Patent Description:
A heat exchanger functioning as a condenser mounted on an indoor unit of an air-conditioning apparatus is known. A pressure of liquid refrigerant condensed at the heat exchanger is reduced by an expansion valve to be brought into a two-phase gas-liquid state in which gas refrigerant and liquid refrigerant are mixed. Then, the liquid refrigerant of the refrigerant in the two-phase gas-liquid state is evaporated at the heat exchanger functioning as an evaporator mounted on an outdoor unit, and the refrigerant in the two-phase gas-liquid state becomes low-pressure gas refrigerant. Thereafter, the low-pressure gas refrigerant flowing from the heat exchanger flows into the compressor mounted on the outdoor unit, is compressed to become high-temperature and high-pressure gas refrigerant, and is discharged from the compressor again. This cycle is then repeated.

A heat exchanger employing a plurality of heat transfer tubes having a flat cross-section is known that aims to improve energy efficiency by reducing ventilation resistance and save refrigerant by reducing volume of the tube. However, when the header is downsized to save the refrigerant, a flow resistance in the header increases and a heat exchanger performance deteriorates. Thus, it is difficult to achieve both performance improvement and refrigerant saving.

In order to achieve both performance improvement and refrigerant saving, a heat exchanger including two main header chambers extending substantially in a parallel with the heat transfer tubes, and a plurality of sub-header chambers branched horizontally from the main header chambers and arranged side by side in the parallel direction of the heat transfer tubes, has been proposed (see, for example Patent Literature <NUM>). In this case, by providing the header that allows the refrigerant flowing into the main header chamber to flow out to refrigerant pipes respectively connected to the plurality of sub header chambers, a uniform distribution of the refrigerant is achieved.

However, in the heat exchanger of Patent Literature <NUM>, when a flow passage of the header is made smaller in order to reduce an amount of refrigerant, a pressure loss of the refrigerant increases due to increase of flow resistance and the refrigerant in the two-phase gas-liquid state is distributed non-uniformly. This results in a decrease in the heat exchanger performance.

The present invention has been made to overcome the above-mentioned problems, to provide a heat exchanger and an air-conditioning apparatus employing the heat exchanger in which the heat exchanger performance can be improved by reducing the refrigerant pressure loss and by achieving uniform distribution of the refrigerant.

A heat exchanger according to the present invention includes a plurality of flat tubes extending in a first direction and arranged with spacing from each other in a second direction perpendicular to the first direction, a cross-section of each of the plurality of flat tubes in the second direction being an elongated shape, and a header extending in the second direction and connecting end portions of the adjacent flat tubes of the plurality of flat tubes in the first direction. The header is having inside a flow passage through which refrigerant flows. The flow passage includes a plurality of partition portions each provided between the adjacent flat tubes and configured to block at least a part of the flow passage between the adjacent flat tubes to prevent the refrigerant from flowing in the second direction, a plurality of insertion portions formed between the adjacent partition portions, each of the plurality of insertion portions forming a space where the refrigerant flows in a third direction perpendicular to the first direction and the second direction, each of the plurality of flat tubes being inserted in to each of the plurality of insertion portions, a first communication passage allowing one ends of the adjacent insertion portions in the third direction to communicate with each other, and a second communication passage allowing an other ends of the adjacent insertion portions in the third direction to communicate with each other. A cross-sectional area of the first communication passage, of a cross-section perpendicular to the second direction is larger than a cross-sectional area of the second communication passage, of a cross-section perpendicular to the second direction. The first communication passage is provided with a first refrigerant inlet connected to the flow passage and allowing the refrigerant to flow into the header.

An air-conditioning apparatus employing the heat exchanger according to the present invention includes a heat pump type refrigerant circuit which includes at least a compressor, a condenser, an expansion valve and an evaporator. The condenser or the evaporator is the heat exchanger as described above.

According to the present invention, the flow passage of the header includes a plurality of partition portions each provided between the adjacent flat tubes and configured to block at least a part of the flow passage between the adjacent flat tubes, a plurality of insertion portions formed between the adjacent partition portions, each of the plurality of insertion portions forming a space where the refrigerant flows, each of the plurality of flat tubes being inserted in to each of the plurality of insertion portions, a first communication passage allowing one ends of the adjacent insertion portions in the third direction to communicate with each other, and a second communication passage allowing an other ends of the adjacent insertion portions in the third direction to communicate with each other. In addition, a cross-sectional area of the first communication passage is larger than a cross-sectional area of the second communication passage and the first communication passage is provided with a first refrigerant inlet connected to the flow passage and allowing the refrigerant to flow into the header. According to this configuration, the refrigerant pressure loss due to expansion and contraction of the refrigerant flow that occurs in the insertion portion is reduced and increase of the pressure loss when a diameter of the flow passage is made smaller can be suppressed.

Further, the header includes the first refrigerant connected to the flow passage in at least one of two regions when the header is divided by a center plane passing through the center of a third direction which intersects the first direction and the second direction of the flat tube, and a passage cross-sectional area of the first communication passage in which the first refrigerant inlet is provided is larger than that of the second communication passage. In other words, the header has a configuration in which a communication passage in which the refrigerant is transported mainly by inertia force from the refrigerant inlet to the insertion portion of the flat tube due to a relatively large passage cross-sectional area, and a communication passage in which gas and liquid are exchanged mainly by diffusion through the insertion portion of the flat tube due to a relatively small passage cross-sectional area.

According to this configuration, the non-uniform distribution of the refrigerant due to changes in a flow velocity of the refrigerant is mitigated, and the heat exchanger performance is improved, thereby improving an energy efficiency of an air-conditioning apparatus equipped with the heat exchanger. Thus, the heat exchanger performance can be improved by reducing the refrigerant pressure loss and by achieving uniform distribution of the refrigerant.

Embodiments will be described hereinafter with reference to the drawings. In the drawings, components referred to with the same reference signs are the same or correspond to each other, and this is common throughout the entire specification. The components shown in the entire specification are only examples and the present invention is not limited by the embodiments described below. In addition, the relationship of sizes of the components in the drawings may differ from that of actual ones.

First, an air-conditioning apparatus according to Embodiment <NUM> will be described. <FIG> is a refrigerant circuit diagram showing an example of an air-conditioning apparatus <NUM> according to Embodiment <NUM>. In <FIG>, a flow of refrigerant in a cooling operation is indicated by a broken line arrow, and a flow of refrigerant in a heating operation is indicated by a solid line arrow.

As shown in <FIG>, the air-conditioning apparatus <NUM> includes an outdoor unit <NUM> and an indoor unit <NUM>. The outdoor unit <NUM> includes a heat exchanger <NUM> as an outdoor heat exchanger, an outdoor fan <NUM>, a compressor <NUM>, and a four-way valve <NUM>. The indoor unit <NUM> includes an indoor heat exchanger <NUM>, an expansion device <NUM>, and an indoor fan (not shown). The compressor <NUM>, the four-way valve <NUM>, the heat exchanger <NUM>, the expansion device <NUM>, and the indoor heat exchanger <NUM> are connected by a refrigerant pipe <NUM> to form a refrigerant circuit.

The compressor <NUM> is configured to compress refrigerant. The refrigerant compressed by the compressor <NUM> is discharged and supplied to the four-way valve <NUM>. The compressor <NUM> may be, for example, a rotary compressor, a scroll compressor, a screw compressor, or a reciprocating compressor and the like.

The heat exchanger <NUM> functions as a condenser during a heating operation, and functions as an evaporator during a cooling operation. Although details will be described later, the heat exchanger <NUM> of Embodiment <NUM> is a fin-and-tube type heat exchanger which includes a plurality of fins <NUM> and a plurality of flat tubes <NUM>. Each of the flat tubes <NUM> is a heat transfer tube with an elongated shape. In the heat exchanger <NUM>, the fins <NUM> and the flat tubes <NUM> extend in a first direction Y which is an elongated direction of the flat tubes <NUM>, and arranged alternately side by side in a second direction Z perpendicular to the first direction Y. Each flat tube <NUM> has a flat cross-section perpendicular to the first direction Y and a plurality of refrigerant passages <NUM> through which refrigerant flows and which is formed inside the flat tube <NUM>. A header <NUM> is provided at each end portion of the flat tubes <NUM> in the first direction Y (see <FIG>).

The expansion device <NUM> is configured to reduce a pressure of the refrigerant flowing from the heat exchanger <NUM> or the indoor heat exchanger <NUM> by expanding the refrigerant. The expansion device <NUM> may be, for example, an electric expansion valve which can control a flow rate of the refrigerant. As the expansion device <NUM>, not only the electric expansion valve, but also a mechanical expansion valve employing a diaphragm as a pressure receiving portion, a capillary tube, or the like can be used.

The indoor heat exchanger <NUM> functions as an evaporator during the heating operation, and functions as a condenser during the cooling operation. The indoor heat exchanger <NUM> may be, for example, a fin-and-tube type heat exchanger, a microchannel heat exchanger, a shell-and-tube type heat exchanger, a heat-pipe type heat exchanger, a double-tube type heat exchanger, a plate heat exchanger, or the like.

The four-way valve <NUM> is configured to switch a flow of the refrigerant between the heating operation and the cooling operation. The four-way valve <NUM> switches a flow of the refrigerant to connect a discharge port of the compressor <NUM> with the heat exchanger <NUM> and to connect an inlet port of the compressor <NUM> with the indoor heat exchanger <NUM> during the heating operation. In addition, the four-way valve <NUM> switches the flow of the refrigerant to connect the discharge port of the compressor <NUM> with the indoor heat exchanger <NUM> and to connect the inlet port of the compressor <NUM> with the heat exchanger <NUM> during the cooling operation.

The outdoor fan <NUM> is attached to the heat exchanger <NUM> and configured to supply air, which is heat exchange fluid, to the heat exchanger <NUM>.

The indoor fan (not shown) is attached to the indoor heat exchanger <NUM> and configured to supply air, which is heat exchange fluid, to the indoor heat exchanger <NUM>.

Next, an operation of the air-conditioning apparatus <NUM> will be described together with a flow of the refrigerant. First, the cooling operation performed by the air-conditioning apparatus <NUM> will be described. The flow of the refrigerant during the cooling operation is shown by the solid line arrows in <FIG>. Here, an operation of the air-conditioning apparatus <NUM> is described with a case where the heat exchange fluid is air and the heat exchanged fluid is refrigerant as an example.

As shown in <FIG>, by driving the compressor <NUM>, refrigerant in a gas state of high-temperature and high-pressure is discharged from the compressor <NUM>. Hereinafter, the refrigerant flows in accordance with the broken line arrows. The high-temperature and high-pressure gas refrigerant (single phase) discharged from the compressor <NUM> flows into the heat exchanger <NUM> which functions as a condenser through the four-way valve <NUM>. In the heat exchanger <NUM>, heat is exchanged between the high-temperature and high-pressure gas refrigerant that flows into the heat exchanger <NUM> and the air supplied by the outdoor fan <NUM>. By this heat exchange, the high-temperature and high-pressure gas refrigerant is condensed and becomes high-pressure liquid refrigerant (single phase).

The high-pressure liquid refrigerant supplied from the heat exchanger <NUM> becomes two-phase state refrigerant including low pressure gas refrigerant and liquid refrigerant at the expansion device <NUM>. The two-phase state refrigerant flows into the indoor heat exchanger <NUM> which functions as an evaporator. In the indoor heat exchanger <NUM>, heat is exchanged between the two-phase state refrigerant flows into the indoor heat exchanger <NUM> and the air supplied by the indoor fan (not shown). By this heat exchange, liquid refrigerant in the two-phase state refrigerant is evaporated and the two-phase state refrigerant becomes low-pressure gas refrigerant (single phase). An indoor space is cooled by this heat exchange. The low-pressure gas refrigerant supplied from the indoor heat exchanger <NUM> flows into the compressor <NUM> via the four-way valve <NUM>. The refrigerant flowing into the compressor <NUM> is compressed and again discharged from the compressor <NUM> as the high-temperature and high-pressure gas refrigerant. This cycle is then repeated.

Next, the heating operation performed by the air-conditioning apparatus <NUM> will be described. The flow of the refrigerant during the heating operation is indicated by the broken line arrows in <FIG>.

As shown in <FIG>, by driving the compressor <NUM>, refrigerant in a gas state of high-temperature and high-pressure is discharged from the compressor <NUM>. Hereinafter, the refrigerant flows in accordance with the broken line arrows.

The high-temperature and high-pressure gas refrigerant (single phase) discharged from the compressor <NUM> flows into the indoor heat exchanger <NUM> which functions as a condenser through the four-way valve <NUM>. In the indoor heat exchanger <NUM>, heat is exchanged between the high-temperature and high-pressure gas refrigerant that flows into the indoor heat exchanger <NUM> and the air supplied by the indoor fan (not shown). By this heat exchange, the high-temperature and high-pressure gas refrigerant is condensed and becomes high-pressure liquid refrigerant (single phase). The indoor space is heated by this heat exchange.

The high-pressure liquid refrigerant supplied from the indoor heat exchanger <NUM> becomes two-phase state refrigerant including low pressure gas refrigerant and liquid refrigerant at the expansion device <NUM>. The two-phase state refrigerant flows into the heat exchanger <NUM> which functions as an evaporator. In the heat exchanger <NUM>, heat is exchanged between the two-phase state refrigerant flows into the heat exchanger <NUM> and the air supplied by the outdoor fan <NUM>. By this heat exchange, the liquid refrigerant in the two-phase state refrigerant is evaporated and the two-phase state refrigerant becomes low-pressure gas refrigerant (single phase).

The low-pressure gas refrigerant supplied from the heat exchanger <NUM> flows into the compressor <NUM> via the four-way valve <NUM>. The refrigerant flowing into the compressor <NUM> is compressed and again discharged from the compressor <NUM> as the high-temperature and high-pressure gas refrigerant. This cycle is then repeated.

During the cooling operation and heating operation described above, when the refrigerant flows into the compressor <NUM> in a liquid state, liquid compression is caused. This results in failure of the compressor <NUM>. Therefore, it is desirable that the refrigerant flowing out of the indoor heat exchanger <NUM> during the cooling operation or the heat exchanger <NUM> during the heating operation is gas refrigerant (single phase).

Here, at the evaporator, water in the air is condensed when heat exchange is performed between the air supplied from the fan and the refrigerant flowing inside the heat transfer tubes constituting the evaporator, and water droplets are generated on a surface of the evaporator. The water droplets generated on the surface of the evaporator are dropped downward along surfaces of fins and the heat transfer tubes, and ejected below the evaporator as drain water.

Since the heat exchanger <NUM> functions as the evaporator during the heating operation, water in the air may cause frost on the heat exchanger <NUM> in a low outdoor temperature condition. Therefore, the air-conditioning apparatus <NUM> is configured to perform a "defrosting operation" to remove the frost when an outdoor temperature is equal to or lower than a certain temperature (e.g., <NUM> degree C).

The "defrosting operation" is an operation in which hot gas (high-temperature and high-pressure gas refrigerant) is supplied from the compressor <NUM> to the heat exchanger <NUM> to prevent frost from forming on the heat exchanger <NUM>, which functions as the evaporator. The defrosting operation may be performed when a duration of the heating operation reaches a predetermined value (e.g., <NUM> minutes). The defrosting operation may be performed before the heating operation when a temperature of the heat exchanger <NUM> is equal to or lower than a certain temperature (e.g., minus <NUM> degree C). The frost and ice formed on the heat exchanger <NUM> are melted by the hot gas supplied to the heat exchanger <NUM> during the defrosting operation.

For example, a bypass refrigerant pipe (not shown) may be connected between the discharge port of the compressor <NUM> and the heat exchanger <NUM> so that the hot gas can be supplied directly from the compressor <NUM> to the heat exchanger <NUM> during the defrosting operation. Also, the discharge port of the compressor <NUM> may be connected to the heat exchanger <NUM> via a refrigerant flow switching device (e.g. the four-way valve <NUM>) so that the hot gas can be supplied from the compressor <NUM> to the heat exchanger <NUM>.

Next, the heat exchanger <NUM> mounted in the air-conditioning apparatus <NUM> of Embodiment <NUM> will be described. <FIG> is a perspective view showing an example of the heat exchanger <NUM> mounted on the air-conditioning apparatus <NUM> according to Embodiment <NUM>. <FIG> is a perspective view, partially in cross-section, of the header <NUM> of the heat exchanger <NUM> in <FIG>. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> in <FIG>. <FIG> is a schematic view showing a cross-section taken along A-A of the header <NUM> in <FIG> is a schematic view showing a cross-section taken along B-B of the header <NUM> in <FIG>. <FIG> is a schematic view showing a cross-section taken along C-C of the header <NUM> in <FIG>.

In <FIG>, AF indicated by an arrow represents a flow direction of air supplied from the outdoor fan <NUM> (see <FIG>) to the heat exchanger <NUM>, RF indicated by arrows represents a flow direction of the refrigerant supplied to the heat exchanger <NUM>. Each flat tube <NUM> is arranged so that its flat plane is parallel to the air flow direction AF and is spaced apart from each other so that the flat planes face each other. In other words, each flat tube <NUM> is arranged with spacing from each other in the second direction Z, which is a short-side direction of the elongated shape, in a cross-section perpendicular to the first direction Y. Regarding the flat cross-section of each flat tube <NUM>, a length of its long-side direction may be described as width, a length of its short-side direction may be described as thickness, a long-side direction may be described as a width direction, and a short-side direction may be described as a thickness direction in the following description. The long-side direction (the width direction) of the cross-section of each flat tube <NUM>, which intersects the first direction Y and the second direction Z of each flat tube <NUM>, is a direction parallel to the flat plane, and hereinafter referred to as a third direction X. Further, in each of the drawings, the first direction Y, the second direction Z, and the third direction X are shown as being in a relationship orthogonal to each other. However, the first direction Y, the second direction Z, and the third direction X may intersect at an angle close to <NUM> degrees, for example, <NUM> degrees or the like.

In a typical heat exchanger <NUM>, a large number of flat tubes <NUM> are connected to the header <NUM>, the length of the first direction Y is larger than the length of the third direction X, and the length in the second direction Z is also larger than the length in the third direction X. Thus, the header <NUM> is long in the first direction Y.

As shown in <FIG>, the heat exchanger <NUM> according to Embodiment <NUM> is, for example, a fin-and-tube type heat exchanger of a single-row structure, in which a plurality of fins <NUM> and a plurality of flat tubes <NUM> are alternately stacked along the second direction Z, which is the width direction of the heat exchanger <NUM>. The fins <NUM> may be, for example, a plate fin connected to a large number of flat tubes <NUM>, or may be a corrugated fin sandwiched between flat planes of two flat tubes <NUM>. In the heat exchanger <NUM>, the flat tubes <NUM> are spaced apart from each other and arranged side by side in the horizontal direction, which is the first direction Y, with extending in an up and down direction. The fins <NUM> are interposed between the adjacent flat tubes <NUM>. The header <NUM> is connected to each end portion of the adjacent flat tubes <NUM> in the first direction Y, which is an elongation direction, so that the end portions of the flat tubes communicate with each other. The header <NUM> of Embodiment <NUM> described below may be provided at only one end portion of the flat tubes <NUM> in the first direction Y, or may be provided at both end portions of the flat tubes <NUM> in the first direction Y. In this embodiment, the flat tubes <NUM> are arranged side by side in the horizontal direction, which is the second direction Z, with extending in the up and down direction. However, the second direction Z is not limited thereto. For example, the flat tubes <NUM> may extend in the horizontal direction, which is the second direction Z, and may be spaced apart from each other and arranged side by side in a vertical direction, which is the first direction Y.

As shown in <FIG>, the header <NUM> has a flow passage <NUM> for flowing refrigerant inside. In the flow passage <NUM>, a plurality of partition portions <NUM> are arranged between each adjacent flat tubes <NUM>. The partition portion <NUM> blocks at least a part of the flow passage <NUM> between the adj acent flat tubes <NUM>. In the flow passage <NUM>, a plurality of insertion portions <NUM> into which the flat tubes <NUM> are respectively inserted are provided. Each insertion portion <NUM> is a space formed between the adjacent partition portions <NUM>. The number of the insertion portions <NUM> corresponds to the number of the flat tubes <NUM>.

Here, as shown by a dotted chain line in <FIG>, a center plane <NUM> passing through a center of the third direction X intersecting the first direction Y and the second direction Z of the plurality of flat tubes <NUM> is assumed. Incidentally, since the center plane <NUM> is a plane parallel to the first direction Y and the second direction Z, it is indicated by the dotted chain line in <FIG>. When the header <NUM> is divided into two regions <NUM> and <NUM> with the center plane <NUM> as a boundary, communication passages 22a and 22b are respectively provided in the two regions to allow the adjacent insertion portions <NUM> to communicate with each other. The communication passages 22a and 22b are formed so as to be continuous in the second direction Z in which the flat tubes <NUM> are arranged in parallel, that is, in a direction in which the header <NUM> extends in each of the two regions <NUM> and <NUM>. The communication passage 22a is connected to the refrigerant inlet <NUM> without via the insertion portion <NUM>, and the communication passage 22b is connected to the refrigerant inlet <NUM> via the insertion portion <NUM>. A passage cross-sectional area of the communication passage 22a is larger than a passage cross-sectional area of the communication passage 22b in the other region <NUM>.

<FIG> show a typical example of a configuration in which the communication passages 22a and 22b are provided at both sides of the flat tubes <NUM> in the third direction X in the flow passage <NUM> of the header <NUM>. However, at least one communication passage in each of the two regions <NUM> and <NUM> is sufficient and it is not necessary to provide the communication passages on both sides of the third direction X. A plurality of communication passages 22a and 22b may be provided in either or both of the two regions <NUM> and <NUM>.

Each flat tube <NUM> has a multi-hole tube structure with a plurality of adjacent refrigerant passages <NUM> inside. As shown in <FIG> and <FIG>, the communication passages 22a and 22b are connected to Each refrigerant passage <NUM> inside the flat tube <NUM> at the insertion portion <NUM>. Further, at least one of the two regions <NUM> and <NUM> of the header <NUM> is provided with a refrigerant inlet <NUM> (see <FIG>) as a first refrigerant inlet connected to the flow passage <NUM>.

Next, a flow of the refrigerant in the header <NUM> will be described in comparison with a Comparative Example. <FIG> is a perspective view schematically showing a cross-section of the header <NUM> for explaining a flow of refrigerant in the heat exchanger of Comparative Example. <FIG> is a perspective view, partially in cross-section, of the header <NUM> of the heat exchanger <NUM> in <FIG> for explaining a flow of the refrigerant of the header <NUM> according to Embodiment <NUM>. <FIG> is a conceptual diagram showing a pressure loss reducing effect of the header <NUM> according to Embodiment <NUM>. <FIG> is a schematic view showing a distribution between holes in a flat tube <NUM> of the header <NUM> of the heat exchanger of Comparative Example. <FIG> is a schematic view showing a distribution between holes in the flat tube <NUM> of the header <NUM> according to Embodiment <NUM>. <FIG> is a diagram for explaining the flow of the refrigerant in the header <NUM> according to Embodiment <NUM>. <FIG> is a graph showing conceptually a performance improving effect and a refrigerant amount reducing effect of the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a graph showing an improvement rate of performance loss by refrigerant distribution against a passage cross-sectional area of the heat exchanger according to Embodiment <NUM>.

Generally, in the header, the flat tube <NUM> protrudes into the flow passage <NUM> inside the header <NUM> for a purpose of securing a connection strength between the flat tube <NUM> and the header <NUM>, and preventing deterioration in quality due to a flow of brazing material used for connection into the refrigerant passage <NUM> inside the flat tube <NUM>.

As shown in <FIG>, in the header <NUM> of Comparative Example, a contraction area CA and a broad area BA of a flow passage <NUM> are formed around an insertion portion <NUM> of each flat tube <NUM> in the flow passage <NUM>. Therefore, in the header <NUM> of Comparative Example, since the refrigerant flows in the flow passage <NUM> with repeating contraction and expansion, a refrigerant pressure loss due to the expansion and contraction of the flow which indicates a positive correlation with a mass velocity of the refrigerant has occurred. In particular, when n is the number of the flat tubes <NUM> connected to an upstream side of the header <NUM>, and Gm [kg/m<NUM>s] is an average flow rate of the refrigerant flowing through the flat tube <NUM>, a flow rate of the refrigerant flowing through the insertion portion <NUM> of the n flat tubes <NUM> is n × Gm [kg/m<NUM>s]. Then, the refrigerant flows through the broad area BA and the contraction area CA of the flow passage <NUM> in n times from the flat tube <NUM> connected to the upstream side of the header <NUM> to the flat tube <NUM> connected to a downstream side of the header <NUM>. This results in an increase in the refrigerant pressure loss and a decrease in the heat exchanger performance.

On the other hand, in the heat exchanger <NUM> according Embodiment <NUM>, the partition portions <NUM> are provided at the flow passage <NUM> in the header <NUM>, and the communication passages 22a and 22b for allowing the insertion portions <NUM> of the flat tubes <NUM> to communicate with each other are provided in the flow passage <NUM> in each of the two regions <NUM> and <NUM> of the header <NUM>. Thus, the refrigerant in the two-phase gas-liquid state flows through the communication passages 22a and 22b as shown in <FIG>. The communication passage 22a and 22b are provided at both sides of the third direction X across the center plane <NUM>, and the insertion portions <NUM> function as a flow passage through which the refrigerant flows in the third direction X by the partition portions <NUM>. The refrigerant flows in the third direction X along the long-side direction of the end portion of the flat tube <NUM> in the insertion portion <NUM>. As shown in <FIG>, a typical insertion portion <NUM> has an elongated shape in which a length of the second direction Z is smaller than a width of the third direction X. Further, the insertion portion <NUM> is formed so that a distance from the end portion of the flat tube <NUM> is made to be constant, and the communication passages 22a and 22b is formed to have a constant passage cross-sectional area in the second direction Z. The refrigerant flowing through the communication passages 22a and 22b is distributed to the insertion portion <NUM> sequentially, and then flows into each flat tube <NUM>. This structure is less affected by expansion and contraction due to insertion of the end portion of the flat tube <NUM> which occurs in the structure of Comparative Example shown in <FIG>.

Further, since the passage cross-sectional area of the communication passage 22b is smaller than that of the communication passage 22a, the refrigerant amount is reduced, and a flow rate of the refrigerant to the communication passage 22a from the upstream side to the downstream side is also reduced. Therefore gas-liquid exchange is performed to equalize a gas-liquid ratio of the refrigerant between the different insert portions <NUM>. This reduces an excess supply of liquid refrigerant to downstream due to inertia forces and achieves both refrigerant amount reduction and heat exchanger performance.

In the header <NUM> of Embodiment <NUM>, as compared with the header <NUM> of Comparative Example in which the refrigerant flows repeatedly the contraction area CA and the broad area BA formed around the insertion portion <NUM> of the flow passage <NUM>, the refrigerant flow rate can be reduced to about <NUM>/n. Further, since the number of times that the refrigerant flows the insertion portion <NUM> until reaching the flat tube <NUM> is suppressed to about <NUM> to <NUM> times, it is possible to reduce the pressure loss due to the expansion and contraction of the flow. Therefore, in the heat exchanger <NUM> including the header <NUM> of Embodiment <NUM>, an increase of the pressure loss caused by reducing a diameter of the flow passage <NUM> can be suppressed, and it is possible to achieve both reduction of the refrigerant amount reduction and improvement of the heat exchanger performance.

In <FIG>, a broken line shows a distribution efficiency of the refrigerant in the header <NUM> of Comparative Example, and a solid line shows a distribution efficiency of refrigerant in the header <NUM> of Embodiment <NUM>. As shown in <FIG>, in particular, when focusing on a ratio of a pressure loss due to the expansion and contraction of the aforementioned flow to the pressure loss in the flow passage <NUM> of the header <NUM>, the ratio is larger at a low capacity operation when a mass velocity of the refrigerant is lower than at a high capacity operation when the mass velocity of the refrigerant is high. Here, a circle H of a broken line indicates that, in a reduction effect of pressure loss of refrigerant at the header <NUM> and the header <NUM>, the lower the mass velocity, the greater the reduction effect. This has been shown in tests by the inventors, and the performance improvement effect is particularly significant in the low capacity operation of the air-conditioning apparatus, which dominates a period efficiency. In addition, the refrigerant with lower gas density such as olefin-based refrigerant, propane or DME (dimethyl ether) compared to R32 refrigerant or R410A refrigerant has a higher refrigerant flow velocity per capacity, and thus has a greater performance improvement effect by reducing pressure loss. As the olefin-based refrigerant, HFO1234yf or HFO1234ze(E), etc. may be used.

Next, with reference to <FIG> and <FIG>, distribution of refrigerant in the refrigerant passage <NUM> of the flat tube <NUM> in the header <NUM> of Comparative Example and in the refrigerant passage <NUM> of the flat tube <NUM> in the header <NUM> of Embodiment <NUM> will be described. In general, in order to ensure pressure resistance strength, the flat tube <NUM> and the flat tube <NUM> have a multi-hole tube structure inside in which a plurality of refrigerant passages <NUM> and <NUM> are formed with partitions.

As shown in <FIG>, in the header <NUM> of Comparative Example, the flow passage <NUM> is provided only at one end in the long-side direction of the end portion of each flat tube <NUM>, that is, in the third direction X, and the flow passage <NUM> is provided with a communication passage <NUM> for allowing the insertion portions <NUM> of each flat tube <NUM> to communicate with each other. The refrigerant flows from the end portion at one end of the insertion portion <NUM> which communicates with the communication passage <NUM>, and is sequentially distributed to each refrigerant passage <NUM>. Therefore, uneven distribution occurs between the refrigerant passages <NUM>, and a heat transfer performance is deteriorated.

In contrast, in the header <NUM> of Embodiment <NUM>, the flow passage <NUM> is provided at both end portions of each flat tube <NUM> in the third direction X, and the flow passage <NUM> includes the communication passages 22a and 22b as shown in <FIG>. That is, in the header <NUM>, the two different regions <NUM> and <NUM> in the cross-section of the flat tube <NUM> divided by the center plane <NUM> has the communication passages 22a and 22b to the insertion portion <NUM> of the flat tube <NUM>, respectively. Therefore, occurrence of uneven distribution between the refrigerant passages <NUM> is reduced and the heat exchanger performance is improved.

Further, since at least one of the communication passages 22a and 22b for allowing the insertion portions <NUM> to communicate with each other is provided at the flow passage <NUM> of each of the two different regions <NUM> and <NUM> of the flat tube <NUM> divided by the center plane <NUM>, the refrigerant flows from the communication passage 22a in one region <NUM> into the insertion portion <NUM>. Then, the refrigerant is branched into a main flow flowing to the flat tube <NUM> in the insertion portion <NUM> and a side flow flowing to the communication passage 22b in the other region <NUM>. Since the passage cross-sectional area of the communication passage 22b is smaller than that of the communication passage 22a, a flow velocity of the refrigerant flowing through the communication passage 22b in the other region <NUM> in the first direction is lower and a refrigerant transport effect due to inertial force is relatively small against the communication passage 22a. Therefore, an effect of diffusion caused by a gas-liquid concentration gradient of the flow passage <NUM> increases.

As shown in <FIG>, diffusion occurs between the adjacent insertion portions <NUM> in the adjacent flat tubes <NUM> and exchange of gas refrigerant or liquid refrigerant occurs to make the gas-liquid concentration gradient be gentle. Therefore, in the header <NUM> of Embodiment <NUM>, the uneven distribution of the flow which controls a two-phase gas-liquid ratio (hereinafter referred to as distribution) of the refrigerant that flows in the flat tube <NUM> of the header <NUM> in Comparative Example shown in <FIG> can be reduced and the heat exchanger performance can be improved. Thus, an energy efficiency of the air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM> can be improved.

In <FIG>, a broken line shows a heat exchanger performance of the heat exchanger <NUM> including the header <NUM> of Comparative Example, and a solid line shows a heat exchanger performance of the heat exchanger <NUM> with the header <NUM> of Embodiment <NUM>. As shown in <FIG>, in the heat exchanger <NUM> of Embodiment <NUM>, a sensitivity of a heat exchanger performance to an inner volume of tube is smaller than that in the heat exchanger including the header <NUM> of Comparative Example, and it is possible to maintain the heat exchanger performance at a lower volume. Thus, it indicates that both refrigerant amount reduction and performance improvement can be achieved.

In <FIG>, a horizontal axis is an area ratio of the passage cross-sectional area Sa of the communication passage 22b to the passage cross-sectional area Sb of the communication passage 22b. The value <NUM> indicates the header <NUM> without the communication passage 22b, and the value <NUM> indicates that the passage cross-sectional area of the communication passage 22a is equal to that of the communication passage 22b. Further, a vertical axis shows an improvement rate of performance loss by refrigerant distribution, where a reduction rate of a heat exchanger performance of the heat exchanger <NUM> including the header <NUM> of Comparative Example to a heat exchanger performance of the heat exchanger <NUM> in uniform distribution may be achieved is <NUM>%. The disclosers have confirmed through this evaluation test that reducing the passage cross-sectional area ratio Sb/Sa to less than <NUM> improves the distribution of refrigerant and reduces heat exchanger performance loss by up to <NUM>% or more. When the passage cross-sectional area ratio Sb/Sa is significantly reduced, a wetting length becomes relatively large against the passage cross-sectional area of the communication passage 22b, a distribution improving effect due to diffusion is disturbed by surface tension of liquid film on a wall surface, and performance is reduced. On the other hand, when the passage cross-sectional area ratio Sb/Sa is increased and becomes <NUM>, the inertial force increases due to increase of a flow rate of the refrigerant flowing through the communication passage 22b, a distribution improving effect due to diffusion is disturbed, and performance is reduced. In particular, by making the passage cross-sectional area Sb/Sa larger than <NUM> and smaller than <NUM>, the heat exchanger performance loss is reduced by up to <NUM>% or more and a significant effect can be achieved.

As described above, in the heat exchanger <NUM> and the air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM>, the header <NUM> includes the partition portion <NUM> which blocks at least a part of the flow passage <NUM> between the adjacent flat tubes <NUM>. Additionally, the communication passages 22a and 22b are provided between the insertion portions <NUM> of the flat tubes <NUM>. The insertion portions <NUM> are formed by being sandwiched between the adjacent partition portions <NUM> so as to communicate the insertion portions <NUM> with each other. In this case, the communication passage 22a in the flow passage <NUM> of the header <NUM> is formed without via the insertion portion <NUM> into which the flat tube <NUM> is inserted. According to this configuration, the refrigerant pressure loss due to the expansion and contraction of the refrigerant flow that occurs in the insertion portion <NUM> is reduced, and increase of the pressure loss caused by reducing the diameter of the flow passage <NUM> can be suppressed.

In addition, when the header <NUM> is divided into the two different regions <NUM> and <NUM> by the center plane <NUM> passing through the center of the flat tube <NUM> in the third direction X, the two regions <NUM> and <NUM> is provided with the communication passages 22a and 22b, respectively. At least one region <NUM> of the two regions <NUM> and <NUM>, the refrigerant inlet <NUM> which is connected to the flow passage <NUM> is provided. By providing the refrigerant inlet <NUM> in the communication passage 22a, the header <NUM> has a configuration in which the communication passage 22a for transporting the refrigerant mainly by inertia force from the refrigerant inlet <NUM> to the insertion portion <NUM> of the flat tube <NUM>, and the communication passage 22b for exchanging the gas-liquid mainly by diffusion through the insertion portion <NUM> of the flat tube <NUM> are provided. According to this configuration, uneven distribution of the refrigerant due to changes in refrigerant flow velocity is reduced, and the heat exchanger performance is improved, thereby improving the energy efficiency of the air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM>. Thus, by reducing the refrigerant pressure loss and achieving uniform distribution of the refrigerant, the heat exchanger performance can be improved. Further, at least in a connection portion between the insertion portion <NUM> and the communication passage 22b, the width of the insertion portion <NUM> in the second direction is smaller than the width of the solid partition portion <NUM> in the second direction. According to this configuration, an effect of the inertia force of the refrigerant flow in the communication passage 22a on the flow in the communication passage 22b is reduced, and the heat exchanger performance is improved. Further, since the partition portion <NUM> is wide and solid, it is possible to save refrigerant and this is particularly effective.

In <FIG>, the header <NUM> is provided at a top and a bottom of the heat exchanger <NUM> in a gravity direction. However, the arrangement of the header <NUM> is not limited thereto. The header <NUM> may be provided at only one of the top and the bottom of the heat exchanger <NUM> in the gravity direction. Further, when the flat tubes <NUM> extend toward the second direction Z instead of the first direction Y, and arranged to be spaced apart from each other in the first direction Y, the header <NUM> may be provided at at least one of the left side and right side of the heat exchanger <NUM> perpendicular to the gravity direction. However, it is more effective to place the header <NUM> on the top or the bottom in the gravity direction, since the inhibition of diffusion due to the difference in gas-liquid density can be reduced. Further, in <FIG>, the air-conditioning apparatus <NUM> includes the heat exchanger <NUM> in the outdoor unit <NUM>. However, the heat exchanger <NUM> can be installed in the indoor unit <NUM>, and the effect is not hindered in this case. Further, the header <NUM> may have a region where the partition portion <NUM> is not provided at the upstream side or the downstream side of the header <NUM>.

<FIG> is a schematic cross-sectional view showing a modification of the header <NUM> according to Embodiment <NUM>. As shown in <FIG>, as a configuration of the header <NUM>, for example, a part of the adjacent flat tubes <NUM> may not be partitioned by the partition portion <NUM>. In particular, by reducing the partition portion <NUM> of the communication passage <NUM> at a region where diffusion occurs, it is possible to reduce contribution of the inertial force to the distribution.

Here, a detailed configuration example of the header <NUM> will be described. <FIG> is an exploded perspective view showing an example of the header <NUM> according to Embodiment <NUM>. <FIG> is an exploded perspective view showing a modification of the header <NUM> according to Embodiment <NUM>. <FIG> is an exploded perspective view showing a modification of the header <NUM> according to Embodiment <NUM>. <FIG> is an exploded perspective view showing a modification of the header <NUM> according to Embodiment <NUM>. <FIG> show examples of a component configuration of the header <NUM>.

As shown in <FIG>, in the header <NUM> of Embodiment <NUM>, it is preferable that the plurality of flat tubes <NUM>, the tubular refrigerant inlet <NUM>, and the partition portions <NUM> are assembled to a rectangular box-shaped header <NUM>, and an opening formed at both ends of the header <NUM> in the second direction Z is closed by a cover <NUM>. In this case, it is preferable that the components are joined by, for example, brazing.

As in a modification shown in <FIG>, the header <NUM> may be constructed by rectangular box-shaped covers <NUM> and <NUM> which are open to face each other. In this case, the covers <NUM> and <NUM> are formed with the flow passage <NUM> in which the above-described communication passages 22a and 22b (not shown here for simplicity) are provided, respectively. Then, the plurality of flat tubes <NUM> are assembled to the partition portion <NUM> in a state of being arranged in the second direction Z which is the thickness direction thereof, and the covers <NUM> and <NUM> are assembled so as to cover both ends of the partition portion <NUM> to which the flat tubes <NUM> are assembled in the third direction X which is the width direction of the flat tubes <NUM>. With such a configuration, the position of the flat tube <NUM> can be easily adjusted as compared with a case where the flat tube <NUM> is inserted and assembled to the partition portion <NUM> in the first direction Y. Thus, an occurrence of blocking or collapsing of the flow passage <NUM> due to poor positioning can be suppressed.

Further, as in a modification shown in <FIG>, the header <NUM> may be configured by a member <NUM> formed by extrusion molding in the second direction Z and covers <NUM> that closes both ends of the member <NUM> in the second direction Z. In this case, the communication passages 22a and 22b are formed in a space surrounded by the extrusion member and the partition member. The covers <NUM> cover both ends of the extrusion member <NUM> in the second direction Z. The refrigerant inlet <NUM> is assembled at one end which closes the communication passage 22a. With such a configuration, in addition to the effect of the modification shown in <FIG>, it is easy to adjust the passage cross-sectional area of the communication passages 22a and 22b.

Further, as shown in the modification of <FIG>, the header <NUM> may be formed by stacking a plurality of plate-shaped members <NUM> to <NUM>. In this case, the plate-shaped member <NUM> has penetrating portions <NUM> that penetrate the plate-shaped member <NUM> and hold the plurality of flat tubes <NUM>, and functions as a cover portion. Further, the plate-shaped member <NUM> is provided with a plurality of insertion portions <NUM>. The number of the insertion portions <NUM> corresponds to the number of the flat tubes <NUM>. Incidentally, a size of the penetrating portion <NUM> is the same as an outer periphery of the flat tube <NUM> and smaller than the insertion portion <NUM>. Therefore, the penetrating portion <NUM> closes an upper surface side of the insertion portion <NUM> in a state where the flat tube <NUM> is assembled. The plate-shaped member <NUM> has the communication passages 22a and 22b formed at both end side portions in the third direction X. The plate-shaped member <NUM> is connected to the tubular refrigerant inlet <NUM>, and constitutes a bottom of the header <NUM>. The plate-shaped members <NUM> to <NUM> are stacked and assembled in the first direction Y of the flat tube <NUM> to form the header <NUM>.

<FIG> is a cross-sectional perspective view showing a modification of the header <NUM> according to Embodiment <NUM>. As shown in <FIG>, the communication passages 22a and 22b of the header <NUM> according to Embodiment <NUM> may be placed below the insertion portion <NUM>, as long as the communication passages 22a and 22b are provided in each of the two regions <NUM> and <NUM> divided by the center plane <NUM> of the flat tube <NUM>. With such a configuration, a passage diameter of each of the communication passages 22a and 22b can be designed without increasing the size of the header <NUM> in the air flow direction AF of the heat exchanger <NUM> (i.e., the third direction X of the header <NUM>, see <FIG>). Therefore, it is possible to reduce a space in a case where another heat exchanger <NUM> is provided so that different heat exchangers are arranged at the upstream side and the downstream side of the air flow direction AF of the heat exchanger <NUM> by arranging different flat tubes in parallel in the third direction X of the flat tube <NUM>, or when the heat exchanger <NUM> is installed in a product housing.

<FIG> is a perspective view of, partially in cross-section, the header <NUM> for explaining a flow of the refrigerant of the header <NUM> according to a modification of Embodiment <NUM>. As shown in <FIG>, in the header <NUM>, the plurality of flat tubes <NUM> may be divided into a first heat transfer tube group <NUM> provided at an upstream side of the flow passage <NUM> and a second heat transfer tube group <NUM> provided at a downstream side of the flow passage <NUM> such that a heat transfer portion is provided at the upstream side and the downstream side of the header <NUM>. In this case, by reducing the pressure loss of the flow passage <NUM> in the header <NUM>, a difference of a condensation temperature (or evaporation temperature) of the refrigerant between the upstream side of the heat transfer portion and the downstream side of the heat transfer portion is reduced. Thus, there is an advantage of increasing the heat exchanger performance improvement effect.

Next, a heat exchanger <NUM> and an air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM> according to Embodiment <NUM> will be described. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> in the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a schematic view for explaining a distribution performance of a header <NUM> in a heat exchanger according to Comparative Example. <FIG> is a schematic view for explaining a distribution performance of the header <NUM> in the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a schematic view showing a cross-section of the header <NUM> in an X-Z plane of a modification of the heat exchanger <NUM> according to Embodiment <NUM>. For convenience purpose and visibility, a reference sign of each part of the header <NUM> is omitted in <FIG>. The header <NUM> in <FIG> is the same as and correspond to that in <FIG>.

In Embodiment <NUM>, the header <NUM> is partially modified from the header <NUM> of Embodiment <NUM>. Since an overall configuration of the heat exchanger <NUM> and the air-conditioning apparatus <NUM> of Embodiment <NUM> is the same as that of Embodiment <NUM>, it is not shown and described in detail here, and similar or corresponding components are denoted by the same reference signs as Embodiment <NUM>. The header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM> basically has a configuration in which two regions are symmetrical across the center plane <NUM>. In contrast, the two regions may be asymmetrical as shown in Embodiment <NUM>.

As shown in <FIG>, the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM> includes a refrigerant inlet <NUM> provided at an eccentric position along the third direction X of the flat tube <NUM>, which is the air flow direction AF of the heat exchanger <NUM> (see <FIG>), with the center plane <NUM> of the header <NUM> as a border. In accordance with this configuration, a position of a communication passage 22a of one region <NUM> side is eccentric in the third direction X from a position symmetrical to a position of a communication passage 22b of the other region <NUM> side across the center plane <NUM>. In other words, a position where the refrigerant inlet <NUM> is connected to the communication passage 22a of one region <NUM> side is shifted in the third direction X from a position symmetrical to a position of the communication passage 22b of the other region <NUM> side about the center plane <NUM>. For example, in Embodiment <NUM>, the refrigerant inlet <NUM> is provided at a position eccentric to one region <NUM> side of two regions which are different from each other in the third direction X of the header <NUM>. The arrangement of the refrigerant inlet <NUM> is not limited thereto. The refrigerant inlet <NUM> may be provided at a position eccentric to the other region <NUM> side.

As shown in <FIG>, in a configuration of Comparative Example, a flow passage <NUM>, in which the communication passage <NUM> is formed, is provided only at one end of the flat tube <NUM> in the third direction X. Therefore, an amount of liquid transported to the flat tube <NUM> is dominated by inertial force. Thus, the liquid refrigerant is transported disproportionately more to the flat tubes <NUM> located in downstream in an operation with a large mass velocity, and is transported disproportionately more to the flat tubes <NUM> located in upstream in an operation with a low mass velocity. This results in reducing the heat exchanger performance.

In contrast, as shown in <FIG>, with respect to a distribution characteristic of the refrigerant from the communication passages 22a and 22b to the insertion portion <NUM> in the header <NUM> of the heat exchanger <NUM> of Embodiment <NUM>, diffusion of the refrigerant by the inertial force is dominant in the communication passage 22a in one region <NUM>. Additionally, in the communication passage 22b in the other region <NUM>, diffusion due to collision from the insertion portion <NUM> to the communication passage 22b is dominant. In this case, in the operation with the large mass velocity, the inertial force of the refrigerant flowing through the communication passage 22a in one region <NUM> increases, the amount of the liquid refrigerant transported to the insertion portion <NUM> of the flat tubes <NUM> in downstream increases, and the amount of refrigerant flowing into the communication passage 22b in the other region <NUM> also increases. On the other hand, in the operation with the low mass velocity, the inertial force of the refrigerant flowing through the communication passage 22a in one region <NUM> decreases, the amount of the liquid refrigerant transported to the insertion portion <NUM> of the flat tubes <NUM> in downstream decreases, and the amount of refrigerant transported to the communication passage 22b in the other region <NUM> by diffusion increases. Thus, a sensitivity of refrigerant distribution to mass velocity is reduced, and the performance is improved in a wide capacity range.

Further, as shown in <FIG>, when the refrigerant inlet <NUM> is in one region <NUM> eccentrically from the center plane <NUM> of the cross-section of the flat tube <NUM>, a passage diameter of the communication passage 22a in one region <NUM> is defined as a hydraulic diameter D1 and a passage diameter of the communication passage 22b in the other region <NUM> is defined as a hydraulic diameter D2. In this case, by making the hydraulic diameter D1 of the communication passage 22b in one region <NUM> larger than the hydraulic diameter D2 of the communication passage 22b in the other region <NUM>, a liquid transport effect by diffusion in the communication passage 22b in the other region <NUM> is improved. This results in improvement of the performance (see <FIG>). For example, as a means for reducing the hydraulic diameter D2, a porous body <NUM> may be provided in the communication passage 22b of the flow passage <NUM> in the other region <NUM> as shown in <FIG> so that a wetting edge area of a passage (liquid passage) through which the refrigerant passes in the communication passage 22b increases.

As described above, in the heat exchanger <NUM> and the air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM> of Embodiment <NUM>, the refrigerant inlet <NUM> is provided at a position eccentric in the third direction X of the flat tube <NUM> which is the air flow direction AF of the heat exchanger <NUM> (see <FIG>) from the center plane <NUM> of the header <NUM>. With respect to the distribution characteristic of the refrigerant from the communication passages 22a and 22b to the insertion portion <NUM>, the inertial force of the refrigerant is dominant in the communication passage 22a in one region <NUM> and diffusion due to collision from the insertion portion <NUM> to the communication passage 22b is dominant in the communication passage 22b in the other region <NUM>. Therefore, the sensitivity of refrigerant distribution to mass velocity is reduced, and the performance is improved in a wide capacity range.

Further, when the passage diameter of the communication passage 22a in one region <NUM> is defined as the hydraulic diameter D1 and the passage diameter of the communication passage 22b in the other region <NUM> is defined as the hydraulic diameter D2, the hydraulic diameter D1 is larger than the hydraulic diameter D2. According to this configuration, the liquid transport effect by diffusion in the communication passage 22b in the other region <NUM> is improved, and the heat exchanger performance can be improved.

Next, a heat exchanger <NUM> and an air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM> according to Embodiment <NUM> will be described. <FIG> is a perspective view showing, partially in cross-section, a header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> in <FIG>. <FIG> is a schematic view showing a cross-section of the header <NUM> in <FIG> in a D-D field of view. <FIG> is a schematic cross-sectional view showing a modification of the header <NUM> in <FIG>.

In Embodiment <NUM>, the header <NUM> of Embodiment <NUM> is partially modified, and a configuration of the heat exchanger <NUM> and the air-conditioning apparatus <NUM> is the same as that of Embodiment <NUM>. Therefore, description thereof is omitted, and same or corresponding components are denoted by the same reference signs as Embodiment <NUM>.

As shown in <FIG>, the header <NUM> according to Embodiment <NUM> includes a refrigerant inlet <NUM> provided at a position eccentric in the third direction X of the flat tube <NUM> which is the air flow direction AF of the heat exchanger <NUM> (see <FIG>) from the center plane <NUM> of the header <NUM> (see <FIG>). Specifically, the refrigerant inlet <NUM> is provided, for example, on one region <NUM> side of the two regions <NUM> and <NUM>. Further, the header <NUM> has a contraction hole <NUM> only in the communication passage 22a of the flow passage <NUM> to which the refrigerant inlet <NUM> is connected. The contraction hole <NUM> is provided at a connecting part which connects the communication passage 22a and the insertion portions <NUM> to which the flat tubes <NUM> are inserted. As shown in <FIG>, it is preferable that a plurality of contraction holes <NUM> are provided so that each contraction hole <NUM> is positioned on the same line as each flat tube <NUM> with respect to the insertion portions <NUM> (<FIG>) of the header <NUM> which extends in the third direction X of the flat tube <NUM>.

As described above, in the header <NUM> of Embodiment <NUM>, the contraction hole <NUM> is provided between the communication passage 22a in one region <NUM> which includes the refrigerant inlet <NUM> and the insertion portion <NUM> of the flat tube <NUM>. With such a configuration, a sensitivity of two-phase gas-liquid distribution to inertial forces is reduced. In addition, since the contraction hole <NUM> is not provided in the communication passage 22b, a size of the header is not increased. Therefore, a distribution improvement effect by diffusion in the communication passage 22b in the other region <NUM> is improved, and the heat exchanger performance can be improved.

Incidentally, as shown in <FIG>, each contraction hole <NUM> may be provided at a position eccentric in the first direction Y in which the flat tubes <NUM> are arranged in parallel from a position on the same line as the flat tubes <NUM> with respect to the insertion portion <NUM> (see <FIG> and <FIG>) which extends in the third direction X of the flat tube <NUM> in the header <NUM>.

Thus, since the contraction hole <NUM> is eccentric in the second direction Z with respect to the insertion portion <NUM>, the center of the contraction hole <NUM> deviates from the central axis of the flat tube <NUM> generally located near the center of the insertion portion <NUM>. This causes a reduction of collision to the protruding portion of the flow passage <NUM> of the flat tube <NUM> in the refrigerant flow from the communication passage 22a in one region <NUM> to the communication passage 22b in the other region <NUM>, and a flow rate of the refrigerant in the communication passage 22b in the other region <NUM> is improved. Therefore, due to promotion of agitation, the distribution improvement effect by diffusion and the heat exchanger performance can be improved.

Next, a heat exchanger <NUM> and an air-conditioning apparatus <NUM> equipped with the heat exchanger <NUM> according to Embodiment <NUM> will be described. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>. In Embodiment <NUM>, the header <NUM> of Embodiment <NUM> is partially modified, and a configuration of the heat exchanger <NUM> and the air-conditioning apparatus <NUM> is the same as that of Embodiment <NUM>. Therefore, description thereof is omitted, and same or corresponding components are denoted by the same reference signs as Embodiment <NUM>.

As shown in <FIG>, in the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>, a connection passage <NUM> penetrating the partition portion <NUM> along the third direction X is provided at at least one of the partition portions <NUM> located between the adjacent flat tubes <NUM>. The connection passage <NUM> connects the communication passage 22a to the communication passage 22b in each of two regions <NUM> and <NUM> of the flow passage <NUM> divided by the center plane <NUM> of the flat tube <NUM>. The connection passage <NUM> is parallel to the insertion portion <NUM>. That is, the connection passage <NUM> is provided along the air flow direction AF (see <FIG>) of the heat exchanger <NUM> which is the third direction X of the flat tube <NUM>. No flat tube <NUM> is inserted into the connection passage <NUM>. At least one connection passage <NUM> is provided in the header <NUM>.

As described above, in the header <NUM> of Embodiment <NUM>, the connection passage <NUM> which connects the communication passage 22a and the communication passage 22b in the two regions <NUM> and <NUM> and to which the flat tube <NUM> is not inserted is provided. According to this configuration, a flow with a high refrigerant velocity can be created with respect to the insertion portion <NUM>. Thus, by the refrigerant flowing through the connection passage <NUM>, for example, in the header <NUM> configured eccentrically in one region <NUM>, agitation of the refrigerant in the communication passage 22b in the other region <NUM> is promoted, and the distribution improving effect and the heat exchanger performance can be improved.

Next, a heat exchanger <NUM> according to Embodiment <NUM> will be described. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>. In Embodiment <NUM>, the header <NUM> of Embodiment <NUM> is partially modified, and a configuration of the heat exchanger <NUM> is the same as that of Embodiment <NUM>. Therefore, description thereof is omitted, and the same or corresponding components are denoted by the same reference signs as Embodiment <NUM>.

In the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>, at least a part of the communication passage 22a in one of two regions <NUM> and <NUM> of the flow passage <NUM> divided by the center plane <NUM> of the flat tube <NUM> and the communication passage 22b in the other of two regions is not connected to the insertion portion <NUM>. In other words, the header <NUM> is provided with an insertion portion 23a which blocks one of the communication passage 22a in one region <NUM> and the communication passage 22b in the other region <NUM>. For example, the insertion portion 23a blocks the communication passage 22a in one region <NUM> without directly communicating with the communication passage 22a.

As described above, in the header <NUM> of Embodiment <NUM>, a distribution design of the two-phase refrigerant in accordance with an air volume distribution flowing through the heat exchanger <NUM> (see <FIG>, etc.) is possible, and the heat exchanger performance can be improved. Incidentally, the insertion portion 23a which is not communicated with the communication passage 22a in one region <NUM> is at least communicated with the communication passage 22b in the other region <NUM>.

Next, a heat exchanger <NUM> according to Embodiment <NUM> will be described. <FIG> is a schematic view showing a horizontal cross-section of the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>. In Embodiment <NUM>, the header <NUM> is partially modified, and a configuration of the heat exchanger <NUM> is the same as that of Embodiment <NUM>. Therefore, description thereof is omitted, and the same or corresponding components are denoted by the same reference signs as Embodiment <NUM>.

As shown in <FIG>, the header <NUM> of the heat exchanger <NUM> according to Embodiment <NUM> includes a first heat transfer tube group <NUM> provided at the upstream side of the flow passage <NUM> of the header <NUM>, and a second heat transfer tube group <NUM> provided at the downstream side of the flow passage <NUM>. In addition, the header <NUM> according to Embodiment <NUM> includes two different refrigerant inlets which are a first refrigerant inlet 24a and a second refrigerant inlet 24b. The first refrigerant inlet 24a is connected to the communication passage 22a in one region <NUM>. The second refrigerant inlet 24b is connected to the communication passage 22b in the other region <NUM>. A passage diameter of the second refrigerant inlet 24b is smaller than a passage diameter of the first refrigerant inlet 24a.

Further, it is assumed that a part of or all of the flow passage <NUM> in which the first heat transfer tube group <NUM> and the second heat transfer tube group <NUM> are connected is regarded as the header <NUM>. In this case, when viewed at a cross-section of the flow passage <NUM> in the first direction Y (not shown) which is a horizontal cross-section of the flow passage <NUM> of the header <NUM> shown in <FIG>, a diameter of a part of the communication passage 22b at a position around the second refrigerant inlet 24b and between the first heat transfer tube group <NUM> and the second heat transfer tube group <NUM> is smaller than a diameter of a part of the communication passage 22b at the other position.

As described above, in the header <NUM> of Embodiment <NUM>, the first refrigerant inlet 24a and the second refrigerant inlet 24b are configured such that the passage diameter of the second refrigerant inlet 24b connected to the communication passage 22b having a smaller passage cross-sectional area is smaller than the passage diameter of the first refrigerant inlet 24a connected to the communication passage 22a having a larger passage cross-sectional area. According to this configuration, the flow rate of the refrigerant flowing through the communication passage 22b can be reduced, and a sensitivity of two-phase gas-liquid distribution to inertial force having a positive correlation with refrigerant mass velocity can be reduced. Then, the heat exchanger performance can be improved in a wide operating capacity range.

<FIG> is a schematic view showing a plan section of header <NUM> of a modification of the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a schematic view showing a plan section of header <NUM> of a modification of the heat exchanger <NUM> according to Embodiment <NUM>. As shown in <FIG> and <FIG>, an amount of liquid flowing through the second refrigerant inlet 24b may be "<NUM>. " The flow rate of the refrigerant flowing through the communication passage 22b of the header <NUM> may be "<NUM>," by omitting the second refrigerant inlet 24b as shown in <FIG>, or by providing a partition <NUM> instead of the second refrigerant inlet 24b as shown in <FIG>.

<FIG> is a schematic view showing a plan section of header <NUM> of a modification of the heat exchanger <NUM> according to Embodiment <NUM>. As shown in <FIG>, the communication passages 22a and 22b may be configured integrally with the communication passage of the header <NUM> of the heat exchanger at the upstream side.

<FIG> is a schematic view showing a plan section of header <NUM> of a modification of the heat exchanger <NUM> according to Embodiment <NUM>. As shown in <FIG>, at least one flat tube at the most upstream side of the refrigerant flow may function as the second refrigerant inlet 24b by making some of the flat tubes <NUM> connected to the header <NUM> be flat tubes that constitute the first heat transfer tube group <NUM>. According to this configuration, it is possible to supply the refrigerant to the communication passage 22b with reduced inertial force in the second direction Z. Therefore, the performance improvement effect by diffusion of the gas-liquid in the communication passage 22b can be improved.

Claim 1:
A heat exchanger (<NUM>) comprising:
a plurality of flat tubes (<NUM>) extending in a first direction and arranged with spacing from each other in a second direction perpendicular to the first direction, a cross-section of each of the plurality of flat tubes (<NUM>) in the second direction being an elongated shape; and
a header (<NUM>) extending in the second direction and connecting to end portions of the adjacent flat tubes (<NUM>) of the plurality of flat tubes (<NUM>) in the first direction,
the header (<NUM>) having inside a flow passage (<NUM>) through which refrigerant flows,
the flow passage (<NUM>) including
a plurality of partition portions (<NUM>) each provided between the adjacent flat tubes (<NUM>) and configured to block at least a part of the flow passage (<NUM>) between the adjacent flat tubes (<NUM>) to prevent the refrigerant from flowing in the second direction,
a plurality of insertion portions (<NUM>) formed between the adjacent partition portions (<NUM>), each of the plurality of insertion portions (<NUM>) forming a space where the refrigerant flows in a third direction perpendicular to the first direction and the second direction, each of the plurality of flat tubes (<NUM>) being inserted in to each of the plurality of insertion portions (<NUM>),
a first communication passage (22a) allowing one ends of the adjacent insertion portions (<NUM>) in the third direction to communicate with each other, and
a second communication passage (22b) allowing an other ends of the adjacent insertion portions (<NUM>) in the third direction to communicate with each other,
characterised in that
a cross-sectional area of the first communication passage (22a), of a cross-section perpendicular to the second direction, being larger than a cross-sectional area of the second communication passage (22b), of a cross-section perpendicular to the second direction,
the first communication passage (22a) being provided with a first refrigerant inlet (<NUM>) connected to the flow passage (<NUM>) and allowing the refrigerant to flow into the header (<NUM>).