port. For example, the airflow guide may include an auxiliary fan for adjusting discharge airflow. The disclosure is not limited thereto, and the airflow guide may be omitted.

[0076] The indoor heat exchanger and the blower, which are located on a flow path connecting the inlet port and the discharge port to each other, may be arranged in the housing of the indoor unit.

[0077] The blower may include an indoor fan and a fan motor. For example, the indoor fan may include an axial-flow fan, a diagonal-flow fan, a cross-flow fan, or a centrifugal fan.

[0078] The indoor heat exchanger may be arranged between the blower and the discharge port or may be arranged between the inlet port and the blower. The indoor heat exchanger may absorb heat from air introduced via the inlet port or may transfer heat to air introduced via the inlet port. The indoor heat exchanger may include a heat exchange tube, in which the refrigerant flows, and a heat exchange pin contacting the heat exchange tube to increase a heat transfer area.

[0079] The indoor unit of the air conditioner may include a drain tray arranged under the indoor heat exchanger and collect condensate generated by the indoor heat exchanger. The condensate accommodated in the drain tray may be discharged to the outside thereof via a drain hose. The drain tray may be arranged to support the indoor heat exchanger.

[0080] The indoor unit of the air conditioner may include an input interface. The input interface may include any type of user input means, including a button, a touchscreen, and / or a touchpad. A user may directly input setting data (for example, a desired indoor temperature, setting of an operation mode of cooling / heating / dehumidification / air purification, setting of selection of an ejection port, and / or setting of an air-flow rate).

[0081] The input interface may be connected to an external input device. For example, the input interface may be electrically connected to a wired remote controller. The wired remote controller may be mounted at a certain position (for example, a portion of a wall) in the indoor space. The user may input the setting data regarding operations of the air conditioner by manipulating the wired remote controller. An electrical signal corresponding to the setting data obtained via the wired remote controller may be transmitted to the input interface. In addition, the input interface may include an infrared sensor. The user may remotely input the setting data regarding operations of the air conditioner by using a wireless remote controller. The setting data, which is input via the wireless remote controller, may be transmitted as an infrared signal to the input interface.

[0082] In addition, the input interface may include a microphone. A speech command of the user may be obtained via the microphone. The microphone may convert the speech command of the user into an electrical signal and may transfer the converted electrical signal to an indoor-unit control unit. The indoor-unit control unit may control the components of the air conditioner to perform a function corresponding to the speech command of the user. The setting data (for example, a desired indoor temperature, setting of an operation mode of cooling / heating / dehumidification / air purification, setting of selection of an ejection port, and / or setting of an air-flow rate) obtained via the input interface may be transferred to the indoor-unit control unit described below. For example, the setting data obtained via the input interface may be transmitted to the outside of the indoor unit, that is, the outdoor unit or a server, via the indoor-unit communication unit described below.

[0083] The indoor unit of the air conditioner may include a power module. The power module may be connected to an external power supply and may supply power to the components of the indoor unit.

[0084] The indoor unit of the air conditioner may include an indoor-unit sensor. The indoor-unit sensor may include an environmental sensor arranged in an inner space or an outer space of the housing. For example, the indoor-unit sensor may include one or more temperature sensors and / or humidity sensors, which are arranged in a predefined space inside or outside the housing of the indoor unit. For example, the indoor-unit sensor may include a refrigerant temperature sensor for sensing the temperature of the refrigerant of the refrigerant tube passing through the indoor unit. For example, the indoor-unit sensor may include refrigerant temperature sensors respectively sensing the temperatures of the refrigerant at the entrance, the middle, and / or the exit of the refrigerant tube passing through the indoor heat exchanger.

[0085] For example, each piece of environmental information, which is sensed by the indoor-unit sensor, may be transferred to the indoor-unit control unit described below or may be transmitted to the outside of the indoor unit via the indoor-unit communication unit described below.

[0086] The indoor unit of the air conditioner may include the indoor-unit communication unit. The indoor-unit communication unit may include at least one of a short-range wireless communication module or a long-range wireless communication module. The indoor-unit communication unit may include at least one antenna for wirelessly communicating with another device. The outdoor unit may include an outdoor-unit communication unit. The outdoor-unit communication unit may also include at least one of a short-range wireless communication module or a long-range wireless communication module.

[0087] The short-range wireless communication module may include, but is not limited to, a Bluetooth communication module, a Bluetooth Low Energy (BLE) communication module, a Near-Field Communication module, a WLAN (WiFi) communication module, a Zigbee communication module, an infrared Data Association (IrDA) communication module, a WiFi Direct (WFD) communication module, an ultrawideband (UWB) communication module, an Ant+ communication module, a microwave (μWave) communication module, or the like.

[0088] The long-range wireless communication module may include communication modules performing various types of long-range wireless communication and may include a mobile communication unit. The mobile communication unit transmits radio signals to and receives radio signals from at least one of a base station, an external terminal, or a server, on a mobile communication network.

[0089] The indoor-unit communication unit may communicate with an external device, such as a server, a mobile device, or another household appliance, via an access point (AP) around the indoor-unit communication unit. The AP may connect a local area network (LAN), to which the air conditioner or a user equipment is connected, to a wide area network (WAN) to which the server is connected. The air conditioner or the user equipment may be connected to the server via the WAN. The indoor unit of the air conditioner may include an indoor-unit control unit configured to control the components of the indoor unit, including the blower and the like. The outdoor unit of the air conditioner may include an outdoor-unit control unit configured to control the components of the outdoor unit, including the compressor and the like. The indoor-unit control unit may communicate with the outdoor-unit control unit via the indoor-unit communication unit and the outdoor-unit communication unit. The outdoor-unit communication unit may transmit a control signal, which is generated by the outdoor-unit control unit, to the indoor-unit communication unit or may transfer a control signal, which is transmitted from the indoor-unit communication unit, to the outdoor-unit control unit. That is, the outdoor unit and the indoor unit may perform bidirectional communication. The outdoor unit and the indoor unit may transmit and receive various signals generated during the operation of the air conditioner.

[0090] The outdoor-unit control unit may be electrically connected to the components of the outdoor unit and may control operations of each of the components. For example, the outdoor-unit control unit may adjust a frequency of the compressor and may control the flow path switching valve to switch the circulation direction of the refrigerant. The outdoor-unit control unit may adjust a rotation speed of an outdoor fan. In addition, the outdoor-unit control unit may generate a control signal for adjusting a degree of opening of an expansion valve. The refrigerant may circulate along a refrigerant circulation circuit including the compressor, the flow path switching valve, the outdoor heat exchanger, the expansion valve, and the indoor heat exchanger, under the control of the outdoor-unit control unit.

[0091] Various temperature sensors, which are included in the outdoor unit and the indoor unit, may each transmit an electrical signal corresponding to a detected temperature to the outdoor-unit control unit and / or the indoor-unit control unit. For example, humidity sensors, which are included in the outdoor unit and the indoor unit, may each transmit an electrical signal corresponding to detected humidity to the outdoor-unit control unit and / or the indoor-unit control unit.

[0092] The indoor-unit control unit may obtain a user input from a user equipment including a mobile device or the like via the indoor-unit communication unit and may obtain the user input via a remote controller or directly via the input interface. The indoor-unit control unit may control the components of the indoor unit, including the blower and the like, in response to the user input that is received. The indoor-unit control unit may transmit information regarding the received user input to the outdoor-unit control unit of the outdoor unit.

[0093] The outdoor-unit control unit may control the components of the outdoor unit, including the compressor and the like, based on the information regarding the user input received from the indoor unit. For example, when a control signal corresponding to a user input for selecting an operation mode, such as a cooling operation, a heating operation, a blowing operation, a defrosting operation, or a dehumidification operation, is received from the indoor unit, the outdoor-unit control unit may control the components of the outdoor unit to cause the air conditioner to perform an operation corresponding to the selected operation mode.

[0094] Each of the outdoor-unit control unit and the indoor-unit control unit may include a processor and memory. The indoor-unit control unit may include at least one first processor and at least one first memory, and the outdoor-unit control unit may include at least one second processor and at least one second memory.

[0095] The memory may memorize / store various information required to operate the air conditioner. The memory may store an instruction, an application, data, and / or a program required to operate the air conditioner. For example, the memory may store various programs for a cooling operation, a heating operation, a dehumidification operation, and / or a defrosting operation of the air conditioner. The memory may include volatile memory, such as static random access memory (SRAM) or dynamic random access memory (DRAM), for temporarily memorizing data. In addition, the memory may include nonvolatile memory, such as read-only memory (ROM), erasable programmable read-only memory (EPROM), or electrically erasable programmable read-only memory (EEPROM), for storing data for a long period of time.

[0096] The processor may generate a control signal for controlling the operation of the air conditioner, based on the instruction, the application, the data, and / or the program stored in the memory. The processor may include, as hardware, a logic circuit and an arithmetic circuit. The processor may process data according to the program and / or the instruction provided by the memory and may generate a control signal according to a processing result. The memory and the processor may be implemented by one control circuit or by a plurality of circuits.

[0097] The indoor unit of the air conditioner may include an output interface. The output interface may be electrically connected to the indoor-unit control unit and may output information related to the operation of the air conditioner under the control of the indoor-unit control unit. For example, the information, such as an operation mode, an air-flow direction, an air-flow rate, or a temperature, which is selected by the user input, may be output. In addition, the output interface may output sensing information obtained from the indoor-unit sensor or the outdoor-unit sensor, or a warning / error message.

[0098] The output interface may include a display and a speaker. The speaker is an audio device and may output various sounds. The display may display information input by the user or information provided to the user, as various graphic elements. For example, operation information of the air conditioner may be displayed as at least one of an image or a text. In addition, the display may include an indicator providing certain information. The display may include a liquid-crystal display (LCD) panel, a light-emitting diode (LED) panel, an organic light-emitting diode (OLED) panel, a micro-LED panel, and / or a plurality of LEDs.

[0099] FIG. 8 is a schematic perspective view of a heat exchanger according to the related art. FIG. 9 is a diagram illustrating the flow of a refrigerant in a connection header in the heat exchanger shown in FIG. 8 according to the related art. Referring to FIG. 8, the heat exchanger according to the related art includes a plurality of heat transfer tubes arranged side-by-side in an up-and-down direction, and a vertical-connection header connected to one-side ends of the plurality of heat transfer tubes. Among the plurality of heat transfer tubes, a refrigerant flowing through a plurality of heat transfer tubes arranged at the lower side (a first stage) flows into a plurality of heat transfer tubes arranged at the upper side (a second stage), via the vertical-connection header. As shown in FIG. 9, in the heat exchanger according to the related art and shown in FIG. 8, the refrigerant in a gas-liquid dual-phase state is separated into a gas-phase refrigerant and a liquid-phase refrigerant in a space in the vertical-connection header, and thus, so-called liquid accumulation, by which the liquid-phase refrigerant is accumulated in the space, may occur. The liquid accumulation mainly occurs in a lower region of the space in the vertical-connection header. When the liquid accumulation has occurred, the refrigerant in the gas-liquid dual-phase state is non-uniformly distributed in the plurality of heat transfer tubes at the downstream side (the second stage). Accordingly, in the heat exchanger, maldistribution of the refrigerant occurs, and thus, heat exchange efficiency may deteriorate.

[0100] The disclosure provides an air conditioner capable of improving the heat exchange efficiency of a heat exchanger. The disclosure provides an air conditioner including a heat exchanger capable of causing a refrigerant to uniformly flow into a plurality of heat transfer tubes on the downstream side, the plurality of heat transfer tubes on the downstream side being connected to a plurality of heat transfer tubes on the upstream side by a connection header. However, aspects of the disclosure are not limited to the above aspects, and the above and other aspects of the disclosure may be clearly understood by those of ordinary skill in the art from the following description. Hereinafter, embodiments of an air conditioner including a heat exchanger are described with reference to the accompanying drawings.

[0101] FIG. 7 is a schematic configuration diagram of an embodiment of an air conditioner according to the disclosure. Referring to FIG. 7, the air conditioner may include an indoor heat exchanger 201, a compressor 202, an outdoor heat exchanger 203, and an expansion device 204. The indoor heat exchanger 201, the compressor 202, the outdoor heat exchanger 203, and the expansion device 204 may be connected to each other by a refrigerant tube. The outdoor heat exchanger 203 is mounted in an outdoor unit and may perform heat exchange between a refrigerant and outdoor air by using a phase change (for example, evaporation or condensation) of the refrigerant. For example, while the refrigerant is being condensed in the outdoor heat exchanger 203, the refrigerant may emit heat to the outdoor air, and while the refrigerant flowing through the outdoor heat exchanger 203 is being evaporated, the refrigerant may absorb heat from the outdoor air. The indoor heat exchanger 201 is mounted in an indoor unit and may perform heat exchange between the refrigerant and indoor air by using a phase change (for example, evaporation or condensation) of the refrigerant. For example, while the refrigerant is being evaporated in the indoor heat exchanger 201, the refrigerant may absorb heat from the indoor air, and as the indoor air cooled through the indoor heat exchanger 201 that is cooled is blown, an indoor space may be cooled. In addition, while the refrigerant is being condensed in the indoor heat exchanger 201, the refrigerant may emit heat to the indoor air, and as the indoor air heated through the indoor heat exchanger 201 having high temperature is blown, the indoor space may be heated. The compressor 202 compresses a refrigerant gas between the indoor heat exchanger 201 and the outdoor heat exchanger 203. The expansion device 204 reduces the pressure of the refrigerant between the indoor heat exchanger 201 and the outdoor heat exchanger 203. During cooling, the refrigerant circulates through the compressor 202, the outdoor heat exchanger 203, the expansion device 204, and the indoor heat exchanger 201 in the stated order, the outdoor heat exchanger 203 functions as a condenser, and the indoor heat exchanger 201 functions as an evaporator. During heating, the refrigerant circulates through the compressor 202, the indoor heat exchanger 201, the expansion device 204, and the outdoor heat exchanger 203 in the stated order, the outdoor heat exchanger 203 functions as an evaporator, and the indoor heat exchanger 201 functions as a condenser. Embodiments of a heat exchanger 100, which are described below, may be applied to the indoor heat exchanger 201 and / or the outdoor heat exchanger 203.

[0102] FIG. 1 is a schematic perspective view illustrating a whole configuration of the heat exchanger 100 according to an embodiment of the disclosure. FIG. 2 is a schematic front view of the heat exchanger 100 shown in FIG. 1, according to an embodiment of the disclosure. FIG. 3 is a diagram illustrating a first row and a second row in a separated state, of the heat exchanger 100 shown in FIG. 1, according to an embodiment of the disclosure. The heat exchanger 100, which constitutes a refrigerant circuit of an air conditioner, may be applied to one or both of the outdoor heat exchanger 203 and the indoor heat exchanger 201.

[0103] Referring to FIGS. 1 to 3, the heat exchanger 100 may include a plurality of heat exchange units 1 and one or more connection units 2. The heat exchanger 100 further includes an inlet tube 3 and an outlet tube 4. Each of the plurality of heat exchange units 1 includes a plurality of heat transfer tubes 10, through which the refrigerant flows. The plurality of heat transfer tubes 10 may be parallel to each other. The one or more connection units 2 connect the plurality of heat exchange units 1 to each other in series. A connection unit 2 connects two adjacent heat exchange units 1 to each other. For example, the plurality of heat exchange units 1 are connected to each other in series by a plurality of connection units 2, thereby forming a plurality of refrigerant flow paths. At least one of the plurality of connection units 2 may connect two adjacent heat exchange units 1 to each other for at least one of the plurality of refrigerant flow paths not to join another refrigerant flow path (e.g., so that refrigerant in a first refrigerant flow path does not mix with refrigerant in a second refrigerant flow path in the connection unit 2). At least one of the plurality of connection units 2 may connect two adjacent heat exchange units 1 to each other for none of the plurality of refrigerant flow paths to join each other.

[0104] The refrigerant is introduced into the plurality of heat exchange units 1 via the inlet tube 3. The inlet tube 3 is connected to one of the plurality of heat exchange units 1. The refrigerant is discharged from the plurality of heat exchange units 1 via the outlet tube 4. The outlet tube 4 is connected to a heat exchange unit 1 that is different from the heat exchange unit 1 to which the inlet tube 3 is connected, among the plurality of heat exchange units 1. The refrigerant flowing into the heat exchanger 100 via the inlet tube 3 flows along the refrigerant flow paths and is discharged from the heat exchanger 100 via the outlet tube 4.

[0105] Hereinafter, the arrangement direction of the plurality of heat transfer tubes 10 is referred to as an up-and-down direction, the extension direction of the plurality of heat transfer tubes 10 is referred to as a left-and-right direction, and a direction that is orthogonal to the up-and-down direction and the left-and-right direction is referred to as a front-and-rear direction. The front-and-rear direction is a direction in which air exchanging heat with the refrigerant flows in the heat exchanger 100.

[0106] For example, when the heat exchanger 100 functions as a condenser, a heat exchange unit 1 on the upstream side (the side on which the inlet tube 3 is mounted), among the plurality of heat exchange units 1 arranged in two rows in the front-and-rear direction, may be located on the leeward side, and a heat exchange unit 1 on the downstream side (the side on which the outlet tube 4 is mounted) may be located on the windward side. For example, when the heat exchanger 100 functions as an evaporator, a heat exchange unit 1 on the upstream side (the side on which the inlet tube 3 is mounted), among the plurality of heat exchange units 1 arranged in two rows in the front-and-rear direction, may be located on the windward side, and a heat exchange unit 1 on the downstream side (the side on which the outlet tube 4 is mounted) may be located on the leeward side.

[0107] The heat exchange unit 1 includes a plurality of heat transfer tubes 10. Referring to FIGS. 1 to 3, the plurality of heat transfer tubes 10 may extend in the left-and-right direction and may arranged side-by-side at certain intervals in the up-and-down direction. A heat transfer tube 10 may have a flat-tube shape. An upper surface and a lower surface of the heat transfer tube 10 may each be a flat surface, and the plurality of heat transfer tubes 10 may be arranged in the up-and-down direction for the flat surfaces thereof to face each other. The heat transfer tube 10 may include a multi-hole tube including a plurality of refrigerant flow paths in which the refrigerant flows. A refrigerant flow path may extend in the extension direction of the heat transfer tube 10, for example, the left-and-right direction.

[0108] Via one of both ends of the heat exchange unit 1 in the left-and-right direction, that is, via one of a first end 11 and a second end 12 of the heat exchange unit 1, the refrigerant is introduced into the plurality of heat transfer tubes 10. Therefore, the refrigerant flows in the same direction in the plurality of heat transfer tubes 10 that are included in one heat exchange unit 1.

[0109] As described above, the heat exchanger 100 include the plurality of heat exchange units 1. For example, the heat exchanger 100 according to the present embodiment of the disclosure includes six heat exchange units 1. Each of the plurality of heat exchange units 1 includes a plurality of heat transfer tubes 10. Each of the plurality of heat exchange units 1 may include a same number of heat transfer tubes 10. For example, each of the plurality of heat exchange units 1 according to the present embodiment of the disclosure includes six heat transfer tubes 10. The heat transfer tubes 10, which are included in the plurality of heat exchange units 1, may have almost same dimensions (lengths, widths, and thicknesses). Here, when the heat transfer tubes 10 are referred to as having almost same dimensions, it means that errors in the dimensions of the heat transfer tubes 10 are in +1%.

[0110] Hereinafter, when there is no need to distinguish the six heat exchange units from each other, for example, when features common to the six heat exchange units are described, a reference numeral indicating a heat exchange unit is represented by “1”. When there is a need to distinguish the six heat exchange units from each other, the six heat exchange units are distinguished from each other by respectively giving the reference numerals “1A”, “1B”, “1C”, “1D”, “1E”, and “1F” to the six heat exchange units. In addition, heat transfer tubes, which are included in each of the heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F, are distinguished from each other by respectively giving the reference numerals “10A”, “10B”, “10C”, “10D”, “10E”, and “10F” to the heat transfer tubes. When there is no need to distinguish the heat transfer tubes in the heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F from each other, for example, when features common to the heat transfer tubes of all the heat exchange units are described, a reference numeral indicating a heat transfer tube is represented by “10”.

[0111] For example, referring to FIGS. 1 to 3, the heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F may have an arrangement structure having three stages in the up-and-down direction and two rows in the front-and-rear direction. The heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F are arranged in three stages in the up-and-down direction and two rows in the front-and-rear direction, for the extension direction of each of the heat transfer tubes 10A, 10B, 10C, 10D, 10E, and 10F, that is, the flow direction of the refrigerant, to be parallel to each other. In other words, a group of the heat exchange units 1A, 1B, and 1C arranged in three stages in the up-and-down direction and a group of the heat exchange units 1D, 1E, and 1F arranged in three stages in the up-and-down direction are arranged in two rows in the front-and-rear direction. In each of the group of the heat exchange units 1A, 1B, and 1C and the group of the heat exchange units 1D, 1E, and 1F, the stages in the up-and-down direction are respectively referred to as a first stage, a second stage, and a third stage from bottom to top. That is, in each of the group of the heat exchange units 1A, 1B, and 1C and the group of the heat exchange units 1D, 1E, and 1F, the heat exchange unit 1A and the heat exchange unit 1F each correspond to the first stage. In addition, the heat exchange units 1A, 1B, and 1C arranged on the front side in the front-and-rear direction correspond to a first row, and the heat exchange units 1D, 1E, and 1F arranged on the rear side in the front-and-rear direction correspond to a second row. Two heat exchange units in the same stage, among the heat exchange units 1A, 1B, and 1C in the first row and the heat exchange units 1D, 1E, and 1F in the second row, are arranged adjacent to each other in the front-and-rear direction at the same height. For example, the heat exchange unit 1A at the first stage in the first row and the heat exchange unit 1F at the first stage in the second row are arranged adjacent to each other in the front-and-rear direction at the same height. In addition, the heat transfer tubes 10A, 10B, and 10C of the heat exchange units 1A, 1B, and 1C in the first row and the heat transfer tubes 10D, 10E, and 10F of the heat exchange units 1D, 1E, and 1F in the second row are arranged for the heat transfer tubes 10A, 10B, and 10C to correspond to the heat transfer tubes 10D, 10E, and 10F one-to-one in the front-and-rear direction at the same height. That is, the heat transfer tubes 10A of the heat exchange unit 1A at the first stage in the first row and the heat transfer tubes 10F of the heat exchange unit 1F at the first stage in the second row are arranged for the heat transfer tubes 10A correspond to the heat transfer tubes 10F one-to-one in the front-and-rear direction at the same height.

[0112] Referring to FIGS. 1 to 3, a connection unit 2 connects two heat exchange units 1 that are adjacent to each other in the up-and-down direction or the front-and-rear direction. That is, the connection unit 2 provides a connection passage for the refrigerant to move from one heat exchange unit 1 to another heat exchange unit 1 that is adjacent to the one heat exchange unit 1 in the up-and-down direction or the front-and-rear direction. The connection unit 2 connects two respective ends of two heat exchange units 1 in the left-and-right direction to each other, the two heat exchange units 1 being adjacent to each other.

[0113] The connection unit 2 connects downstream-side ends of the heat transfer tubes 10 of the heat exchange unit 1 located on the upstream side, among two adjacent heat exchange units 1, to upstream-side ends of the heat transfer tubes 10 of the heat exchange unit 1 located on the downstream side. The connection unit 2 causes the refrigerant flowing along the heat transfer tubes 10 of the upstream-side heat exchange unit 1 to flow into the heat transfer tubes 10 of the downstream-side heat exchange unit 1 by switching the flow direction of the refrigerant. Here, the switching of the flow direction of the refrigerant refers to causing the flow direction of the refrigerant flowing into the connection unit 2 to be opposite to the flow direction of the refrigerant discharged from the connection unit 2. Therefore, the refrigerant flows in opposite directions respectively in two heat exchange units 1 connected to each other by the connection unit 2. In other words, the refrigerant flows in a first direction along the heat transfer tubes 10 of the upstream-side heat exchange unit 1, and the refrigerant flows in a second direction, which is opposite to the first direction, along the heat transfer tubes 10 of the downstream-side heat exchange unit 1.

[0114] For example, the heat exchanger 100 according to the present embodiment of the disclosure includes five connection units 2, and the six heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F are sequentially connected to each other in series in the stated order by the five connection units 2. For example, the connection units 2 may include a vertical-switching connection unit 2X for switching the flow direction of the refrigerant to the up-and-down direction, and a horizontal-switching connection unit 2Y for switching the flow direction of the refrigerant to a horizontal direction, for example, the front-and-rear direction. The vertical-switching connection unit 2X connects one-side ends of two heat exchange units 1 in the left-and-right direction to each other, the two heat exchange units 1 being adjacent to each other in the up-and-down direction. In other words, the vertical-switching connection unit 2X connects, to each other, a first heat exchange unit and a second heat exchange unit that are adjacent to each other in the up-and-down direction. The vertical-switching connection unit 2X connects a downstream-side end of the first heat exchange unit, which is located relatively upstream, to an upstream-side end of the second heat exchange unit, which is located relatively downstream. The refrigerant flowing in the first direction in a plurality of first heat transfer tubes of the first heat exchange unit is introduced into a plurality of second heat transfer tubes of the second heat exchange unit by the vertical-switching connection unit 2X and flows in the second direction that is opposite to the first direction. The horizontal-switching connection unit 2Y connects one-side ends of two heat exchange units 1 in the left-and-right direction to each other, the two heat exchange units 1 being adjacent to each other in the front-and-rear direction. In other words, the horizontal-switching connection unit 2Y connects, to each other, the second heat exchange unit and a third heat exchange unit that are adjacent to each other in the front-and-rear direction. The horizontal-switching connection unit 2Y connects a downstream-side end of the second heat exchange unit, which is located relatively upstream, to an upstream-side end of the third heat exchange unit, which is located relatively downstream. The refrigerant flowing in the second direction in the plurality of second heat transfer tubes of the second heat exchange unit is introduced into a plurality of third heat transfer tubes of the third heat exchange unit by the horizontal-switching connection unit 2Y and flows in the first direction that is opposite to the second direction. In the present embodiment of the disclosure, the connection units 2 include four vertical-switching connection units 2X and one horizontal-switching connection unit 2Y.

[0115] Referring to FIGS. 1 to 3, the refrigerant is introduced into the heat exchanger 100 via the inlet tube 3. The inlet tube 3 is connected to a first end 11 or a second end 12 of one heat exchange unit 1 among the plurality of heat exchange units 1, and the refrigerant is introduced into a plurality of heat transfer tubes 10 of the one heat exchange unit 1 via the inlet tube 3. In the present embodiment of the disclosure, the inlet tube 3 is connected to the second end 12 of the heat exchange unit 1A and causes the refrigerant to flow into the heat transfer tubes 10A. For example, one inlet tube 3 is connected to a flow divider 5 mounted at the second end 12 of the heat exchange unit 1A, and thus, the refrigerant introduced via the inlet tube 3 is divided and flows into six heat transfer tubes 10A.

[0116] Referring to FIGS. 1 to 3, the refrigerant is discharged from the heat exchanger 100 via the outlet tube 4. The outlet tube 4 is connected to a first end 11 or a second end 12 of another heat exchange unit 1 except for the heat exchange unit 1 connected to the inlet tube 3, among the plurality of heat exchange units 1, and the refrigerant is discharged out of a plurality of heat transfer tubes 10 of the other heat exchange unit 1 via the outlet tube 4. In the present embodiment of the disclosure, the outlet tube 4 is connected to a second end 12 of the heat exchange unit 1F, and the refrigerant is discharged out of the heat transfer tubes 10F via the outlet tube 4. For example, six outlet tubes 4 are provided and respectively correspond one-to-one to six heat transfer tubes 10F. The refrigerant having flowed along the six heat transfer tubes 10F is discharged to the outside of the heat exchanger 100 via the six outlet tubes 4.

[0117] The plurality of heat exchange units 1 are connected to each other in series by the one or more connection units 2, thereby forming a series of refrigerant flow paths, through which the refrigerant flows. In the present embodiment of the disclosure, the six heat exchange units 1A, 1B, 1C, 1D, 1E, and 1F are sequentially connected to each other in the stated order by the five connection units 2, thereby forming a series of refrigerant flow paths.

[0118] The refrigerant is introduced into the heat exchange unit 1A on the most upstream side via the inlet tube 3, passes through the heat exchange units 1B, 1C, 1D, 1E, and 1F, and is discharged from the heat exchange unit 1F on the most downstream side via the outlet tube 4.

[0119] For example, a phase change of the refrigerant, when the heat exchanger 100 functions as a condenser, is described with reference to FIG. 3.

[0120] First, the refrigerant in the gas state flows into the flow divider 5 via the inlet tube 3 and is divided by the flow divider 5 to flow into the plurality of heat transfer tubes 10A of the heat exchange unit 1A at the first stage in the first row. The refrigerant in the gas state, which has exchanged heat with air while passing through the plurality of heat transfer tubes 10A, for example, from left to right, comes out of the plurality of heat transfer tubes 10A and is introduced into a plurality of heat transfer tubes 10B of the heat exchange unit 1B at the second stage in the first row via the vertical-switching connection unit 2X, for example, a vertical-switching connection unit 2X-AB.

[0121] For example, in the heat exchange unit 1B, the refrigerant may undergo a phase change from the gas state to the gas-liquid dual-phase state. The refrigerant in the dual-phase state, which has exchanged heat with air while passing through the plurality of heat transfer tubes 10B from right to left, is sequentially introduced into a plurality of heat transfer tubes 10C of the heat exchange unit 1C at the third stage in the first row via a vertical-switching connection unit 2X-BC, into a plurality of heat transfer tubes 10D of the heat exchange unit 1D at the third stage in the second row via a horizontal-switching connection unit 2Y, into a plurality of heat transfer tubes 10E of the heat exchange unit 1E at the second stage in the second row via a vertical-switching connection unit 2X-DE, and into the plurality of heat transfer tubes 10F of the heat exchange unit 1F at the first stage in the second row via a vertical-switching connection unit 2X-EF, in the stated order. For example, in the heat exchange unit 1F, the refrigerant may undergo a phase change from the gas-liquid dual-phase state to the liquid state. The refrigerant in the liquid state, which has flowed along the plurality of heat transfer tubes 10F, is discharged to the outside of the heat exchanger 100 via the outlet tube 4.

[0122] In an embodiment of the disclosure, for the temperature difference between the refrigerant flowing along the plurality of heat transfer tubes 10 and air passing through the plurality of heat exchange units 1 to be as large as possible in each row of the plurality of heat exchange units 1 arranged in two rows in the front-and-rear direction, the heat exchange units 1A, 1B, and 1C in the first row corresponding to the upstream side of the refrigerant flow path may be arranged on the leeward side, and the heat exchange units 1D, 1E, and 1F in the second row corresponding to the downstream side of the refrigerant flow path may be arranged on the windward side.

[0123] In an embodiment of the disclosure, each of the plurality of connection units 2 may include a plurality of connection flow paths 20 causing the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the upstream side, among two adjacent heat exchange units 1, to individually communicate with the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the downstream side. Each of the connection units 2 may include a plurality of connection flow paths 20 that are independent of each other. The plurality of connection flow paths 20 may connect the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the upstream side and the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the downstream side to each other in a one-to-one relationship. The horizontal-switching connection unit 2Y may include, as the plurality of connection flow paths 20, a plurality of horizontal-connection flow paths 20Y (see FIG. 1), and the vertical-switching connection unit 2X may include, as the plurality of connection flow paths 20, a plurality of vertical-connection flow paths 20X (see FIGS. 4 and 6).

[0124] For example, the plurality of connection flow paths 20 may be formed in the form of a plurality of cavities in an inner space of the connection unit 2 configured as a block body. The number of cavities may equal to the number of heat transfer tubes 10. For example, the plurality of connection flow paths 20 may include a same number of tube members as the plurality of heat transfer tubes 10. In the present embodiment of the disclosure, six connection flow paths 20, which are independent of each other, are formed in the connection unit 2, and six heat transfer tubes 10 of the heat exchange unit 1 on the upstream side are connected to six heat transfer tubes 10 of the heat exchange unit 1 on the downstream side in a one-to-one relationship.

[0125] In an embodiment of the disclosure, the plurality of connection units 2 may connect the plurality of heat exchange units 1 to each other for the respective flow-path lengths of the plurality of refrigerant flow paths to be almost equal. Here, when the respective flow-path lengths of the plurality of refrigerant flow paths are referred to as being almost equal, it means that errors in the respective flow-path lengths of the plurality of refrigerant flow paths are in +1%. In an embodiment of the disclosure, the respective flow-path lengths of the plurality of connection flow paths 20 may be almost equal. Here, when the respective flow-path lengths of the plurality of connection flow paths 20 are referred to as being almost equal, it means that errors in the respective flow-path lengths of the plurality of connection flow paths 20 are in +1%. In an embodiment of the disclosure, the plurality of connection flow paths 20 may connect, to each other, two heat transfer tubes 10 located at the same arrangement position (for example, the same stage based on a counting sequence from the top or from the bottom) in the up-and-down direction.

[0126] For example, FIG. 4 is a schematic enlarged view of the connection unit 2 according to an embodiment of the disclosure. Referring to FIG. 4, six vertical-connection flow paths 20X mounted in the vertical-switching connection unit 2X-AB connect the six heat transfer tubes 10A of the heat exchange unit 1A and the six heat transfer tubes 10B of the heat exchange unit 1B to each other in the manner of connecting the heat transfer tubes 10A and 10B located at the same position in the up-and-down direction to each other. For example, in FIG. 4, one of the six vertical-connection flow paths 20X connects the heat transfer tube 10A, which is arranged at the first place from the top in the heat exchange unit 1A, to the heat transfer tube 10B, which is arranged likewise at the first place from the top in the heat exchange unit 1B. In addition, referring to FIG. 1, six horizontal-connection flow paths 20Y mounted in the horizontal-switching connection unit 2Y connect six heat transfer tubes 10C of the heat exchange unit 1C and six heat transfer tubes 10D of the heat exchange unit 1D to each other in the manner of connecting the heat transfer tubes 10C and 10D located at the same position in the up-and-down direction to each other. For example, one of the six horizontal-connection flow paths 20Y connects the heat transfer tube 10C, which is arranged at the third place from the bottom in the heat exchange unit 1C, to the heat transfer tube 10D, which is arranged likewise at the third place from the bottom in the heat exchange unit 1D. In this way, in the present embodiment of the disclosure, six independent refrigerant flow paths, which pass through the six heat exchange units 1 and have almost equal flow-path lengths, may be formed.

[0127] When the temperature difference between adjacent heat transfer tubes 10 of the heat exchange unit 1 is large, heat exchange between the adjacent heat transfer tubes 10 occurs. This is a factor of deteriorating heat exchange efficiency by hindering heat exchange between the refrigerant flowing along the heat transfer tube 10 and air. According to the heat exchanger 100 according to an embodiment of the disclosure, in each heat exchange unit 1, the refrigerant having a temperature at the same level flows through a plurality of heat transfer tubes 10 that are vertically arranged. Therefore, because the temperature difference between the adjacent heat transfer tubes 10 in each heat exchange unit 1 is suppressed, the heat exchange between the adjacent heat transfer tubes 10 may be suppressed, and heat loss due to the heat exchange between the adjacent heat transfer tubes 10 may be suppressed.

[0128] The refrigerant having passed through a plurality of heat transfer tubes 10 of an upstream-side heat exchange unit 1 flows into a plurality of heat transfer tubes 10 of a downstream-side heat exchange unit 1 adjacent to the upstream-side heat exchange unit 1 via the plurality of connection flow paths 20 of the connection unit 2, without joining or dividing, the plurality of heat transfer tubes 10 of the downstream-side heat exchange unit 1 respectively corresponding to the plurality of heat transfer tubes 10 of an upstream-side heat exchange unit 1. Even when the refrigerant in the gas-liquid dual-phase state flows through the plurality of heat transfer tubes 10 of the upstream-side heat exchange unit 1, because the refrigerant in the gas-liquid dual-phase state uniformly flows into the corresponding plurality of heat transfer tubes 10 of the downstream-side heat exchange unit 1, the heat exchange efficiency of the heat exchanger 100 may be maintained.

[0129] Because the plurality of connection flow paths 20 connect two heat transfer tubes 10, which are located at the same arrangement position in two adjacent heat exchange units 1, to each other in a one-to-one relationship, it is easy to cause the respective flow-path lengths of the plurality of refrigerant flow paths, which are formed by the plurality of heat transfer tubes 10 of the plurality of heat exchange units 1, to be almost equal.

[0130] Because the plurality of connection flow paths 20 of the connection unit 2 connecting two adjacent heat exchange units 1 to each other have almost equal flow-path lengths, it is unlikely for the difference in pressure loss between the plurality of refrigerant flow paths to be generated, and thus, the maldistribution of the refrigerant may be reduced.

[0131] Because the inlet tube 3 and the outlet tube 4 are arranged on one side of the heat exchanger 100 with reference to the left-and-right direction, a plumbing work or the like is simple. For example, in the above-described embodiment of the disclosure, the inlet tube 3 and the outlet tube 4 are arranged at the second end 12 of the heat exchange unit 1A at the first stage in the first row and at the second end 12 of the heat exchange unit 1F at the first stage in the second row, respectively.

[0132] In the embodiment of the heat exchanger 100 described above, the plurality of refrigerant flow paths undergo no joining (e.g., mixing) or no dividing in all the plurality of connection units 2, but the disclosure is not limited thereto. It is only required for the plurality of refrigerant flow paths to undergo no joining or no dividing in at least one of the plurality of connection units 2. In addition, the plurality of connection units 2 may include at least one connection flow path 20 causing one heat transfer tube 10 of one heat exchange unit 1 to individually communicate with one heat transfer tube 10 of another heat exchange unit 1 adjacent to the one heat exchange unit 1, and by doing this, because the maldistribution of the refrigerant may be suppressed from being generated in a refrigerant flow path formed by two heat transfer tubes 10 connected to each other by the at least one connection flow path 20, the heat exchange efficiency may be maintained.

[0133] The number of heat exchange units 1 in the heat exchanger 100 is not limited to 6, and may be plural, that is two or more. In addition, at least two of the plurality of heat exchange units 1 may be arranged adjacent to each other in the up-and-down direction and are connected by the vertical-switching connection unit 2X in which no flow combiner or no flow divider is included. Furthermore, an arrangement method (the number of stages and the number of rows) of the heat exchange units 1 may be suitably determined according to purposes thereof.

[0134] The heat exchanger 100 may function as an evaporator as well as a condenser. In this case, the heat exchange units 1 in the first row, which are on the upstream side of the refrigerant flow path, may be arranged on the windward side, and the heat exchange units 1 in the second row, which are on the downstream side of the refrigerant flow path, may be arranged on the leeward side. By doing this, the temperature difference between the refrigerant passing through the heat exchanger 100 and air may be increased, thereby improving the heat exchange efficiency.

[0135] FIG. 5 is a diagram separately illustrating a first row and a second row of a heat exchanger 100 according to an embodiment of the disclosure. Referring to FIG. 5, the heat exchanger 100 according to the present embodiment of the disclosure may include a dummy heat transfer tube 6 arranged between two heat exchange units 1 that are vertically adjacent to each other. The dummy heat transfer tube 6 refers to a heat transfer tube in which no refrigerant flows. One dummy heat transfer tube 6 may be provided, or two or more dummy heat transfer tubes 6 may be provided. The dummy heat transfer tube 6 may be, for example, a heat transfer tube not communicating with the connection flow path 20 of the connection unit 2. The dummy heat transfer tube 6 may be obtained by blocking an inner passage, through which the refrigerant flows, of a general heat transfer tube.

[0136] According to such a configuration, because heat exchange between two heat exchange units 1 vertically adjacent to each other may be reduced or cut off by the dummy heat transfer tube 6, the heat exchange efficiency of the heat exchanger 100 may be maintained. When the refrigerant in the gas-liquid dual-phase state flows through one of two adjacent heat exchange units 1 and the refrigerant in the gas state or the liquid state flows through the other heat exchange unit 1, because the temperature difference between the two heat exchange units 1 is relatively large, the dummy heat transfer tube 6 may be mounted between such two heat exchange units 1. For example, as shown in FIG. 5, dummy heat transfer tubes 6 may be respectively mounted between the heat exchange unit 1A, through which the refrigerant in the gas state flows, and the heat exchange unit 1B, through which the refrigerant in the gas-liquid dual-phase state flows, and between the heat exchange unit 1E, through which the refrigerant in the gas-liquid dual-phase state flows, and the heat exchange unit 1F, through which the refrigerant in the liquid state flows.

[0137] A heat exchange system may be configured by stacking two or more heat exchangers 100 according to the above-described embodiments of the disclosure in the up-and-down direction. In this case, two heat exchangers 100 vertically adjacent to each other may be stacked to be plane-symmetric to each other in a horizontal direction. For example, the first row of the heat exchanger 100 on the lower side may include the heat exchange units 1A, 1B, and 1C sequentially arranged in the stated order from bottom to top, and the first row of the heat exchanger 100 on the upper side may include the heat exchange units 1C, 1B, and 1A sequentially arranged in the stated order from bottom to top. According to such a configuration, because the two identical heat exchange units 1C of the two heat exchangers 100 are arranged adjacent to each other, the temperature difference between boundary portions of the two heat exchangers 100 may be reduced, and thus, heat loss due to heat exchange between the two heat exchangers 100 may be reduced.

[0138] In the above-described embodiments of the disclosure, although the inlet tube 3 is connected to the heat exchange unit 1A, the inlet tube 3 may be connected to the heat exchange unit 1F. In this case, the outlet tube 4 may be connected to the heat exchange unit 1A.

[0139] In the above-described embodiments of the disclosure, the vertical-connection flow path 20X connects, to each other, two heat transfer tubes 10 respectively at the same arrangement positions in two adjacent heat exchange units 1, but the disclosure is not limited thereto. The vertical-connection flow path 20X may connect, to each other, two heat transfer tubes 10 respectively at different arrangement positions in two heat exchange units 1.

[0140] FIG. 6 is a schematic enlarged view of the connection unit 2 according to an embodiment of the disclosure. Referring to FIG. 6, the plurality of connection flow paths 20X of the vertical-switching connection unit 2X connect the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the lower side to the plurality of heat transfer tubes 10 of the heat exchange unit 1 on the upper side, in the manner of connecting two heat transfer tubes 10 respectively located at symmetric positions to each other in the up-and-down direction. For example, the heat exchange unit 1A at the first stage in the first row and the heat exchange unit 1B at the second stage in the first row are connected to each other by the vertical-switching connection unit 2X-AB. The six heat transfer tubes 10A of the heat exchange unit 1A at the first stage in the first row are respectively indicated by ①, ②, ③, ④, ⑤, and ⑥ in the stated order from top to bottom, and the six heat transfer tubes 10B of the heat exchange unit 1B at the second stage in the first row are respectively indicated by ①, ②, ③, ④, ⑤, and ⑥ in the stated order from top to bottom. The six connection flow paths 20X connect the six heat transfer tubes 10A and the six heat transfer tubes 10B to each other in pairs, such as ①-⑥, ②-⑤, ③-④, ④-③, ⑤-②, and ⑥-①. Likewise, the six connection flow paths 20X of the vertical-switching connection unit 2X-BC, which connects the heat exchange unit 1B at the second stage in the first row and the heat exchange unit 1C at the third stage in the first row, connect the six heat transfer tubes 10B and the six heat transfer tubes 10C to each other in pairs, such as ①-⑥, ②-⑤, ③-④, ④-③, ⑤-②, and ⑥-①.

[0141] According to such a configuration, each of the six refrigerant flow paths passing through the heat exchange units 1A, 1B, and 1C includes two connection flow paths 20X, and the sum of the respective lengths of the two connection flow paths 20X in each of the six refrigerant flow paths is almost equal. Therefore, the respective lengths of the six refrigerant flow paths passing through the heat exchange units 1A, 1B, and 1C may be almost equal. Therefore, because the respective path lengths of the plurality of refrigerant flow paths may be made almost equal in a relatively simple manner, the difference in pressure loss between the respective refrigerant flow paths may be reduced, thereby reducing the maldistribution of the refrigerant.

[0142] In the embodiments of the heat exchanger 100, among the plurality of heat exchange units 1 arranged in the front-and-rear direction and the up-and-down direction, the inlet tube 3 is connected to the heat exchange unit 1A at the front row (the first row), and the outlet tube 4 is connected to the heat exchange unit 1F at the rear row (the second row). That is, the inlet tube 3 and the outlet tube 4 are respectively connected to two heat exchange units 1 that are respectively in different rows in the front-and-rear direction. However, the arrangement type of the inlet tube 3 and the outlet tube 4 is not limited thereto.

[0143] FIG. 10 is a schematic perspective view illustrating a whole configuration of a heat exchanger 201 according to an embodiment of the disclosure. FIG. 11 illustrates schematic front and rear views of the heat exchanger 201, shown in FIG. 10, according to an embodiment of the disclosure. The heat exchanger 201 according to the present embodiment of the disclosure may be an indoor heat exchanger installed indoors, and an example, in which the indoor heat exchanger 201 functions as an evaporator, is described below. In the indoor heat exchanger 201 according to the present embodiment of the disclosure, the inlet tube 3 and the outlet tube 4 are respectively connected to two heat exchange units 1 that are at the same row and are respectively in different stages in the up-and-down direction.

[0144] Referring to FIGS. 10 and 11, the indoor heat exchanger 201 may include a plurality of heat exchange units 1 arranged in the front-and-rear direction and the up-and-down direction, and a plurality of connection units 2 connecting the plurality of heat exchange units 1 to each other in series to form a refrigerant flow path L. The inlet tube 3 is connected to one of the plurality of heat exchange units 1 and introduces a refrigerant into one end of the refrigerant flow path L. The outlet tube 4, which discharges the refrigerant from the other end of the refrigerant flow path L, is connected to another one of the plurality of heat exchange units 1. For example, referring to FIGS. 10 and 11, four heat exchange units 1G, 1H, 1I, and 1J and three connection units 2 are illustrated.

[0145] In the present embodiment of the disclosure, air exchanging heat with the refrigerant of the indoor heat exchanger 201 flows from the heat exchange units 1G and 1H at the front row (the first row) toward the heat exchange units 11 and 1J at the rear row (the second row), among the plurality of heat exchange units 1 arranged in the front-and-rear direction. Hereinafter, the front-row (the first-row) side may also be referred to as a windward side, and the rear-row (the second-row) side may also be referred to as a leeward side. A configuration of each of a plurality of heat exchange units 1G to 1J is the same as that of the heat exchange unit 1 of the embodiment described above, and thus, repeated descriptions are omitted. The four heat exchange units 1G, 1H, 1I, and 1J are arranged in two stages in the up-and-down direction and in two rows in the front-and-rear direction for an extension direction of heat transfer tubes 10 in the four heat exchange units 1G, 1H, 1I, and 1J to be parallel to each other. In addition, the number of heat exchange units 1 forming the heat exchanger 201 is not limited to four. The plurality of heat exchange units 1 may be arranged in two or more rows in the front-and-rear direction and in two or more stages in the up-and-down direction. Two heat exchange units 1G and 1H arranged in the up-and-down direction in the first row on the windward side may be grouped and referred to as a windward heat exchange unit group 14, and two heat exchange units 11 and 1J arranged in the up-and-down direction in the second row on the leeward side may be grouped and referred to as a leeward heat exchange unit group 15.

[0146] A connection unit 2 individually connects heat transfer tubes 10 of two adjacent heat exchange units 1 to each other. In the present embodiment of the disclosure, the connection unit 2 includes one vertical-switching connection unit 2X and two horizontal-switching connection units 2Y. The vertical-switching connection unit 2X connects the heat exchange unit 1I and the heat exchange unit 1J to each other. The horizontal-switching connection units 2Y may include a horizontal-switching connection unit 2Y-GI, which connects the heat exchange unit 1G and the heat exchange unit 1I to each other, and a horizontal-switching connection unit 2Y-JH, which connects the heat exchange unit 1J and the heat exchange unit 1H to each other.

[0147] The inlet tube 3 and the outlet tube 4 are connected to the windward heat exchange unit group 14. The inlet tube 3 is connected to the heat exchange unit 1G arranged in the first stage in the windward heat exchange unit group 14, and the outlet tube 4 is connected to the heat exchange unit 1H arranged in the second stage in the windward heat exchange unit group 14 and is arranged above the inlet tube 3 based on the up-and-down direction.

[0148] According to such a configuration, a refrigerant introduced into the heat exchange unit 1G through the inlet tube 3 passes through the heat exchange unit 1I, the heat exchange unit 1J, and the heat exchange unit 1H in the stated order and is discharged from the outlet tube 4.

[0149] FIG. 12 is a schematic configuration diagram of an embodiment of an air conditioner AC according to the disclosure. Referring to FIG. 12, the air conditioner AC may include an indoor heat exchanger 201, a compressor 202, an outdoor heat exchanger 203, an expansion valve (an expansion device) 204, a flow path switching valve (not shown), and the like. The indoor heat exchanger 201, the compressor 202, the outdoor heat exchanger 203, the expansion valve 204, and the flow path switching valve are connected to each other by a refrigerant tube to form a refrigerant circuit R. The air conditioner AC may include a flow rate controller 400 for controlling a flow rate of a refrigerant flowing through the refrigerant circuit R. FIG. 11 illustrates a flow direction of the refrigerant when the heat exchanger 201 functions as an evaporator, that is, when the air conditioner AC performs a cooling operation. The air conditioner AC may be controlled to cause the degree of superheat of the refrigerant discharged from the outlet tube 4 of the indoor heat exchanger 201, which functions as an evaporator, to be equal to or greater than a certain value.

[0150] The indoor heat exchanger 201 may be mounted inside a casing of an indoor unit installed in a building, and the outdoor heat exchanger 203, the compressor 202, the expansion valve 204, and the flow path switching valve may be mounted inside a casing of an outdoor unit installed outside the building.

[0151] The outdoor heat exchanger 203 may include a plurality of heat exchange units 1 arranged in the front-and-rear direction and the up-and-down direction, and an inlet tube and an outlet tube of the outdoor heat exchanger 203 may be respectively connected to two heat exchange units 1 located in different rows in the front-and-rear direction. The heat exchanger 203 may function as a condenser, the inlet tube may be connected to a heat exchange unit 1 located on the leeward side, and the outlet tube may be connected to a heat exchange unit 1 located on the windward side.

[0152] The flow rate controller 400 may include a processor, for example, a central processing unit (CPU), memory, an input / output (I / O) interface, a communication interface, and the like. The flow rate controller 400 is operated by executing, by the processor, a certain program stored in the memory. The flow rate controller 400 may control the amount of the refrigerant, which is introduced into the indoor heat exchanger 201, by controlling, for example, the degree of valve opening of the expansion valve 204 or an operation of the compressor 202, and thus, may control the degree of superheat of the refrigerant, which is discharged from the outlet tube 4 of the indoor heat exchanger 201, to be equal to or greater than a certain value. The degree of superheat refers to a degree by which the temperature of the refrigerant exceeds the saturation temperature thereof. The degree of superheat is controlled to be, for example, 1 degree to 6 degrees.

[0153] FIG. 13A is a diagram illustrating the flow of a refrigerant when the indoor heat exchanger 201 functions as an evaporator. FIG. 13B is a diagram illustrating temperature changes of air and a refrigerant passing through heat exchange units in the second stage when the indoor heat exchanger 201 functions as an evaporator. Referring to FIGS. 13A and 13B, the flow rate controller 400 controls the flow rate of the refrigerant to cause a degree of superheat to be given the refrigerant flowing along the heat transfer tubes 10 of the heat exchange unit 1H (to cause the refrigerant temperature to be greater than the saturation temperature), in a certain region (referred to as a superheat-securing region SH, hereinafter) set on a one-end side of the heat exchange unit 1H to which the outlet tube 4 is connected. The superheat-securing region SH may be set over a certain length starting from one end of the heat exchange unit 1H, to which the outlet tube 4 is connected, toward the other end of the heat exchange unit 1H.

[0154] FIG. 14A is a diagram illustrating the flow of a refrigerant when a heat exchanger, in which an inlet tube is connected to a heat exchange unit in the first row (the windward side) and an outlet tube is connected to a heat exchange unit in the second row (the leeward side), functions as an evaporator. FIG. 14B is a diagram illustrating temperature changes of air and a refrigerant passing through the heat exchanger shown in FIG. 14A when the heat exchanger shown in FIG. 14A functions as an evaporator. It is described with reference to FIGS. 13A, 13B, 14A, and 14B that the indoor heat exchanger 201 according to the present embodiment of the disclosure may secure a relatively larger temperature difference between the refrigerant and air in the vicinity of the outlet tube 4.

[0155] Referring to FIG. 13B, it can be seen that, even when the heat exchange unit 1H on the windward side gives a degree of superheat to the refrigerant, a sufficient temperature difference is secured between the refrigerant having the given degree of superheat and air on the windward side at a high temperature. Referring to FIG. 14A, a heat exchange unit connected to an outlet tube and located on the leeward side (in the first stage in the second row) gives a degree of superheat to a refrigerant. Air, which has a temperature reduced by heat exchange with a heat exchange unit on the windward side (in the first stage in the first row), passes through the heat exchange unit on the leeward side (in the first stage in the second row). Therefore, as shown in FIG. 14B, it may be difficult to secure a sufficient temperature difference between the air and the refrigerant that has the degree of superheat given by the heat exchange unit on the leeward side (in the first stage in the second row).

[0156] The flow rate controller 400 may control the amount of the refrigerant, which is introduced into the outdoor heat exchanger 203, by controlling, for example, an operation of the compressor 202, and thus, may perform control to cause a degree of supercooling to be given to the refrigerant discharged from the outlet tube of the outdoor heat exchanger 203 (to cause the refrigerant temperature to be less than the saturation temperature).

[0157] By connecting the outlet tube 4 to the heat exchange unit 1H on the windward side as in the indoor heat exchanger 201 of the present embodiment of the disclosure, a temperature difference between the refrigerant and air in the vicinity of the outlet tube 4 may be as large as possible, and even when a large degree of superheat is given to the refrigerant in the vicinity of the outlet tube 4, a temperature difference between the refrigerant and air may be sufficiently secured, thereby ensuring the heat exchange efficiency. In addition, because even the inlet tube 3 is arranged on the windward side, a temperature difference in the vicinity of the inlet tube 3 may also be secured.

[0158] Because the refrigerant having flowed through the insides of the respective heat transfer tubes 10 of the heat exchange units 1G, 1I, and 1J on the upstream side flows through the respective heat transfer tubes 10 of the heat exchange unit 1H on the downstream side by the connection unit 2 without joining or dividing, a temperature change of the refrigerant according to the flow direction of the refrigerant flowing through the insides of the respective heat transfer tubes 10 is uniform. Therefore, the non-uniformity in positions at which the temperature of the refrigerant exceeds the saturation temperature thereof (positions at which a degree of superheat is given) in the respective heat transfer tubes 10 may be reduced. That is, the positions at which the temperature of the refrigerant exceeds the saturation temperature thereof may be uniform for the respective heat transfer tubes 10. As a result, according to the heat exchanger 201, even when the superheat-securing region SH is reduced, a degree of superheat may be surely given to the refrigerant flowing through each of the heat transfer tubes 10. In addition, by reducing the superheat-securing region SH having a small temperature difference from air, the total heat exchange efficiency of the heat exchanger 1 may be ensured. By mounting the outlet tube of the outdoor heat exchanger 203, which functions as a condenser, on the windward side, even when a degree of supercooling is given to the outlet tube, a temperature difference between the refrigerant and air in the vicinity of the outlet tube may be sufficiently secured.

[0159] FIG. 15A is a diagram illustrating the flow of a refrigerant when the indoor heat exchanger 201 functions as a condenser. FIG. 15B is a diagram illustrating temperature changes of air and a refrigerant passing through the indoor heat exchanger 201 when the indoor heat exchanger 201 shown in FIG. 15A functions as a condenser. An example in which the indoor heat exchanger 201 functions as a condenser, that is, an example in which the air conditioner AC performs a heating operation, is described with reference to FIGS. 15A and 15B.

[0160] When the indoor heat exchanger 201 functions as a condenser, because the flow direction of the refrigerant is opposite to that in the above example in which the indoor heat exchanger 201 functions as an evaporator, the respective functions of the inlet tube and the outlet tube are changed with each other. Specifically, in FIGS. 15A and 15B, the reference numeral “4” represents an inlet tube, and the reference numeral “3” represents an outlet tube.

[0161] When the outlet tube 3 is arranged above the inlet tube 4 based on the up-and-down direction, because the condensed liquid-phase refrigerant needs to flow against gravity, the refrigerant may be stagnant in part, and the heat exchange efficiency may deteriorate. However, according to the indoor heat exchanger 201, which functions as a condenser, of the present embodiment of the disclosure, the inlet tube 4 is arranged above the outlet tube 3 based on the up-and-down direction. Because the condensed liquid-phase refrigerant flows from top to bottom without flowing against gravity, the refrigerant is unlikely to be stagnant.

[0162] Because the flow of the refrigerant in the refrigerant circuit R is inverted, the respective functions of the inlet tube and the outlet tube of the outdoor heat exchanger 203 are also be changed with each other. Therefore, the outlet tube is arranged on the leeward side, and the inlet tube is arranged on the windward side.

[0163] The flow rate controller 400 controls the amount of the refrigerant, which is introduced into the indoor heat exchanger 201, by controlling, for example, the degree of valve opening of the expansion valve 204 or an operation of the compressor 202, and thus, controls the degree of supercooling of the refrigerant, which is discharged from the outlet tube 3 of the indoor heat exchanger 201, to be equal to or greater than a certain value. The flow rate controller 400 controls the flow rate of the refrigerant to cause a degree of supercooling to be given to the refrigerant flowing through the respective heat transfer tubes 10 (to cause the temperature of the refrigerant to be less than the saturation temperature), in a region (referred to as a supercooling region SC, hereinafter) set on a one-end side of the heat exchange unit 1G to which the outlet tube 3 is connected. The degree of supercooling is set to be, for example, 5 degrees to 10 degrees.

[0164] FIG. 15B is a graph illustrating temperature changes of air and a refrigerant passing through the heat exchange units 11 and 1G in the first stage of the heat exchanger 201 that is used as a condenser. Referring to FIG. 15B, because the outlet tube 3 is mounted on the windward side, a large temperature difference between the refrigerant and air in the outlet tube 3 may be secured. The outdoor heat exchanger 203, which functions as an evaporator during a heating operation, has little need to secure a degree of superheat in the vicinity of the outlet tube thereof. The flow rate controller 400 may control the amount of the refrigerant, which is introduced into the outdoor heat exchanger 203, by controlling, for example, an operation of the compressor 202, and thus, may perform control to cause a degree of superheat not to be given to the refrigerant discharged from the outlet tube of the outdoor heat exchanger 203 (to cause the refrigerant temperature not to be greater than the saturation temperature). As such, even when the indoor heat exchanger 201 functions as a condenser, because the outlet tube 3 is mounted on the windward side, a temperature difference between the refrigerant and air in the vicinity of the outlet tube 3 may be as large as possible, and even when the outlet tube 4 gives a large degree of supercooling to the refrigerant, a temperature difference between the refrigerant and air may be sufficiently secured, thereby ensuring the heat exchange efficiency.

[0165] Even in the outdoor heat exchanger 203 functioning as an evaporator, because the outlet tube not giving a degree of superheat is mounted on the windward side, a temperature difference between the refrigerant and air may be sufficiently secured in the whole refrigerant flow path in the outdoor heat exchanger 203.

[0166] As such, according to the air conditioner AC of the present embodiment of the disclosure, the indoor heat exchanger 201 and the outdoor heat exchanger 203 respectively having different connection types of the outlet tube and the inlet tube are used. That is, in the indoor heat exchanger 201, the inlet tube 3 is connected to one of a plurality of windward heat exchange units, and the outlet tube 4 is connected to another one of the plurality of windward heat exchange units. In addition, the inlet tube and the outlet tube of the outdoor heat exchanger 203 are respectively connected to two heat exchange units respectively in different heat exchange unit groups from among a plurality of heat exchange unit groups 14 and 15 arranged in an air-flow direction. According to the air conditioner AC as such, the heat exchange efficiency in each of the heat exchangers (that is, 201 and 203) may be ensured in both a heating operation and a cooling operation, and as a result, the heat exchange efficiency in the whole refrigerant circuit may be maintained at a high level.

[0167] The number of rows of heat exchange unit groups in the indoor heat exchanger 201 is not limited to two, and the indoor heat exchanger 201 may include a plurality of rows of heat exchange unit groups. A heat exchange unit group refers to a plurality of heat exchange units that are in the same row in the front-and-rear direction and are arranged in the up-and-down direction. Even when there are three or more rows of heat exchange unit groups, the inlet tube and the outlet tube may be respectively connected to two heat exchange units of the same heat exchange unit group. However, the disclosure is not limited thereto. The inlet tube and the outlet tube may be connected to a heat exchange unit group arranged on the windward side rather than to a heat exchange unit group arranged on the most leeward side. That is, the inlet tube and the outlet tube are not connected to the heat exchange unit group arranged on the most leeward side. The inlet tube and the outlet tube may be connected to a heat exchange unit group arranged on the most windward side.

[0168] An air conditioner according to an aspect of the disclosure includes an indoor heat exchanger and an outdoor heat exchanger, wherein at least one of the indoor heat exchanger and the outdoor heat exchanger includes: a plurality of heat exchange units each including a plurality of heat transfer tubes, through which a refrigerant flows; and a plurality of connection units connecting the plurality of heat exchange units to each other in series to form a plurality of refrigerant flow paths, each of the plurality of connection units connects two adjacent heat exchange units to each other for flow directions of the refrigerant flowing through the two adjacent heat exchange units to be opposite to each other, and at least one of the plurality of connection units connects two adjacent heat exchange units to each other for at least one of the plurality of refrigerant flow paths not to join another refrigerant flow path. According to such a configuration, because at least one of the plurality of refrigerant flow paths in a connection unit is connected from a heat exchange unit on the upstream side to a heat exchange unit on the downstream side without joining or dividing, a deterioration in the heat exchange efficiency of the heat exchanger due to the maldistribution of the refrigerant may be reduced or suppressed.

[0169] In an embodiment of the disclosure, at least one of the plurality of connection units may connect two adjacent heat exchange units to each other for none of the plurality of refrigerant flow paths to join each other. By doing this, because all the plurality of refrigerant flow paths in the connection units are connected from the heat exchange unit on the upstream side to the heat exchange unit on the downstream side with no joining or no dividing, a deterioration in the heat exchange efficiency of the heat exchanger due to the maldistribution of the refrigerant may be further reduced or suppressed. In addition, when the refrigerant in the gas-liquid dual-phase state flows through the heat exchanger, a deterioration in the heat exchange efficiency due to liquid accumulation in the connection units may be reduced or suppressed.

[0170] In an embodiment of the disclosure, the plurality of connection units may connect the plurality of heat exchange units to each other for the respective flow-path lengths of the plurality of refrigerant flow paths to be almost equal. By doing this, pressure loss in the plurality of refrigerant flow paths may be uniform.

[0171] In an embodiment of the disclosure, each of the plurality of connection units includes a plurality of connection flow paths connecting heat transfer tubes of two adjacent heat exchange units among the plurality of heat exchange units to each other, and the respective flow-path lengths of the plurality of connection units may be almost equal. By doing this, pressure loss in the plurality of connection flow paths may be uniform.

[0172] In an embodiment of the disclosure, the plurality of connection flow paths may connect heat transfer tubes of two adjacent heat exchange units among the plurality of heat exchange units to each other in the manner of connecting two heat transfer tubes at the same positions in the respective heat exchange units to each other. By doing this, the respective lengths of the plurality of refrigerant flow paths may be almost equal.

[0173] In an embodiment of the disclosure, each of the plurality of connection units includes a plurality of connection flow paths connecting heat transfer tubes of two adjacent heat exchange units among the plurality of heat exchange units to each other, and the plurality of connection flow paths may connect heat transfer tubes of two adjacent heat exchange units among the plurality of heat exchange units to each other in the manner of connecting, to each other, two heat transfer tubes located to be symmetric to each other. By doing this, when an even number of connection units are provided, the sum of the respective lengths of the plurality of connection flow paths arranged in series in each of the plurality of refrigerant flow paths may be equal, and thus, pressure loss in the connection units may be uniform.

[0174] In an embodiment of the disclosure, each of the plurality of heat exchange units may include a same number of heat transfer tubes.

[0175] In an embodiment of the disclosure, the respective lengths of the plurality of heat transfer tubes in each of the plurality of heat exchange units may be almost equal.

[0176] In an embodiment of the disclosure, the air conditioner may further include at least one dummy heat transfer tube, which is arranged between the two adjacent heat exchange units, and in which no refrigerant flows. In a situation in which two heat exchange units are arranged adjacent to each other, when there is a temperature difference between the heat exchange unit on the upstream side and the heat exchange unit on the downstream side, heat exchange may occur between two heat transfer tubes respectively in the two heat exchange units and facing each other. In this case, heat loss may increase, and thus, the heat exchange efficiency of the whole heat exchanger may deteriorate. Because the dummy heat transfer tube may hinder heat exchange between the two heat exchange units, the heat exchange efficiency of the heat exchanger may be maintained.

[0177] In an embodiment of the disclosure, the plurality of heat exchange units may include: a first heat exchange unit including a plurality of first heat transfer tubes, which are arranged side-by-side in the up-and-down direction, and in which the refrigerant flows in a first direction; and a second heat exchange unit including a plurality of second heat transfer tubes, which are arranged side-by-side in the up-and-down direction, and in which the refrigerant flows in a second direction that is opposite to the first direction, the second heat exchange unit being arranged adjacent to the first heat exchange unit in the up-and-down direction. The connection units may include a vertical-switching connection unit, which connects downstream-side ends of the plurality of first heat transfer tubes to upstream-side ends of the plurality of second heat transfer tubes to introduce the refrigerant flowing along the first heat transfer tubes into the second heat transfer tubes. The vertical-switching connection unit may include a plurality of vertical-connection flow paths causing the plurality of first heat transfer tubes to individually communicate with the plurality of second heat transfer tubes.

[0178] In an embodiment of the disclosure, the number of first heat transfer tubes, the number of second heat transfer tubes, and the number of vertical-connection flow paths may be equal to each other, and the plurality of vertical-connection flow paths may cause the plurality of first heat transfer tubes to individually communicate with the plurality of second heat transfer tubes.

[0179] Because the plurality of first heat transfer tubes of the first heat exchange unit communicate with the plurality of second heat transfer tubes of the second heat exchange unit in a one-to-one relationship via the plurality of vertical-connection flow paths, the refrigerant flowing through the plurality of first heat transfer tubes flows into the plurality of second heat transfer tubes respectively corresponding thereto without joining or dividing. Therefore, the generation of maldistribution in the plurality of refrigerant flow paths of the heat exchanger may be suppressed more certainly, and the heat exchange efficiency may be maintained at a higher level.

[0180] In an embodiment of the disclosure, the plurality of vertical-connection flow paths may connect the plurality of first heat transfer tubes and the plurality of second heat transfer tubes to each other in the manner of connecting, to each other, a first heat transfer tube and a second heat transfer tube located at the same positions respectively in the first heat exchange unit and the second heat exchange, and the respective flow-path lengths of the plurality of vertical-connection flow paths may be almost equal.

[0181] In an embodiment of the disclosure, each of the plurality of vertical-connection flow paths may connect, to each other, a first heat transfer tube and a second heat transfer tube located symmetrically to each other in the up-and-down direction, when connecting the plurality of first heat transfer tubes of the first heat exchange unit to the plurality of second heat transfer tubes of the second heat exchange unit.

[0182] In the plurality of refrigerant flow paths formed by causing the plurality of first heat transfer tubes to individually communicate with the plurality of second heat transfer tubes via the vertical-connection flow paths, when the respective flow-path lengths of the plurality of refrigerant flow paths are different, a difference in pressure loss is generated between the plurality of refrigerant flow paths, and thus, the maldistribution of the refrigerant may occur. By causing a first heat transfer tube and a second heat transfer tube, which are located at the same arrangement positions respectively in the first heat exchange unit and the second heat exchange, to communicate with each other, the plurality of vertical-connection flow paths may cause the respective flow-path lengths of the plurality of refrigerant flow paths to be uniform, thereby reducing the maldistribution of the refrigerant. In addition, when the respective flow-path lengths of the plurality of vertical-connection flow paths are almost equal, because the respective lengths of the plurality of refrigerant flow paths, which are formed by connecting the first heat transfer tubes and the second heat transfer tubes to each other via the vertical-connection flow paths, may be almost equal, a difference in pressure loss between the plurality of refrigerant flow paths may be reduced, and the maldistribution of the refrigerant may be reduced.

[0183] In an embodiment of the disclosure, the plurality of heat exchange units may include a third heat exchange unit arranged adjacent to the second heat exchange unit in a horizontal direction, the third heat exchange unit including a plurality of heat transfer tubes, which are arranged side-by-side in the up-and-down direction, and in which the refrigerant flows in the first direction that is opposite to the second direction. The connection units may include a horizontal-switching connection unit, which connects downstream-side ends of the second heat transfer tubes to upstream-side ends of the third heat transfer tubes to introduce the refrigerant flowing along the second heat transfer tubes into the third heat transfer tubes. The horizontal-switching connection unit may include a plurality of horizontal-connection flow paths causing the plurality of second heat transfer tubes to individually communicate with the plurality of third heat transfer tubes.

[0184] By doing this, because the plurality of second heat transfer tubes of the second heat exchange unit individually communicate with the plurality of third heat transfer tubes of the third heat exchange unit by the horizontal-connection flow paths, the refrigerant flowing through plurality of second heat transfer tubes of the second heat exchange unit flow into the plurality of third heat transfer tubes respectively corresponding thereto without joining or re-dividing in the horizontal-switching connection unit. Therefore, the refrigerant in the gas-liquid dual-phase state may uniformly flow into the plurality of third heat transfer tubes of the third heat exchange unit, and thus, the heat exchange efficiency of the heat exchanger may be maintained.

[0185] When the plurality of heat exchange units are used for an evaporator, because the temperature of a vapor decreases due to pressure loss generated when the refrigerant flows along the heat transfer tubes, the refrigerant in the gas-liquid dual-phase state, which is introduced into the heat transfer tubes, has a temperature gradually decreasing as the refrigerant travels downstream. In an embodiment of the disclosure, the plurality of heat exchange units may function as an evaporator, the first heat exchange unit and the second heat exchange unit may be arranged on the windward side, and the third heat exchange unit may be arranged on the leeward side. By doing this, the temperature difference between the refrigerant and air may be increased, thereby improving the heat exchange efficiency.

[0186] The plurality of heat exchange units may function as a condenser, the first heat exchange unit and the second heat exchange unit may be arranged on the leeward side, and the third heat exchange unit may be arranged on the windward side.

[0187] In an embodiment of the disclosure, the plurality of heat exchange units may include a leeward heat exchange unit group, which includes a plurality of leeward heat exchange units arranged in a direction orthogonal to an air-flow direction and the plurality of refrigerant flow paths, and a windward heat exchange unit group, which includes a plurality of windward heat exchange units arranged in the direction orthogonal to the air-flow direction and the plurality of refrigerant flow paths and is arranged on a more windward side than the leeward heat exchange unit group. The indoor heat exchanger may include an inlet tube, which is connected to one of the plurality of windward heat exchange units and introduces a refrigerant into the plurality of refrigerant flow paths, and an outlet tube, which is connected to another one of the plurality of windward heat exchange units and discharges the refrigerant from the plurality of refrigerant flow paths.

[0188] According to such a configuration, because the outlet tube is connected to the windward heat exchange unit group, a temperature difference between the refrigerant and air in the vicinity of the outlet tube may be increased, and even when the outlet tube gives a large degree of superheat to the refrigerant, the temperature difference between the refrigerant and air may be sufficiently secured, thereby ensuring the heat exchange efficiency. Even during a slow operation occupying the most of air conditioning operation time (for example, even when the temperature difference between the refrigerant in the indoor heat exchanger and air is reduced because an indoor temperature is close to a set temperature), the temperature difference between the refrigerant and air may be secured to be as large as possible, thereby ensuring the heat exchange efficiency. Therefore, the cooling and heating efficiency of the air conditioner may significantly improve. In addition, because both the outlet tube and the inlet tube are arranged on the windward side, even when an operation switches between an evaporator and a condenser by inverting the flow direction of the refrigerant (for example, even when the operation of the air conditioner switches from a cooling operation to a heating operation or vice versa), the temperature difference between the refrigerant and air in the vicinity of the outlet tube may be maintained to be large, and thus, the indoor heat exchanger is suitable for purposes of indoor units.

[0189] In an embodiment of the disclosure, the plurality of heat exchange units may include a plurality of heat exchange unit groups, which are arranged in the air-flow direction and each includes a plurality of heat exchange units arranged in the direction orthogonal to the air-flow direction and the plurality of refrigerant flow paths. The outdoor heat exchanger may include an inlet tube, which is connected to a heat exchange unit in one of the plurality of heat exchange unit groups and introduces the refrigerant into the plurality of refrigerant flow paths, and an outlet tube, which is connected to a heat exchange unit in another one of the plurality of heat exchange unit groups and discharges the refrigerant from the plurality of refrigerant flow paths.

[0190] Aspects and effects of the disclosure are not limited to the aspects and effects described above, and other aspects and effects of the disclosure will be clearly understood by those of ordinary skill in the art from the detailed description herein.

[0191] Heretofore, while the air conditioner of the disclosure has been particularly shown and described with reference to embodiments of the disclosure and the accompanying drawings, the disclosure is not limited to the embodiments described above, and various changes in form and details may be made therein without departing from the spirit and scope of the disclosure.

Claims

1. An air conditioner comprising:an indoor heat exchanger; andan outdoor heat exchanger,wherein at least one of the indoor heat exchanger and the outdoor heat exchanger includes:a first heat exchange unit including a first plurality of heat transfer tubes through which a refrigerant is flowable,a second heat exchange unit including a second plurality of heat transfer tubes through which the refrigerant is flowable, anda connection unit connecting the first heat exchange unit and the second heat exchange unit to each other in series so that the refrigerant flows through the first plurality of heat transfer tubes in a first direction, then through the connection unit, and then through the second plurality of heat transfer tubes in a second direction opposite to the first direction, and the refrigerant that flowed through at least one heat transfer tube of the first plurality of heat transfer tubes does not mix in the connection unit with the refrigerant that flowed through other heat transfer tubes of the first plurality of heat transfer tubes.

2. The air conditioner of claim 1, wherein the connection unit connects the first heat exchange unit and the second heat exchange unit so that the refrigerant that flowed through each heat transfer tube of the first plurality of heat transfer tubes does not mix in the connection unit with the refrigerant that flowed through another heat transfer tube of the first plurality of heat transfer tubes.

3. The air conditioner of claim 1, wherein the connection unit connects the first heat exchange unit and the second heat exchange unit so that a first refrigerant flow path length that the refrigerant travels through a first heat transfer tube of the first plurality of heat transfer tubes, then through the connection unit, and then through a first heat transfer tube of the second plurality of heat transfer tubes is almost equal to a second refrigerant flow path length that the refrigerant travels through a second heat transfer tube of the first plurality of heat transfer tubes, then through the connection unit, and then through a second heat transfer tube of the second plurality of heat transfer tubes.

4. The air conditioner of claim 1, whereinthe connection unit includes a plurality of connection flow paths, each connection flow path of the plurality of connection flow paths having a connection flow path length,the first plurality of heat transfer tubes, the second plurality of heat transfer tubes, and the plurality of connection flow paths respectively correspond to one another, andeach connection flow path of the plurality of connection flow paths connects, to each other, a heat transfer tube of the first plurality of heat transfer tubes and a heat transfer tube of the second plurality of heat transfer tubes, andeach connection flow path length of the plurality of connection flow paths are almost equal.

5. The air conditioner of claim 4, wherein each connection flow path of the plurality of connection flow paths connects heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes based on heat transfer tube positions within the first heat exchange unit and the second heat exchange unit respectively, so that first heat transfer tube positions of heat transfer tubes of the first plurality of heat transfer tubes respectively correspond to second heat transfer tube positions of heat transfer tubes of the second plurality of heat transfer tubes.

6. The air conditioner of claim 1, whereinthe connection unit includes a plurality of connection flow paths and each connection flow path of the plurality of connection flow paths connects, to each other, a heat transfer tube of the first plurality of heat transfer tubes and a heat transfer tube of the second plurality of heat transfer tubes,the first plurality of heat transfer tubes, the second plurality of heat transfer tubes, and the plurality of connection flow paths respectively correspond to one another, andeach connection flow path of the plurality of connection flow paths connects heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes based on heat transfer tube positions within the first heat exchange unit and the second heat exchange unit respectively, so that first heat transfer tube positions of heat transfer tubes of the first plurality of heat transfer tubes symmetrically correspond to second heat transfer tube positions of heat transfer tubes of the second plurality of heat transfer tubes.

7. The air conditioner of claim 1, whereina number of heat transfer tubes of the first plurality of heat transfer tubes is equal to a number of heat transfer tubes of the second plurality of heat transfer tubes, andrespective lengths of heat transfer tubes of the first plurality of heat transfer tubes and heat transfer tubes of the second plurality of heat transfer tubes are almost equal.

8. The air conditioner of claim 1, further comprising at least one dummy heat transfer tube, which is between the first heat exchange unit and the second heat exchange unit, and through which no refrigerant is flowable.

9. The air conditioner of claim 1, whereinthe first plurality of heat transfer tubes are arranged side-by-side in an up- and down direction,the second plurality of heat transfer tubes are arranged side-by-side in the up- and down direction,the second heat exchange unit is adjacent to the first heat exchange unit in the up- and down direction,the connection unit includes a vertical-switching connection unit connecting downstream-side ends of the first plurality of heat transfer tubes to upstream-side ends of the second plurality of heat transfer tubes to introduce the refrigerant that flowed through the first plurality of heat transfer tubes into the second plurality of heat transfer tubes, andthe vertical-switching connection unit includes a plurality of vertical-connection flow paths configured so that heat transfer tubes of the first plurality of heat transfer tubes individually communicate with heat transfer tubes of the second plurality of heat transfer tubes.

10. The air conditioner of claim 9, wherein a number of heat transfer tubes of the first plurality of heat transfer tubes, a number of heat transfer tubes of the second plurality of heat transfer tubes, and a number of vertical-connection flow paths are equal to one another.

11. The air conditioner of claim 10, whereinthe plurality of vertical-connection flow paths connect the first plurality of heat transfer tubes to the second plurality of heat transfer tubes so that a first heat transfer tube of the first plurality of heat transfer tubes and a second heat transfer tube of the second plurality of heat transfer tubes which individually communicate are located at a same position in an up-and-down direction within the first heat exchange unit and the second heat exchange unit respectively, andflow-path lengths of the plurality of vertical-connection flow paths are almost equal.

12. The air conditioner of claim 10, wherein the plurality of vertical-connection flow paths connect the first plurality of heat transfer tubes to the second plurality of heat transfer tubes so that a first heat transfer tube of the first plurality of heat transfer tubes and a second heat transfer tube of the second plurality of heat transfer tubes are symmetric to each other in an up-and-down direction about a plane between the first heat exchange unit and the second heat exchange unit.

13. The air conditioner of claim 9, whereinthe at least one of the indoor heat exchanger and the outdoor heat exchanger includes:a third heat exchange unit including a third plurality of heat transfer tubes through which the refrigerant is flowable, which are arranged side-by-side in an up-and-down direction,the third heat exchange unit is arranged adjacent to the second heat exchange unit in a horizontal direction,the connection unit includes a horizontal-switching connection unit connecting downstream-side ends of the second plurality of heat transfer tubes to upstream-side ends of the third plurality of heat transfer tubes to introduce the refrigerant that flowed through the second plurality of heat transfer tubes into the third plurality of heat transfer tubes, andthe horizontal-switching connection unit includes a plurality of horizontal-connection flow paths configured so that heat transfer tubes of the second plurality of heat transfer tubes individually communicate with heat transfer tubes of the third plurality of heat transfer tubes.

14. The air conditioner of claim 1, wherein the plurality of heat exchange units comprise:a leeward heat exchange unit group, which comprises a plurality of leeward heat exchange units arranged in a direction orthogonal to an air-flow direction and the plurality of refrigerant flow paths; anda windward heat exchange unit group, which comprises a plurality of windward heat exchange units arranged in the direction orthogonal to the air-flow direction and the plurality of refrigerant flow paths and is arranged on a more windward side than the leeward heat exchange unit group, andthe indoor heat exchanger comprises:an inlet tube connected to one of the plurality of windward heat exchange units and introducing the refrigerant into the plurality of refrigerant flow paths; andan outlet tube connected to another one of the plurality of windward heat exchange units and discharging the refrigerant from the plurality of refrigerant flow paths.

15. The air conditioner of claim 14, wherein the plurality of heat exchange units comprise a plurality of heat exchange unit groups, which are arranged in the air-flow direction and each comprise a plurality of heat exchange units arranged in the direction orthogonal to the air-flow direction and the plurality of refrigerant flow paths, andthe outdoor heat exchanger comprises:an inlet tube connected to a heat exchange unit in one of the plurality of heat exchange unit groups and introducing the refrigerant into the plurality of refrigerant flow paths; andan outlet tube connected to a heat exchange unit in another one of the plurality of heat exchange unit groups and discharging the refrigerant from the plurality of refrigerant flow paths.

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