Heat exchanger, air conditioner and operating method for air conditioner

Abstract

To provide a heat exchanger capable of improving frosting-proof capacity and suppressing residual ice during a defrosting operation and suppressing deterioration of defrosting performance and an air conditioner.SOLUTION: A heat exchanger includes a plurality of flat heat transfer pipes and a corrugated fin, and removes frost formed on the corrugated fin by using a hot gas refrigerant when serving as an evaporator. A front edge part of the corrugated fin projects to the windward of pipe front end parts of the plurality of heat transfer pipes. A fin part includes: a front edge projecting part on the windward side of a brazing part located on the most windward side of the plurality of heat transfer pipes and the corrugated fin; and a plurality of louvers each having a louver slit and an inclined plate part. Viewed in the pipe axial direction of the plurality of heat transfer pipes, when a dimension of the fin part in the air flowing direction is defined as fin length LF and a minimum line segment length between the position of the front edge part and the position of the pipe front part is defined as Lt, relation of Lt / LF satisfies a formula of 0<Lt / LF<0.22. During a defrosting operation when an outside air temperature is lower than 0°C and wind blows to the heat exchanger, generation of residual ice at a tip part of the fin is suppressed.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a heat exchanger having corrugated fins, an air conditioner, and an operation method of the air conditioner.

Background Art

[0002] Conventionally, in a heat exchanger that functions as an evaporator with low-temperature outside air, a heat exchanger has been proposed in which the front edge of a corrugated fin protrudes from the tip of a flat tube (see, for example, Patent Document 1). By adopting such a structure, the heat exchanger of Patent Document 1 reduces the fin efficiency at the front edge of the fin and relatively raises the temperature at the tip, thereby suppressing the frosting amount at the front edge of the fin of the heat exchanger and improving the frost resistance. It is also said that damage due to deformation can be prevented. Note that the fin efficiency is the ratio of the amount of heat energy actually radiated from the fin to the amount of heat radiation when the temperature of the fin is uniform throughout the area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The heat exchanger of Patent Document 1 is a heat exchanger in which flat tubes are arranged so as to extend in the vertical direction, and corrugated fins are sandwiched between the flat tubes. When attempting to improve the frost resistance and form fins protruding from the flat tubes as in the heat exchanger of Patent Document 1, although the frost resistance of the heat exchanger is improved during the frosting operation, during the defrosting operation, the frost is less likely to melt at the tip of the fins, and residual ice may be generated. In particular, under conditions where the heat exchanger is exposed to external wind, the water melted at the tip of the fins is difficult to drain, and the protruding portions of the fins protruding from the flat tubes are refrozen by the external wind again, causing a significant decrease in the defrosting performance.

[0005] In order to solve the above problems, an object of the present disclosure is to obtain a heat exchanger, an air conditioner, and an operation method of the air conditioner that can achieve both an improvement in frost resistance and suppression of the generation of residual ice during the defrosting operation, and suppress a decrease in the defrosting performance.

Means for Solving the Problems

[0006] A heat exchanger according to the present disclosure includes a plurality of flat heat transfer tubes each having a flat cross section and a plurality of flow paths formed by through holes, the flat heat transfer tubes being arranged vertically and spaced apart from one another, and corrugated fins being arranged between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, and when frost forms on the surfaces of the corrugated fins while the heat exchanger functions as an evaporator, the heat exchanger performs a defrosting operation to remove the formed frost by flowing hot gas refrigerant through the corrugated fins, and the corrugated fins are formed so that plate-like fin portions are connected in a wave-like pattern in the tube axial direction of the plurality of flat heat transfer tubes, and a direction perpendicular to the tube axial direction and the tube juxtaposition direction in which the plurality of flat heat transfer tubes are arranged in a juxtaposition direction is defined as an air flow direction. When the above formula is used, in the air flow direction, among the plurality of flat heat transfer tubes, the leading edge portion, which is the tip of the windward side of the corrugated fin, protrudes so as to be positioned on the windward side relative to the flow of air flowing between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, and the fin portion includes a leading edge protrusion that forms a portion extended on the windward side relative to the brazed portion of the portion located most windward between the plurality of flat heat transfer tubes and the corrugated fin, and a plurality of louvers having louver slits extending in the tube juxtaposition direction and plate portions inclined with respect to the flat plate portion of the fin portion, and the dimension of the fin portion in the air flow direction when viewed in the tube axial direction of the plurality of flat heat transfer tubes is defined as the fin length L F The minimum line length between the leading edge and the front end of the pipe in the air flow direction is L t When the L t / L F The relationship between <L t / L F <0.22, the formation of residual ice at the tip of the fin section is suppressed during defrosting operation when the outside air temperature is below 0°C and wind is blowing toward the heat exchanger.

[0007] An air conditioning apparatus according to the present disclosure includes the above-described heat exchanger.

[0008] In addition, the operation method of the air conditioner according to the present disclosure is an operation method of an air conditioner including a heat exchanger that functions as an evaporator. The heat exchanger has a plurality of flow paths formed by through holes and a flat cross section, and includes a plurality of flat heat transfer tubes arranged vertically and spaced apart from each other, and corrugated fins disposed between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes. The corrugated fins are formed such that a plate-shaped fin portion extends in a wave shape in the tube axis direction of the plurality of flat heat transfer tubes. When the air flow direction is defined as the direction orthogonal to the tube axis direction and the tube arrangement direction (the direction in which the plurality of flat heat transfer tubes are arranged side by side), in the air flow direction, the leading edge portion, which is the tip portion on the upwind side of the corrugated fins with respect to the air flow flowing between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, protrudes so as to be located more upstream than the tube front end portion, which is the tip portion on the upwind side of the plurality of flat heat transfer tubes. The fin portion includes a front edge protruding portion that constitutes a portion extending upstream from the brazed portion of the portion located most upstream among the plurality of flat heat transfer tubes and the corrugated fins, and a plurality of louvers having a louver slit extending in the tube arrangement direction and a plate portion inclined with respect to the flat plate portion of the fin portion. When viewed in the tube axis direction of the plurality of flat heat transfer tubes, the dimension of the fin portion in the air flow direction is defined as the fin length L F and the minimum line segment length between the position of the leading edge portion and the position of the tube front end portion in the air flow direction is defined as L t In the case where it is defined, the relationship of L t / L F in the fin portion and the plurality of flat heat transfer tubes satisfies the formula 0 < L t / L F < 0.22. In the defrosting operation of removing frost formed on the surface of the corrugated fins by flowing hot gas refrigerant through the heat exchanger under the condition that the outside air temperature is less than 0°C and wind blows against the heat exchanger, defrosting is performed so that no frost remains at the tip of the fin portion.

Advantages of the Invention

[0009] The heat exchanger, air conditioner, and method for operating an air conditioner according to the present disclosure include a front edge protruding portion in which the fin portion of the heat exchanger extends upstream of the brazed portion of the portion located most upstream of the plurality of flat heat transfer tubes and the corrugated fins. Further, in the heat exchanger, the relationship between L t / L F satisfies the formula 0 < L t / L F < 0.22. By having the above configuration, the heat exchanger can achieve both improved frost resistance and suppression of the generation of remaining ice during the defrosting operation, and can suppress a decrease in defrosting performance.

Brief Description of the Drawings

[0010]

Figure 1

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Modes for Carrying Out the Invention

[0011] Hereinafter, the heat exchanger and the air conditioner according to the embodiments will be described with reference to the accompanying drawings and the like. In the following drawings, those denoted by the same reference numerals are the same or corresponding to each other, and are common throughout the entire text of the embodiments described below. And the form of the constituent elements shown throughout the specification is merely an example, and is not limited to the form described in the specification. In particular, the combination of constituent elements is not limited to the combination in each embodiment, and the constituent elements described in other embodiments can be applied to other embodiments. Further, in the following description, the upper side in the figure is referred to as the "upper side" and the lower side as the "lower side" for explanation. Furthermore, for the sake of easy understanding, terms indicating directions (such as "right", "left", etc.) are used as appropriate, but these are for the purpose of explanation, and the present disclosure is not limited by these terms. Also, regarding the high and low of humidity and temperature, they are not determined in relation to absolute values in particular, but are relatively determined in the state and operation of the device and the like. And in the drawings, the relationship of the sizes of the respective constituent members may be different from the actual ones.

[0012] Embodiment 1. [Configuration of Heat Exchanger 10] FIG. 1 is a diagram for explaining the configuration of the heat exchanger 10 according to Embodiment 1. The arrows in FIG. 1 indicate the flow of the refrigerant when the heat exchanger 10 is used as an evaporator. When the heat exchanger 10 is used as an evaporator, a low-temperature and low-pressure refrigerant flows through the refrigerant flow path inside the flat heat transfer tube 1. When the heat exchanger 10 is used as a condenser, a high-temperature and high-pressure refrigerant flows through the refrigerant flow path inside the flat heat transfer tube 1.

[0013] As shown in FIG. 1, the heat exchanger 10 of Embodiment 1 is a corrugated fin tube type heat exchanger having a parallel piping configuration. The heat exchanger 10 includes a plurality of flat heat transfer tubes 1, a plurality of corrugated fins 2, and a pair of headers 3.

[0014] The pair of headers 3 are each connected by piping to other devices constituting the air conditioner 90 (see FIG. 28), and are pipes through which the refrigerant, which is a fluid serving as a heat exchange medium, flows in and out, and branches or merges the refrigerant. The pair of headers 3 includes a first header 3A and a second header 3B. The first header 3A and the second header 3B are arranged at intervals in the vertical direction. When the heat exchanger 10 is used as an evaporator, the liquid refrigerant passes through the upper second header 3B, and the gaseous refrigerant passes through the lower first header 3A. When the heat exchanger 10 is used as a condenser, the gaseous refrigerant passes through the upper second header 3B, and the liquid refrigerant passes through the lower first header 3A.

[0015] Between the pair of headers 3, a plurality of flat heat transfer tubes 1 are arranged perpendicular to each header 3, and the plurality of flat heat transfer tubes 1 are arranged parallel to each other. The plurality of flat heat transfer tubes 1 are arranged in parallel at equal intervals in a direction orthogonal to the air flow direction Y (see FIG. 2). The plurality of flat heat transfer tubes 1 are arranged in parallel with a space therebetween. Hereinafter, the direction in which the plurality of flat heat transfer tubes 1 are arranged in parallel (the left-right direction in FIG. 1) is referred to as the "tube parallel arrangement direction X", and the axial direction of the flat heat transfer tube 1 (the up-down direction in FIG. 1) is referred to as the "tube axial direction Z". The tube axial direction Z is the up-down direction of the heat exchanger 10. Also, the direction orthogonal to the "tube parallel arrangement direction X" and the "tube axial direction Z" is referred to as the "air flow direction Y". In the air flow direction Y, air flows in the direction of the white arrows described later (see FIGS. 2 to 4).

[0016] FIG. 2 is a schematic perspective view of a part of the heat exchanger 10 according to Embodiment 1. The white arrow in FIG. 2 indicates the direction in which air flows. The flat heat transfer tube 1 has a flat cross-section. The flat heat transfer tube 1 is a heat transfer tube in which the outer surface on the longitudinal side of the flat cross-section (hereinafter referred to as the flat surface 1a) is planar, and the outer surface on the short side of the flat shape is curved. The flat heat transfer tube 1 is a multi-hole flat heat transfer tube having a plurality of flow paths 1b formed by through holes inside the tube.

[0017] Each flat heat transfer tube 1 is arranged vertically. The through holes of the flat heat transfer tube 1 extend in the vertical direction and communicate with a pair of headers 3. The flat heat transfer tube 1 is arranged such that the longitudinal side of the flat cross-section is along the air flow direction Y. Both ends of each flat heat transfer tube 1 are inserted into insertion holes (not shown) formed in each of the pair of headers 3 and brazed, thereby being joined to the pair of headers 3. As the brazing filler metal, for example, a filler metal containing aluminum is used.

[0018] Between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1, corrugated fins 2 are arranged. The corrugated fins 2 are arranged to increase the heat transfer area between the refrigerant and the outside air. The corrugated fins 2 are formed such that plate-like fin portions 24 described later are alternately folded back in the tube axis direction Z of the plurality of flat heat transfer tubes 1. The corrugated fins 2 are formed by corrugating a flat plate-like fin material and are bent by a zigzag folding that repeats mountain folds and valley folds, and are formed in a wave shape like a bellows. Here, the bent portions due to the unevenness formed in the wave shape become the tops of the wave shape. In Embodiment 1, the tops of the corrugated fins 2 are arranged in the height direction. The corrugated fins 2 are formed such that plate-like fin portions 24 described later are connected in a wave shape in the tube axis direction Z of the plurality of flat heat transfer tubes 1.

[0019] FIG. 3 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 according to Embodiment 1, cut along the air flow direction Y. The white arrows in FIG. 3 indicate the direction in which air flows. The diagonal solid arrows in FIG. 3 indicate the flow of condensed water 4. The condensed water 4 is water formed by condensation of moisture in the air and adhering to the surface of the heat exchanger 10. As shown in FIGS. 2 and 3, the corrugated fin 2 is joined to the flat surface 1a of the flat heat transfer tube 1, excluding a front edge protruding portion 2a, which will be described later, protruding upstream of the flat heat transfer tube 1 in the air flow direction Y. This joined portion is brazed and joined with a brazing material.

[0020] The material of the fin material constituting the corrugated fin 2 is, for example, an aluminum alloy. And a brazing material layer is clad on the surface of the fin material constituting the corrugated fin 2. The main material of the clad brazing material layer is, for example, a brazing material containing aluminum of an aluminum-silicon system. Here, the plate thickness of the fin material constituting the corrugated fin 2 is about 50 μm to 200 μm, for example.

[0021] The corrugated fin 2 has a configuration in which plate-like fin portions 24 are connected in a wave shape in the tube axis direction Z. The corrugated fin 2 has a shape in which the fin portions 24 are connected in the tube axis direction Z with alternately reverse inclinations when viewed in the air flow direction Y. The fin portion 24 has a flat plate portion 21 in a flat plate shape and curved top portions 20 at both ends of the flat plate portion 21 in the tube juxtaposition direction X. The corrugated fin 2 is joined to the flat heat transfer tube 1 in surface contact with the flat surface 1a of the flat heat transfer tube 1 at the top portion 20.

[0022] A plurality of louvers 22 are formed side by side in the air flow direction Y in the fin portion 24. The louver 22 has a louver slit 22a through which air passes and a plate portion 22b that guides air to the louver slit 22a. The plate portion 22b is inclined with respect to the flat plate portion 21. The louver slit 22a and the plate portion 22b are configured in a rectangular shape extending in the tube juxtaposition direction X. The louver 22 is formed by cutting and raising the plate portion 22b from the flat plate portion 21.

[0023] The plurality of louvers 22 are divided into a first louver group 22A formed upstream of the drainage slit 23 (described later) formed in the fin portion 24 in the air flow direction Y, and a second louver group 22B formed downstream of the drainage slit 23 in the air flow direction Y. The drainage slit 23 is an opening for dropping the water accumulated on the upper surface of the fin portion 24, particularly on the flat plate portion 21 that is nearly horizontal, to the lower surface side.

[0024] Here, an example of the configuration of the fin portion 24 will be described with reference to FIG. 3. The center auxiliary line l1 is a virtual center auxiliary line in the plate thickness direction of the plate portion 22b of the first louver group 22A, and the center auxiliary line l2 is a virtual center auxiliary line in the plate thickness direction of the plate portion 22b of the second louver group 22B. As shown in FIG. 3, when defining the upper and lower surfaces of the flat plate portion 21 based on the direction of gravity g, the plate portions 22b of the first louver group 22A and the second louver group 22B are set to have inclined directions such that the center auxiliary line l1 and the center auxiliary line l2 intersect on the lower surface side.

[0025] The plate portion 22b of the first louver group 22A and the plate portion 22b of the second louver group 22B are inclined in opposite directions with respect to the flat plate portion 21. By forming the plate portion 22b of the louver 22 in such a direction, the condensed water 4 flowing along the plate portion 22b of the louver 22 formed in a certain fin portion 24 is guided toward the drainage slit 23 of the fin portion 24 below it. Therefore, the heat exchanger 10 having this configuration can greatly improve the drainage performance. Note that the configuration of the louver 22 in the fin portion 24 shown in FIG. 3 is an example, and the configuration of the louver 22 is not limited to the configuration shown in FIG. 3.

[0026] The fin portion 24 is formed with a drainage slit 23 for draining the condensed water 4 generated on the fin portion 24. The drainage slit 23 is a through hole formed in the corrugated fin 2. Under the conditions of low-temperature outside air, the moisture in the air condenses, and condensed water 4 is generated on the surfaces of the flat heat transfer tube 1 and the corrugated fin 2. The condensed water 4 generated on the surface of the fin portion 24 of the corrugated fin 2 flows down from the drainage slit 23 to the lower fin portion 24.

[0027] The drain slit 23 is formed in a rectangular shape that extends longitudinally in a direction orthogonal to the pipe arrangement direction X, that is, the air flow direction Y. The drain slit 23 is formed, for example, at the central portion of the fin portion 24 in the air flow direction Y. However, the formation position of the drain slit 23 is not limited to the central portion.

[0028] In FIG. 1, an example is shown in which the drain slits 23 are formed in a single row in the air flow direction Y. However, the number of rows of the drain slits 23 may be two or more. When multiple rows of drain slits 23 are formed, the multiple rows of drain slits 23 are formed adjacent to each other, for example, at the central portion of the fin portion 24 in the air flow direction Y. "Adjacent" is intended to mean that there is no louver 22 between the drain slits 23.

[0029] When multiple rows of drain slits 23 are formed, the region between the multiple rows of drain slits 23 is typically flat, similar to the flat plate portion 21. Among the multiple rows of drain slits 23, a flat region similar to the flat plate portion 21 may also be formed between the drain slit 23 on the most upstream side in the air flow direction Y and the first louver group 22A, and between the drain slit 23 on the most downstream side in the air flow direction Y and the second louver group 22B. Note that the number of rows of the drain slits 23 is synonymous with the number of the drain slits 23. Hereinafter, the number of the drain slits 23 will be indicated using either the expression "number of rows" or "number".

[0030] FIG. 4 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 1. FIG. 4 shows the heat exchanger 10 when viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1. Also, the white arrows in FIG. 4 indicate the direction in which air flows. The corrugated fin 2 will be described in more detail with reference to FIG. 4. Note that the drain slit 23 is not shown in FIG. 4. The corrugated fin 2 has a leading edge portion 2b, which is the leading end portion on the upwind side of the corrugated fin 2, with respect to the air flow that flows between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y.

[0031] Each of the plurality of flat heat transfer tubes 1 has a tube front end portion 1c which is the leading end portion on the upwind side of the plurality of flat heat transfer tubes 1 with respect to the air flow flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y. The corrugated fin 2 protrudes such that the leading edge portion 2b is located on the upwind side of the tube front end portion 1c with respect to the air flow flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y.

[0032] The fin portion 24 includes a front edge protruding portion 2a that constitutes a portion extending upstream of the brazed portion 10a which is the uppermost portion of the plurality of flat heat transfer tubes 1 and the corrugated fin 2. The hatched portion in FIG. 4 indicates the front edge protruding portion 2a. The front edge protruding portion 2a constitutes a portion between the brazed portion 10a and the leading edge portion 2b in the air flow direction Y. That is, the front edge protruding portion 2a constitutes a portion protruding outside the flat heat transfer tube 1 in the air flow direction Y. Further, the fin portion 24 includes a plurality of louvers 22 having a louver slit 22a (see FIG. 2) extending in the tube juxtaposition direction X and a plate portion 22b (see FIG. 2) inclined with respect to the flat plate portion 21 of the fin portion 24.

[0033] Here, as shown in FIG. 4, when viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1, the dimension of the fin portion 24 in the air flow direction Y is defined as the fin length L F And defined as. The fin length L F Is the distance between both edges between the leading edge portion 2b and the trailing edge portion 2c of the fin portion 24 in the air flow direction Y. Also, when viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1, the minimum line segment length between the position of the leading edge portion 2b and the position of the tube front end portion 1c in the air flow direction Y is defined as L t And defined as. More specifically, the minimum line segment length is L t Is the length in the air flow direction Y between the position of the virtual leading edge portion 2b extended in the tube juxtaposition direction X and the position of the tube front end portion 1c when viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1.

[0034] The heat exchanger 10 has L in the fin portion 24 and the plurality of flat heat transfer tubes 1 t / LF The relationship satisfies the formula 0 < L t / L F < 0.22. The heat exchanger 10 is configured such that the L t / L F relationship in the fin portion 24 and the plurality of flat heat transfer tubes 1 satisfies the formula 0.06 < L t / L F < 0.22, which is more preferable. Regarding setting the L t / L F relationship in the fin portion 24 and the plurality of flat heat transfer tubes 1 within the following range, an explanation will be given in relation to the low-temperature heating capacity of the heat exchanger. t / L F ), which is referred to as the protrusion length ratio of the fin portion 24. Here, regarding setting the protrusion length ratio (L

[0035] The low-temperature heating capacity of the heat exchanger refers to the heating capacity of the heat exchanger under a low outside air environment. Under the conditions of low outside air, moisture in the air condenses on the fin surface of the heat exchanger, forming frost. That is, under the conditions of low outside air, the heat exchanger operates while frosting. At this time, as the frosting progresses, the flow path through which air passes is blocked, and the capacity gradually decreases.

[0036] Therefore, when a certain amount of frost has grown, the heat exchanger stops the operation of the outdoor fan and performs a defrosting operation by flowing hot gas refrigerant into the heat exchanger. Since heating stops during the defrosting operation, the heating capacity of the heat exchanger becomes zero. After the frost has melted sufficiently, the heat exchanger restarts the compressor and the blower and starts the heating operation again. That is, the low-temperature heating capacity is defined as the integrated capacity of the heat exchanger to operate while frosting, averaged by the sum of the time of operating while frosting and the time of the defrosting operation.

[0037] FIG. 5 is a conceptual diagram showing the temperature distribution of the fin portion 24 in the air flow direction Y of the heat exchanger 10L according to the comparative example. The white arrow in FIG. 5 indicates the direction in which air flows. FIG. 5(a) is a conceptual diagram of the heat exchanger 10L, and FIG. 5(b) is the fin length L of the fin portion 24 in the air flow direction Y of the heat exchanger 10LF It is a conceptual diagram showing the relationship with the surface temperature of the fin part 24.

[0038] The heat exchanger 10L according to the comparative example is a device in which the leading edge 2b of the fin part 24 does not protrude upstream with respect to the air flow in the air flow direction Y. In Fig. 5(b), the horizontal axis represents the fin length L of the fin part 24 F is shown, and the vertical axis represents the temperature (°C). The solid line A in (b) represents the surface temperature of the fin part 24, and the dashed line B represents the temperature of the air around the heat exchanger 10L. The A1 part in (b) indicates the position of the leading edge 2b of the fin part 24, and the A2 part indicates the position of the trailing edge 2c.

[0039] Fig. 6 is a conceptual diagram showing the temperature distribution of the fin part 24 of the heat exchanger 10 according to Embodiment 1 in the air flow direction Y. In Fig. 6, the hatched part indicates the leading edge protrusion 2a. The white arrow in Fig. 6 indicates the direction in which the air flows. Fig. 6(a) is a conceptual diagram of the heat exchanger 10, and Fig. 6(b) is the fin length L of the fin part 24 of the heat exchanger 10 in the air flow direction Y F It is a conceptual diagram showing the relationship with the surface temperature of the fin part 24.

[0040] The heat exchanger 10 is a device in which the leading edge 2b of the fin part 24 protrudes upstream with respect to the air flow in the air flow direction Y as described above. In Fig. 6(b), the horizontal axis represents the fin length L of the fin part 24 F is shown, and the vertical axis represents the temperature (°C). The solid line A in (b) represents the surface temperature of the fin part 24 with respect to the position of the fin part 24 in the air flow direction Y, and the dashed line B represents the temperature of the air around the fin part 24 of the heat exchanger 10 with respect to the position of the fin part 24 in the air flow direction Y. The A1 part in (b) indicates the position of the leading edge 2b of the fin part 24, and the A2 part indicates the position of the trailing edge 2c.

[0041] Using FIGS. 5 and 6, the formation of frost on the surface of the fin portion 24 in the heating operation of the heat exchanger 10 disposed outdoors under the conditions of low-temperature outside air will be described. As shown in FIG. 5, since the fin portion 24 of the heat exchanger 10L according to the comparative example has no protruding portion on the windward side, the temperature becomes close to the refrigerant saturation temperature flowing inside the adjacent flat heat transfer tube 1 by heat conduction. It is assumed that the refrigerant saturation temperature is a constant temperature. Therefore, the temperature difference H1 between the surface temperature of the fin portion 24 indicated by the solid line A and the temperature of the air indicated by the broken line B, which is higher than the surface temperature of the fin portion 24, is the largest at the upstream portion of the fin portion 24. Therefore, in the heat exchanger 10L of the comparative example, condensed water 4 is likely to be generated at the upstream portion of the fin portion 24 and the frosting amount is the largest at the upstream portion of the fin portion 24, so that the air passage is suddenly blocked by frost and the heating low-temperature capacity is reduced.

[0042] On the other hand, as shown in FIG. 6, the heat exchanger 10 according to Embodiment 1 has a protruding portion on the windward side of the fin portion 24. In the heat exchanger 10 according to Embodiment 1, since the front edge portion 2b, which is the tip portion on the windward side of the fin portion 24, is at a distance from the flat heat transfer tube 1, the surface temperature at the tip portion on the windward side of the fin portion 24 is higher than the refrigerant saturation temperature flowing inside the flat heat transfer tube 1. Therefore, the temperature difference H2 between the temperature of the air at the tip portion on the windward side of the fin portion 24 and the surface temperature of the fin portion 24 becomes smaller than the temperature difference H1 of the heat exchanger according to the comparative example. The heat exchanger 10 is less likely to generate condensed water 4 at the upstream portion of the fin portion 24 than the heat exchanger 10L of the comparative example, and the frosting amount can be suppressed at the upstream portion, so that a sudden blockage of the air passage by frost can be suppressed, and thereby the heating low-temperature capacity can be improved.

[0043] FIG. 7 shows the protruding length ratio (L t / L F) It is a diagram showing the relationship with the heating low-temperature capacity (%). As described above, when the heat exchanger operates for heating under environmental conditions of low outside air temperature, the corrugated fins are frosted. When the heat exchanger is frosted by a certain amount, the heating capacity decreases, so the operation switches from heating operation to defrosting operation. During the defrosting operation, the heat exchanger cannot provide heating or the heating capacity decreases. Generally, during the defrosting operation, the frost is melted by flowing a refrigerant with a temperature higher than 0°C into the heat exchanger, and usually the fan is stopped at that time.

[0044] However, even when the defrosting operation is performed, if the outside air temperature is less than 0°C and wind blows on the heat exchanger, the heat for melting the ice is taken away by the wind, so the time until the frost melts becomes longer, and even after defrosting for a long time, frost (ice) may remain at the tip of the fin part (residual frost). Therefore, there is a need for a heat exchanger 10 that has a portion where the fin part 24 protrudes upward against the wind to suppress the amount of frost formation and is less likely to generate residual frost during the defrosting operation. That is, there is a need for a heat exchanger that can achieve both improved frost resistance and suppression of the generation of residual ice during the defrosting operation, and suppresses the deterioration of the defrosting performance.

[0045] Therefore, the inventor focused on the protrusion length ratio (L t / L F ) of the fin part 24. For the corrugated fin 2 with the protruding length of the fin part 24 changed, after a certain amount of frosting, an outside air temperature of about 0°C and a certain wind speed were given as the outside wind, and an experiment was conducted to perform the defrosting operation under those conditions and measure the time required for defrosting (the time when the frosting was almost gone visually). The inventor experimentally confirmed that no residual frost occurs at the tip of the fin part when the relationship of L t / L F satisfies the formula 0 < L t / L F < 0.22.

[0046] Note that although the remaining frost is also affected by the wind speed conditions and the defrosting operation conditions, it is strongly affected by the thickness of the fin portion 24. The thickness of the fin portion 24 is strongly affected by the heat conduction from the flat heat transfer tube 1. In particular, when the thickness of the fin portion 24 is as thin as 0.15 mm or less, as roughly shown in FIG. 7, the heating operation capacity is a change that depends on the protruding length ratio (L t / L F ). Also, as shown in the hatched portion F of FIG. 7, when the protruding length ratio (L t / L F ) of the fin portion 24 becomes larger than 0.22, residual ice is likely to occur.

[0047] As shown in FIG. 7, in the heat exchanger 10, the protruding length ratio (L t / L F ) is greater than 0 and less than 0.22, and the heating low-temperature capacity can be significantly improved. When the fin portion 24 of the heat exchanger 10 protrudes such that the protruding length ratio (L t / L F ) is 0.22 or more, there is almost no improvement effect on the heating low-temperature capacity, and residual frost is likely to occur.

[0048] [Effect of Heat Exchanger 10] The fin portion 24 of the heat exchanger 10 includes a front edge protruding portion 2a that constitutes a portion extending upstream of the brazed portion 10a at the most upstream position of the plurality of flat heat transfer tubes 1 and the corrugated fins 2. Also, in the heat exchanger 10, the relationship of L t / L F is configured to satisfy the formula 0 < L t / L F < 0.22. The heat exchanger 10 can improve the frost resistance by including the front edge protruding portion 2a in the fin portion 24, and the relationship of L t / L F is 0 < L t / L FBy being configured to satisfy the formula <0.22, it is possible to suppress residual ice at the tip of the fin portion 24 even during the defrosting operation. That is, the heat exchanger 10 has the above configuration, so that while improving the frost adhesion resistance, it is possible to suppress residual ice at the tip of the fin portion 24 even during the defrosting operation, and the heating low-temperature capacity can be improved. The heat exchanger 10 has the above configuration, so that it is possible to achieve both an improvement in frost adhesion resistance and suppression of the generation of residual ice during the defrosting operation, and to suppress a decrease in defrosting performance. The heat exchanger 10 can improve the defrosting performance compared to a heat exchanger in which residual ice grows.

[0049] Also, in the heat exchanger 10, the relationship of L in the fin portion 24 and the plurality of flat heat transfer tubes 1 t / L F is configured to satisfy the formula 0.06 < L t / L F <0.22. By having the above configuration, the heat exchanger 10 can improve the frost adhesion resistance and suppress residual ice at the tip of the fin portion 24 even during the defrosting operation, and can improve the heating low-temperature capacity. Also, as can be seen by comparing the case where L t / L F is 0 and 0.06 in FIG. 7, the heating operation capacity when L t / L F is 0.06 is at least 10% higher than the heating operation capacity when L t / L F is 0. That is, the heat exchanger 10 can improve the heating low-temperature capacity by at least 10% or more by being configured such that 0.06 < L t / L F compared to the case where there is no protrusion on the front edge portion 2b side of the fin portion 24.

[0050] Embodiment 2. FIG. 8 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 2, cut along the air flow direction Y. FIG. 9 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10M according to the comparative example, cut along the air flow direction Y. Embodiment 2 further specifies the configuration of the louver 22. The white arrows in FIGS. 8 and 9 indicate the direction in which air flows. The dashed arrows in FIGS. 8 and 9 indicate an example of the direction in which the condensed water 4 flows. Hereinafter, Embodiment 2 will be described. However, descriptions of parts that overlap with Embodiment 1 will be omitted, and the same reference numerals will be given to the same or corresponding parts as those in Embodiment 1.

[0051] Among the plurality of louvers 22, the plate portion 22b of the louver 221 provided at the position closest to the leading edge portion 2b and at the most upstream position has the following structure. As shown in FIG. 8, the plate portion 22b of the louver 221 has an inclined surface 22d that guides the condensed water 4 adhering to the fin portion 24 to the trailing edge portion 2c side of the corrugated fin 2 on the side opposite to the leading edge portion 2b in the air flow direction Y. The upper surface of the plate portion 22b of the louver 221 is formed to face inward in the air flow direction Y. The plate portion 22b of the louver 221 is formed to be positioned below the flat plate portion 21. The lower tip portion of the plate portion 22b of the louver 221 is formed to face the center side and downward of the heat exchanger 10 in the air flow direction Y.

[0052] As shown in FIG. 9, the plate portion 22b of the louver 221 in the heat exchanger 10M according to the comparative example has an inclined surface 22e that guides the condensed water 4 adhering to the fin portion 24 to the front edge portion 2b side of the corrugated fin 2 in the air flow direction Y. The upper surface of the plate portion 22b of the louver 221 in the heat exchanger 10M according to the comparative example is formed to face outward in the air flow direction Y. In the case of the heat exchanger 10M according to the comparative example, the condensed water 4 flows along the plate portion 22b toward the front edge portion 2b side and moves toward the remaining frost 4a due to the surface tension in the fin portion 24. The remaining frost 4a grows due to the adhesion of the condensed water and the influence of the outside air and becomes even larger. Therefore, the heat exchanger 10M according to the comparative example is affected by the enlarged remaining frost 4a, resulting in a decrease in heat exchange performance and a possible decrease in defrosting performance.

[0053] [Effect of Heat Exchanger 10] The plate portion 22b of the louver 221 in the heat exchanger 10 according to Embodiment 2 has an inclined surface 22d that guides the condensed water 4 adhering to the fin portion 24 to the trailing edge portion 2c side of the corrugated fin 2 on the side opposite to the front edge portion 2b in the air flow direction Y. By guiding the condensed water 4 in a direction opposite to the front edge portion 2b, the heat exchanger 10 can suppress the movement of the condensed water 4 to the remaining frost 4a and reduce the frost growth due to the outside air.

[0054] Embodiment 3. FIG. 10 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 3. FIG. 11 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 3 cut along the air flow direction Y. Embodiment 3 specifies the position of the drain slit 23. In FIG. 10, the hatched portion indicates the front edge protruding portion 2a. The white arrows in FIGS. 10 and 11 indicate the direction in which air flows. Hereinafter, Embodiment 3 will be described. However, descriptions of parts that overlap with Embodiment 1 or Embodiment 2 will be omitted, and the same reference numerals will be given to the same parts or corresponding parts as in Embodiment 1 and Embodiment 2.

[0055] In the fin portion 24, at the position of the central portion 1C of the width of the plurality of flat heat transfer tubes 1 in the air flow direction Y, at least one drain slit 23 for draining the condensed water 4 on the upper surface of the fin portion 24 is formed so as to extend in the tube juxtaposition direction X. The drain slit 23 is an opening formed in the fin portion 24 and is a through hole. The number of the drain slits 23 may be one or a plurality. The drain slit 23 only needs to be formed at approximately the central portion 1C of the width of the plurality of flat heat transfer tubes 1 in the air flow direction Y, and the formation position of the drain slit 23 may be offset toward the front edge portion 2b side with respect to the central portion 1C, or may be offset toward the rear edge portion 2c side.

[0056] [Effect of heat exchanger 10] In the fin portion 24, at the position of the central portion 1C of the width of the plurality of flat heat transfer tubes 1 in the air flow direction Y, at least one drain slit 23 for draining the condensed water 4 on the upper surface of the fin portion 24 is formed so as to extend in the tube juxtaposition direction X. The heat exchanger 10 according to Embodiment 3 efficiently drains the condensed water 4 on the surface of the fin portion 24 near the center of the fin portion 24, thereby suppressing the condensed water 4 from conducting to the remaining frost 4a at the front edge portion 2b and reducing the frost growth due to the external wind.

[0057] Embodiment 4. FIG. 12 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 4. FIG. 13 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 4 cut in the air flow direction Y. Embodiment 4 further specifies the configuration of the front edge protruding portion 2a. The white arrows in FIGS. 12 and 13 indicate the direction in which air flows. The dashed arrows in FIGS. 12 and 13 indicate an example of the direction in which the condensed water 4 flows. Hereinafter, Embodiment 4 will be described, but the description of the parts overlapping with Embodiments 1 to 3 will be omitted, and the same reference numerals will be given to the same parts or corresponding parts as those in Embodiments 1 to 3.

[0058] The front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 4 includes a first edge folding portion 2a1 that is bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21. The hatched portion in FIG. 12 indicates the first edge folding portion 2a1. The edge of the first edge folding portion 2a1 forms a step 2a2 with respect to the flat plate portion 21. The first edge folding portion 2a1 is a portion where the plate-like member constituting the fin portion 24 is overlapped on the upper side with respect to the flat plate portion 21. The corrugated fin 2 has the first edge folding portion 2a1 at the end portion on the front edge portion 2b side in the air flow direction Y. The bent portion of the first edge folding portion 2a1 constitutes the front edge portion 2b of the fin portion 24. The edge portion of the first edge folding portion 2a1 facing the inside of the heat exchanger 10 forms a step 2a2. The step 2a2 constitutes a wall extending in the tube axis direction Z and the tube juxtaposition direction X, and prevents the condensed water 4 from moving to the front edge portion 2b side.

[0059] [Effect of the heat exchanger 10] The front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 4 includes a first edge folding portion 2a1 that is bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21. The edge of the first edge folding portion 2a1 forms a step 2a2 with respect to the flat plate portion 21. The heat exchanger 10 according to Embodiment 4 has the first edge folding portion 2a1, and by forming the step 2a2 in the front edge protruding portion 2a, it is possible to suppress the condensed water 4 from being conducted to the front edge portion 2b and reduce the growth of frost due to external wind. Further, the heat exchanger 10 according to Embodiment 4 forms the first edge folding portion 2a1 by bending the edge of the fin portion 24, and increases the thermal conductivity by increasing the thickness of the plate of the fin portion 24 on the front edge portion 2b side, making it easier to melt the frost on the front edge portion 2b side. Therefore, the heat exchanger 10 according to Embodiment 4 has the first edge folding portion 2a1, so that it can improve the frost resistance and suppress the remaining ice at the fin tip even during the defrosting operation, and improve the heating low temperature capacity.

[0060] The heat exchanger 10 according to Embodiment 4 has the first edge folding portion 2a1, and can improve the fin strength of the front edge protruding portion 2a as compared with the case where it does not have such a configuration. Further, since the heat exchanger 10 has the first edge folding portion 2a1, the thickness of the fin material can be increased to improve the strength of the fin tip portion. When manufacturing the structure in which the fin portion 24 protrudes upstream, the corrugated fin 2 is less likely to fall down, and the manufacturability can be improved.

[0061] Embodiment 5. FIG. 14 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 5, cut along the air flow direction Y. Embodiment 5 further specifies the configuration of the front edge protruding portion 2a. The white arrow in FIG. 14 indicates the direction in which air flows. The broken-line arrow in FIG. 14 indicates an example of the direction in which the condensed water 4 flows. Hereinafter, Embodiment 5 will be described. However, descriptions of the portions overlapping with Embodiments 1 to 4 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in Embodiments 1 to 4.

[0062] The front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 5 includes a second edge folding portion 2a3 that is bent to the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21. The edge of the second edge folding portion 2a3 forms a step 2a2 with respect to the flat plate portion 21. The second edge folding portion 2a3 is a portion where the plate-like member constituting the fin portion 24 is overlapped with the flat plate portion 21 on the lower side. The corrugated fin 2 has the second edge folding portion 2a3 at the end portion on the front edge portion 2b side in the air flow direction Y. The bent portion of the second edge folding portion 2a3 constitutes the front edge portion 2b of the fin portion 24. The edge portion of the second edge folding portion 2a3 facing the inside of the heat exchanger 10 forms a step 2a2.

[0063] As shown in FIG. 14, in the corrugated fin 2, the first edge folding portion 2a1 and the second edge folding portion 2a3 are alternately formed in the tube axis direction Z. That is, the corrugated fin 2 includes the first edge folding portion 2a1 and the second edge folding portion 2a3.

[0064] [Effect of Heat Exchanger 10] The front edge protrusion 2a of the heat exchanger 10 according to Embodiment 5 includes a second edge-folded portion 2a3 that is bent to the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21. By having the second edge-folded portion 2a3, the heat exchanger 10 according to Embodiment 5 can improve the fin strength of the front edge protrusion 2a as compared with the case where it does not have such a configuration.

[0065] Further, the front edge protrusion 2a of the heat exchanger 10 according to Embodiment 5 includes a first edge-folded portion 2a1 that is bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21. Therefore, similar to the heat exchanger 10 according to Embodiment 4, by having the first edge-folded portion 2a1, the heat exchanger 10 can improve the frost resistance and suppress the remaining ice at the fin tips even during the defrosting operation, and can improve the heating low-temperature capacity. By having the first edge-folded portion 2a1 and the second edge-folded portion 2a3, the heat exchanger 10 according to Embodiment 5 can improve the fin strength of the front edge protrusion 2a as compared with the case where it does not have such a configuration.

[0066] Embodiment 6. FIG. 15 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 6. Embodiment 6 specifies the position of the drain slit 23, and the drain slit 23 is formed at a position different from that in Embodiment 3. In FIG. 15, the hatched portion indicates the front edge protrusion 2a. The white arrow in FIG. 15 indicates the direction in which air flows. Hereinafter, Embodiment 6 will be described. For those that overlap with Embodiments 1 to 5, the description will be omitted, and the same reference numerals will be given to the same or corresponding parts as in Embodiments 1 to 5.

[0067] In the front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 6, at least one drain slit 23 for draining the condensed water 4 (see FIG. 2) on the upper surface of the fin portion 24 is formed so as to extend in the tube juxtaposition direction X. The drain slit 23 is an opening formed in the fin portion 24 and is a through-hole. The number of the drain slits 23 may be one or a plurality. The drain slit 23 is an opening having a long lateral width along the tube juxtaposition direction X. At least a part of the drain slit 23 is formed on the windward side with respect to the position of the most windward brazed portion 10a. That is, at least a part of the drain slit 23 is formed in the fin portion 24 between the position of the front edge portion 2b and the position of the most windward brazed portion 10a.

[0068] [Effect of Heat Exchanger 10] In the front edge protruding portion 2a of the heat exchanger 10, at least one drain slit 23 for draining the condensed water 4 (see FIG. 2) on the upper surface of the fin portion 24 is formed so as to extend in the tube juxtaposition direction X. Since the drain slit 23 is provided in the front edge protruding portion 2a of the heat exchanger 10, the condensed water 4 can be prevented from being conducted to the front edge portion 2b, and the growth of frost due to the external wind can be suppressed. That is, since the drain slit 23 is provided in the front edge protruding portion 2a of the heat exchanger 10, the condensed water 4 can be prevented from being conducted to the remaining frost and re-freezing, and the growth of the remaining frost can be suppressed.

[0069] Embodiment 7. FIG. 16 is a schematic plan view of a first example of a part of the heat exchanger 10 according to Embodiment 7. FIG. 17 is a schematic cross-sectional view of a first example of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 7, cut in the air flow direction Y. FIG. 18 is a schematic plan view of a second example of a part of the heat exchanger 10 according to Embodiment 7. FIG. 19 is a schematic cross-sectional view of a second example of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 7, cut in the air flow direction Y. Embodiment 7 further specifies the configuration of the front edge protruding portion 2a. In FIGS. 16 and 18, the hatched portion indicates the front edge protruding portion 2a. The white arrows in FIGS. 16 to 19 indicate the direction in which air flows. Hereinafter, Embodiment 7 will be described. However, descriptions of portions overlapping with Embodiments 1 to 6 will be omitted, and the same reference numerals will be given to the same or corresponding portions as those in Embodiments 1 to 6.

[0070] As shown in FIGS. 16 and 17, in the front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 7, a convex portion 25 that forms a wall protruding upward from the flat plate portion 21 is provided so as to extend in the tube juxtaposition direction X. Alternatively, as shown in FIGS. 18 and 19, in the front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 7, a concave portion 26 that is a recessed wall formed on the upper surface of the flat plate portion 21 is provided so as to extend in the tube juxtaposition direction.

[0071] The convex portion 25 is a rib provided on the upper surface of the front edge protruding portion 2a. The convex portion 25 protrudes upward from the surface of the flat plate portion 21. Note that the convex portion 25 may be provided on the lower surface of the front edge protruding portion 2a. The concave portion 26 is a depression or groove provided on the upper surface of the front edge protruding portion 2a. The concave portion 26 is recessed downward from the upper surface of the flat plate portion 21. The number of the convex portions 25 and the concave portions 26 may be one or a plurality. The convex portions 25 and the concave portions 26 are formed on the windward side of the position of the brazed portion 10a that is the most upstream. That is, the convex portions 25 and the concave portions 26 are formed in the fin portion 24 between the position of the front edge portion 2b and the position of the brazed portion 10a that is the most upstream. The convex portion 25 is a wall that obstructs the movement of the condensed water 4. The concave portion 26 can obstruct the movement of the condensed water 4 by allowing the condensed water to flow into it.

[0072] [Effect of Heat Exchanger 10] In the front edge protruding portion 2a of the heat exchanger 10 according to Embodiment 7, a convex portion 25 or a concave portion 26 is provided so as to extend in the tube juxtaposition direction X. When the convex portion 25 is provided in the front edge protruding portion 2a of the heat exchanger 10, the heat exchanger 10 can suppress the condensed water 4 from being conducted to the tip side of the fin portion 24, and can suppress the regrowth of frost due to the outside air. When the concave portion 26 is provided in the front edge protruding portion 2a of the heat exchanger 10, the heat exchanger 10 can suppress the condensed water 4 from being conducted to the tip side of the fin portion 24, and can suppress the regrowth of frost due to the outside air. That is, when the convex portion 25 or the concave portion 26 is provided in the front edge protruding portion 2a of the heat exchanger 10, the heat exchanger 10 can suppress the condensed water 4 from flowing to the tip portion of the fin portion 24, suppress the generation of remaining frost, and improve the frost adhesion resistance. Further, when the convex portion 25 or the concave portion 26 is provided in the front edge protruding portion 2a of the heat exchanger 10, the fin strength of the front edge protruding portion 2a can be improved as compared with the case where the heat exchanger 10 does not have such a configuration.

[0073] Embodiment 8. FIG. 20 is a schematic side view of the heat exchanger 10 according to Embodiment 8. FIG. 21 is a schematic plan view of a part of an end portion of the heat exchanger 10 in the tube axis direction Z according to Embodiment 8. FIG. 22 is a schematic plan view of a part of a central portion of the heat exchanger 10 in the tube axis direction Z according to Embodiment 8. Embodiment 8 further specifies the relationship between the corrugated fin 2 and the flat heat transfer tube 1. FIG. 20 shows the heat exchanger 10 when viewed in the tube juxtaposition direction X. In FIGS. 21 and 22, the hatched portion indicates the front edge protruding portion 2a. The white arrows in FIGS. 20 to 22 indicate the direction in which air flows. Hereinafter, Embodiment 8 will be described. However, descriptions of the parts overlapping with Embodiments 1 to 7 will be omitted, and the same reference numerals will be given to the same parts or corresponding parts as those in Embodiments 1 to 7.

[0074] A plurality of flat heat transfer tubes 1 are curved in the air flow direction Y such that when viewed in the tube arrangement direction X, the central portion 10c in the tube axis direction Z protrudes with respect to both end portions 10c1. That is, when viewed in the tube arrangement direction X, the flat heat transfer tube 1 is curved with respect to the vertical direction. Here, when viewed in the tube arrangement direction X, the length by which the corrugated fins 2 protrude from the plurality of flat heat transfer tubes 1 in the air flow direction Y is defined as the protrusion length δ. The corrugated fins 2 are formed to protrude in the upwind direction with respect to the tip end portion of the flat heat transfer tube 1. The protrusion length δ is the distance between the tube front end portion 1c, which is the upwind side tip end portion of the flat heat transfer tube 1 of the heat exchanger 10 in the air flow direction Y, and the leading edge portion 2b of the corrugated fins 2 when viewed in the tube arrangement direction X. The portion constituting the protrusion length δ is included in the leading edge protrusion portion 2a.

[0075] The corrugated fins 2 have different protrusion lengths δ in the upwind direction at the positions of the heat exchanger 10 in the tube axis direction Z. As shown in FIGS. 20 and 21, in the heat exchanger 10, the protrusion length δ in the vicinity of the lower end portion 10b of the corrugated fins 2 in the tube axis direction Z is defined as the lower protrusion length δ1. As shown in FIGS. 20 and 22, in the heat exchanger 10, the protrusion length δ at the central portion of the corrugated fins 2 in the tube axis direction Z is defined as the central portion protrusion length δ2. As shown in FIG. 20, the heat exchanger 10 is configured such that the lower protrusion length δ1 in the vicinity of the lower end portion 10b of the corrugated fins 2 in the tube axis direction Z is smaller than the central portion protrusion length δ2 at the central portion of the corrugated fins 2 in the tube axis direction Z. The portion of the vicinity of the lower end portion 10b of the heat exchanger 10 that constitutes the lower protrusion length δ1 is a portion closer to the lower end portion 10c11 with respect to the central portion 10c in the tube axis direction Z and is a portion near the first header 3A.

[0076] [Effect of Heat Exchanger 10] In the heat exchanger 10 according to Embodiment 8, the lower protruding length δ1 in the vicinity of the lower end portion 10b of the corrugated fin 2 in the tube axis direction Z is configured to be smaller than the central protruding length δ2 in the central portion of the corrugated fin 2 in the tube axis direction Z. With this configuration, the heat exchanger 10 according to Embodiment 8 can suppress the remaining frost at the tip of the front edge protruding portion 2a by reducing the protruding length δ of the fin portion 24 in the vicinity of the lower end portion 10b where more condensed water forms and remaining frost is more likely to remain compared to the central portion 10c.

[0077] Embodiment 9. FIG. 23 is a schematic plan view of a part of an end portion of the heat exchanger 10 according to Embodiment 9 in the tube axis direction Z. It further specifies the configuration of the corrugated fin 2. The white arrow in FIG. 23 indicates the direction in which air flows. Hereinafter, Embodiment 9 will be described. However, descriptions of parts overlapping with Embodiments 1 to 8 will be omitted, and the same reference numerals will be given to the same or corresponding parts as those in Embodiments 1 to 8.

[0078] The corrugated fin 2 has a trailing edge portion 2c, which is the tip portion on the leeward side of the corrugated fin 2, with respect to the air flow flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y.

[0079] Each of the plurality of flat heat transfer tubes 1 has a tube trailing end portion 1d, which is the tip portion on the leeward side of the plurality of flat heat transfer tubes 1, with respect to the air flow flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y. The corrugated fin 2 protrudes such that the trailing edge portion 2c is located on the leeward side of the tube trailing end portion 1d with respect to the air flow flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y.

[0080] The fin portion 24 includes a trailing edge protruding portion 2e that constitutes a portion extending downstream of the brazing portion 10d of the portion located most downstream among the plurality of flat heat transfer tubes 1 and the corrugated fins 2. In FIG. 23, the hatched portion on the leading edge portion 2b side indicates the leading edge protruding portion 2a, and the hatched portion on the trailing edge portion 2c side indicates the trailing edge protruding portion 2e. The trailing edge protruding portion 2e constitutes a portion between the brazing portion 10d and the trailing edge portion 2c in the air flow direction Y. That is, the trailing edge protruding portion 2e constitutes a portion protruding outside the flat heat transfer tube 1 in the air flow direction Y.

[0081] [Effect of the heat exchanger 10] The fin portion 24 includes a trailing edge protruding portion 2e that constitutes a portion extending downstream of the brazing portion 10d of the portion located most downstream among the plurality of flat heat transfer tubes 1 and the corrugated fins 2. When the heat exchanger 10 has to suppress the extension length of the leading edge protruding portion 2a due to residual frost, by having this configuration, by extending the portion on the trailing edge portion 2c side, the heat transfer area can be increased, and the heating low temperature capacity can be improved while suppressing the residual frost. By having this configuration, the heat exchanger 10 protrudes also on the downstream side of the fin portion 24, so that the surface area can be increased and the frost resistance can be improved.

[0082] Embodiment 10. FIG. 24 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 10. FIG. 25 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 10, cut in the air flow direction Y. Embodiment 10 further specifies the configuration of the trailing edge protruding portion 2e. The white arrows in FIGS. 24 and 25 indicate the direction in which air flows. The dashed arrows in FIGS. 24 and 25 indicate an example of the direction in which the condensed water 4 flows. In FIG. 25, the fin portion 24 includes the first edge folding portion 2a1 on the leading edge portion 2b side, but may include the second edge folding portion 2a3 (see FIG. 14) instead of the first edge folding portion 2a1, or may include neither the first edge folding portion 2a1 nor the second edge folding portion 2a3. Hereinafter, Embodiment 10 will be described. However, descriptions of the parts overlapping with Embodiments 1 to 9 will be omitted, and the same reference numerals will be given to the same or corresponding parts as those in Embodiments 1 to 9.

[0083] The trailing edge protruding portion 2e of the heat exchanger 10 according to Embodiment 10 includes a third edge folding portion 2e1 that is bent to the upper surface side of the fin portion 24 and overlaps the flat plate portion 21. The hatched portion in FIG. 24 indicates the third edge folding portion 2e1. The edge of the third edge folding portion 2e1 forms a step 2e2 with respect to the flat plate portion 21. The third edge folding portion 2e1 is a portion where the plate-like member constituting the fin portion 24 is overlapped on the upper side with respect to the flat plate portion 21. The corrugated fin 2 has the third edge folding portion 2e1 at the end on the trailing edge portion 2c side in the air flow direction Y. The bent portion of the third edge folding portion 2e1 constitutes the trailing edge portion 2c of the fin portion 24. The edge portion of the third edge folding portion 2e1 facing the inside of the heat exchanger 10 forms a step 2e2. The step 2e2 constitutes a wall extending in the tube axis direction Z and the tube juxtaposition direction X, and prevents the condensed water 4 from moving to the trailing edge portion 2c side.

[0084] [Effect of the heat exchanger 10] The trailing edge protrusion 2e of the heat exchanger 10 according to Embodiment 10 includes a third edge folding portion 2e1 that is bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21. The edge of the third edge folding portion 2e1 forms a step 2e2 with respect to the flat plate portion 21. The heat exchanger 10 according to Embodiment 10 has the third edge folding portion 2e1, and by forming the step 2e2 in the trailing edge protrusion 2e, it is possible to suppress the condensed water 4 from being conducted to the trailing edge portion 2c and reduce the growth of frost due to the outside wind. Further, the heat exchanger 10 according to Embodiment 10 forms the third edge folding portion 2e1 by bending the edge of the fin portion 24, and increases the thermal conductivity by increasing the thickness of the plate of the fin portion 24 on the trailing edge portion 2c side, making it easier to melt the frost on the trailing edge portion 2c side. Therefore, the heat exchanger 10 according to Embodiment 10 has the third edge folding portion 2e1, so that while improving the frost resistance, it is possible to suppress the remaining ice at the fin rear end even during the defrosting operation, and improve the heating low temperature capacity.

[0085] The heat exchanger 10 according to Embodiment 10 has the third edge folding portion 2e1, and can improve the fin strength of the trailing edge protrusion 2e as compared with the case where it does not have such a configuration. Further, the heat exchanger 10 has the third edge folding portion 2e1, so that the thickness of the fin material can be increased and the strength of the fin tip portion can be improved. When manufacturing a structure in which the fin portion 24 protrudes to the downstream side, the corrugated fin 2 is less likely to fall down, and the manufacturability can be improved. Further, the heat exchanger 10 can further improve the above effects by providing both the first edge folding portion 2a1 or the second edge folding portion 2a3 (see FIG. 14) and the third edge folding portion 2e1.

[0086] Embodiment 11. FIG. 26 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of the heat exchanger 10 according to Embodiment 11, taken along the air flow direction Y. Embodiment 11 further specifies the configuration of the trailing edge projecting portion 2e. The white arrow in FIG. 26 indicates the direction in which air flows. The dashed arrow in FIG. 26 shows an example of the direction in which the condensed water 4 flows. In FIG. 26, the fin portion 24 includes a first edge folding portion 2a1 and a second edge folding portion 2a3 on the leading edge portion 2b side, but it may not include the first edge folding portion 2a1 and the second edge folding portion 2a3. Hereinafter, Embodiment 11 will be described. For the parts that overlap with Embodiments 1 to 10, the description will be omitted, and the same reference numerals will be given to the same or corresponding parts as in Embodiments 1 to 10.

[0087] The trailing edge projecting portion 2e of the heat exchanger 10 according to Embodiment 11 includes a fourth edge folding portion 2e3 that is bent to the lower surface side of the fin portion 24 and overlaps the flat plate portion 21. The edge of the fourth edge folding portion 2e3 forms a step 2e2 with respect to the flat plate portion 21. The fourth edge folding portion 2e3 is a portion where the plate-like member constituting the fin portion 24 is overlapped on the lower side with respect to the flat plate portion 21. The corrugated fin 2 has a fourth edge folding portion 2e3 at the end on the trailing edge portion 2c side in the air flow direction Y. The bent portion of the fourth edge folding portion 2e3 constitutes the trailing edge portion 2c of the fin portion 24. The edge portion of the fourth edge folding portion 2e3 facing the inside of the heat exchanger 10 forms a step 2a2.

[0088] As shown in FIG. 26, in the corrugated fin 2, the third edge folding portion 2e1 and the fourth edge folding portion 2e3 are alternately formed in the tube axis direction Z. That is, the corrugated fin 2 includes the third edge folding portion 2e1 and the fourth edge folding portion 2e3.

[0089] [Effect of the heat exchanger 10] The trailing edge protrusion 2e of the heat exchanger 10 according to Embodiment 11 includes a fourth edge folding portion 2e3 that is bent to the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21. By having the fourth edge folding portion 2e3, the heat exchanger 10 according to Embodiment 11 can improve the fin strength of the trailing edge protrusion 2e as compared with the case where it does not have such a configuration. By having the fourth edge folding portion 2e3, the heat exchanger 10 can increase the thickness of the fin material and improve the strength of the fin tip portion, and when manufacturing a structure in which the fin portion 24 protrudes to the downstream side, the corrugated fin 2 is less likely to fall down, and the manufacturability can be improved. Further, by providing both the first edge folding portion 2a1 or the second edge folding portion 2a3 (see FIG. 14) and the fourth edge folding portion 2e3, the heat exchanger 10 can further improve the above effects.

[0090] Further, the trailing edge protrusion 2e of the heat exchanger 10 according to Embodiment 11 includes a third edge folding portion 2e1 that is bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21. Therefore, similar to the heat exchanger 10 according to Embodiment 10, by having the third edge folding portion 2e1, the heat exchanger 10 can improve the frost resistance and suppress the remaining ice at the fin tip even during the defrosting operation, and can improve the heating low-temperature capacity. By having the third edge folding portion 2e1 and the fourth edge folding portion 2e3, the heat exchanger 10 according to Embodiment 11 can improve the fin strength of the trailing edge protrusion 2e as compared with the case where it does not have such a configuration. Further, by providing both the first edge folding portion 2a1 and the second edge folding portion 2a3 (see FIG. 14) and the third edge folding portion 2e1 and the fourth edge folding portion 2e3, the heat exchanger 10 can further improve the above effects.

[0091] Embodiment 12. FIG. 27 is a schematic plan view of a part of the heat exchanger 10 according to Embodiment 12. Embodiment 12 further specifies the configuration of the fin portion 24. The white arrow in FIG. 27 indicates the direction in which air flows. In FIG. 27, the hatched portion on the front edge portion 2b side indicates the front edge side edge fold portion 2f described later, and the hatched portion on the rear edge portion 2c side indicates the rear edge side edge fold portion 2g. Hereinafter, Embodiment 12 will be described. For those that overlap with Embodiments 1 to 11, the description will be omitted, and the same or corresponding parts as those in Embodiments 1 to 11 will be given the same reference numerals.

[0092] The corrugated fin 2 projects such that the trailing edge portion 2c, which is the tip portion on the leeward side of the corrugated fin 2 with respect to the flow of air flowing between adjacent flat heat transfer tubes 1, is located on the leeward side of the tube trailing end portion 1d, which is the tip portion on the leeward side of the plurality of flat heat transfer tubes 1. The fin portion 24 includes a trailing edge projecting portion 2e that constitutes a portion extending on the leeward side of the brazed portion 10d, which is the portion located most on the leeward side of the plurality of flat heat transfer tubes 1 and the corrugated fin 2.

[0093] The leading edge projecting portion 2a includes a leading edge side edge fold portion 2f that is bent to the upper surface side or the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21. The leading edge side edge fold portion 2f bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21 is the first edge fold portion 2a1 (see FIG. 26) described above. The leading edge side edge fold portion 2f bent to the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21 is the second edge fold portion 2a3 (see FIG. 26) described above. The edge of the leading edge side edge fold portion 2f forms a step 2a2 with respect to the flat plate portion 21.

[0094] The trailing edge projecting portion 2e includes a trailing edge side edge fold portion 2g that is bent to the upper surface side or the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21. The trailing edge side edge fold portion 2g bent to the upper surface side of the fin portion 24 and overlapped with the flat plate portion 21 is the third edge fold portion 2e1 (see FIG. 26) described above. The trailing edge side edge fold portion 2g bent to the lower surface side of the fin portion 24 and overlapped with the flat plate portion 21 is the fourth edge fold portion 2e3 (see FIG. 26) described above. The edge of the trailing edge side edge fold portion 2g forms a step 2e2 with respect to the flat plate portion 21.

[0095] When viewed in the tube axis direction Z, the fin portion 24 is configured such that the area S1 of the trailing edge side edge folded portion 2g is larger than the area S2 of the leading edge side edge folded portion 2f.

[0096] The length L1 of the trailing edge protruding portion 2e in the air flow direction Y is longer than the length L2 of the leading edge protruding portion 2a. The length L1 of the trailing edge protruding portion 2e is the length between the brazing portion 10d and the trailing edge portion 2c in the air flow direction Y. The length L2 of the leading edge protruding portion 2a is the length between the brazing portion 10d and the leading edge portion 2b in the air flow direction Y. The trailing edge protruding portion 2e protrudes from the flat heat transfer tube 1 more than the leading edge protruding portion 2a.

[0097] Note that the heat exchanger 10 is not limited to the one in which the protruding amount of the trailing edge protruding portion 2e from the flat heat transfer tube 1 is larger than that of the leading edge protruding portion 2a. The heat exchanger 10 may have the same protruding amount for the trailing edge protruding portion 2e and the leading edge protruding portion 2a, or the protruding amount of the leading edge protruding portion 2a may be larger than that of the trailing edge protruding portion 2e. When the length L1 of the trailing edge protruding portion 2e in the air flow direction Y is longer than the length L2 of the leading edge protruding portion 2a, the heat exchanger 10 can increase the surface area and improve the frost resistance by protruding also on the downstream side of the fin portion 24.

[0098] [Effect of Heat Exchanger 10] When viewed in the tube axis direction Z, the fin portion 24 is configured such that the area S1 of the trailing edge side edge folded portion 2g is larger than the area S2 of the leading edge side edge folded portion 2f. By being configured in such a way, the heat exchanger 10 can improve the strength of the fin portion 24 when the protruding length of the fin portion 24 on the trailing edge portion 2c side is longer than that on the leading edge portion 2b side, as compared with the case where it does not have such a configuration.

[0099] Embodiment 13. FIG. 28 is a diagram showing the configuration of the air conditioner 90 according to Embodiment 13. Embodiment 13 relates to an air conditioner 90 as an example of a refrigeration cycle device including the heat exchanger 10 of Embodiments 1 to 12. The air conditioner 90 uses the heat exchanger 10 of Embodiments 1 to 12 as the outdoor heat exchanger 230.

[0100] As shown in FIG. 28, the air conditioner 90 constitutes a refrigerant circuit by piping-connecting the outdoor unit 200 and the indoor unit 100 with the gas refrigerant pipe 300 and the liquid refrigerant pipe 400. The outdoor unit 200 has a compressor 210, a four-way valve 220, an outdoor heat exchanger 230, and an outdoor fan 240. Although it is assumed that one outdoor unit 200 and one indoor unit 100 are piping-connected in the air conditioner of Embodiment 13, the number of units is arbitrary.

[0101] The compressor 210 compresses and discharges the inhaled refrigerant. Although not particularly limited, the compressor 210 can change the capacity of the compressor 210 by arbitrarily changing the operating frequency, for example, by means of an inverter circuit or the like. The four-way valve 220 is a valve that switches the flow of the refrigerant according to whether it is in the cooling operation or the heating operation.

[0102] The outdoor heat exchanger 230 performs heat exchange between the refrigerant and the outdoor air. The outdoor heat exchanger 230 functions as an evaporator during the heating operation, evaporating and vaporizing the refrigerant. Also, the outdoor heat exchanger 230 functions as a condenser during the cooling operation, condensing and liquefying the refrigerant. The outdoor fan 240 sends outdoor air into the outdoor heat exchanger 230 to promote heat exchange in the outdoor heat exchanger 230.

[0103] On the other hand, the indoor unit 100 has an indoor heat exchanger 110, a decompression device 120, and an indoor fan 130. The indoor heat exchanger 110 performs heat exchange between the indoor air to be air-conditioned and the refrigerant. The indoor heat exchanger 110 functions as a condenser during the heating operation, condensing and liquefying the refrigerant. Also, the indoor heat exchanger 110 functions as an evaporator during the cooling operation, evaporating and vaporizing the refrigerant.

[0104] The pressure reducing device 120 reduces the pressure of the refrigerant and expands it. The pressure reducing device 120 is composed of, for example, an electronic expansion valve. When the pressure reducing device 120 is composed of an electronic expansion valve, the pressure reducing device 120 adjusts the opening degree based on an instruction from a control device (not shown). The indoor fan 130 passes the indoor air through the indoor heat exchanger 110 and supplies the air that has passed through the indoor heat exchanger 110 into the room.

[0105] Next, the operations of the devices of the air conditioner 90 will be described based on the flow of the refrigerant. First, the heating operation will be described. During the heating operation, the four-way valve 220 is switched to the dotted line side in FIG. 28. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the indoor heat exchanger 110. The gas refrigerant that has flowed into the indoor heat exchanger 110 condenses and liquefies by exchanging heat with the air in the air-conditioning target space. The liquefied refrigerant is decompressed by the pressure reducing device 120 to become a gas-liquid two-phase state and then flows into the outdoor heat exchanger 230. The refrigerant that has flowed into the outdoor heat exchanger 230 evaporates and gasifies by exchanging heat with the outdoor air sent from the outdoor fan 240. The gasified refrigerant passes through the four-way valve 220 and is inhaled into the compressor 210 again. By circulating the refrigerant in the above manner, the air conditioner 90 performs air conditioning related to heating.

[0106] Next, the cooling operation will be described. During the cooling operation, the four-way valve 220 is switched to the solid line side in FIG. 28. The high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 210 passes through the four-way valve 220 and flows into the outdoor heat exchanger 230. The gas refrigerant that has flowed into the outdoor heat exchanger 230 condenses and liquefies by exchanging heat with the outdoor air supplied by the outdoor fan 240. The liquefied refrigerant is decompressed by the pressure reducing device 120 to become a gas-liquid two-phase state and then flows into the indoor heat exchanger 110. The refrigerant that has flowed into the indoor heat exchanger 110 evaporates and gasifies by exchanging heat with the air in the air-conditioning target space. The gasified refrigerant passes through the four-way valve 220 and is inhaled into the compressor 210 again. By circulating the refrigerant in the above manner, the air conditioner 90 performs air conditioning related to cooling.

[0107] Next, the defrosting operation will be described. When performing a heating operation in a low-temperature environment where the surface temperature of the flat heat transfer tube 1 (see FIG. 1) and the corrugated fin 2 (see FIG. 1) is 0°C or lower, frosting occurs on the outdoor heat exchanger 230. When the amount of frost on the outdoor heat exchanger 230 exceeds a certain level, the air passage of the outdoor heat exchanger 230 through which the air generated by the outdoor fan 240 passes is blocked, the performance of the outdoor heat exchanger 230 deteriorates, and the heating performance deteriorates. Therefore, when the heating performance deteriorates, the air conditioner 90 performs a defrosting operation to melt the frost on the surface of the outdoor heat exchanger 230.

[0108] In the defrosting operation, the outdoor fan 240 is stopped, the four-way valve 220 is switched to the same state as during the cooling operation, and the high-temperature and high-pressure gas refrigerant flows into the outdoor heat exchanger 230. As a result, the frost adhering to the flat heat transfer tube 1 and the corrugated fin 2 melts. When the defrosting operation is started, the high-temperature and high-pressure gas refrigerant flows into the flat heat transfer tube 1 through the header 3 (see FIG. 1). Then, the frost adhering to the flat heat transfer tube 1 and the corrugated fin 2 melts and changes into water due to the high-temperature refrigerant flowing into the flat heat transfer tube 1. The water generated by the melting of the frost is drained downward along the flat heat transfer tube 1 or the corrugated fin 2 to the lower part of the outdoor heat exchanger 230. When the adhered frost has melted, the air conditioner 90 ends the defrosting operation and resumes the heating operation. Note that the timing for ending the defrosting operation and resuming the heating operation can be determined by a known method. For example, when the detected temperature of a temperature sensor (not shown) reaches a predetermined temperature, or when the defrosting operation has been performed for a certain period of time, the defrosting operation may be ended and the heating operation may be resumed.

[0109] [Effect of the air conditioner 90] Since the air conditioner 90 according to the 13th embodiment includes the heat exchanger 10 according to the 1st to 12th embodiments, it can exhibit the same effects as the heat exchanger 10. For example, the air conditioner 90 can achieve both an improvement in frost resistance and a suppression of the generation of remaining ice during the defrosting operation, and can suppress a deterioration in defrosting performance.

[0110] Each of the above-described Embodiments 1 to 13 can be implemented in combination with each other. For example, a drain slit 23 may be formed in the trailing edge protruding portion 2e. Further, the trailing edge protruding portion 2e may have a convex portion 25 or a concave portion 26. Further, the configurations shown in the above embodiments are merely examples, and it is also possible to combine them with other known techniques, and it is also possible to omit or change a part of the configuration without departing from the gist.

Explanation of Reference Numerals

[0111] 1 Flat heat transfer tube, 1C Central portion, 1a Flat surface, 1b Flow path, 1c Tube front end portion, 1d Tube rear end portion, 2 Corrugated fin, 2a Leading edge protruding portion, 2a1 First edge folding portion, 2a2 Step, 2a3 Second edge folding portion, 2b Leading edge portion, 2c Trailing edge portion, 2e Trailing edge protruding portion, 2e1 Third edge folding portion, 2e2 Step, 2e3 Fourth edge folding portion, 2f Leading edge side edge folding portion, 2g Trailing edge side edge folding portion, 3 Header, 3A First header, 3B Second header, 4 Condensate water, 4a Residual frost, 10 Heat exchanger, 10L Heat exchanger, 10M Heat exchanger, 10a Brazed portion, 10b Near the lower end portion, 10c Central portion, 10c1 Both end portions, 10c11 Lower end portion, 10d Brazed portion, 20 Top portion, 21 Flat plate portion, 22 Louver, 22A First louver group, 22B Second louver group, 22a Louver slit, 22b Plate portion, 22d Inclined surface, 22e Inclined surface, 23 Drain slit, 24 Fin portion, 25 Convex portion, 26 Concave portion, 90 Air conditioner, 100 Indoor unit, 110 Indoor heat exchanger, 120 Pressure reducing device, 130 Indoor fan, 200 Outdoor unit, 210 Compressor, 220 Four-way valve, 221 Louver, 230 Outdoor heat exchanger, 240 Outdoor fan, 300 Gas refrigerant pipe, 400 Liquid refrigerant pipe.

Claims

1. A plurality of flat heat transfer tubes having a flat cross-section, formed with a plurality of flow paths formed by through holes, and arranged vertically with a space therebetween; and corrugated fins disposed between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes. When frost is formed on the surface of the corrugated fins when functioning as an evaporator, a defrosting operation is performed to remove the formed frost by flowing hot gas refrigerant, and the heat exchanger is: The corrugated fins are: A plate-shaped fin portion is formed to be continuous in a wave shape in the tube axis direction of the plurality of flat heat transfer tubes. When the direction orthogonal to the tube axis direction and the tube arrangement direction, which is the parallel arrangement direction of the plurality of flat heat transfer tubes, is defined as the air flow direction, in the air flow direction, the leading edge portion, which is the tip of the corrugated fins on the upwind side with respect to the air flow between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, protrudes so as to be located upwind of the tube front end portion, which is the tip of the plurality of flat heat transfer tubes on the upwind side. The fin portion is: A front edge protruding portion that constitutes a portion extending upwind of the brazed portion of the uppermost upwind portion of the plurality of flat heat transfer tubes and the corrugated fins; A plurality of louvers having a louver slit extending in the tube arrangement direction and a plate portion inclined with respect to the flat plate portion of the fin portion; Including When viewed in the tube axis direction of the plurality of flat heat transfer tubes, the dimension of the fin portion in the air flow direction is defined as fin length L Ｆ and when the minimum line segment length between the position of the leading edge portion and the position of the front end portion of the tube in the air flow direction is defined as L ｔ then The relationship between L in the fin part and the plurality of flat heat transfer tubes ｔ / L Ｆ is 0 < L ｔ / L Ｆ A heat exchanger configured to satisfy the formula of <0.22, so that residual ice is suppressed from occurring at the tip of the fin portion during a defrosting operation when the outside air temperature is less than 0°C and wind blows against the heat exchanger.

2. The relationship between L in the fin part and the plurality of flat heat transfer tubes ｔ / L Ｆ is 0.06 < L ｔ / L Ｆ The heat exchanger according to claim 1, which is configured to satisfy the formula of < 0.22

3. Among the plurality of louvers, the plate portion of the louver provided at the position closest to the leading edge portion and provided at the uppermost upwind position is: The heat exchanger according to claim 1 or 2, having an inclined surface for guiding the condensed water adhering to the fin portion to the trailing edge side of the corrugated fin on the side opposite to the leading edge portion in the air flow direction.

4. On the fin portion, At least one drain slit for dropping and draining the condensed water on the upper surface of the fin portion is formed to extend in the tube arrangement direction at the position of the center of the width of the plurality of flat heat transfer tubes in the air flow direction. The heat exchanger according to claim 1 or 2.

5. On the front edge protruding portion, At least one drain slit for dropping and draining the condensed water on the upper surface of the fin portion is formed to extend in the tube arrangement direction. The heat exchanger according to claim 1 or 2.

6. On the front edge protruding portion, The heat exchanger according to claim 1 or 2, wherein a convex portion that constitutes a wall protruding upward from the flat plate portion or a concave portion that is a recessed wall formed on the upper surface of the flat plate portion is provided so as to extend in the direction in which the tubes are arranged side by side.

7. The plurality of flat heat transfer tubes are formed to be curved in the air flow direction such that the central portion in the tube axis direction protrudes with respect to both end portions when viewed in the direction in which the tubes are arranged side by side, when the length by which the corrugated fins protrude from the plurality of flat heat transfer tubes in the air flow direction when viewed in the direction in which the tubes are arranged side by side is defined as a protruding length δ, The lower protrusion length δ in the vicinity of the lower end of the corrugated fin in the tube axis direction １ is configured to be smaller than the central protrusion length δ at the central portion of the corrugated fin in the tube axis direction, ２ The heat exchanger according to claim 1 or 2, wherein the heat exchanger is configured as described above.

8. The front edge protruding portion includes a first edge folding portion that is folded to the upper surface side of the fin portion and overlapped with the flat plate portion, the edge of the first edge folding portion forms a step with respect to the flat plate portion. The heat exchanger according to claim 1 or 2.

9. The front edge protruding portion includes a second edge folding portion that is folded to the lower surface side of the fin portion and overlapped with the flat plate portion, the edge of the second edge folding portion forms a step with respect to the flat plate portion, the corrugated fins are formed such that the first edge folding portion and the second edge folding portion are alternately formed in the tube axis direction. The heat exchanger according to claim 8.

10. The corrugated fins are such that in the air flow direction, the trailing edge portion, which is the tip portion on the leeward side of the corrugated fins with respect to the flow of air flowing between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, protrudes to a position more on the leeward side than the tube trailing end portion, which is the tip portion on the leeward side of the plurality of flat heat transfer tubes, the fin portion includes a trailing edge protruding portion that constitutes a portion extending to the leeward side of the brazed portion of the portion located most on the leeward side of the plurality of flat heat transfer tubes and the corrugated fins. The heat exchanger according to claim 1 or 2.

11. The trailing edge protruding portion includes a third edge folding portion that is folded to the upper surface side of the fin portion and overlapped with the flat plate portion, the edge of the third edge folding portion forms a step with respect to the flat plate portion. The heat exchanger according to claim 10.

12. The trailing edge protruding portion includes a fourth edge folding portion that is folded to the lower surface side of the fin portion and overlapped with the flat plate portion, [[ID= ​ ​ ​ ​ ​ In the air flow direction, among the plurality of flat heat transfer tubes, the trailing edge portion, which is the tip portion on the leeward side of the corrugated fin, protrudes so as to be located on the leeward side of the tube trailing end portion, which is the tip portion on the leeward side of the plurality of flat heat transfer tubes, with respect to the air flow that flows between adjacent flat heat transfer tubes. The fin portion is including a trailing edge protruding portion that constitutes a portion extending to the leeward side of the brazed portion of the portion located most leeward among the plurality of flat heat transfer tubes and the corrugated fin. The leading edge protruding portion is including a leading edge side edge folded portion that is bent on the upper surface side or the lower surface side of the fin portion and overlapped with the flat plate portion. The edge of the leading edge side edge folded portion forms a step with respect to the flat plate portion. The trailing edge protruding portion is including a trailing edge side edge folded portion that is bent on the upper surface side or the lower surface side of the fin portion and overlapped with the flat plate portion. The edge of the trailing edge side edge folded portion forms a step with respect to the flat plate portion. The fin portion is The heat exchanger according to claim 1 or 2, wherein when viewed in the tube axis direction, the area of the trailing edge side edge folded portion is configured to be larger than the area of the leading edge side edge folded portion.

14. An air conditioner having the heat exchanger according to claim 1 or 2.

15. A method of operating an air conditioner including a heat exchanger that functions as an evaporator, wherein the heat exchanger has a plurality of flat heat transfer tubes formed with a flat cross-section and having a plurality of flow paths formed by through holes, and the plurality of flat heat transfer tubes are arranged vertically and juxtaposed with a space therebetween, and a corrugated fin disposed between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes. The corrugated fin is formed such that a plate-like fin portion is continuously formed in a wave shape in the tube axis direction of the plurality of flat heat transfer tubes. When the direction orthogonal to the tube axis direction and the tube juxtaposition direction, which is the juxtaposition direction of the plurality of flat heat transfer tubes, is defined as the air flow direction, in the air flow direction, the leading edge portion, which is the tip portion on the windward side of the corrugated fin, protrudes so as to be located on the windward side of the tube front end portion, which is the tip portion on the windward side of the plurality of flat heat transfer tubes, with respect to the air flow that flows between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes. The fin portion is a leading edge protruding portion that constitutes a portion extending to the windward side of the brazed portion of the portion located most windward among the plurality of flat heat transfer tubes and the corrugated fin. A plurality of louvers having louver slits extending in the direction of the tube arrangement and plate portions inclined with respect to the flat plate portions of the fin portions, including, When viewed in the tube axis direction of the plurality of flat heat transfer tubes, the dimension of the fin portion in the air flow direction is defined as fin length L Ｆ When the minimum line segment length between the position of the leading edge portion and the position of the front end portion of the tube in the air flow direction is defined as L ｔ then The relationship between L in the fin part and the plurality of flat heat transfer tubes ｔ / L Ｆ is 0 < L ｔ / L Ｆ It is configured to satisfy the formula of ｔ / L < 0.22, and under the condition that the outside air temperature is less than 0°C and wind blows against the heat exchanger, in the defrosting operation of removing the frost formed on the surface of the corrugated fin by flowing hot gas refrigerant through the heat exchanger, a method for operating an air conditioner that defrosts so that no frost remains at the tip of the fin portion.

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