Patent Description:
A given existing heat exchanger includes a plurality of flat tubes extending in a vertical direction and spaced from each other in a horizontal direction, a plurality of fins which are each connected between associated adjacent ones of the flat tubes and which transfer heat to the flat tubes, and headers provided at upper and lower ends of the flat tubes, see, for example, <CIT>.

The heat exchanger of <CIT> is provided in an outdoor unit of an air-conditioning apparatus that is capable of both cooling operation and heating operation. In the case where the heating operation is performed in a low-temperature environment in which an outdoor air temperature is low and the surface temperature of the heat exchanger is lower than or equal to <NUM> degrees C, frost forms on the heat exchanger. Thus, when the amount of the frost that forms on the heat exchanger reaches a certain amount or more, a defrosting operation of causing the frost on a surface of the heat exchanger to melt is performed. In the defrosting operation, high-temperature and high-pressure gas refrigerant is caused to flow into the flat tubes though one of the headers, to thereby remove the frost.

Document <CIT> shows a condenser/evaporator for use in a heat pump system in a construction having first and second, curved, generally congruent tubular headers with one of the headers being an upper header and the other of the headers being a lower header. A first row of elongated tube slots is located in the upper header while a second row of elongated tube slots is located in the lower header. Each tube slot in the first row has a corresponding tube slot in the second row and corresponding tube slots in the rows are aligned with one another. Elongated, straight, flattened tubes extend between the headers in parallel with each other and a first port is provided for refrigerant in one of the headers and a second port is provided for refrigerant in the other of the headers.

Document <CIT> shows each of partitioning boards being installed respectively in headers on the both sides so that each of the headers may be partitioned longitudinally where they are respectively divided into two chambers, say, upper and lower chambers. Furthermore, the partitioning board on the left side is installed more or less on an upper position on the central part of the header whereas the partitioning board is installed to such a position which shares one third of the entire length from the lower end. As a result, as the refrigerant flows from an inlet side passage group A of tube groups equivalent to a condensation section or further from an intermediate passage group B up to an outlet side passage group C equivalent to an excess cooling section, the passage cross sectional area of each flow passage group is reduced so that the pressure loss due to the circulation of refrigerant may be reduced. It is, therefore, possible to carry out heat exchange with high efficiency.

In such an existing heat exchanger as described in <CIT>, in the defrosting operation, as refrigerant that has flowed into the flat tubes from a header flows farther, the refrigerant is further cooled, and the more downward the flowing refrigerant, the higher the ratio of the liquid phase of the refrigerant. Then, the higher the ratio of liquid phase of the refrigerant, the lower the velocity of the refrigerant, as a result of which the refrigerant more easily flows backward. If the refrigerant flows backward, the defrosting performance is deteriorated.

The present disclosure is applied to solve the above problem, and relates to a heat exchanger that reduces the probability with which refrigerant will flow backward, an outdoor unit including the heat exchanger, and an air-conditioning apparatus including the outdoor unit.

A heat exchanger according to the invention is defined in claim <NUM>.

Furthermore, an outdoor unit of an air-conditioning apparatus according to another embodiment of the present disclosure includes the heat exchanger described above.

Furthermore, an air-conditioning apparatus according to still another embodiment of the present disclosure includes the outdoor unit described above.

In the heat exchanger according to the embodiment of the present disclosure, the outdoor unit including the heat exchanger, and the air-conditioning apparatus including the outdoor unit, the partition plate is provided such that in each of the regions of the heat exchange body, refrigerant flows in the opposite direction to the flow direction of refrigerant in an adjacent one of the regions, and is provided such that regarding the regions of the heat exchange body, the more downstream a region in the flow of refrigerant in the case where the heat exchanger operates as a condenser, the smaller the flow passage cross-sectional area of the region. In such a manner, since regarding the regions, the more downstream a region in the flow of refrigerant in the case where the heat exchanger operates as a condenser, the smaller the flow passage cross-sectional area of the region, it is possible to reduce lowering of the flow velocity of the refrigerant, even when the ratio of the liquid phase of the refrigerant becomes higher, and thus reduce the probability that backflow of the refrigerant will occur.

The embodiments of the present disclosure will be described with reference to the drawings. This description, however, is not limiting. Furthermore, in each of references which will be referred to below, relationships in size between components may be different from actual ones.

<FIG> is a refrigerant circuit diagram of an air-conditioning apparatus <NUM> including a heat exchanger <NUM> according to Embodiment <NUM>. In <FIG>, solid arrows indicate the flow of refrigerant during cooling operation, and dashed arrows indicate the flow of refrigerant during heating operation.

As illustrated in <FIG>, the heat exchanger <NUM> according to Embodiment <NUM> is provided in an outdoor unit <NUM> of an air-conditioning apparatus <NUM> that includes the outdoor unit <NUM> and an indoor unit <NUM>. The outdoor unit <NUM> includes a compressor <NUM>, a flow switching device <NUM>, and a fan <NUM> in addition to the heat exchanger <NUM>. The indoor unit <NUM> includes an expansion device <NUM>, an indoor heat exchanger <NUM>, and an indoor fan <NUM>.

The air-conditioning apparatus <NUM> includes a refrigerant circuit in which the compressor <NUM>, the flow switching device <NUM>, the heat exchanger <NUM>, the expansion device <NUM>, and the indoor heat exchanger <NUM> are connected by refrigerant pipes and refrigerant is circulated. The air-conditioning apparatus <NUM> is capable of performing both the cooling operation and the heating operation. The operation of the air-conditioning apparatus <NUM> is switched to one of the cooling operation and the heating operation by a switching operation of the flow switching device <NUM>.

The compressor <NUM> sucks low-temperature and low-pressure refrigerant, compresses the sucked refrigerant to change it into high-temperature and high-pressure refrigerant, and discharges the high-temperature and high-pressure refrigerant. The compressor <NUM> is, for example, an inverter compressor whose capacity is the rate of delivery per unit time and is controlled by varying an operating frequency.

The flow switching device <NUM> is, for example, a four-way valve, and performs switching between the cooling operation and the heating operation by switching the flow direction of refrigerant. In order that the cooling operation be performed, the state of the flow switching device <NUM> is switched to a state indicated by solid lines in <FIG>, whereby a discharge side of the compressor <NUM> is connected to the heat exchanger <NUM>. In contrast, in order that the heating operation be performed, the state of the flow switching device <NUM> is switched to a state indicated by dashed lines in <FIG>, whereby the discharge side of the compressor <NUM> is connected to the indoor heat exchanger <NUM>.

The heat exchanger <NUM> causes heat exchange to be performed between outdoor air and refrigerant. In the cooling operation, the heat exchanger <NUM> operates as a condenser that condenses the refrigerant by causing the refrigerant to transfer heat to the outdoor air. Furthermore, in the heating operation, the heat exchanger <NUM> operates as an evaporator that evaporates the refrigerant and cool the outdoor air with the heat of vaporization which is required for evaporation of the refrigerant.

The fan <NUM> supplies outdoor air to the heat exchanger <NUM>. The amount of air that is sent from the fan <NUM> to the heat exchanger <NUM> is adjusted under a control of the rotation speed of the fan <NUM>.

The expansion device <NUM> is, for example, an electronic expansion valve whose opening degree can be adjusted. The opening degree of the expansion device <NUM> is adjusted, thereby controlling the pressure of refrigerant that flows into the heat exchanger <NUM> or the indoor heat exchanger <NUM>. In Embodiment <NUM>, the expansion device <NUM> is provided in the indoor unit <NUM>; however, the expansion device <NUM> may be provided in the outdoor unit <NUM>. The place of installation of the expansion device <NUM> is not limited.

The indoor heat exchanger <NUM> causes heat exchange to be performed between indoor air and refrigerant. In the cooling operation, the indoor heat exchanger <NUM> operates as an evaporator that evaporates the refrigerant and cool the indoor air with the heat of vaporization that is required for evaporation of the refrigerant. In the heating operation, the indoor heat exchanger <NUM> operates as a condenser that causes the heat of the refrigerant to be transferred to the indoor air, thereby condensing the refrigerant.

The indoor fan <NUM> supplies indoor air to the indoor heat exchanger <NUM>. The amount of air that is sent from the indoor fan <NUM> to the indoor heat exchanger <NUM> is adjusted under a control of the rotation speed of the indoor fan <NUM>.

<FIG> is a perspective view of the heat exchanger <NUM> according to Embodiment <NUM>.

As illustrated in <FIG>, the heat exchanger <NUM> includes a heat exchange body <NUM> including a plurality of flat tubes <NUM> and a plurality of fins <NUM>. The flat tubes <NUM> are arranged and spaced from each other in parallel in a horizontal direction, thereby enabling a wind generated by the fan <NUM> to flow, and the flat tubes <NUM> also extend in a vertical direction to allow refrigerant to flow in the vertical direction in the flat tubes <NUM>. The fins <NUM> are each connected between associated adjacent ones of the flat tubes <NUM>, and transfer heat to these flat tubes <NUM>. It should be noted that the fins <NUM> are provided to improve the efficiency of heat exchange between air and refrigerant. For example, corrugated fins are used as the fins <NUM>; however, the fins <NUM> are not limited to the corrugated fins. The fins <NUM> may be omitted, since air and refrigerant exchange heat with each other at surfaces of the flat tubes <NUM>.

At a lower end of the heat exchange body <NUM>, a lower header <NUM> is provided. In the lower header <NUM>, lower ends of the flat tubes <NUM> of the heat exchange body <NUM> are directly inserted. Furthermore, at an upper end of the heat exchange body <NUM>, an upper header <NUM> is provided. In the upper header <NUM>, upper ends of the flat tubes <NUM> of the heat exchange body <NUM> are directly inserted.

The lower header <NUM> is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> via a gas pipe <NUM> (see <FIG>, which will be referred later), and will also be referred to as "gas header". In the cooling operation, the lower header <NUM> causes high-temperature and high-pressure gas refrigerant from the compressor <NUM> to flow into the heat exchanger <NUM>, and in the heating operation, causes low-temperature and low-pressure gas refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

The upper header <NUM> is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> via a liquid pipe <NUM> (see <FIG>), and will also be referred to as "liquid header". In the heating operation, the upper header <NUM> causes low-temperature and low-pressure two-phase refrigerant to flow into the heat exchanger <NUM>, and in the cooling operation, causes low-temperature and high-pressure liquid refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

The flat tubes <NUM>, the fins <NUM>, the lower header <NUM>, and the upper header <NUM> are all made of aluminum, and are joined together by brazing.

High-temperature and high-pressure gas refrigerant discharged from the compressor <NUM> flows into the heat exchanger <NUM> via the flow switching device <NUM>. After having flowed into the heat exchanger <NUM>, the high-temperature and high-pressure gas refrigerant condenses while transferring heat to outdoor air taken in by the fan <NUM>, in heat exchange with the outdoor air, and as a result, changes into low-temperature and high-pressure liquid refrigerant, which then flows out of the heat exchanger <NUM>. After having flowed out of the heat exchanger <NUM>, the low-temperature and high-pressure liquid refrigerant is decompressed by the expansion device <NUM> to change into low-temperature and low-pressure two-phase gas-liquid refrigerant, and the low-temperature and low-pressure two-phase gas-liquid refrigerant then flows into the indoor heat exchanger <NUM>. After having flowed into the indoor heat exchanger <NUM>, the low-temperature and low-pressure two-phase gas-liquid refrigerant evaporates while receiving heat from indoor air taken in by the indoor fan <NUM>, in heat exchange with the indoor air, and also cooling the indoor air, and as a result, changes into low-temperature and low-pressure gas refrigerant, and the low-temperature and low-pressure gas refrigerant then flows out of the indoor heat exchanger <NUM>. After having flowed out of the indoor heat exchanger <NUM>, the low-temperature and low-pressure gas refrigerant is sucked into the compressor <NUM> to change back into high-temperature and high-pressure gas refrigerant.

High-temperature and high-pressure gas refrigerant discharged from the compressor <NUM> flows into the indoor heat exchanger <NUM> via the flow switching device <NUM>. After having flowed into the indoor heat exchanger <NUM>, the high-temperature and high-pressure gas refrigerant condenses while transferring heat to indoor air taken in by the indoor fan <NUM>, in heat exchange with the indoor air, and thus heating the indoor air, and as a result, changes into low-temperature and high-pressure liquid refrigerant, and the low-temperature and high-pressure liquid refrigerant then flows out of the indoor heat exchanger <NUM>. After having flowed out of the indoor heat exchanger <NUM>, the low-temperature and high-pressure liquid refrigerant is decompressed by the expansion device <NUM> to change into low-temperature and low-pressure two-phase gas-liquid refrigerant, and the low-temperature and low-pressure two-phase gas-liquid refrigerant then flows into the heat exchanger <NUM>. After having flowed into the heat exchanger <NUM>, the low-temperature and low-pressure two-phase gas-liquid refrigerant evaporates while receiving heat from outdoor air taken in by the fan <NUM>, in heat exchange with the outdoor air, and as a result, changes into low-temperature and low-pressure gas refrigerant, and the low-temperature and low-pressure gas refrigerant flows out of the heat exchanger <NUM>. After having flowed out of the heat exchanger <NUM>, the low-temperature and low-pressure gas refrigerant is sucked into the compressor <NUM> to change back into high-temperature and high-pressure gas refrigerant.

In the case where the heating operation is performed in a low-temperature environment in which the surface temperatures of the flat tubes <NUM> and the fins <NUM> drop to <NUM> degrees C or less, frost forms on the heat exchanger <NUM>. When the amount of frost that forms on the heat exchanger <NUM> reaches a given amount or more, an air passage at the heat exchanger <NUM> through which a wind from the fan <NUM> passes is closed by the frost, as a result of which the performance of the heat exchanger <NUM> is deteriorated and a heating performance is also deteriorated. Thus, in the case where the heating performance is deteriorated, a defrosting operation of causing the frost on a surface of the heat exchanger <NUM> to melt is performed.

In the defrosting operation, the fan <NUM> is stopped, and the state of the flow switching device <NUM> is switched to the same state as in the cooling operation, whereby high-temperature and high-pressure gas refrigerant flows into the heat exchanger <NUM>. As a result, the frost adhering to the flat tubes <NUM> and the fins <NUM> melt. When the defrosting operation is started, the high-temperature and high-pressure gas refrigerant flows into each of the flat tubes <NUM> via the lower header <NUM>. Then, the high-temperature refrigerant that has flowed into the flat tubes <NUM> causes the frost adhering to the flat tubes <NUM> and the fins <NUM> to melt and change into water. The water into which the frost melts and changes (hereinafter referred to as "defrost water") drains from and along the flat tubes <NUM> or the fins <NUM> toward a region located below the heat exchanger <NUM>. When the adhering frost melts, the defrosting operation is ended, and the heating operation is resumed.

In the defrosting operation, refrigerant that has flowed from the lower header <NUM> is further cooled as it flows through the flat tubes <NUM>, such that the more downstream the flowing refrigerant, the higher the ratio of the liquid phase of the refrigerant. The higher the ratio of the liquid-phase of the refrigerant, the lower the velocity of the refrigerant, as a result of which the refrigerant more easily flows backward. In the related art, when the refrigerant flows backward, the defrosting performance is deteriorated.

<FIG> is a front view schematically illustrating the flow of refrigerant in the defrosting operation at the heat exchanger <NUM> according to Embodiment <NUM>. In <FIG>, outlined arrows and black dashed arrows all indicate flows of refrigerant.

In the heat exchanger <NUM> according to Embodiment <NUM>, in the lower header <NUM> and the upper header <NUM>, respective partition plates <NUM> are provided as illustrated in <FIG>. The partition plates <NUM> are provided to partition the heat exchange body <NUM> into a plurality of regions in the horizontal direction. Furthermore, the partition plates <NUM> are provided such that refrigerant in each of the regions of the heat exchange body <NUM> flows in the opposite direction to the flow direction of refrigerant in an adjacent one of the regions that is adjacent to the above region, and is provided such that regarding the regions of the heat exchange body <NUM>, the more downstream the region in the flow of refrigerant in the case where the heat exchanger <NUM> operates as a condenser (the flow of refrigerant being hereinafter referred to as "defrosting-operation refrigerant flow"), the smaller the flow passage cross-sectional area of the region.

In Embodiment <NUM>, at each of the lower header <NUM> and the upper header <NUM>, a single partition plate <NUM> is provided. That is, the total number of the partition plates <NUM> is two. It should be noted that the number of the partition plates <NUM> is not limited to <NUM>, but may be <NUM> or may be larger than or equal to <NUM>. Furthermore, the heat exchange body <NUM> is partitioned by the partition plates <NUM> into three regions, that is, a first region <NUM>, a second region <NUM>, and a third region <NUM>. In the flow of refrigerant in the defrosting operation, that is, the defrosting-operation refrigerant flow, the first region <NUM> is located most upstream, and the third region <NUM> is located most downstream.

Moreover, as illustrated in <FIG>, in the first and third regions <NUM> and <NUM> of the heat exchange body <NUM>, the refrigerant flows upward in the vertical direction, that is, the flow of the refrigerant is an upward flow, and in the second region <NUM> of the heat exchange body <NUM>, the refrigerant flows downward in the vertical direction, that is, the flow of the refrigerant is a downward flow. Therefore, each of the regions of the heat exchange body <NUM> is provided such that in the region, refrigerant flows in the opposite direction to the flow direction of refrigerant that flows in the adjacent region. It should be noted that as indicated by arrows in <FIG>, the refrigerant flows through components and regions in the following order: the gas pipe <NUM>, the lower header <NUM>, the first region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, the second region <NUM> of the heat exchange body <NUM>, the lower header <NUM>, the third region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, and the liquid pipe <NUM>.

Furthermore, L1 > L2 > L3, where L1, L2, and L3 are the lengths of the first, second, and third regions <NUM>, <NUM> and <NUM> of the heat exchange body <NUM> in the horizontal direction, respectively. Therefore, the first region <NUM> of the heat exchange body <NUM> has the largest flow passage cross-sectional area, and a largest number of flat tubes <NUM> are provided in the first region <NUM>. The third region <NUM> of the heat exchange body <NUM> has the smallest flow passage cross-sectional area, and a smallest number of flat tubes <NUM> are provided. That is, in the regions of the heat exchange body <NUM>, the more downstream the region in the defrosting-operation refrigerant flow, the smaller the flow passage cross-sectional area of the region.

In such a manner, in Embodiment <NUM>, a region located downstream in the defrosting-operation refrigerant flow is made to have a smaller flow passage cross-sectional area than a region located upstream in the defrosting-operation refrigerant flow, on the premise that in these regions, the refrigerant flows at the same flow rate, whereby the velocity of the refrigerant in the above region located downstream is higher than that in the above region located upstream. Therefore, even in the case where the more downstream the region, the higher the ratio of the liquid phase of the refrigerant in the region, it is possible to reduce the possibility with which back-flow of the refrigerant will occur, and also reduce deterioration of the defrosting performance that would be caused by the back-flow of the refrigerant.

Furthermore, the heat exchanger <NUM> is configured such that in the case where the refrigerant flows upward in a region of the heat exchange body <NUM> that is located most downward when the heat exchanger <NUM> operates as a condenser, the flow of the refrigerant in the above region which is located most downstream and in which the refrigerant flows upward (which will be hereinafter referred to as "region Z") has a flooding constant C greater than <NUM>. The flooding constant C is defined based on the flow rate of refrigerant that flows into the region Z in an intermediate load capacity (<NUM>% capacity) operation when the heat exchanger <NUM> operates as a condenser.

For example, according to a well-known Wallis formula, the flooding constant C is expressed by C = JG<NUM> + JL<NUM>.

JG is a dimensionless gas apparent velocity, and JL is a dimensionless liquid apparent velocity. JG and JL are expressed by the following equations:<MAT><MAT>.

<FIG> is a diagram illustrating the flow passage cross-sectional area of a flat tube <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>.

Deq is an equivalent diameter [m] that is defined by the number N of flat tubes <NUM> disposed in the region Z and the flow passage cross-sectional areas A<NUM> (the total area of hatched areas as illustrated in <FIG>), and is calculated as Deq = [(<NUM> × Aeq)/<NUM>]<NUM>. It should be noted that Aeq is calculated as Aeq = A<NUM> × N.

ρL is the liquid density [kg/m<NUM>] of refrigerant, ρG is the gas density [kg/m<NUM>] of refrigerant, and ρL and ρG are each a state quantity that can be calculated according to the kind and pressure of refrigerant that flows into the heat exchanger <NUM>.

UG is the gas apparent velocity [m/s], and UL is the liquid apparent velocity [m/s]. UG is calculated as UG = (G × x)/ρG, and UL is calculated as UL = [G × (<NUM> - x)]/ρL.

G is calculated as G = M/A eq, where G is the maximum velocity of flow [kg/m<NUM>s] of high-temperature and high-pressure gas refrigerant that flows into the heat exchanger <NUM>, and M is the maximum quantity of flow [kg/s] of the high-temperature and high-pressure gas refrigerant that flows into the heat exchanger <NUM>.

x is the quality of the refrigerant that flows into the region Z, and can be calculated, for example, based on the amount or performance of heat exchange at the heat exchanger <NUM>. For example, assuming that the quality of the refrigerant varies from <NUM> to <NUM> between an inlet and an outlet of the heat exchanger <NUM>, and the amount of heat exchange ∝ the heat transfer area, x can be estimated by the ratio of the number of flat tubes <NUM> disposed in a region situated upstream of the region Z to the total number of flat tubes <NUM> of the heat exchanger <NUM>. For example, in Embodiment <NUM>, x can be defined as x = <NUM> - (the number of flat tubes in the first region + the number of flat tubes in the second region)/(the number of flat tubes in the first region + the number of flat tubes in the second region + the number of flat tubes in the third region).

As described above, the heat exchanger <NUM> is configured such that in the case where the refrigerant flows upward through a region of the heat exchange body <NUM> that is located most downward, when the heat exchanger <NUM> operates as a condenser, the flow of the refrigerant in the region Z of the heat exchange body <NUM> has a flooding constant C greater than <NUM>. It is therefore possible to more reliably reduce the probability that backflow of the refrigerant will occur, even in the case where the refrigerant flows upward through the region of the heat exchange body <NUM> that is located most downward when the heat exchanger <NUM> operates as a condenser.

As described above, the heat exchanger <NUM> according to Embodiment <NUM> includes the heat exchange body <NUM> including the flat tubes <NUM> spaced from each other in the horizontal direction, the upper header <NUM> provided at the upper end of the heat exchange body <NUM>, the lower header <NUM> provided at the lower end of the heat exchange body <NUM>, and the partition plate <NUM> provided in at least one of the upper header <NUM> and the lower header <NUM> to partition the heat exchange body <NUM> into a plurality of regions in the horizontal direction. The partition plate <NUM> is provided to partition off the regions such that in each of the regions, refrigerant flows in the opposite direction to the flow direction of refrigerant in one of the regions that is adjacent to the above region, and also provided such that regarding the regions, the more downstream the region in the flow direction of the refrigerant in the case where the heat exchanger <NUM> operates as a condenser, the smaller the flow passage cross-sectional area of the region.

In the heat exchanger <NUM> according to Embodiment <NUM>, the partition plate <NUM> is provided to partition the heat exchange body <NUM> into the regions such that in each of the regions, refrigerant flows in the opposite direction to the flow direction of refrigerant in the adjacent region, and also provided such that regarding the regions, the more downstream the region in the flow direction of the refrigerant in the case where the heat exchanger <NUM> operates as a condenser, the smaller the flow passage cross-sectional flow direction of the refrigerant in the case where the heat exchanger <NUM> operates as a condenser, the smaller the flow passage cross-sectional area of the region, it is possible to reduce lowering of the flow velocity of the refrigerant even when the ratio of the liquid phase of the refrigerant becomes higher, and is thus also possible to reduce the probability that backflow of the refrigerant will occur.

Furthermore, the outdoor unit <NUM> according to Embodiment <NUM> includes the above heat exchanger <NUM>. The outdoor unit <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the heat exchanger <NUM>.

Moreover, the air-conditioning apparatus <NUM> according to Embodiment <NUM> includes the above outdoor unit <NUM>. The air-conditioning apparatus <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the outdoor unit <NUM>.

Regarding Embodiment <NUM>, components that are the same as or equivalent to those in Embodiment <NUM> will be denoted by the same reference signs, and configurations, etc., that are the same as those in Embodiment <NUM> and have already been described regarding Embodiment <NUM> will not be re-described.

<FIG> is a front view schematically illustrating the flow of refrigerant in the heat exchanger <NUM> according to Embodiment <NUM> in the defrosting operation. In <FIG>, outlined arrows and dashed arrows all indicate the flow of refrigerant.

In the heat exchanger <NUM> according to Embodiment <NUM>, as illustrated in <FIG>, two partition plates <NUM> are provided in the lower header <NUM>, and a single partition plate <NUM> is provided in the upper header <NUM>. That is, a three partition plates <NUM> are provided in total. Furthermore, the heat exchange body <NUM> is partitioned by the partition plates <NUM> into four regions, that is, a first region <NUM>, a second region <NUM>, a third region <NUM>, and a fourth region <NUM>. However, the number of partition plates <NUM> is not limited to <NUM>, but may be an odd number larger than or equal to <NUM>.

A portion of the lower header <NUM> which is located most upstream in the defrosting-operation refrigerant flow and which will be hereinafter referred to as "first portion <NUM>" is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> by the gas pipe <NUM>. The first portion <NUM> of the lower header <NUM> causes, in the cooling operation, high-temperature and high-pressure gas refrigerant from the compressor <NUM> to flow into the heat exchanger <NUM>, and causes, in the heating operation, low-temperature and low-pressure gas refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

A portion of the lower header <NUM> which is located most downstream in the defrosting-operation refrigerant flow and which will be hereinafter referred to as "second portion <NUM>" is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> by the liquid pipe <NUM>. The second portion <NUM> of the lower header <NUM> causes, in the heating operation, low-temperature and low-pressure two-phase refrigerant to flow into the heat exchanger <NUM> in the heating operation, and causes, in the cooling operation, low-temperature and high-pressure liquid refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

Furthermore, as illustrated in <FIG>, in the first and third regions <NUM> and <NUM> of the heat exchange body <NUM>, the refrigerant flows upward, that is, the flow of the refrigerant is the upward flow, and in the second and fourth regions <NUM> and <NUM> of the heat exchange body <NUM>, the refrigerant flows downward, that is, the flow of the refrigerant is the downward flow. Therefore, each of the regions of the heat exchange body <NUM> is provided such that in the region, refrigerant flows in the opposite direction to that in one of the regions that is adjacent to the above region. It should be noted that in the defrosting operation, as indicated by arrows in <FIG>, the refrigerant flows through components and regions in the following order: the gas pipe <NUM>, the lower header <NUM>, the first region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, the second region <NUM> of the heat exchange body <NUM>, the lower header <NUM>, the third region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, the fourth region <NUM> of the heat exchange body <NUM>, the lower header <NUM>, and then the liquid pipe <NUM>.

Furthermore, L1 > L2 > L3 > L4, where L1, L2, L3, and L4 are the lengths of the first region <NUM>, the second region <NUM>, the third region <NUM>, and the fourth region <NUM> of the heat exchange body <NUM> in the horizontal direction, respectively. Therefore, of these regions, in the first region <NUM> of the heat exchange body <NUM>, the number of flat tubes <NUM> provided is the largest, and the first region has the largest flow passage cross-sectional area; and in the fourth region <NUM> of the heat exchange body <NUM>, the number of flat tubes <NUM> provided is the smallest, and the fourth region <NUM> has the smallest flow passage cross-sectional area. That is, regarding the regions of the heat exchange body <NUM>, in the defrosting-operation refrigerant flow, the more downstream the region, the smaller the flow passage cross-sectional area of the region.

In such a manner, the flow of the refrigerant in the fourth region <NUM> which is the most downward one of the regions of the heat exchange body <NUM> in the defrosting-operation refrigerant flow is the downward flow, whereby it is possible to reduce the probability with which backflow will occur, even in the case where the more downward the refrigerant, the higher the ratio of the liquid phase of the refrigerant. Furthermore, since a region located downstream has a smaller flow passage cross-sectional area than a region situated upstream, on the premise that in these regions, the refrigerant flows at the same flow rate, the flow velocity of refrigerant in the region situated downstream is higher than that in the region situated upstream. It is therefore possible to further reduce the probability with which backflow will occur, even in the case where the more downward the flowing refrigerant, the higher the ratio of the liquid phase of the refrigerant, and further reduce deterioration of the defrosting performance which would be caused by backflow of the refrigerant.

As described above, in the heat exchanger <NUM> according to Embodiment <NUM>, when the heat exchanger <NUM> operates as a condenser, the flow of refrigerant that flows in the most downward region is the downward flow.

In the heat exchanger <NUM> according to Embodiment <NUM>, when the heat exchanger <NUM> operates as a condenser, refrigerant that flows in the most downward region flows downward, whereby it is possible to reduce the probability with which backflow will occur, even in the case where the more downward the flowing refrigerant, the higher the ratio of the liquid phase of the refrigerant.

Moreover, the air-conditioning apparatus <NUM> according to Embodiment <NUM> includes the above outdoor unit <NUM>. The air-conditioning apparatus <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the above outdoor unit <NUM>.

<FIG> is a front view schematically illustrating the defrosting-operation refrigerant flow at a heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a cross-sectional view of the heat exchanger <NUM> that is taken along line A-A in <FIG>. In <FIG>, outlined arrows and dashed arrows all indicate the flow of refrigerant.

As illustrated in <FIG> and <FIG>, the heat exchanger <NUM> according to Embodiment <NUM> further includes an extension pipe <NUM> that extends in a longitudinal direction of the lower header <NUM>.

At least part of the extension pipe <NUM> is in contact with the lower header <NUM>. Furthermore, the extension pipe <NUM> is provided below the lower header <NUM>. The lower header <NUM> is connected to the liquid pipe <NUM>, and the extension pipe <NUM> is connected to the gas pipe <NUM>. Furthermore, an opening port <NUM> is formed at a contact position between the extension pipe <NUM> and the lower header <NUM>, whereby the extension pipe <NUM> and the lower header <NUM> communicate with each other. This opening port <NUM> is formed below the first region <NUM> of the heat exchange body <NUM>.

In the defrosting operation, as indicated by arrows in <FIG>, the refrigerant flows through components and regions in the following order: the gas pipe <NUM>, the extension pipe <NUM>, the lower header <NUM>, the first region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, the second region <NUM> of the heat exchange body <NUM>, the lower header <NUM>, the third region <NUM> of the heat exchange body <NUM>, the upper header <NUM>, the fourth region <NUM> of the heat exchange body <NUM>, the lower header <NUM>, and then the liquid pipe <NUM>.

In Embodiment <NUM>, the extension pipe <NUM> is provided to extend in parallel with the lower header <NUM>, and is at least partly in contact with the lower header <NUM>. Furthermore, the extension pipe <NUM> is provided under the lower header <NUM>. In such a manner, since the extension pipe <NUM> is at least partly in contact with the lower header <NUM>, when high-temperature and high-pressure gas refrigerant flows through the extension pipe <NUM> in the defrosting operation, heat can be transferred from the extension pipe <NUM> to the lower header <NUM>. Then, the heat transferred to the lower header <NUM> is further transferred to defrost water in the vicinity of the lower header <NUM>, thereby raising the temperature of the defrost water. Therefore, even when the heating operation is resumed after the defrosting operation ends, it is possible to reduce the probability with which the defrost water in the vicinity of the lower header <NUM> will re-freeze. As a result, it is possible to reduce deterioration of a heating performance and damage to the heat exchanger <NUM>. Furthermore, since the extension pipe <NUM> is provided under the lower header <NUM>, the extension pipe <NUM> does not obstruct the path of drainage of the defrost water, and it is therefore possible to prevent deterioration of the drainage.

<FIG> is a cross-sectional view of a modification of the heat exchanger <NUM> that is taken along line A-A in <FIG>.

In Embodiment <NUM>, the extension pipe <NUM> is provided separate from the lower header <NUM>; however, the extension pipe <NUM> may be formed integrally with the lower header <NUM>. In such a case, in the modification, a second partition plate <NUM> that divides the inside of the lower header <NUM> in the vertical direction is provided inside the lower header <NUM> as illustrated in <FIG>. Thus, the lower header <NUM> has an upper first flow passage <NUM> and a lower second flow passage <NUM>. Moreover, an upper portion of the lower header <NUM> is connected to the liquid pipe <NUM>, and the first flow passage <NUM> communicates with the liquid pipe <NUM>. Furthermore, a lower portion of the lower header <NUM> is connected to the gas pipe <NUM>, and the second flow passage <NUM> communicates with the gas pipe <NUM>. That is, a portion of the lower header <NUM> that forms the second flow passage <NUM> corresponds to the extension pipe <NUM> of Embodiment <NUM>, and a portion of the lower header <NUM> that forms the second flow passage <NUM> corresponds to the lower header <NUM> of Embodiment <NUM>.

In such a manner, in the heat exchanger <NUM> according to the modification of Embodiment <NUM>, the second flow passage <NUM> of the lower header <NUM> is formed in parallel with the first flow passage <NUM> of the lower header <NUM>, and the second flow passage <NUM> is formed adjacent to the first flow passage <NUM>, with the second partition plate <NUM> interposed between the second flow passage <NUM> and the first flow passage <NUM>. Therefore, when high-temperature and high-pressure gas refrigerant flows through the second flow passage <NUM> in the defrosting operation, heat can be transferred from the second flow passage <NUM> of the lower header <NUM> to the first flow passage <NUM> of the lower header <NUM> via the second partition plate <NUM>. Then, the heat transferred to the first flow passage <NUM> of the lower header <NUM> is further transferred to defrost water in the vicinity of the lower header <NUM>, thus raising the temperature of the defrost water. Therefore, even when the heating operation is resumed after the defrosting operation ends, it is possible to reduce the probability that the defrost water in the vicinity of the lower header <NUM> will re-freeze. Thus, it is also possible to reduce deterioration of the heating performance and damage to the heat exchanger <NUM>. Furthermore, since the second flow passage <NUM> of the lower header <NUM> is provided under the first flow passage <NUM> of the lower header <NUM>, the second flow passage <NUM> does not obstruct the path of drainage of the defrost water, and it is therefore possible to prevent deterioration of the drainage.

As described above, the heat exchanger <NUM> according to Embodiment <NUM> includes an extension pipe <NUM> through which the refrigerant flows out when the heat exchanger <NUM> operates as an evaporator and through which the refrigerant flows in when the heat exchanger <NUM> operates as a condenser. Moreover, the extension pipe <NUM> is provided to extend in the longitudinal direction of the lower header <NUM> and is at least partly in contact with the lower header <NUM>.

In the heat exchanger <NUM> according to Embodiment <NUM>, since the extension pipe <NUM> is at least partly in contact with the lower header <NUM>, when high-temperature and high-pressure gas refrigerant flows through the extension pipe <NUM> in the defrosting operation, heat can be transferred from the extension pipe <NUM> to the lower header <NUM>. Then, the heat transferred to the lower header <NUM> is further transferred to defrost water in the vicinity of the lower header <NUM>, thereby raising the temperature of the defrost water. Therefore, even when the heating operation is resumed after the defrosting operation ends, it is possible to reduce the probability with which the defrost water in the vicinity of the lower header <NUM> will re-freeze. As a result, it is also possible to reduce deterioration of the heating performance and damage to the heat exchanger <NUM>.

The outdoor unit <NUM> according to Embodiment <NUM> includes the above heat exchanger <NUM>. The outdoor unit <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the heat exchanger <NUM>.

The air-conditioning apparatus <NUM> according to Embodiment <NUM> includes the above outdoor unit <NUM>. The air-conditioning apparatus <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the outdoor unit <NUM>.

<FIG> is a front view schematically illustrating a bending region <NUM> of a heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a plan view schematically illustrating the bending region <NUM> of the heat exchanger <NUM> according to Embodiment <NUM>.

The heat exchanger <NUM> may be subjected to bending, for example, in order to improve the heat exchange performance by densely mounting the heat exchanger <NUM> in the outdoor unit <NUM> and to make the outdoor unit <NUM> smaller. In that case, the bending is performed on the inside of the bending region <NUM> as illustrated in <FIG>. Also, in this case, in the case where the partition plate <NUM> is provided in the bending region <NUM>, the partition plate <NUM> is deformed when the heat exchanger <NUM> is subjected to the bending, thus deteriorating the heat exchange performance. In view of this point, in Embodiment <NUM>, the partition plate <NUM> is not provided in the bending region <NUM>, but is provided outside the bending region <NUM>. In such a manner, since the partition plate <NUM> is provided outside the bending region <NUM>, the partition plate <NUM> is not deformed even when the heat exchanger <NUM> is subjected to the bending. It is therefore possible to reduce deterioration of the heat exchange performance while improving the heat exchange performance and reducing the size of the outdoor unit <NUM>.

As described above, in the heat exchanger <NUM> according to Embodiment <NUM>, the upper header <NUM> and the lower header <NUM> have a bending region <NUM> where the heat exchanger <NUM> is subjected to the bending, and the partition plate <NUM> is provided in a region other than the bending region <NUM>.

In the heat exchanger <NUM> according to Embodiment <NUM>, the partition plate <NUM> is provided outside the bending region <NUM>, whereby the partition plate <NUM> is not deformed even when the heat exchanger <NUM> is subjected to the bending. It is therefore possible to reduce the deterioration of the heat exchange performance while improving the heat exchange performance and reducing the size of the outdoor unit <NUM>.

Furthermore, the air-conditioning apparatus <NUM> according to Embodiment <NUM> includes the above outdoor unit <NUM>. The air-conditioning apparatus <NUM> according to Embodiment <NUM> can obtain similar advantages to those of the outdoor unit <NUM>.

<FIG> is a front view schematically illustrating the defrosting-operation refrigerant flow at a heat exchanger <NUM> according to Embodiment <NUM>. In <FIG>, outlined arrows and dashed arrows all indicate the flow of refrigerant.

As illustrated in <FIG>, the heat exchanger <NUM> according to Embodiment <NUM> has a plurality of heat exchange units. Specifically, the heat exchanger <NUM> includes a first heat exchange unit 30a and a second heat exchange unit 30b. The first heat exchange unit 30a includes a first heat exchange body 31a, a first lower header 34a, and a first upper header 35a. The first heat exchange body 31a includes a plurality of flat tubes <NUM> and a plurality of fins <NUM>. The first lower header 34a is provided at a lower end of the first heat exchange body 31a. The first upper header 35a is provided at an upper end of the first heat exchange body 31a. Furthermore, the second heat exchange unit 30b includes a second heat exchange body 31b, a second lower header 34b, and a second upper header 35b. The second heat exchange body 31b includes a plurality of flat tubes <NUM> and a plurality of fins <NUM>. The second lower header 34b is provided at a lower end of the second heat exchange body 31b. The second upper header 35b is provided at an upper end of the second heat exchange body 31b.

The first lower header 34a is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> by the gas pipe <NUM>. The first lower header 34a causes, in the cooling operation, high-temperature and high-pressure gas refrigerant from the compressor <NUM> to flow into the heat exchanger <NUM>, and causes, in the heating operation, low-temperature and low-pressure gas refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

The second lower header 34b is connected to the refrigerant circuit of the air-conditioning apparatus <NUM> by the liquid pipe <NUM>. The second lower header 34b causes, in the heating operation, low-temperature and low-pressure two-phase refrigerant to flow into the heat exchanger <NUM>, and causes, in the cooling operation, low-temperature and high-pressure liquid refrigerant subjected to heat exchange at the heat exchanger <NUM> to flow out therefrom to the refrigerant circuit.

Furthermore, the first upper header 35a and the second upper header 35b are connected to each other by a connecting pipe <NUM> to communicate with each other. Instead of the first upper header 35a and the second upper header 35b, the first lower header 34a and the second lower header 34b may be connected to each other by the connecting pipe <NUM> to communicate with each other. In this case, in Embodiment <NUM>, the gas pipe <NUM> is connected to the first upper header 35a, and the liquid pipe <NUM> is connected to the second lower header 34b.

Furthermore, in the second heat exchange unit 30b, partition plates <NUM> are provided. To be more specific, in the second lower header 34b and the second upper header 35b, respective partition plates <NUM> are provided. That is, the total number of partition plates <NUM> is two. The second heat exchange body 31b is partitioned by the partition plates <NUM> into three regions, namely a first region 31b1, a second region 31b2, and a third region 31b3. However, the number of partition plates <NUM> is not limited to <NUM>, but may be <NUM> or may be larger than or equal to <NUM>. It should be noted that in the first heat exchange unit 30a, no partition plate <NUM> is provided.

Moreover, as illustrated in <FIG>, in the first and third regions 31b1 and 31b3 of the second heat exchange body 31b, the refrigerant flows upward, that is, the flow of the refrigerant is the upward flow, and in the second region 31b2 of the second heat exchange body 31b, the refrigerant flows downward, that is, the flow of the refrigerant is the downward flow. Furthermore, in the first heat exchange body 31a, the refrigerant flows upward. Therefore, each of the regions of the heat exchange body <NUM> is provided such that in the region, the refrigerant flows in the opposite direction to the flow direction of the refrigerant in one of the regions that is adjacent to the above region. It should be noted that in the defrosting operation, as indicated by arrows in <FIG>, the refrigerant flows through components and regions in the following order: the gas pipe <NUM>, the first lower header 34a, the first heat exchange body 31a, the first upper header 35a, the connecting pipe <NUM>, a first region 35b1 of the second upper header 35b, the first region 31b1 of the second heat exchange body 31b, a first flow passage 34b1 of the second lower header 34b, the second region 31b2 of the second heat exchange body 31b, a second region 35b2 of the second upper header 35b, the third region 31b3 of the second heat exchange body 31b, a second flow passage 34b2 of the second lower header 34b, and then the liquid pipe <NUM>.

Furthermore, L1 > L2 > L3 > L4, where L1, L2, L3, and L4 are the lengths of the first heat exchange body 31a and the first region 31b1, second region 31b2 and third regions 31b3 of the second heat exchange body 31b in the horizontal direction, respectively. Therefore, in the first heat exchange body 31a, the number of flat tubes <NUM> provided is the largest, and the first heat exchange body 31a has the largest flow passage cross-sectional area; and in the third region 31b3 of the second heat exchange body 31b, the number of flat tubes <NUM> provided is the smallest, and the third region 31b has the smallest flow passage cross-sectional area. That is, the above regions, that is, the first heat exchange body 31a and the regions of the second heat exchange body 31b, are provided such that the most downstream the region in the defrosting-operation refrigerant flow, the smaller the flow passage cross-sectional area of the region.

In such a manner, in the defrosting-operation refrigerant flow, in a region located downstream, the flow passage cross-sectional area is made smaller than that of a region located upstream, on the premise that in these regions, the refrigerant flows at the same flow rate, whereby the flow velocity of the refrigerant in the region located downstream can be higher than that in the region located upstream. It is therefore possible to reduce the probability with which backflow of the refrigerant will occur, even in the case where the more downstream the refrigerant, the higher the ratio of the liquid phase of the refrigerant, and is also possible to reduce deterioration of the defrosting performance which would be caused by the backflow of the refrigerant.

Furthermore, the heat exchanger <NUM> is formed to include the first heat exchange unit 30a and the second heat exchange unit 30b, and the first heat exchange unit 30a and the second heat exchange unit 30b are connected by the connecting pipe <NUM>, whereby the heat exchanger <NUM> can be easily subjected to the bending. Furthermore, since the first heat exchange unit 30a and the second heat exchange unit 30b are connected to each other, it suffices that the gas pipe <NUM> is connected only to a header of either the first heat exchange unit 30a or the second heat exchange unit 30b. It is therefore possible to reduce the space for pipe arrangement, and improve the heat exchange performance by densely mounting the heat exchanger <NUM> in the outdoor unit <NUM>.

Although it is described above that the heat exchanger <NUM> according to Embodiment <NUM> includes two heat exchange units, it is not limiting. The heat exchanger <NUM> may include three or more heat exchange units. In the case where the heat exchanger <NUM> includes three or more heat exchange units, the upper headers or lower headers of adjacent ones of the heat exchange units are connected to each other by the connecting pipe <NUM>, and the adjacent heat exchange units communicate with each other through the upper headers or the lower headers.

As described above, in the heat exchanger <NUM> according to Embodiment <NUM>, the heat exchange body <NUM> includes a first heat exchange body 31a and a second heat exchange body 31b. Furthermore, the upper header <NUM> includes a first upper header 35a provided at an upper end of the first heat exchange body 31a and a second upper header 35b provided at an upper end of the second heat exchange body 31b. Furthermore, the lower header <NUM> includes a first lower header 34a provided at a lower end of the first heat exchange body 31a and a second lower header 34b provided at a lower end of the second heat exchange body 31b. In addition, the first upper header 35a and the second upper header 35b or the first lower header 34a and the second lower header 34b are connected to each other by the connecting pipe <NUM> to communicate with each other.

In the heat exchanger <NUM> according to Embodiment <NUM>, since the first upper header 35a and the second upper header 35b or the first lower header 34a and the second lower header 34b are connected to each other by the connecting pipe <NUM> to communicate with each other, the heat exchanger <NUM> can be easily subjected to the bending. Furthermore, since the first heat exchange unit 30a and the second heat exchange unit 30b are connected to each other, it suffices that the gas pipe <NUM> is connected only to a header of either the first heat exchange unit 30a or the second heat exchange unit 30b. It is therefore possible to reduce the space for pipe arrangement, and improve the heat exchange performance by densely mounting the heat exchanger <NUM> in the outdoor unit <NUM>.

<FIG> is a front view schematically illustrating the defrosting-operation refrigerant flow at a heat exchanger <NUM> according to Embodiment <NUM>.

In the heat exchanger <NUM> according to Embodiment <NUM>, as illustrated in <FIG>, the first heat exchange body 31a and the second heat exchange body 31b have different lengths in the vertical direction, and the first heat exchange body 31a is longer than the second heat exchange body 31b. Furthermore, the first heat exchange body 31a and the second heat exchange body 31b are provided at the same level, or the first heat exchange body 31a is provided at a higher level than the second heat exchange body 31b.

Moreover, the first upper header 35a and the second upper header 35b are connected to each other by a connecting pipe <NUM> to communicate with each other.

Thus, in the defrosting-operation refrigerant flow, the refrigerant flows downward or in the horizontal direction in the connecting pipe <NUM>. It is therefore possible to reduce the probability with which backflow will occur that would do if the refrigerant flows upward in the connecting pipe <NUM>, and also to reduce deterioration of the defrosting performance which would be caused by backflow of the refrigerant.

The heat exchanger <NUM> according to Embodiment <NUM> includes two heat exchange units; however, the number of heat exchange units in the heat exchanger <NUM> is not limited to two. The heat exchanger <NUM> may include three or more heat exchange units. In the case where the heat exchanger <NUM> includes three or more heat exchange units, the upper headers or lower headers of adjacent ones of the heat exchange units are connected to each other by a connecting pipe <NUM>, and the adjacent heat exchange units communicate with each other through the upper headers or the lower headers; and also in the defrosting-operation refrigerant flow, the refrigerant flows downward or in the horizontal direction through each connecting pipe <NUM>.

As described above, in the heat exchanger <NUM> according to Embodiment <NUM>, the first heat exchange body 31a and the second heat exchange body 31b have different lengths, and when the heat exchanger <NUM> operates as a condenser, the refrigerant flows downward or in the horizontal direction through the connecting pipe <NUM>.

In the heat exchanger <NUM> according to Embodiment <NUM>, when the heat exchanger <NUM> operates as a condenser, in the connecting pipe <NUM>, the refrigerant flows downward or horizontally. It is therefore possible to reduce the probability with which backflow will occur that would do if the refrigerant flows upward in the connecting pipe <NUM>, and also to reduce deterioration of the defrosting performance which would be caused by backflow of the refrigerant.

Regarding Embodiment <NUM>, components that are the same as or equivalent to those in any of Embodiments <NUM> to <NUM> will be denoted by the same reference signs, and configurations, etc., that are the same as those in any of Embodiments <NUM> to <NUM> and have already been described regarding Embodiments <NUM> to <NUM> will not be re-described.

<FIG> is a perspective view schematically illustrating related components of a heat exchanger <NUM> according to Embodiment <NUM>.

As illustrated in <FIG>, the heat exchanger <NUM> according to Embodiment <NUM> includes a plurality of flat tubes <NUM> and a plurality of corrugated fins 39a. Each of the corrugated fins 39a is formed in a corrugated shape and has a plurality of apices <NUM>, and each of the apices <NUM> is in surface contact with a flat surface of an associated adjacent one of the flat tubes <NUM>, except for an end of the apex <NUM> that projects upstream in the flow direction of air (hereinafter referred to as "first direction") in the space between associated two flat tubes <NUM>. It should be noted that the corrugated fin 39a is joined to the flat tubes <NUM> by brazing. The corrugated fin 39a is made, for example, of a plate material of an aluminum alloy. Moreover, a brazing filler metal layer is stacked on a surface of the plate material, and the brazing filler metal layer is formed, for example, of a brazing filler metal containing Al-Si based aluminum. Furthermore, the plate material has a plate thickness of approximately <NUM> to <NUM>.

The corrugated fin 39a has fin surfaces <NUM> each of which is located between associated ones of the apices <NUM> that are adjacent in a direction in which the flat tubes <NUM> are arranged (which will be hereinafter referred to as "second direction") of the flat tubes <NUM>, and the fin surfaces <NUM> are arranged in a height direction. Furthermore, each of the fin surfaces <NUM> has louvers <NUM> and a drainage slit <NUM>. The louvers <NUM> are arranged in the first direction at the fin surface <NUM>. That is, the louvers <NUM> are arranged in the flow direction of air. The louvers <NUM> are formed by cutting and raising parts of the fin surface <NUM>. Also, by cutting up parts of the fin surface <NUM>, slits 360a are formed in positions associated with the louvers <NUM> to allow air to pass through the slits 360a. The louvers <NUM> serve to guide air that passes through the slits 360a.

The fin surfaces <NUM> have drainage slits <NUM> each of which is formed close to a central portion of an associated one of the fin surfaces <NUM> in the first direction, and each of which allows water on the fin surface <NUM> to be let out. The drainage slits <NUM> each have a rectangle extending in the second direction. As described later, the drainage slits <NUM> of ones of the fin surfaces <NUM> that are adjacent to each other at least in the height direction are located such that central positions of the above drainage slits <NUM> in the second direction are displaced from each other, and the positions of ends of the above drainage slits <NUM> are different from each other in the second direction.

When the heat exchanger <NUM> operates as an evaporator, the temperatures of the surfaces of the flat tubes <NUM> and the corrugated fins 39a are lower than that of air that passes through the heat exchanger <NUM>. Therefore, moisture in the air condenses on the surfaces of the flat tubes <NUM> and the corrugated fins 39a, thereby generating condensed water <NUM>.

Condensed water <NUM> generated on each of the fin surfaces <NUM> of each of the corrugated fins 39a flows through an associated drainage slit <NUM> and falls onto an associated lower fin surface <NUM>. In this case, in a region where the amount of the condensed water <NUM> is large, the condensed water <NUM> easily flows over the fin surface <NUM>, and thus also easily falls onto the lower fin surface <NUM> through the drainage slit <NUM>. On the other hand, in a region where the amount of the condensed water <NUM> is small, the condensed water <NUM> is easily retained and stay on the above fin surface <NUM>, and does not easily flow over the fin surface <NUM>.

<FIG> is a front view schematically illustrating the heat exchanger <NUM> according to Embodiment <NUM>. <FIG> is a diagram for explanation of positional relationships between drainage slits <NUM> in fin surfaces <NUM> of corrugated fins 39a as illustrated in <FIG>. It should be noted that (a) to (e) in <FIG> illustrate fin surfaces <NUM> located at positions (a) to (e) in <FIG>, respectively.

As described above, as illustrated in <FIG> and <FIG>, the drainage slits <NUM> of ones of the fin surfaces <NUM> that are adjacent to each other at least in the height direction are located such that the central positions of the above drainage slits <NUM> in the second direction are displaced from each other, and the positions of the ends of the above drainage slits <NUM> are different from each other in the second direction. In the heat exchanger <NUM> according to Embodiment <NUM>, although it is not limited, it is assumed that the drainage slits <NUM> of the fin surfaces <NUM> of each of the corrugated fins 39a are provided such that drainage slits <NUM> whose central positions in the second direction are the same as each other are periodically located in the corrugated fin 39a.

Therefore, condensed water <NUM> that has fallen, from an end of a drainage slit <NUM> in a fin surface <NUM> in the second direction, falls onto a subsequent lower fin surface <NUM>. Then, the condensed water <NUM> that has fallen onto the subsequent lower fin surface <NUM> joins condensed water <NUM> retained on the subsequent lower fin surface <NUM>. Thus, the amount of resultant condensed water <NUM> obtained by the above joining is increased, and this condensed water <NUM> easily falls through the drainage slit <NUM> of the above subsequent lower fin surface <NUM>, onto a further subsequent lower fin surface <NUM>. Therefore, the amount of condensed water <NUM> retained on the fin surface <NUM> is decreased. Accordingly, it is possible to efficiently drain water and reduce the deterioration of the defrosting operation.

<FIG> is a diagram for explanation of the flow of condensed water <NUM> on surfaces of a corrugated fin 39a in the heat exchanger <NUM> according to Embodiment <NUM>.

An apex <NUM> of the corrugated fin 39a that is joined to a flat tube <NUM> is formed by bending the corrugated fin 39a, and at the apex <NUM>, the distance between fin surfaces <NUM> is short. Thus, condensed water <NUM> at the apex <NUM> is easily retained and stay at the apex <NUM> by surface tension.

In the heat exchanger <NUM> according to Embodiment <NUM>, for example, as illustrated in (d) and (e) in <FIG> and <FIG>, at a fin surface <NUM>, an end of a drainage slit <NUM> in the second direction can be provided at or near the apex <NUM>. At the fin surface <NUM>, in the case where the end of the drainage slit <NUM> in the second direction is located at or near the apex <NUM>, condensed water <NUM> at the apex <NUM> and condensed water <NUM> that falls from an upper fin surface <NUM> can join each other, whereby the effect of the surface tension is eliminated, and the condensed water <NUM> at the apex <NUM> thus flows out from the apex <NUM> and falls onto a lower fin surface <NUM>. Furthermore, drainage slits <NUM> are provided at both ends of an associated one of respective fin surfaces <NUM> in the second direction as illustrated in (a) to (c) in <FIG>, whereby it is possible to further efficiently drain water.

As described above, in the heat exchanger <NUM> according to Embodiment <NUM>, the fin surfaces <NUM> have respective drainage slits <NUM> for drainage of water, and positions of ends of the drainage slits <NUM> formed in ones of the fin surfaces <NUM> that are adjacent to each other in the height direction are different from each other in an arrangement direction of the flat tubes <NUM> in which they are arranged.

In the heat exchanger <NUM> according to Embodiment <NUM>, condensed water <NUM> having fallen from an end of a drainage slit <NUM> in each fin surface <NUM> in the arrangement direction of the flat tubes <NUM> falls onto a subsequent lower fin surface <NUM>. Then, the condensed water <NUM> that has fallen onto the subsequent lower fin surface <NUM> joins condensed water <NUM> retained on the lower fin surface <NUM>, whereby those condensed water <NUM> is combined, the amount of the combined condensed water <NUM> increases, and the combined condensed water <NUM> easily flows and fall onto a further lower in surface <NUM> through an associated drainage slit <NUM>. Thus, the amount of the above condensed water <NUM> retained on the fin surface <NUM> decreases. It is therefore possible to efficiently drain water, and reduce the deterioration of the defrosting operation.

Claim 1:
A heat exchanger (<NUM>) comprising:
a heat exchange body (<NUM>) having a plurality of flat tubes (<NUM>) arranged and spaced from each other in a horizontal direction;
an upper header (<NUM>) provided at an upper end of the heat exchange body (<NUM>);
a lower header (<NUM>) provided at a lower end of the heat exchange body (<NUM>); and
a partition plate (<NUM>) provided in at least one of the upper header (<NUM>) and the lower header (<NUM>) to partition the heat exchange body (<NUM>) into a plurality of regions in a horizontal direction,
the partition plate (<NUM>) is provided such that in each of the regions, refrigerant flows in the opposite direction to a flow direction of the refrigerant in an adjacent one of the regions, and is provided such that regarding the regions, the more downward a region in a flow of the refrigerant when the heat exchanger (<NUM>) operates as a condenser, the smaller a flow passage cross-sectional area of the region, the heat exchanger being characterized in that the upper header (<NUM>) and the lower header (<NUM>) have a bending region (<NUM>) in which bending is performed, and in that
the partition plate (<NUM>) is provided in a region other than the bending region (<NUM>).