Heat exchanger and air-conditioning apparatus

A heat exchanger according to the present invention includes a heat exchanging unit, and a distributing and joining unit connected to the heat exchanging unit and including a distributing flow passage and a joining flow passage. The distributing and joining unit separately includes a first header including the distributing flow passage formed therein and excluding the joining flow passage, and a second header juxtaposed to the first header and including the joining flow passage formed therein and excluding the distributing flow passage. At least one of the first header and the second header is a stacking type header including a plurality of plate-like members including partial flow passages formed therein and stacked so that the partial flow passages are communicated with each other to form the distributing flow passage or the joining flow passage.

CROSS REFERENCE TO RELATED APPLICATION

This application is a U.S. national stage application of International Application No. PCT/JP2013/079247, filed on Oct. 29, 2013, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a heat exchanger and an air-conditioning apparatus.

BACKGROUND

As a related-art heat exchanger, there is known a heat exchanger including a heat exchanging unit including a plurality of stages of refrigerant flow passages allowing refrigerant to flow in from end portions on one side thereof and flow out of end portions on the other side thereof that are juxtaposed to the end portions on the one side, and a distributing and joining unit connected to the heat exchanging unit and including a distributing flow passage allowing the refrigerant to be distributed and flow out, and a joining flow passage allowing the refrigerant to be joined and flow out (for example, see Patent Literature 1).

PATENT LITERATURE

In such a heat exchanger, the distributing flow passage and the joining flow passage of the distributing and joining unit are formed in a single header. Thus, for example, when the heat exchanger acts as an evaporator so that refrigerant in a two-phase gas-liquid state flows into the heat exchanger and refrigerant in a superheated gas state flows out of the heat exchanger, low-temperature refrigerant passes through the distributing flow passage of the header, whereas high-temperature refrigerant passes through the joining flow passage of the header. As a result, heat is exchanged due to a temperature difference between the low-temperature refrigerant and the high-temperature refrigerant. Further, when the heat exchanger acts as a condenser so that refrigerant in a superheated gas state flows into the heat exchanger and refrigerant in a subcooled liquid state flows out of the heat exchanger, high-temperature refrigerant passes through the distributing flow passage of the header, whereas low-temperature refrigerant passes through the joining flow passage of the header. As a result, heat is exchanged due to a temperature difference between the high-temperature refrigerant and the low-temperature refrigerant. In other words, such a heat exchanger has a problem in that the heat exchange efficiency is low.

SUMMARY

The present invention has been made in view of the problem as described above, and thus has an object to provide a heat exchanger enhanced in heat exchange efficiency. Further, the present invention has an object to provide an air-conditioning apparatus including the heat exchanger as described above.

A heat exchanger according to the present invention includes a heat exchanging unit including a plurality of stages of refrigerant flow passages each allowing refrigerant to flow in from an end portion on one side of each of the refrigerant flow passages, turn back at a first turn-back portion, and flow out of an end portion on an other side juxtaposed to the end portion on the one side, and a distributing and joining unit connected to the heat exchanging unit, the distributing and joining unit including a distributing flow passage allowing the refrigerant to be distributed and flow into a plurality of the end portions on the one side, and a joining flow passage allowing the refrigerant to be joined and flow out of a plurality of the end portions on the other side. The distributing and joining unit separately includes a first header including the distributing flow passage formed therein and excluding the joining flow passage, and a second header juxtaposed to the first header, the second header including the joining flow passage formed therein and excluding the distributing flow passage. At least one of the first header and the second header includes a stacking type header including a plurality of plate-like members including partial flow passages formed therein and stacked to each other so that the partial flow passages are communicated with each other to form the distributing flow passage or the joining flow passage.

In the exchanger according to the present invention, the distributing and joining unit separately includes the first header including the distributing flow passage formed therein and excluding the joining flow passage, and the second header juxtaposed to the first header and including the joining flow passage formed therein and excluding the distributing flow passage. The at least one of the first header and the second header is the stacking type header. Thus, the heat exchange between the refrigerant passing through the distributing flow passage and the refrigerant passing through the joining flow passage is controlled, and the refrigerant passing through the distributing flow passage or the joining flow passage is heated or cooled. As a result, the heat exchange efficiency is enhanced.

DETAILED DESCRIPTION

A heat exchanger according to the present invention is described below with reference to the drawings.

Note that, the configuration, operation, and other matters described below are merely examples, and the heat exchanger according to the present invention is not limited to such configuration, operation, and other matters. Further, in the drawings, the same or similar components are denoted by the same reference signs, or the reference signs therefor are omitted. Further, the illustration of details in the structure is appropriately simplified or omitted. Further, overlapping description or similar description is appropriately simplified or omitted.

Further, in the following, there is described a case where the heat exchanger according to the present invention is applied to an air-conditioning apparatus, but the present invention is not limited to such a case, and for example, the heat exchanger according to the present invention may be applied to other refrigeration cycle apparatus including a refrigerant circuit. Still further, there is described a case where the heat exchanger according to the present invention is an outdoor heat exchanger of the air-conditioning apparatus, but the present invention is not limited to such a case, and the heat exchanger according to the present invention may be an indoor heat exchanger of the air-conditioning apparatus. Still further, there is described a case where the air-conditioning apparatus switches between a heating operation and a cooling operation, but the present invention is not limited to such a case, and the air-conditioning apparatus may perform only the heating operation or the cooling operation.

A heat exchanger according to Embodiment 1 is described.

<Configuration of Heat Exchanger>

The configuration of the heat exchanger according to Embodiment 1 is described below.

(Schematic Configuration of Heat Exchanger)

The schematic configuration of the heat exchanger according to Embodiment 1 is described below.

FIG. 1is a perspective view of the heat exchanger according to Embodiment 1.

As illustrated inFIG. 1, a heat exchanger1includes a heat exchanging unit2and a distributing and joining unit3. The heat exchanging unit2corresponds to a “heat exchanging unit” of the present invention.

The heat exchanging unit2includes a windward heat exchanging unit21arranged on a windward side in a passing direction of air passing through the heat exchanging unit2(white arrow inFIG. 1), and a leeward heat exchanging unit31arranged on a leeward side in the air passing direction. The windward heat exchanging unit21includes a plurality of windward heat transfer tubes22and a plurality of windward fins23joined to the plurality of windward heat transfer tubes22by, for example, brazing. The leeward heat exchanging unit31includes a plurality of leeward heat transfer tubes32and a plurality of leeward fins33joined to the plurality of leeward heat transfer tubes32by, for example, brazing. The heat exchanging unit2may be constructed of two rows including the windward heat exchanging unit21and the leeward heat exchanging unit31, or may be constructed of three or more rows.

Each of the windward heat transfer tube22and the leeward heat transfer tube32is a flat tube, and a plurality of flow passages are formed inside the flat tube. Each of the plurality of windward heat transfer tubes22and each of the plurality of leeward heat transfer tubes32are bent into a hair-pin shape at portions between end portions on one side and end portions on the other side so that turn-back portions22aand32aare formed, respectively. The windward heat transfer tubes22and the leeward heat transfer tubes32are arranged in a plurality of stages in a direction intersecting with the passing direction of the air passing through the heat exchanging unit2(white arrow inFIG. 1). The end portions on the one side and the end portions on the other side of each of the plurality of windward heat transfer tubes22and each of the plurality of leeward heat transfer tubes32are juxtaposed to be opposed to the distributing and joining unit3. Each of the windward heat transfer tube22and the leeward heat transfer tube32may be a circular tube (for example, a circular tube having a diameter of 4 mm). Each of the plurality of flow passages formed in the flat tube or a flow passage formed in the circular tube corresponds to a “refrigerant flow passage” of the present invention. The turn-back portion22acorresponds to a “first turn-back portion” of the present invention. The turn-back portion32acorresponds to a “third turn-back portion” of the present invention.

Instead of the configuration in which the windward heat transfer tube22and the leeward heat transfer tube32are bent into a hair-pin shape at the portions between the end portions on the one side and the end portions on the other side so that the turn-back portions22aand32aare formed, respectively, the end portion on the one side of each of the windward heat transfer tube22and the leeward heat transfer tube32and the end portion on the one side of each of the windward heat transfer tube22and the leeward heat transfer tube32in a stage above or below a stage of the above-mentioned ends may be connected to each other through a coupling member including a flow passage formed therein so that the refrigerant is turned back. In such a case, the flow passage formed in the coupling member corresponds to the “first turn-back portion” or the “third turn-back portion” of the present invention.

The distributing and joining unit3includes a stacking type header51and a tubular header61. The stacking type header51and the tubular header61are juxtaposed along the passing direction of the air passing through the heat exchanging unit2(white arrow inFIG. 1). A refrigerant pipe (not shown) is connected to the stacking type header51through a connection pipe52. A refrigerant pipe (not shown) is connected to the tubular header61through a connection pipe62. Each of the connection pipe52and the connection pipe62is, for example, a circular pipe.

The stacking type header51is connected to the windward heat exchanging unit21, and a distributing and joining flow passage51ais formed inside the stacking type header51. When the heat exchanging unit2acts as an evaporator, the distributing and joining flow passage51aserves as a distributing flow passage allowing refrigerant flowing in from the refrigerant pipe (not shown) to be distributed and flow out to the plurality of windward heat transfer tubes22of the windward heat exchanging unit21. When the heat exchanging unit2acts as a condenser, the distributing and joining flow passage51aserves as a joining flow passage allowing refrigerant flowing in from the plurality of windward heat transfer tubes22of the windward heat exchanging unit21to be joined and flow out to the refrigerant pipe (not shown).

The tubular header61is connected to the leeward heat exchanging unit31, and a distributing and joining flow passage61ais formed inside the tubular header61. When the heat exchanging unit2acts as a condenser, the distributing and joining flow passage61aserves as a distributing flow passage allowing refrigerant flowing in from the refrigerant pipe (not shown) to be distributed and flow out to the plurality of leeward heat transfer tubes32of the leeward heat exchanging unit31. When the heat exchanging unit2acts as an evaporator, the distributing and joining flow passage61aserves as a joining flow passage allowing refrigerant flowing in from the plurality of leeward heat transfer tubes32of the leeward heat exchanging unit31to be joined and flow out to the refrigerant pipe (not shown).

That is, when the heat exchanging unit2acts as an evaporator, the heat exchanger1separately includes the stacking type header51including the distributing flow passage (distributing and joining flow passage51a) formed therein and excluding the joining flow passage (distributing and joining flow passage61a), and the tubular header61including the joining flow passage (distributing and joining flow passage61a) formed therein and excluding the distributing flow passage (distributing and joining flow passage51a). In such a case, the stacking type header51corresponds to a “first header” of the present invention, whereas the tubular header61corresponds to a “second header” of the present invention.

Further, when the heat exchanging unit2acts as a condenser, the heat exchanger1separately includes the tubular header61including the distributing flow passage (distributing and joining flow passage61a) formed therein and excluding the joining flow passage (distributing and joining flow passage51a), and the stacking type header51including the joining flow passage (distributing and joining flow passage51a) formed therein and excluding the distributing flow passage (distributing and joining flow passage61a). In such a case, the tubular header61corresponds to the “first header” of the present invention, whereas the stacking type header51corresponds to the “second header” of the present invention.

(Configuration of Stacking Type Header)

The configuration of the stacking type header of the heat exchanger according to Embodiment 1 is described below.

FIG. 2is a perspective view of the heat exchanger according to Embodiment 1 under a state in which the stacking type header is disassembled. Note that, inFIG. 2, the arrows indicate the flows of the refrigerant in the case where the distributing and joining flow passage51aof the stacking type header51functions as the distributing flow passage.

As illustrated inFIG. 2, the stacking type header51is constructed in such a manner that a first plate-like member53including a partial flow passage53aformed therein, a plurality of second plate-like members54_1to54_3including partial flow passages54a_1to54a_3formed therein, and a third plate-like member55including partial flow passages55aformed therein are stacked through intermediation of a plurality of cladding members56_1to56_4including partial flow passages56aformed therein. A brazing material is applied to one or both surfaces of each of the cladding members56_1to56_4. In the following, in some cases, the first plate-like member53, the plurality of second plate-like members54_1to54_3, the third plate-like member55, and the plurality of cladding members56_1to56_4are collectively referred to as the “plate-like member”.

Each of the partial flow passages53a,55a, and56ais a circular through hole. Each of the partial flow passages54a_1to54a_3is a linear (for example, Z-shaped or S-shaped) through groove in which the height of the end portion on the one side in the gravity direction and the height of the end portion on the other side in the gravity direction are different from each other. The refrigerant pipe (not shown) is connected to the partial flow passage53athrough the connection pipe52. The windward heat transfer tube22is connected to each of the partial flow passages55athrough a connection pipe57. The connection pipe57is, for example, a circular pipe. The partial flow passage55amay be a through hole shaped along the outer peripheral surface of the windward heat transfer tube22so that the windward heat transfer tube22is directly connected to the through hole without the connection pipe57.

The partial flow passage56aof the cladding member56_1is formed at a position opposed to the partial flow passage53a. The partial flow passages56aof the cladding member56_4are each formed at a position opposed to a corresponding one of the partial flow passages55a. The end portion on the one side and the end portion on the other side of each of the partial flow passages54a_1to54a_3are opposed to the partial flow passages56aof a corresponding one of the cladding members56_2to56_4stacked adjacently on a side closer to the windward heat exchanging unit21. A part of a portion between the end portion on the one side and the end portion on the other side of each of the partial flow passages54a_1to54a_3is opposed to the partial flow passage56aof a corresponding one of the cladding members56_1to56_3stacked adjacently on a side farther away from the windward heat exchanging unit21.

When the plate-like members are stacked, the partial flow passages53a,54a_1to54a_3,55a, and56aare communicated with each other so that the distributing and joining flow passage51ais formed. The distributing and joining flow passage51afunctions as the distributing flow passage when the refrigerant flows in a direction indicated by the arrows inFIG. 2, and functions as the joining flow passage when the refrigerant flows in a direction opposite to the direction indicated by the arrows inFIG. 2.

When the distributing and joining flow passage51afunctions as the distributing flow passage, the refrigerant passing through the connection pipe52to flow into the partial flow passage53apasses through the partial flow passage56ato flow into a portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_1, and hits against the surface of the cladding member56_2so that the refrigerant is branched in two directions. The branched refrigerant flows out of the partial flow passage54a_1through each of the end portion on the one side and the end portion on the other side of the partial flow passage54a_1. Then, the refrigerant passes through the partial flow passage56ato flow into a portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_2, and hits against the surface of the cladding member56_3so that the refrigerant is branched in two directions. The branched refrigerant flows out of the partial flow passage54a_2through each of the end portion on the one side and the end portion on the other side of the partial flow passage54a_2. Then, the refrigerant passes through the partial flow passage56ato flow into a portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_3, and hits against the surface of the cladding member56_4so that the refrigerant is branched in two directions. The branched refrigerant flows out of the partial flow passage54a_3through each of the end portion on the one side and the end portion on the other side of the partial flow passage54a_3. Then, the refrigerant passes through the partial flow passage56aand the partial flow passage55ato flow into the connection pipe57.

When the distributing and joining flow passage51afunctions as the joining flow passage, the refrigerant passing through the connection pipes57to flow into the partial flow passages55apasses through the partial flow passages56ato flow into the end portion on the one side and the end portion on the other side of each of the partial flow passages54a_3, and then flows into a corresponding one of the partial flow passages56acommunicated with the portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_3so that the flows of the refrigerant are joined to each other. The respective joined refrigerant flows into the end portion on the one side and the end portion on the other side of each of the partial flow passages54a_2, and then flows into a corresponding one of the partial flow passages56acommunicated with the portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_2so that the flows of the refrigerant are joined to each other. The respective joined refrigerant flows into the end portion on the one side and the end portion on the other side of the partial flow passage54a_1, and then flows into the partial flow passage56acommunicated with the portion between the end portion on the one side and the end portion on the other side of the partial flow passage54a_1so that the flows of the refrigerant are joined to each other. The joined refrigerant passes through the partial flow passage53ato flow into the connection pipe52.

Note that, the first plate-like member53, the second plate-like members54_1to54_3, and the third plate-like member55may be directly stacked without the cladding members56_1to56_4. When the first plate-like member53, the second plate-like members54_1to54_3, and the third plate-like member55are stacked through intermediation of the cladding members56_1to56_4, the partial flow passages56afunction as refrigerant partitioning flow passages so that the flows of the refrigerant passing through the partial flow passages53a,54a_1to54a_3, and55aare reliably partitioned from each other. Further, plate-like members obtained by integrating the first plate-like member53, the second plate-like members54_1to54_3, and the third plate-like member55with the cladding members56_1to56_4stacked adjacent to the corresponding plate-like members may be directly stacked.

The configuration of the tubular header of the heat exchanger according to Embodiment 1 is described below.

FIG. 3is a perspective view of the tubular header of the heat exchanger according to Embodiment 1. Note that, inFIG. 3, the arrows indicate the flows of the refrigerant in the case where the distributing and joining flow passage61aof the tubular header61functions as the joining flow passage.

As illustrated inFIG. 3, the tubular header61is arranged so that an axial direction of a cylindrical portion63having a closed end portion on one side and a closed end portion on the other side is parallel to the gravity direction. The axial direction of the cylindrical portion63is not limited to be parallel to the gravity direction. When the tubular header61is arranged so that the axial direction of the cylindrical portion63is parallel to a longitudinal direction of the stacking type header51, space saving is achieved in the distributing and joining unit3. Note that, the cylindrical portion63may be, for example, a tubular portion having an elliptical shape in cross section.

The refrigerant pipe (not shown) is connected to a side wall of the cylindrical portion63through the connection pipe62. The leeward heat transfer tubes32are connected to the side wall of the cylindrical portion63through a plurality of connection pipes64. Each of the connection pipes64is, for example, a circular pipe. The leeward heat transfer tubes32may be directly connected to the side wall of the cylindrical portion63without the connection pipes64. The distributing and joining flow passage61ais formed inside the cylindrical portion63. The distributing and joining flow passage61afunctions as the joining flow passage when the refrigerant flows in a direction indicated by the arrows inFIG. 3, and functions as the distributing flow passage when the refrigerant flows in a direction opposite to the direction indicated by the arrows inFIG. 3.

When the distributing and joining flow passage61afunctions as the joining flow passage, the refrigerant flowing into the plurality of connection pipes64passes through an inside of the cylindrical portion63to flow into the connection pipe62so that the flows of the refrigerant are joined to each other. When the distributing and joining flow passage61afunctions as the distributing flow passage, the refrigerant flowing into the connection pipe62passes through the inside of the cylindrical portion63to flow into each of the plurality of connection pipes64so that the refrigerant is distributed.

The connection pipe62and the plurality of connection pipes64are preferably connected so that, among circumferential directions of the cylindrical portion63, a direction of connection of the connection pipe62and a direction of connection of each of the plurality of connection pipes64are not aligned in a straight line. With this configuration, it is possible to enhance the uniformity in distribution of the refrigerant flowing into the plurality of connection pipes64when the distributing and joining flow passage61afunctions as the distributing flow passage.

(Connection Between Heat Exchanging Unit and Distributing and Joining Unit)

Connection between the heat exchanging unit and the distributing and joining unit of the heat exchanger according to Embodiment 1 is described below.

FIG. 4andFIG. 5are explanatory views for illustrating the connection between the heat exchanging unit and the distributing and joining unit of the heat exchanger according to Embodiment 1. Note that,FIG. 5is a sectional view taken along the line A-A ofFIG. 4.

As illustrated inFIG. 4andFIG. 5, a windward joint member41is joined to each of an end portion22bon one side and an end portion22con the other side of the windward heat transfer tube22. A flow passage is formed inside the windward joint member41. An end portion on one side of the flow passage is shaped along the outer peripheral surface of the windward heat transfer tube22, whereas an end portion on the other side of the flow passage is formed into a circular shape. A leeward joint member42is joined to each of an end portion32bon one side and an end portion32con the other side of the leeward heat transfer tube32. A flow passage is formed inside the leeward joint member42. An end portion on one side of the flow passage is shaped along the outer peripheral surface of the leeward heat transfer tube32, whereas an end portion on the other side of the flow passage is formed into a circular shape.

The windward joint member41joined to the end portion22con the other side of the windward heat transfer tube22and the leeward joint member42joined to the end portion32bon the one side of the leeward heat transfer tube32are connected to each other through a lateral bridging pipe43. The lateral bridging pipe43is, for example, a circular pipe bent into an arc shape. The connection pipe57of the stacking type header51is connected to the windward joint member41joined to the end portion22bon the one side of the windward heat transfer tube22. The connection pipe64of the tubular header61is connected to the leeward joint member42joined to the end portion32con the other side of the leeward heat transfer tube32. A flow passage formed inside the lateral bridging pipe43corresponds to a “second turn-back portion” of the present invention.

The windward joint member41and the connection pipe57may be integrated with each other. Further, the leeward joint member42and the connection pipe64may be integrated with each other. Still further, the windward joint member41, the leeward joint member42, and the lateral bridging pipe43may be integrated with each other.

FIG. 6is an explanatory view for illustrating connection between the heat exchanging unit and the distributing and joining unit in a modified example of the heat exchanger according to Embodiment 1. Note that,FIG. 6is a sectional view taken along the line corresponding to the line A-A ofFIG. 4.

Note that, the windward heat transfer tube22and the leeward heat transfer tube32may be arranged so that the end portion22bon the one side and the end portion22con the other side of the windward heat transfer tube22and the end portion32bon the one side and the end portion32con the other side of the leeward heat transfer tube32are arranged in a staggered pattern in side view of the heat exchanger1as illustrated inFIG. 5, or alternatively in a lattice pattern in side view of the heat exchanger1as illustrated inFIG. 6.

FIG. 7andFIG. 8are explanatory views for illustrating connection between the heat exchanging unit and the distributing and joining unit in modified examples of the heat exchanger according to Embodiment 1. Note that,FIG. 7andFIG. 8are sectional views taken along the lines corresponding to the line A-A ofFIG. 4.

Further, as illustrated inFIG. 7andFIG. 8, the end portion22con the other side of the windward heat transfer tube22and the end portion22bon the one side of the windward heat transfer tube22in a stage above a stage of the above-mentioned windward heat transfer tube22may be connected to each other through a windward vertical bridging pipe44, and the end portion32con the other side of the leeward heat transfer tube32and the end portion32bon the one side of the leeward heat transfer tube32in a stage below a stage of the above-mentioned leeward heat transfer tube32may be connected to each other through a leeward vertical bridging pipe45. Each of the windward vertical bridging pipe44and the leeward vertical bridging pipe45is, for example, a circular pipe bent into an arc shape. A flow passage formed inside the windward vertical bridging pipe44corresponds to the “second turn-back portion” of the present invention. A flow passage formed inside the leeward vertical bridging pipe45also corresponds to the “second turn-back portion” of the present invention.

<Configuration of Air-Conditioning Apparatus to which Heat Exchanger is Applied>

The configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 1 is applied is described below.

FIG. 9andFIG. 10are diagrams for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 1 is applied. Note that,FIG. 9is an illustration of a case where an air-conditioning apparatus91performs a heating operation. Further,FIG. 10is an illustration of a case where the air-conditioning apparatus91performs a cooling operation.

As illustrated inFIG. 9andFIG. 10, the air-conditioning apparatus91includes a compressor92, a four-way valve93, an outdoor heat exchanger (heat source-side heat exchanger)94, an expansion device95, an indoor heat exchanger (load-side heat exchanger)96, an outdoor fan (heat source-side fan)97, an indoor fan (load-side fan)98, and a controller99. The compressor92, the four-way valve93, the outdoor heat exchanger94, the expansion device95, and the indoor heat exchanger96are connected by refrigerant pipes to form a refrigerant circuit. The four-way valve93may be any other flow switching device.

The outdoor heat exchanger94corresponds to the heat exchanger1. The heat exchanger1is provided so that the stacking type header51is arranged on a windward side of an air flow to be generated through drive of the outdoor fan97, whereas the tubular header61is arranged on a leeward side of the air flow. The outdoor fan97may be arranged on the windward side of the heat exchanger1, or on the leeward side of the heat exchanger1.

The controller99is connected to, for example, the compressor92, the four-way valve93, the expansion device95, the outdoor fan97, the indoor fan98, and various sensors. The controller99switches the flow passage of the four-way valve93to switch between the heating operation and the cooling operation.

<Operations of Heat Exchanger and Air-Conditioning Apparatus>

The operations of the heat exchanger according to Embodiment 1 and the air-conditioning apparatus to which the heat exchanger is applied are described below.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Heating Operation)

With reference toFIG. 9, the flow of the refrigerant during the heating operation is described below.

The refrigerant in a high-pressure and high-temperature gas state discharged from the compressor92passes through the four-way valve93to flow into the indoor heat exchanger96, and is condensed through heat exchange with air supplied by the indoor fan98, to thereby heat the inside of the room. The condensed refrigerant is brought into a high-pressure subcooled liquid state to flow out of the indoor heat exchanger96. The refrigerant then turns into refrigerant in a low-pressure two-phase gas-liquid state by the expansion device95. The refrigerant in the low-pressure two-phase gas-liquid state flows into the outdoor heat exchanger94, and is evaporated through heat exchange with air supplied by the outdoor fan97. The evaporated refrigerant is brought into a low-pressure superheated gas state to flow out of the outdoor heat exchanger94. The refrigerant then passes through the four-way valve93to be sucked into the compressor92. That is, during the heating operation, the outdoor heat exchanger94acts as an evaporator.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage51aof the stacking type header51so that the refrigerant is distributed to flow into the end portion22bon the one side of the windward heat transfer tube22of the windward heat exchanging unit21. The refrigerant flowing into the end portion22bon the one side of the windward heat transfer tube22passes through the turn-back portion22ato reach the end portion22con the other side of the windward heat transfer tube22. The refrigerant passes through the lateral bridging pipe43to flow into the end portion32bon the one side of the leeward heat transfer tube32of the leeward heat exchanging unit31. The refrigerant flowing into the end portion32bon the one side of the leeward heat transfer tube32passes through the turn-back portion32ato reach the end portion32con the other side of the leeward heat transfer tube32. The refrigerant flows into the distributing and joining flow passage61aof the tubular header61so that the refrigerant is joined.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Cooling Operation)

With reference toFIG. 10, the flow of the refrigerant during the cooling operation is described below.

The refrigerant in a high-pressure and high-temperature gas state discharged from the compressor92passes through the four-way valve93to flow into the outdoor heat exchanger94, and is condensed through heat exchange with air supplied by the outdoor fan97. The condensed refrigerant is brought into a high-pressure subcooled liquid state (or a low-quality two-phase gas-liquid state) to flow out of the outdoor heat exchanger94. The refrigerant is then brought into a low-pressure two-phase gas-liquid state by the expansion device95. The refrigerant in the low-pressure two-phase gas-liquid state flows into the indoor heat exchanger96, and is evaporated through heat exchange with air supplied by the indoor fan98, to thereby cool the inside of the room. The evaporated refrigerant is brought into a low-pressure superheated gas state to flow out of the indoor heat exchanger96. The refrigerant then passes through the four-way valve93to be sucked into the compressor92. That is, during the cooling operation, the outdoor heat exchanger94acts as a condenser.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage61aof the tubular header61so that the refrigerant is distributed to flow into the end portion32con the other side of the leeward heat transfer tube32of the leeward heat exchanging unit31. The refrigerant flowing into the end portion32con the other side of the leeward heat transfer tube32passes through the turn-back portion32ato reach the end portion32bon the one side of the leeward heat transfer tube32. The refrigerant passes through the lateral bridging pipe43to flow into the end portion22con the other side of the windward heat transfer tube22of the windward heat exchanging unit21. The refrigerant flowing into the end portion22con the other side of the windward heat transfer tube22passes through the turn-back portion22ato reach the end portion22bon the one side of the windward heat transfer tube22. The refrigerant flows into the distributing and joining flow passage51aof the stacking type header51so that the refrigerant is joined.

<Actions of Heat Exchanger>

Actions of the heat exchanger according to Embodiment 1 are described below.

FIG. 11is a graph for showing an overview of refrigerant temperature change in the case where the heat exchanger according to Embodiment 1 acts as an evaporator.FIG. 12is a graph for showing an overview of refrigerant temperature change in the case where the heat exchanger according to Embodiment 1 acts as a condenser. Note that, inFIG. 11andFIG. 12, the refrigerant temperature change in the heat exchanger1according to Embodiment 1 is indicated by the solid line. Further, a heat exchanger in a case where the distributing flow passage and the joining flow passage are formed in a single header is provided as a heat exchanger according to Comparative Example-1, and the refrigerant temperature change in this heat exchanger is indicated by the chain line. Still further, a heat exchanger in a case where the distributing flow passage and the joining flow passage are formed in separate headers and both of the headers are not stacking type headers is provided as a heat exchanger according to Comparative Example-2, and the refrigerant temperature change in this heat exchanger is indicated by the broken line.

(Actions of Heat Exchanger According to Comparative Example-1)

With reference toFIG. 11andFIG. 12, actions of the heat exchanger according to Comparative Example-1 are described.

When the heat exchanger acts as an evaporator, refrigerant in a two-phase gas-liquid state flows into the heat exchanger. Thus, the refrigerant in the two-phase gas-liquid state passes through the distributing flow passage, the heat transfer tube of the heat exchanger, and other portions, and the resistance of the flow passages causes a pressure drop to decrease the saturation temperature of the refrigerant. Thus, the refrigerant temperature is decreased. In this process, when the refrigerant is heated by air and thus completely evaporated, the refrigerant is brought into a superheated gas state, and hence the refrigerant temperature is increased. The refrigerant flowing out of the leeward heat exchanging unit flows into the joining flow passage at a higher temperature than that of a case where the refrigerant flows into the distributing flow passage. The distributing flow passage and the joining flow passage are formed in a single header, and hence the refrigerant flowing into the joining flow passage is cooled through heat exchange with the refrigerant yet to be heated and passing through the distributing flow passage.

Further, when the heat exchanger acts as a condenser, refrigerant in a superheated gas state flows into the heat exchanger. The distributing flow passage and the joining flow passage are formed in a single header, and hence the refrigerant flowing into the distributing flow passage is cooled through heat exchange with the cooled refrigerant passing through the joining flow passage. The refrigerant passing through the distributing flow passage passes through the heat transfer tube of the heat exchanger and other portions to be brought into a two-phase gas-liquid state and then a subcooled liquid state, and then flows into the joining flow passage. The distributing flow passage and the joining flow passage are formed in a single header, and hence the refrigerant flowing into the joining flow passage is heated through heat exchange with the refrigerant yet to be cooled and passing through the distributing flow passage.

(Actions of Heat Exchanger According to Comparative Example-2)

With reference toFIG. 11andFIG. 12, actions of the heat exchanger according to Comparative Example-2 are described.

In the heat exchanger according to Comparative Example-2, the distributing flow passage and the joining flow passage are formed in separate headers unlike the heat exchanger according to Comparative Example-1. Thus, when the heat exchanger acts as an evaporator, the refrigerant flowing into the joining flow passage does not exchange heat with the refrigerant yet to be heated and passing through the distributing flow passage, thereby controlling the decrease in temperature of the heated refrigerant. As a result, the heat exchange efficiency is enhanced. Further, when the heat exchanger acts as a condenser, the refrigerant flowing into the joining flow passage does not exchange heat with the refrigerant yet to be cooled and passing through the distributing flow passage, thereby controlling the increase in temperature of the cooled refrigerant. As a result, the heat exchange efficiency is enhanced.

(Actions of Heat Exchanger According to Embodiment 1 when Acting as Evaporator)

With reference toFIG. 11, actions of the heat exchanger according to Embodiment 1 when the heat exchanger acts as an evaporator are described.

In the heat exchanger1, similarly to the heat exchanger according to Comparative Example-2, when the heat exchanger1acts as an evaporator, the distributing and joining flow passage51athat functions as the distributing flow passage and the distributing and joining flow passage61athat functions as the joining flow passage are formed in the stacking type header51and the tubular header61, respectively, that is, formed in separate headers, thereby controlling the decrease in temperature of the heated refrigerant. As a result, the heat exchange efficiency is enhanced.

Further, in the heat exchanger1, the distributing and joining flow passage51athat functions as the distributing flow passage is formed in the stacking type header51, and hence the refrigerant flowing into the distributing and joining flow passage61athat functions as the joining flow passage has an even higher temperature. As a result, the heat exchange efficiency is enhanced. That is, the stacking type header51has a larger surface area than, for example, a distributor including capillary tubes partially arranged in flow passages, and hence, before flowing into the windward heat exchanging unit21, the refrigerant passing through the distributing and joining flow passage51ais heated by the air supplied to the heat exchanger1along with the drive of the outdoor fan97. Further, in the stacking type header51, the refrigerant passes through the distributing and joining flow passage51awhile the refrigerant is finely branched, and hence the performance of heat transfer from the outer surface of the header to the refrigerant is enhanced as compared to the tubular header61or other portions. Thus, before flowing into the windward heat exchanging unit21, the refrigerant passing through the distributing and joining flow passage51ais further heated by the air supplied to the heat exchanger1along with the drive of the outdoor fan97. As a result, the refrigerant is completely evaporated in an early stage when passing through the distributing and joining flow passage51a, the windward heat transfer tube22, the leeward heat transfer tube32, or other portions. Thus, the refrigerant flowing into the distributing and joining flow passage61athat functions as the joining flow passage has an even higher temperature.

Still further, the stacking type header51is arranged on the windward side with respect to the tubular header61, and hence the air supplied to the heat exchanger1along with the drive of the outdoor fan97hits against the stacking type header51before the air is cooled. Thus, before flowing into the windward heat exchanging unit21, the refrigerant passing through the distributing and joining flow passage51ais further heated. As a result, the heat exchange efficiency is further enhanced. In particular, when the stacking type header51and the tubular header61are juxtaposed along the passing direction of the air supplied to the heat exchanger1along with the drive of the outdoor fan97, the stacking type header51serves as an air screen for the tubular header61to enhance the aerodynamic performance of the outdoor fan97, and the heat exchanging unit2can be upsized to enhance the heat exchange efficiency.

Yet further, the distributing and joining flow passage51aof the stacking type header51allows the refrigerant to be distributed by repeatedly branching the refrigerant into two flows, thereby controlling decrease in uniformity in distribution of the refrigerant flowing into the plurality of windward heat transfer tubes22and the plurality of leeward heat transfer tubes32. Specifically, as described above, the refrigerant passing through the distributing and joining flow passage51ais heated to a higher degree than refrigerant in the heat exchanger according to Comparative Example-1 or the heat exchanger according to Comparative Example-2, and hence the quality approximates 50% so that the refrigerant is liable to be affected by the gravity or another factor. As a result, it is difficult to uniformly distribute the refrigerant to the plurality of windward heat transfer tubes22. However, the distributing and joining flow passage51aof the stacking type header51allows the refrigerant to be distributed by repeatedly branching the refrigerant into two flows, and hence the refrigerant is less liable to be affected by the gravity or another factor even under such a situation. As a result, it is possible to uniformly distribute the refrigerant to the plurality of windward heat transfer tubes22.

(Actions of Heat Exchanger According to Embodiment 1 when Acting as Condenser)

With reference toFIG. 12, actions of the heat exchanger according to Embodiment 1 when the heat exchanger acts as a condenser are described.

In the heat exchanger1, similarly to the heat exchanger according to Comparative Example-2, when the heat exchanger1acts as a condenser, the distributing and joining flow passage61athat functions as the distributing flow passage and the distributing and joining flow passage51athat functions as the joining flow passage are formed in the tubular header61and the stacking type header51, respectively, that is, formed in separate headers, thereby controlling the increase in temperature of the cooled refrigerant. As a result, the heat exchange efficiency is enhanced.

Further, in the heat exchanger1, the distributing and joining flow passage51athat functions as the joining flow passage is formed in the stacking type header51, and hence the refrigerant flowing out of the distributing and joining flow passage51athat functions as the joining flow passage has an even lower temperature. As a result, the heat exchange efficiency is enhanced. That is, the stacking type header51has a larger surface area than, for example, the distributor including capillary tubes partially arranged in the flow passages, and hence, the refrigerant passing through the distributing and joining flow passage51ais cooled by the air supplied to the heat exchanger1along with the drive of the outdoor fan97. Further, in the stacking type header51, the flows of the refrigerant pass through the distributing and joining flow passage51awhile the flows are gradually joined to each other, and hence the performance of heat transfer from the outer surface of the header to the refrigerant is enhanced as compared to the tubular header61or other portions. Thus, the refrigerant passing through the distributing and joining flow passage51ais further cooled by the air supplied to the heat exchanger1along with the drive of the outdoor fan97.

Still further, in the heat exchanger1, when the heat exchanger1acts as a condenser, the refrigerant flows from the plurality of leeward heat transfer tubes32to the plurality of windward heat transfer tubes22. That is, the passing direction of the air supplied to the heat exchanger1along with the drive of the outdoor fan97and the passing direction of the refrigerant in the row direction of the heat exchanging unit2have a counterflow relationship therebetween. Thus, the heat exchange efficiency is enhanced, thereby being adaptable to a case where the difference in refrigerant temperature between the inlet and the outlet of the heat exchanger1is increased when the heat exchanger1acts as a condenser. In addition, the heat exchange efficiency is further enhanced synergistically with the configuration in which the distributing and joining flow passage61athat functions as the distributing flow passage and the distributing and joining flow passage51athat functions as the joining flow passage are formed in separate headers and the distributing and joining flow passage51athat functions as the joining flow passage is formed in the stacking type header51.

Still further, the stacking type header51is arranged on the windward side with respect to the tubular header61, and hence the air supplied to the heat exchanger1along with the drive of the outdoor fan97hits against the stacking type header51before the air is heated. Thus, the refrigerant passing through the distributing and joining flow passage51ais further cooled. As a result, the heat exchange efficiency is further enhanced. In particular, when the stacking type header51and the tubular header61are juxtaposed along the passing direction of the air supplied to the heat exchanger1along with the drive of the outdoor fan97, the stacking type header51serves as the air screen for the tubular header61to enhance the aerodynamic performance of the outdoor fan97, and the heat exchanging unit2can be upsized to enhance the heat exchange efficiency.

A heat exchanger according to Embodiment 2 is described.

Note that, overlapping description or similar description to that of Embodiment 1 is appropriately simplified or omitted.

<Configuration of Heat Exchanger>

The configuration of the heat exchanger according to Embodiment 2 is described below.

(Schematic Configuration of Heat Exchanger)

The schematic configuration of the heat exchanger according to Embodiment 2 is described below.

FIG. 13is a perspective view of the heat exchanger according to Embodiment 2.

As illustrated inFIG. 13, the heat exchanging unit2includes only the windward heat exchanging unit21. The windward heat transfer tubes22are arranged in a plurality of stages in the direction intersecting with the passing direction of the air passing through the heat exchanging unit2(white arrow inFIG. 13). Each of the plurality of windward heat transfer tubes22is bent into a hair-pin shape at the portion between the end portion on the one side and the end portion on the other side so that the turn-back portion22ais formed. The end portion on the one side and the end portion on the other side of each of the plurality of windward heat transfer tubes22are juxtaposed to be opposed to the stacking type header51. Each of the windward heat transfer tubes22may be a circular tube (for example, a circular tube having a diameter of 4 mm). Each of the plurality of flow passages formed in the flat tube or a flow passage formed in the circular tube corresponds to the “refrigerant flow passage” of the present invention. The turn-back portion22acorresponds to the “first turn-back portion” of the present invention.

The stacking type header51is connected to the windward heat exchanging unit21, and the distributing and joining flow passage51ais formed inside the stacking type header51. When the heat exchanging unit2acts as an evaporator, the distributing and joining flow passage51aserves as the distributing flow passage allowing refrigerant flowing in from the refrigerant pipe (not shown) to be distributed and flow out to the plurality of windward heat transfer tubes22of the windward heat exchanging unit21. When the heat exchanging unit2acts as a condenser, the distributing and joining flow passage51aserves as the joining flow passage allowing refrigerant flowing in from the plurality of windward heat transfer tubes22of the windward heat exchanging unit21to be joined and flow out to the refrigerant pipe (not shown).

The tubular header61is connected to the windward heat exchanging unit21, and the distributing and joining flow passage61ais formed inside the tubular header61. When the heat exchanging unit2acts as a condenser, the distributing and joining flow passage61aserves as the distributing flow passage allowing refrigerant flowing in from the refrigerant pipe (not shown) to be distributed and flow out to the plurality of windward heat transfer tubes22of the windward heat exchanging unit21. When the heat exchanging unit2acts as an evaporator, the distributing and joining flow passage61aserves as the joining flow passage allowing refrigerant flowing in from the plurality of windward heat transfer tubes22of the windward heat exchanging unit21to flow out to the refrigerant pipe (not shown).

That is, when the heat exchanging unit2acts as an evaporator, the heat exchanger1separately includes the stacking type header51including the distributing flow passage (distributing and joining flow passage51a) formed therein and excluding the joining flow passage (distributing and joining flow passage61a), and the tubular header61including the joining flow passage (distributing and joining flow passage61a) formed therein and excluding the distributing flow passage (distributing and joining flow passage51a). In such a case, the stacking type header51corresponds to the “first header” of the present invention, whereas the tubular header61corresponds to the “second header” of the present invention.

Further, when the heat exchanging unit2acts as a condenser, the heat exchanger1separately includes the tubular header61including the distributing flow passage (distributing and joining flow passage61a) formed therein and excluding the joining flow passage (distributing and joining flow passage51a), and the stacking type header51including the joining flow passage (distributing and joining flow passage51a) formed therein and excluding the distributing flow passage (distributing and joining flow passage61a). In such a case, the tubular header61corresponds to the “first header” of the present invention, whereas the stacking type header51corresponds to the “second header” of the present invention.

(Connection Between Heat Exchanging Unit and Distributing and Joining Unit)

Connection between the heat exchanging unit and the distributing and joining unit of the heat exchanger according to Embodiment 2 is described below.

FIG. 14andFIG. 15are explanatory views for illustrating the connection between the heat exchanging unit and the distributing and joining unit of the heat exchanger according to Embodiment 2. Note that,FIG. 15is a sectional view taken along the line B-B ofFIG. 14.

As illustrated inFIG. 14andFIG. 15, the windward joint member41is joined to each of the end portion22bon the one side and the end portion22con the other side of the windward heat transfer tube22. The connection pipe57of the stacking type header51is connected to the windward joint member41joined to the end portion22bon the one side of the windward heat transfer tube22. The connection pipe64of the tubular header61is connected to the windward joint member41joined to the end portion22con the other side of the windward heat transfer tube22.

FIG. 16is an explanatory view for illustrating connection between the heat exchanging unit and the distributing and joining unit in a modified example of the heat exchanger according to Embodiment 2. Note that,FIG. 16is a sectional view taken along the line corresponding to the line B-B ofFIG. 14.

As illustrated inFIG. 16, the end portion22con the other side of the windward heat transfer tube22and the end portion22bon the one side of the windward heat transfer tube22in a stage below a stage of the above-mentioned windward heat transfer tube22may be connected to each other through the windward vertical bridging pipe44. The flow passage formed inside the windward vertical bridging pipe44corresponds to the “second turn-back portion” of the present invention.

<Operations of Heat Exchanger and Air-Conditioning Apparatus>

The operations of the heat exchanger according to Embodiment 2 and the air-conditioning apparatus to which the heat exchanger is applied are described below.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Heating Operation)

FIG. 17is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 2 is applied. Note that,FIG. 17is an illustration of a case where the air-conditioning apparatus91performs the heating operation.

With reference toFIG. 17, the flow of the refrigerant during the heating operation is described below.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage51aof the stacking type header51so that the refrigerant is distributed to flow into the end portion22bon the one side of the windward heat transfer tube22of the windward heat exchanging unit21. The refrigerant flowing into the end portion22bon the one side of the windward heat transfer tube22passes through the turn-back portion22ato reach the end portion22con the other side of the windward heat transfer tube22. The refrigerant flows into the distributing and joining flow passage61aof the tubular header61so that the refrigerant is joined.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Cooling Operation)

FIG. 18is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 2 is applied. Note that,FIG. 18is an illustration of the case where the air-conditioning apparatus91performs the cooling operation.

With reference toFIG. 18, the flow of the refrigerant during the cooling operation is described below.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage61aof the tubular header61so that the refrigerant is distributed to flow into the end portion22con the other side of the windward heat transfer tube22of the windward heat exchanging unit21. The refrigerant flowing into the end portion22con the other side of the windward heat transfer tube22passes through the turn-back portion22ato reach the end portion22bon the one side of the windward heat transfer tube22. The refrigerant flows into the distributing and joining flow passage51aof the stacking type header51so that the refrigerant is joined.

<Actions of Heat Exchanger>

Actions of the heat exchanger according to Embodiment 2 are described below.

Also in the heat exchanger1according to Embodiment 2, the refrigerant temperature is changed similarly to the heat exchanger1according to Embodiment 1, that is, similarly toFIG. 11andFIG. 12. In other words, also in the heat exchanger1according to Embodiment 2, similar actions to those of the heat exchanger1according to Embodiment 1 are attained.

A heat exchanger according to Embodiment 3 is described.

Note that, overlapping description or similar description to that of each of Embodiment 1 and Embodiment 2 is appropriately simplified or omitted. Further, in the following, there is described a case where two rows of the heat exchanging units2of the heat exchanger1are constructed as in the heat exchanger1according to Embodiment 1, but the heat exchanging unit2of the heat exchanger1may be constructed of a single row of the heat exchanging unit as in the heat exchanger1according to Embodiment 2.

<Configuration of Heat Exchanger>

The configuration of the heat exchanger according to Embodiment 3 is described below.

(Schematic Configuration of Heat Exchanger)

The schematic configuration of the heat exchanger according to Embodiment 3 is described below.

FIG. 19is a perspective view of the heat exchanger according to Embodiment 3.

As illustrated inFIG. 19, the heat exchanging unit2includes a windward upper-stage heat exchanging unit21A and a leeward upper-stage heat exchanging unit31A arranged on the upper side in the gravity direction, and a windward lower-stage heat exchanging unit21B and a leeward lower-stage heat exchanging unit31B arranged on the lower side in the gravity direction. The windward upper-stage heat exchanging unit21A and the leeward upper-stage heat exchanging unit31A may be juxtaposed to the windward lower-stage heat exchanging unit21B and the leeward lower-stage heat exchanging unit31B in, for example, a direction perpendicular to the gravity direction.

An upper stacking type header51A is connected to the windward upper-stage heat exchanging unit21A, and a distributing and joining flow passage51Aa is formed inside the upper stacking type header51A. A lower stacking type header51B is connected to the windward lower-stage heat exchanging unit21B, and a distributing and joining flow passage51Ba is formed inside the lower stacking type header51B. Each of the upper stacking type header51A and the lower stacking type header51B is connected to a distributor71including capillary tubes partially arranged in flow passages. When the heat exchanging unit2acts as an evaporator, the distributor71distributes refrigerant flowing in from the refrigerant pipe to the upper stacking type header51A and the lower stacking type header51B. When the heat exchanging unit2acts as a condenser, the distributor71joins flows of refrigerant flowing in from the upper stacking type header51A and the lower stacking type header51B to flow out to the refrigerant pipe. The heat exchanging unit2may be divided even more finely, and the distributor71may distribute the refrigerant to three or more flow passages.

That is, when the heat exchanging unit2acts as an evaporator, the heat exchanger1separately includes the upper stacking type header51A and the lower stacking type header51B each including the distributing flow passage (distributing and joining flow passage51Aa and distributing and joining flow passage51Ba) formed therein and excluding the joining flow passage (distributing and joining flow passage61a), and the tubular header61including the joining flow passage (distributing and joining flow passage61a) formed therein and excluding the distributing flow passage (distributing and joining flow passage51Aa and distributing and joining flow passage51Ba). In such a case, the upper stacking type header51A and the lower stacking type header51B each correspond to the “first header” of the present invention, whereas the tubular header61corresponds to the “second header” of the present invention.

Further, when the heat exchanging unit2acts as a condenser, the heat exchanger1separately includes the tubular header61including the distributing flow passage (distributing and joining flow passage61a) formed therein and excluding the joining flow passage (distributing and joining flow passage51Aa and distributing and joining flow passage51Ba), and the upper stacking type header51A and the lower stacking type header51B each including the joining flow passage (distributing and joining flow passage51Aa and distributing and joining flow passage51Ba) formed therein and excluding the distributing flow passage (distributing and joining flow passage61a). In such a case, the tubular header61corresponds to the “first header” of the present invention, whereas the upper stacking type header51A and the lower stacking type header51B each correspond to the “second header” of the present invention.

<Operations of Heat Exchanger and Air-conditioning Apparatus>

The operations of the heat exchanger according to Embodiment 3 and the air-conditioning apparatus to which the heat exchanger is applied are described below.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Heating Operation)

FIG. 20is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 3 is applied. Note that,FIG. 20is an illustration of a case where the air-conditioning apparatus91performs the heating operation.

With reference toFIG. 20, the flow of the refrigerant during the heating operation is described below.

In the outdoor heat exchanger94, the refrigerant is distributed by the distributor71to flow into the distributing and joining flow passage51Aa and the distributing and joining flow passage51Ba of the upper stacking type header51A and the lower stacking type header51B. Then, the refrigerant is further distributed to flow into the windward upper-stage heat exchanging unit21A and the windward lower-stage heat exchanging unit21B. The refrigerant passing through the windward upper-stage heat exchanging unit21A and the windward lower-stage heat exchanging unit21B passes through the leeward upper-stage heat exchanging unit31A and the leeward lower-stage heat exchanging unit31B to flow into the distributing and joining flow passage61aof the tubular header61so that the flows of the refrigerant are joined to each other.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Cooling Operation)

FIG. 21is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 3 is applied. Note that,FIG. 21is an illustration of the case where the air-conditioning apparatus91performs the cooling operation.

With reference toFIG. 21, the flow of the refrigerant during the cooling operation is described below.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage61aof the tubular header61so that the refrigerant is distributed to flow into the leeward upper-stage heat exchanging unit31A and the leeward lower-stage heat exchanging unit31B. The refrigerant passing through the leeward upper-stage heat exchanging unit31A and the leeward lower-stage heat exchanging unit31B passes through the windward upper-stage heat exchanging unit21A and the windward lower-stage heat exchanging unit21B to flow into the distributing and joining flow passage51Aa and the distributing and joining flow passage51Ba of the upper stacking type header51A and the lower stacking type header51B so that the flows of the refrigerant are joined to each other. Then, the flows of the refrigerant are further joined to each other by the distributor71.

<Actions of Heat Exchanger>

Actions of the heat exchanger according to Embodiment 3 are described below.

Also in the heat exchanger1according to Embodiment 3, the refrigerant temperature is changed similarly to the heat exchanger1according to Embodiment 1, that is, similarly toFIG. 11andFIG. 12. In other words, also in the heat exchanger1according to Embodiment 3, similar actions to those of the heat exchanger1according to Embodiment 1 are attained.

Further, the heat exchanger1includes the upper stacking type header51A and the lower stacking type header51B, which are connected to the distributor71. The distributor71is capable of uniformly distributing the refrigerant, but has a small surface area. Thus, in a case where the distributing and joining unit3is constructed of only the distributor71, the refrigerant passing through the distributing and joining unit3cannot be heated when the heat exchanger1acts as an evaporator, whereas the refrigerant passing through the distributing and joining unit3cannot be cooled when the heat exchanger1acts as a condenser. Further, in a case where the distributing and joining unit3is constructed of a single stacking type header51as in the heat exchanger1according to Embodiment 1, the heat exchanging unit2cannot be divided in the manufacture, with the result that the manufacture becomes difficult and the manufacturing facility is upsized. In contrast, in a case where the heat exchanger1includes the upper stacking type header51A and the lower stacking type header51B, which are connected to the distributor71, the surface area is secured to enhance the heat exchange efficiency, and the refrigerant can be uniformly distributed when the heat exchanger1acts as an evaporator. Further, the situations where the manufacture becomes difficult and the manufacturing facility is upsized are controlled. Still further, the heat exchanger1can be upsized by increasing the numbers of the stacking type headers, and thus the components are shared.

In addition, the heat exchanger1includes a single tubular header61. Thus, for example, the component cost and the number of assembling steps are reduced. Note that, the tubular header61allows refrigerant in a gas state to be distributed when the heat exchanger1acts as a condenser. Thus, the uniformity in distribution of the refrigerant is secured even when the tubular header61is divided and divided portions are not connected to the distributor.

A heat exchanger according to Embodiment 4 is described.

Note that, overlapping description or similar description to that of each of Embodiment 1 to Embodiment 3 is appropriately simplified or omitted. Further, in the following, there is described a case where two rows of the heat exchanging units2of the heat exchanger1are constructed as in the heat exchanger1according to Embodiment 1, but the heat exchanging unit2of the heat exchanger1may be constructed of a single row of the heat exchanging unit as in the heat exchanger1according to Embodiment 2. Still further, there is described a case where the heat exchanging unit2of the heat exchanger1is divided as in the heat exchanger1according to Embodiment 3, but the heat exchanging unit2of the heat exchanger1is not limited to be divided as in the heat exchanger1according to each of Embodiments 1 and 2.

<Configuration of Heat Exchanger>

The configuration of the heat exchanger according to Embodiment 4 is described below.

(Schematic Configuration of Heat Exchanger)

The schematic configuration of the heat exchanger according to Embodiment 4 is described below.

FIG. 22is a perspective view of the heat exchanger according to Embodiment 4.

As illustrated inFIG. 22, the heat exchanger1includes the heat exchanging unit2, a lower-stage heat exchanging unit2A arranged below the heat exchanging unit2in the gravity direction, the distributing and joining unit3, and a lower-stage distributing and joining unit3A arranged below the distributing and joining unit3in the gravity direction. The lower-stage heat exchanging unit2A has a similar configuration to that of the heat exchanging unit2. The lower-stage distributing and joining unit3A has a similar configuration to that of the distributing and joining unit3. The lower-stage heat exchanging unit2A and the lower-stage distributing and joining unit3A have shorter dimensions in the height direction than the heat exchanging unit2and the distributing and joining unit3, respectively. The heat exchanging unit2corresponds to an “upper-stage heat exchanging unit” of the present invention. The lower-stage heat exchanging unit2A corresponds to the “heat exchanging unit” of the present invention.

The connection pipe52of the stacking type header51of the lower-stage distributing and joining unit3A is connected to the refrigerant pipe (not shown). The connection pipe62of the tubular header61of the lower-stage distributing and joining unit3A is connected to the distributor71.

That is, when the heat exchanging unit2acts as an evaporator, the lower-stage distributing and joining unit3A of the heat exchanger1separately includes the stacking type header51including the distributing flow passage (distributing and joining flow passage51a) formed therein and excluding the joining flow passage (distributing and joining flow passage61a), and the tubular header61including the joining flow passage (distributing and joining flow passage61a) formed therein and excluding the distributing flow passage (distributing and joining flow passage51a). In such a case, the stacking type header51corresponds to the “first header” of the present invention, whereas the tubular header61corresponds to the “second header” of the present invention.

Further, when the heat exchanging unit2acts as a condenser, the lower-stage distributing and joining unit3A of the heat exchanger1separately includes the tubular header61including the distributing flow passage (distributing and joining flow passage61a) formed therein and excluding the joining flow passage (distributing and joining flow passage51a), and the stacking type header51including the joining flow passage (distributing and joining flow passage51a) formed therein and excluding the distributing flow passage (distributing and joining flow passage61a). In such a case, the tubular header61corresponds to the “first header” of the present invention, whereas the stacking type header51corresponds to the “second header” of the present invention.

<Operations of Heat Exchanger and Air-Conditioning Apparatus>

The operations of the heat exchanger according to Embodiment 4 and the air-conditioning apparatus to which the heat exchanger is applied are described below.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Heating Operation)

FIG. 23is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 4 is applied. Note that,FIG. 23is an illustration of a case where the air-conditioning apparatus91performs the heating operation.

With reference toFIG. 23, the flow of the refrigerant during the heating operation is described below.

In the outdoor heat exchanger94, the refrigerant flows into the distributing and joining flow passage51aof the stacking type header51of the lower-stage distributing and joining unit3A at a higher temperature than that of the air supplied to the heat exchanger1along with the drive of the outdoor fan97so that the refrigerant is distributed to flow into the windward heat exchanging unit21of the lower-stage heat exchanging unit2A. The refrigerant flowing into the windward heat exchanging unit21of the lower-stage heat exchanging unit2A passes through the leeward heat exchanging unit31of the lower-stage heat exchanging unit2A to flow into the distributing and joining flow passage61aof the tubular header61of the lower-stage distributing and joining unit3A so that the flows of the refrigerant are joined to each other. The joined refrigerant flows into the distributor71so that the refrigerant is distributed to connection pipes52A and52B of the heat exchanging unit2.

(Operations of Heat Exchanger and Air-Conditioning Apparatus During Cooling Operation)

FIG. 24is a diagram for illustrating the configuration of the air-conditioning apparatus to which the heat exchanger according to Embodiment 4 is applied. Note that,FIG. 24is an illustration of the case where the air-conditioning apparatus91performs the cooling operation.

With reference toFIG. 24, the flow of the refrigerant during the cooling operation is described below.

In the outdoor heat exchanger94, the refrigerant passes through the connection pipes52A and52B of the heat exchanging unit2to flow into the distributor71so that the flows of the refrigerant are joined to each other. The joined refrigerant flows into the distributing and joining flow passage61aof the tubular header61of the lower-stage distributing and joining unit3A so that the refrigerant is distributed to flow into the leeward heat exchanging unit31of the lower-stage heat exchanging unit2A. The refrigerant flowing into the leeward heat exchanging unit31of the lower-stage heat exchanging unit2A passes through the windward heat exchanging unit21of the lower-stage heat exchanging unit2A to flow into the distributing and joining flow passage51aof the stacking type header51of the lower-stage distributing and joining unit3A so that the flows of the refrigerant are joined to each other. The joined refrigerant flows out to the refrigerant pipe.

<Actions of Heat Exchanger>

Actions of the heat exchanger according to Embodiment 4 are described below.

FIG. 25is a graph for showing an overview of refrigerant temperature change in the case where the heat exchanging unit of the heat exchanger according to Embodiment 4 acts as an evaporator.

As illustrated inFIG. 25, when the heat exchanging unit2acts as an evaporator, the refrigerant flowing into the lower-stage heat exchanging unit2A at a higher temperature than that of the air supplied to the heat exchanger1along with the drive of the outdoor fan97heats the windward heat transfer tube22and the leeward heat transfer tube32of the lower-stage heat exchanging unit2A, and hence the refrigerant temperature is decreased. The temperature of the refrigerant flowing out of the lower-stage heat exchanging unit2A is further decreased due to the pressure drop caused while the refrigerant passes through the connection pipe62, the distributor71, and the connection pipes52A and52B. This temperature is lower than that of the air supplied to the heat exchanger1. When the refrigerant flowing into the heat exchanging unit2is heated by the air and thus completely evaporated, the refrigerant is brought into a superheated gas state, and hence the refrigerant temperature is increased.

Thus, dew condensation on the windward fins23and the leeward fins33of the lower-stage heat exchanging unit2A or other portions is controlled. Further, in particular, when the temperature of the air supplied to the heat exchanger1along with the drive of the outdoor fan97is 0 degrees Celsius or less, a situation where frost adheres to be deposited on the windward fins23and the leeward fins33of the lower-stage heat exchanging unit2A or other portions is controlled. Still further, during a defrosting operation for melting the frost adhering to the heat exchanging unit2, a situation where water of the melting frost accumulated on the windward fins23and the leeward fins33of the lower-stage heat exchanging unit2A or other portions freezes again to be deposited is controlled. That is, in the heat exchanger1, the stability of the quality of the refrigeration cycle is enhanced.

Further, in the lower-stage heat exchanging unit2A of the heat exchanger1, the distributing flow passage and the joining flow passage are formed in separate headers. Thus, the refrigerant flowing into the distributing flow passage does not exchange heat with the refrigerant having heated the windward heat transfer tube22and the leeward heat transfer tube32of the lower-stage heat exchanging unit2A and passing through the joining flow passage, thereby controlling the decrease in temperature of the refrigerant yet to be heated. As a result, the efficiency to enhance the above-mentioned stability of the quality of the refrigeration cycle is enhanced.

The present invention has been described above with reference to Embodiment 1 to Embodiment 4, but the present invention is not limited to those embodiments. For example, a part or all of the respective embodiments may be combined.