Heat exchanger and air conditioner

Abstract

The present invention provides a heat exchanger comprising a plurality of flat heat transfer pipes and a corrugated fin. A front edge part, which is the leading end part on the upwind side of the corrugated fin, protrudes so as to be located farther on the upwind side than a pipe front end part, which is the leading end part on the upwind side of the plurality of flat heat transfer pipes. A fin part includes: a front edge protruding part constituting the portion extending farther on the upwind side than a brazed part of the most upwind portions of the plurality of flat heat transfer pipes and the corrugated fin; and a plurality of louvers having louver slits and inclined plate parts. The heat exchanger is configured such that, when viewed in the pipe axial direction of the plurality of flat heat transfer pipes, with a fin length LF being defined as the dimension of the fin part in the air flow direction and Lt being defined as the minimum line-segment length between the position of the front edge part and the position of the pipe front end part in the air flow direction, the relation Lt / LF satisfies the expression 0 < Lt / LF < 0.22.

Description

Heat exchanger and air conditioning device

[0001] The present disclosure relates to a heat exchanger having corrugated fins and an air conditioning apparatus.

[0002] Conventionally, heat exchangers that function as evaporators in low-temperature outdoor air have been proposed in which the leading edges of the corrugated fins protrude beyond the tips of the flat tubes (see, for example, Patent Document 1). The heat exchanger of Patent Document 1 is said to be able to suppress the amount of frost formation on the leading edges of the fins of the heat exchanger, improve frost resistance, and prevent damage due to deformation by reducing the fin efficiency of the leading edges of the fins and relatively increasing the temperature of the tips. Note that fin efficiency is the ratio of the amount of heat energy actually radiated from the fins to the amount of heat radiation when the fin temperature is uniform throughout the entire area.

[0003] International Publication No. 2013 / 035436

[0004] The heat exchanger of Patent Document 1 has flat tubes arranged to extend vertically, with corrugated fins sandwiched between the flat tubes. In an attempt to improve frost resistance, such as in the heat exchanger of Patent Document 1, by forming the fins to protrude beyond the flat tubes, the frost resistance of the heat exchanger is improved during frosting operation, but frost is less likely to melt at the tips of the fins during defrosting operation, which can result in residual ice. In particular, when the heat exchanger is exposed to outside wind, water melted at the tips of the fins is less likely to drain, and the protruding portions of the fins protruding from the flat tubes are re-frozen by the outside wind, resulting in a significant reduction in defrosting performance.

[0005] In order to solve the above-mentioned problems, the present disclosure aims to provide a heat exchanger and an air conditioning apparatus that can achieve both improved frost resistance and suppression of residual ice formation during defrosting operation, thereby suppressing a decrease in defrosting performance.

[0006] The heat exchanger according to the present disclosure comprises a plurality of flat heat transfer tubes each having a flat cross section, a plurality of flow paths formed by through holes, and arranged vertically and spaced apart from one another; and corrugated fins arranged between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, wherein the corrugated fins are formed so that plate-like fin portions are connected in a wave-like pattern in the tube axis direction of the plurality of flat heat transfer tubes, and when a direction perpendicular to the tube axis direction and the tube juxtaposition direction in which the plurality of flat heat transfer tubes are arranged is defined as an air flow direction, the corrugated fins are arranged so that adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes are connected in the air flow direction. The front 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 the flat heat transfer tubes, and the fin portion includes a front edge protrusion that constitutes a portion extended on the windward side relative to the brazed portion of the part located most windward between the flat heat transfer tubes and the corrugated fin, and a plurality of louvers each having a louver slit extending in the tube juxtaposition direction and a plate portion 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 flat heat transfer tubes is defined as a fin length L. Ｆ The minimum line length between the position of the leading edge and the position of the front end of the pipe in the air flow direction is L ｔ When the L is defined as the fin portion and the plurality of flat heat transfer tubes, ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ <0.22.

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

[0008] In the heat exchanger and air conditioning apparatus according to the present disclosure, the fin portion of the heat exchanger includes a leading edge protrusion that forms a portion extending upwind from the brazed portion of the portion of the flat heat transfer tubes and the corrugated fin that is located most upwind. ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ<0.22. By having the above configuration, the heat exchanger can achieve both improved frost resistance and suppression of residual ice generation during defrosting operation, and can suppress deterioration of defrosting performance.

[0009] FIG. 1 is a diagram illustrating the configuration of a heat exchanger according to embodiment 1. FIG. 2 is a schematic perspective view of a portion of the heat exchanger according to embodiment 1. FIG. 3 is a schematic cross-sectional view of a flat plate portion of a corrugated fin according to embodiment 1 cut in the air flow direction. FIG. 4 is a schematic plan view of a portion of the heat exchanger according to embodiment 1. FIG. 5 is a conceptual diagram illustrating the temperature distribution of the fin portion in the air flow direction of a heat exchanger according to a comparative example. FIG. 6 is a conceptual diagram illustrating the temperature distribution of the fin portion in the air flow direction of a heat exchanger according to embodiment 1. ｔ / L Ｆ1 is a diagram showing the relationship between the heating low-temperature capacity [%] and the heating low-temperature capacity [%]. FIG. 1 is a schematic cross-sectional view of the flat plate portion of the corrugated fin of the heat exchanger according to embodiment 2, cut in the air flow direction. FIG. 2 is a schematic cross-sectional view of the flat plate portion of the corrugated fin of the heat exchanger according to the comparative example, cut in the air flow direction. FIG. 3 is a schematic plan view of a portion of the heat exchanger according to embodiment 3. FIG. 4 is a schematic cross-sectional view of the flat plate portion of the corrugated fin of the heat exchanger according to embodiment 3, cut in the air flow direction. FIG. 5 is a schematic plan view of a portion of the heat exchanger according to embodiment 4. FIG. 6 is a schematic cross-sectional view of the flat plate portion of the corrugated fin of the heat exchanger according to embodiment 4, cut in the air flow direction. FIG. 7 is a schematic cross-sectional view of the flat plate portion of the corrugated fin of the heat exchanger according to embodiment 5, cut in the air flow direction. FIG. 8 is a schematic plan view of a portion of the heat exchanger according to embodiment 6. FIG. 9 is a schematic plan view of a first example of a portion of the heat exchanger according to embodiment 7. FIG. 10 is a schematic cross-sectional view of the first example of the flat plate portion of the corrugated fin of the heat exchanger according to embodiment 7, cut in the air flow direction. FIG. 11 is a schematic plan view of a second example of a portion of the heat exchanger according to embodiment 7. 13 is a schematic cross-sectional view of a second example of a flat plate portion of a corrugated fin of a heat exchanger according to embodiment 7, cut in the air flow direction. FIG. 14 is a schematic side view of a heat exchanger according to embodiment 8. FIG. 15 is a schematic plan view of a part of an end portion in the pipe axis direction of a heat exchanger according to embodiment 8. FIG. 16 is a schematic plan view of a part of a central portion in the pipe axis direction of a heat exchanger according to embodiment 8. FIG. 17 is a schematic plan view of a part of an end portion in the pipe axis direction of a heat exchanger according to embodiment 9. FIG. 18 is a schematic plan view of a part of a heat exchanger according to embodiment 10. FIG. 19 is a schematic cross-sectional view of a flat plate portion of a corrugated fin of a heat exchanger according to embodiment 10, cut in the air flow direction. FIG. 19 is a schematic cross-sectional view of a flat plate portion of a corrugated fin of a heat exchanger according to embodiment 11, cut in the air flow direction. FIG. 19 is a schematic plan view of a part of a heat exchanger according to embodiment 12. FIG. 19 is a diagram showing the configuration of an air conditioning apparatus according to embodiment 13.

[0010] A heat exchanger and an air conditioning apparatus according to embodiments will be described below with reference to the accompanying drawings. In the following drawings, components with the same reference numerals are identical or equivalent and will be common throughout the following embodiments. The configurations of components shown throughout the specification are merely illustrative and are not limited to those described in the specification. In particular, the combinations of components are not limited to those in each embodiment, and components described in other embodiments may be applied to other embodiments. In the following description, the upper side in the drawings will be referred to as the "upper side" and the lower side as the "lower side." Furthermore, for ease of understanding, directional terms (e.g., "right," "left," etc.) will be used as appropriate, but these terms are for illustrative purposes only and do not limit the present disclosure. Furthermore, the levels of humidity and temperature are not determined in relation to absolute values, but are determined relatively based on the state and operation of the device, etc. The relative sizes of components in the drawings may differ from the actual sizes.

[0011] Embodiment 1. [Configuration of Heat Exchanger 10] Fig. 1 is a diagram illustrating the configuration of a heat exchanger 10 according to Embodiment 1. Arrows in Fig. 1 indicate the flow of refrigerant when the heat exchanger 10 is used as an evaporator. When the heat exchanger 10 is used as an evaporator, low-temperature and low-pressure refrigerant flows through the refrigerant flow paths in the flat heat transfer tubes 1. When the heat exchanger 10 is used as a condenser, high-temperature and high-pressure refrigerant flows through the refrigerant flow paths in the flat heat transfer tubes 1.

[0012] 1, a heat exchanger 10 according to the first embodiment is a parallel-piped corrugated fin tube heat exchanger. 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.

[0013] The pair of headers 3 are each connected to other devices that make up the air conditioning apparatus 90 (see FIG. 28 ) and are pipes through which a refrigerant, a fluid that serves as a heat exchange medium, flows in and out and through which the refrigerant branches or merges. 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 with a gap between them vertically. When the heat exchanger 10 is used as an evaporator, liquid refrigerant passes through the upper second header 3B, and gaseous refrigerant passes through the lower first header 3A. When the heat exchanger 10 is used as a condenser, gaseous refrigerant passes through the upper second header 3B, and liquid refrigerant passes through the lower first header 3A.

[0014] A plurality of flat heat transfer tubes 1 are arranged between the pair of headers 3, perpendicular to each header 3, and parallel to one another. The plurality of flat heat transfer tubes 1 are arranged side by side at equal intervals in a direction perpendicular to the air flow direction Y (see FIG. 2 ). The plurality of flat heat transfer tubes 1 are arranged side by side with intervals between them. Hereinafter, the direction in which the plurality of flat heat transfer tubes 1 are arranged side by side (the left-right direction in FIG. 1 ) will be referred to as the "pipe arrangement direction X," and the axial direction of the flat heat transfer tubes 1 (the up-down direction in FIG. 1 ) will be referred to as the "pipe axis direction Z." The pipe axis direction Z is the vertical direction of the heat exchanger 10. The direction perpendicular to the "pipe arrangement direction X" and the "pipe axis direction Z" will be referred to as the "air flow direction Y." In the air flow direction Y, air flows in the direction of the outline arrows (see FIGS. 2 to 4 ), which will be described later.

[0015] Figure 2 is a schematic perspective view of a portion of the heat exchanger 10 according to the first embodiment. The white arrows in Figure 2 indicate the direction of air flow. 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 longer side of the flat cross section (hereinafter referred to as the flat surface 1a) is flat and the outer surface on the shorter 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.

[0016] Each flat heat transfer tube 1 is arranged standing upright in the vertical direction. The through holes of the flat heat transfer tubes 1 extend in the vertical direction and communicate with the pair of headers 3. The flat heat transfer tubes 1 are arranged so that the longitudinal sides of their flat cross sections are aligned with the air flow direction Y. Each flat heat transfer tube 1 is joined to the pair of headers 3 by inserting both ends of the flat heat transfer tube 1 into insertion holes (not shown) formed in each of the pair of headers 3 and brazing them together. A brazing material containing aluminum, for example, is used for the brazing.

[0017] Among the plurality of flat heat transfer tubes 1, corrugated fins 2 are arranged between adjacent flat heat transfer tubes 1. 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 so that plate-shaped fin portions 24, described later, are alternately folded 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-shaped fin material and folding it in a zigzag pattern with repeated mountain folds and valley folds, forming a corrugated shape like an accordion. Here, the folded portions due to the unevenness created by the corrugated shape become the peaks of the corrugated shape. In the first embodiment, the peaks of the corrugated fins 2 are aligned along the height direction. The corrugated fins 2 are formed so that the plate-shaped fin portions 24, described later, are connected in a corrugated shape in the tube axis direction Z of the plurality of flat heat transfer tubes 1.

[0018] FIG. 3 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 according to the first embodiment, taken along the air flow direction Y. The outline arrows in FIG. 3 indicate the air flow direction. The diagonal solid arrows in FIG. 3 indicate the flow of condensed water 4. The condensed water 4 refers to water that condenses from moisture in the air and adheres 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 1 a of the flat heat transfer tube 1, except for a leading edge protrusion 2 a (described later) that protrudes upstream of the flat heat transfer tube 1 in the air flow direction Y. This joint is brazed and joined using a brazing material.

[0019] The fin material constituting the corrugated fins 2 is made of, for example, an aluminum alloy. The surface of the fin material constituting the corrugated fins 2 is clad with a brazing material layer. The main material of the clad brazing material layer is, for example, an aluminum-silicon brazing material containing aluminum. The plate thickness of the fin material constituting the corrugated fins 2 is, for example, approximately 50 μm to 200 μm.

[0020] The corrugated fin 2 has a configuration in which plate-shaped fin portions 24 are connected in a wave-like manner in the tube axis direction Z. When viewed in the air flow direction Y, the corrugated fin 2 has a shape in which the fin portions 24 are connected in the tube axis direction Z with alternating inclinations in opposite directions. The fin portions 24 have flat plate-shaped flat plate portions 21 and curved apex portions 20 at both ends of the flat plate portions 21 in the tube arrangement direction X. The corrugated fin 2 is joined to the flat heat transfer tube 1 at the apex portions 20 in surface contact with the flat surfaces 1 a of the flat heat transfer tube 1.

[0021] A plurality of louvers 22 are formed in the fin portion 24 and aligned in the air flow direction Y. Each louver 22 has louver slits 22a that allow air to pass through and plate portions 22b that guide air to the louver slits 22a. The plate portions 22b are inclined with respect to the flat plate portion 21. The louver slits 22a and the plate portions 22b are configured in a rectangular shape extending in the pipe arrangement direction X. The louvers 22 are formed by cutting and raising the plate portions 22b from the flat plate portion 21.

[0022] The multiple louvers 22 are divided into a first louver group 22A formed upstream in the air flow direction Y of drainage slits 23, which will be described later, formed in the fin portion 24, and a second louver group 22B formed downstream in the air flow direction Y of the drainage slits 23. The drainage slits 23 are openings that allow water that accumulates on the upper surface of the fin portion 24, particularly on the flat plate portion 21 that is nearly horizontal, to fall to the lower surface.

[0023] An example of the configuration of the fin portion 24 will now be described with reference to Fig. 3. The center auxiliary line l1 is an imaginary center auxiliary line in the thickness direction of the plate portion 22b of the first louver group 22A, and the center auxiliary line l2 is an imaginary center auxiliary line in the thickness direction of the plate portion 22b of the second louver group 22B. As shown in Fig. 3, when the upper and lower surfaces of the flat plate portion 21 are defined based on the direction of gravity g, the plate portions 22b of the first louver group 22A and the plate portions 22b of the second louver group 22B are inclined such that the center auxiliary line l1 and the center auxiliary line l2 intersect on the lower surface side.

[0024] The plate portions 22b of the first louver group 22A and the plate portions 22b of the second louver group 22B are inclined in opposite directions relative to the flat plate portion 21. By forming the plate portions 22b of the louvers 22 in this direction, condensation water 4 flowing along the plate portions 22b of the louvers 22 formed in a certain fin portion 24 is guided toward the drainage slits 23 in the fin portion 24 below. Therefore, the heat exchanger 10 having this configuration can significantly improve drainage. Note that the configuration of the louvers 22 in the fin portion 24 shown in FIG. 3 is an example, and the configuration of the louvers 22 is not limited to the configuration shown in FIG. 3.

[0025] The fin portions 24 are formed with drainage slits 23 for draining condensation water 4 formed on the fin portions 24. The drainage slits 23 are through-holes formed in the corrugated fins 2. Under low-temperature outside air conditions, moisture in the air condenses, forming condensation water 4 on the surfaces of the flat heat transfer tubes 1 and the corrugated fins 2. The condensation water 4 formed on the surfaces of the fin portions 24 of the corrugated fins 2 flows down from the drainage slits 23 to the fin portions 24 below.

[0026] The drainage slits 23 are formed in a rectangular shape extending longitudinally in the pipe arrangement direction X, i.e., in a direction perpendicular to the air flow direction Y. As an example, the drainage slits 23 are formed in the center of the fin portion 24 in the air flow direction Y, but the formation position of the drainage slits 23 is not limited to the center.

[0027] 1 shows an example in which the drainage slits 23 are formed in one row in the air flow direction Y, but the number of rows of the drainage slits 23 may be two or more. When multiple rows of the drainage slits 23 are formed, the multiple rows of the drainage slits 23 are formed, for example, adjacent to each other in the central part of the fin portion 24 in the air flow direction Y. "Adjacent to each other" means that there are no louvers 22 between the drainage slits 23.

[0028] When multiple rows of drainage slits 23 are formed, the areas between the multiple rows of drainage slits 23 are typically flat, similar to the flat plate portion 21. Of the multiple rows of drainage slits 23, flat areas may also be formed between the drainage slit 23 located most upstream in the air flow direction Y and the first louver group 22A, and between the drainage slit 23 located most downstream in the air flow direction Y and the second louver group 22B, similar to the flat plate portion 21. Note that the number of rows of drainage slits 23 is synonymous with the number of drainage slits 23, and hereinafter the number of drainage slits 23 will be indicated using either the expression "number of rows" or "number."

[0029] Fig. 4 is a schematic plan view of a portion of the heat exchanger 10 according to the first embodiment. Fig. 4 shows the heat exchanger 10 as viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1. The outline arrows in Fig. 4 indicate the air flow direction. The corrugated fins 2 will be described in more detail using Fig. 4. Note that the drainage slits 23 are not shown in Fig. 4. The corrugated fin 2 has a leading edge 2b, which is the tip of the corrugated fin 2 on the windward side with respect to the flow of air flowing between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1, in the air flow direction Y.

[0030] Each of the plurality of flat heat transfer tubes 1 has a tube front end 1c that is the tip of the plurality of flat heat transfer tubes 1 on the upwind side with respect to the flow of air that flows 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 so that a leading edge 2b is located on the upwind side of the tube front end 1c with respect to the flow of air 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] The fin portion 24 includes a leading edge protrusion 2a that extends upwind from the brazed portion 10a at the windward-most portion of the flat heat transfer tubes 1 and the corrugated fin 2. In Fig. 4, the hatched portion indicates the leading edge protrusion 2a. The leading edge protrusion 2a forms the portion between the brazed portion 10a and the leading edge 2b in the air flow direction Y. In other words, the leading edge protrusion 2a forms a portion that protrudes outward from the flat heat transfer tubes 1 in the air flow direction Y. The fin portion 24 also includes a plurality of louvers 22, each having louver slits 22a (see Fig. 2) extending in the tube arrangement direction X and plate portions 22b (see Fig. 2) inclined relative to the flat plate portion 21 of the fin portion 24.

[0032] 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 a fin length L. Ｆ The fin length L is defined as Ｆ is the distance between the leading edge 2b and the trailing edge 2c of the fin portion 24 in the air flow direction Y. When viewed in the tube axis direction Z of the plurality of flat heat transfer tubes 1, the minimum line length between the position of the leading edge 2b and the position of the tube front end 1c in the air flow direction Y is defined as L ｔ More specifically, the minimum line length is defined as L ｔ is the length in the air flow direction Y between the position of the imaginary leading edge portion 2b extended in the tube arrangement direction X and the position of the tube front end portion 1c when viewed in the tube axis direction Z of the multiple flat heat transfer tubes 1.

[0033] The heat exchanger 10 has a fin portion 24 and a plurality of flat heat transfer tubes 1. ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ The heat exchanger 10 is configured so as to satisfy the formula: L<0.22 between the fin portion 24 and the plurality of flat heat transfer tubes 1. ｔ / L Ｆ The relationship is 0.06<L ｔ / L Ｆ It is more preferable that the fin portion 24 and the plurality of flat heat transfer tubes 1 are configured to satisfy the formula: L<0.22. ｔ / L ＦThe relationship between the projection length ratio of the fin portion 24 and the projection length ratio of the fin portion 24 (L ｔ / L Ｆ The reason for setting the temperature of the heat exchanger in the range below will be explained in relation to the low-temperature heating capacity of the heat exchanger.

[0034] The low-temperature heating capacity of a heat exchanger refers to the heating capacity of the heat exchanger in a low outdoor temperature environment. Under low outdoor temperature conditions, moisture in the air condenses on the fin surfaces of the heat exchanger, forming frost. In other words, under low outdoor temperature conditions, the heat exchanger operates while frosting forms. As the frost builds up, the air flow path of the heat exchanger becomes blocked, gradually reducing its capacity.

[0035] For this reason, when a certain amount of frost has accumulated, the heat exchanger stops operating the outdoor fan and starts defrosting operation by flowing hot gas refrigerant inside the heat exchanger. Because heating stops during defrosting operation, the heating capacity of the heat exchanger becomes zero. After the frost has sufficiently melted, the heat exchanger restarts the compressor and blower and starts heating operation again. In other words, the low-temperature heating capacity is defined as the cumulative capacity of heating operation while frosting occurs in the heat exchanger, averaged over the sum of the time for heating operation while frosting occurs and the time for defrosting operation.

[0036] 5A and 5B are conceptual diagrams 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 arrows in Fig. 5 indicate the air flow direction. Fig. 5A is a conceptual diagram of the heat exchanger 10L, and Fig. 5B is a diagram showing the fin length L of the fin portion 24 in the air flow direction Y of the heat exchanger 10L. Ｆ 10 is a conceptual diagram showing the relationship between the temperature of the fin portion 24 and the surface temperature of the fin portion 24. FIG.

[0037] The heat exchanger 10L according to the comparative example is a device in which the front edge 2b of the fin portion 24 does not protrude upwind with respect to the air flow in the air flow direction Y. In (b) of FIG. 5, the horizontal axis represents the fin length L of the fin portion 24. ＦThe vertical axis represents temperature (°C). The solid line A in (b) represents the surface temperature of the fin portion 24, and the dashed line B represents the temperature of the air surrounding the heat exchanger 10L. Part A1 in (b) represents the position of the leading edge 2b of the fin portion 24, and part A2 represents the position of the trailing edge 2c.

[0038] 6 is a conceptual diagram showing the temperature distribution of the fin portion 24 in the air flow direction Y of the heat exchanger 10 according to the first embodiment. In FIG. 6, the hatched portion indicates the leading edge protrusion 2a. The white arrow in FIG. 6 indicates the air flow direction. FIG. 6(a) is a conceptual diagram of the heat exchanger 10, and FIG. 6(b) is a conceptual diagram showing the fin length L of the fin portion 24 in the air flow direction Y of the heat exchanger 10. Ｆ 10 is a conceptual diagram showing the relationship between the temperature of the fin portion 24 and the surface temperature of the fin portion 24. FIG.

[0039] As described above, the heat exchanger 10 is a device in which the front edge 2b of the fin portion 24 protrudes upwind with respect to the air flow in the air flow direction Y. In (b) of FIG. 6, the horizontal axis represents the fin length L of the fin portion 24. Ｆ , and the vertical axis represents temperature (°C). The solid line A in (b) represents the surface temperature of the fin portion 24 relative to the position of the fin portion 24 in the air flow direction Y, and the dashed line B represents the temperature of the air around the heat exchanger 10 of the fin portion 24 relative to the position of the fin portion 24 in the air flow direction Y. Part A1 in (b) represents the position of the leading edge 2b of the fin portion 24, and part A2 represents the position of the trailing edge 2c.

[0040] 5 and 6 are used to explain the formation of frost on the surfaces of the fins 24 during heating operation of a heat exchanger 10 installed outdoors under low-temperature outdoor air conditions. As shown in FIG. 5 , the fins 24 of the heat exchanger 10L of the comparative example do not have any protruding portions on the windward side, so the refrigerant saturation temperature is close to the refrigerant saturation temperature flowing through the adjacent flat heat transfer tubes 1 due to thermal conduction. The refrigerant saturation temperature is assumed to be a constant temperature. Therefore, the temperature difference H1 between the surface temperature of the fins 24 (shown by the solid line A) and the air temperature (shown by the dashed line B, which is higher than the surface temperature of the fins 24) is greatest at the upstream portion of the fins 24. Therefore, in the heat exchanger 10L of the comparative example, condensation water 4 is likely to form upstream of the fins 24, and the amount of frost is greatest at the upstream portion of the fins 24. This causes rapid airway blockage due to frost, resulting in a decrease in the heating capacity.

[0041] In contrast, as shown in Figure 6, the heat exchanger 10 according to the first embodiment has a fin portion 24 that protrudes toward the windward side. In the heat exchanger 10 according to the first embodiment, the leading edge 2b, which is the windward tip of the fin portion 24, is spaced apart from the flat heat transfer tube 1. This causes the surface temperature at the windward tip of the fin portion 24 to be higher than the saturation temperature of the refrigerant flowing through the flat heat transfer tube 1. Therefore, the temperature difference H2 between the air temperature at the windward tip of the fin portion 24 and the surface temperature of the fin portion 24 is smaller than the temperature difference H1 in the heat exchanger according to the comparative example. The heat exchanger 10 is less likely to produce condensation water 4 upstream of the fin portion 24 than the heat exchanger 10L according to the comparative example, and the amount of frost formation is suppressed upstream. This prevents sudden air passage blockage due to frost, thereby improving the heating low-temperature capacity.

[0042] FIG. 7 shows the protrusion length ratio (L ｔ / L ＦThis figure shows the relationship between the temperature (°C) and the low-temperature heating capacity (%). As mentioned above, frost forms on the corrugated fins of a heat exchanger when the heat exchanger is operated under heating conditions with low outdoor temperatures. When a certain amount of frost forms on the heat exchanger, the heating capacity decreases, and the heat exchanger switches from heating operation to defrosting operation. During defrosting operation, the heat exchanger is unable to heat or its heating capacity decreases. Generally, defrosting operation melts the frost by flowing a refrigerant at a temperature higher than 0°C through the heat exchanger, and the fan is usually stopped during this operation.

[0043] However, even when defrosting is performed, if the outside air temperature is below 0°C and wind is blowing toward the heat exchanger, the heat required to melt the ice is absorbed by the wind, lengthening the time it takes for the frost to completely melt. Even after a long defrosting period, frost (ice) may remain on the tips of the fins (residual frost). Therefore, there is a need for a heat exchanger 10 in which the fins 24 have portions that protrude upwind, thereby reducing the amount of frost formation and reducing the likelihood of residual frost during defrosting. In other words, there is a need for a heat exchanger that can achieve both improved frost resistance and reduced residual ice formation during defrosting, while suppressing a decline in defrosting performance.

[0044] Therefore, the inventors have determined that the protrusion length ratio (L ｔ / L Ｆ The inventors conducted an experiment on corrugated fins 2 with different protruding lengths of the fin portions 24, in which a certain amount of frost had formed, and then performed defrosting under conditions of an outside air temperature of approximately 0°C and a certain wind speed, and measured the time required for defrosting (the time until the frost had almost completely disappeared by visual observation). ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ It has been experimentally confirmed that by satisfying the formula <0.22, residual frost does not occur at the tip of the fin portion.

[0045] The residual frost is influenced by the wind speed conditions and defrosting operation conditions, but is also strongly influenced by the thickness of the fin portion 24. The thickness of the fin portion 24 is strongly influenced by heat conduction from the flat heat transfer tube 1. In particular, when the thickness of the fin portion 24 is thin, ie, 0.15 mm or less, the heating operation capacity is approximately proportional to the protrusion length ratio (L ｔ / L Ｆ) as shown in the hatched area F in FIG. 7. ｔ / L Ｆ ) becomes larger than 0.22, residual ice is more likely to occur.

[0046] As shown in FIG. 7, the heat exchanger 10 has a projection length ratio (L ｔ / L Ｆ ) is greater than 0 and less than 0.22, the low-temperature heating capacity can be significantly improved. ｔ / L Ｆ Even if the fin portion 24 protrudes so that the ratio (%) is 0.22 or more, there is almost no effect of improving the heating low-temperature capacity, and residual frost is likely to occur.

[0047] [Effects of the Heat Exchanger 10] The fin portion 24 of the heat exchanger 10 includes a leading edge protrusion 2a that forms a portion extending upwind from the brazed portion 10a at the windwardmost position between the flat heat transfer tubes 1 and the corrugated fin 2. In addition, the heat exchanger 10 has a L between the fin portion 24 and the flat heat transfer tubes 1. ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ The heat exchanger 10 is configured to satisfy the formula <0.22. The fin portion 24 includes the leading edge protrusion 2a, which can improve the frost resistance. ｔ / L Ｆ The relationship is 0 < L ｔ / L Ｆ <0.22, it is possible to suppress the formation of residual ice at the tips of the fin section 24 even during defrosting operation. In other words, by having the above configuration, the heat exchanger 10 can suppress the formation of residual ice at the tips of the fin section 24 even during defrosting operation while improving frost resistance, thereby improving low-temperature heating capacity. By having the above configuration, the heat exchanger 10 can achieve both improved frost resistance and suppression of the formation of residual ice during defrosting operation, thereby suppressing a decrease in defrosting performance. The heat exchanger 10 can improve defrosting performance compared to heat exchangers in which residual ice grows.

[0048] In addition, the heat exchanger 10 has a L between the fin portion 24 and the plurality of flat heat transfer tubes 1. ｔ / L Ｆ The relationship is 0.06<L ｔ / L Ｆ <0.22. The heat exchanger 10 has the above-described configuration, which improves frost resistance and also makes it possible to suppress remaining ice at the tip of the fin portion 24 during defrosting operation, thereby improving the heating low-temperature capacity. ｔ / L Ｆ As can be seen by comparing the cases where L is 0 and 0.06, ｔ / L Ｆ When is 0.06, the heating operation capacity is ｔ / L Ｆ In other words, the heating operation capacity of the heat exchanger 10 is improved by at least 10% compared to when the fin portion 24 does not protrude from the front edge portion 2b side by 0.06<L ｔ / L Ｆ By configuring the heating system so that: the heating capacity at low temperatures can be improved by at least 10% or more.

[0049] Second Embodiment. Fig. 8 is a schematic cross-sectional view of the flat plate portion 21 of the corrugated fin 2 of a heat exchanger 10 according to a second embodiment, cut in 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 a heat exchanger 10M according to a comparative example, cut in the air flow direction Y. The second embodiment further specifies the configuration of the louvers 22. The outline arrows in Figs. 8 and 9 indicate the direction of air flow. The dashed arrows in Figs. 8 and 9 indicate an example of the direction of condensation water 4 flow. The second embodiment will be described below, but explanations of parts that overlap with the first embodiment will be omitted, and the same or corresponding parts as those in the first embodiment will be denoted by the same reference numerals.

[0050] Of the multiple louvers 22, the plate portion 22b of the louver 221 that is closest to the leading edge 2b and located at the windward side has the following structure. As shown in FIG. 8 , the plate portion 22b of the louver 221 has an inclined surface 22d that guides condensation water 4 adhering to the fin portion 24 toward the trailing edge 2c of the corrugated fin 2, which is opposite the leading edge 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 of the plate portion 22b of the louver 221 is formed to face downward and toward the center of the heat exchanger 10 in the air flow direction Y.

[0051] As shown in FIG. 9 , the plate portions 22b of the louvers 221 in the heat exchanger 10M according to the comparative example have inclined surfaces 22e that guide the condensation water 4 adhering to the fin portions 24 toward the leading edge portions 2b of the corrugated fins 2 in the air flow direction Y. The upper surfaces of the plate portions 22b of the louvers 221 in the heat exchanger 10M according to the comparative example are formed to face outward in the air flow direction Y. In the heat exchanger 10M according to the comparative example, the condensation water 4 flows along the plate portions 22b toward the leading edge portions 2b and moves toward the residual frost 4a due to surface tension on the fin portions 24. The residual frost 4a grows and becomes larger due to the influence of outside wind as the condensation water adheres to it. Therefore, the heat exchanger 10M according to the comparative example is affected by the enlarged residual frost 4a, which may result in a decrease in heat exchange performance and a decrease in defrosting performance.

[0052] [Effects of Heat Exchanger 10] In the heat exchanger 10 according to the second embodiment, the plate portions 22b of the louvers 221 have inclined surfaces 22d that guide the condensation water 4 adhering to the fin portions 24 toward the rear edge portions 2c of the corrugated fins 2, opposite the leading edge portions 2b, in the air flow direction Y. By directing the condensation water 4 in the direction opposite the leading edge portions 2b, the heat exchanger 10 can suppress the movement of the condensation water 4 to the residual frost 4a and reduce frost growth due to outside wind.

[0053] Embodiment 3. Figure 10 is a schematic plan view of a portion of a heat exchanger 10 according to embodiment 3. Figure 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 in the air flow direction Y. Embodiment 3 specifies the position of the drainage slits 23. In Figure 10, the hatched portion indicates the leading edge protrusion 2a. The white arrows in Figures 10 and 11 indicate the air flow direction. Hereinafter, embodiment 3 will be described, but descriptions of parts that overlap with embodiment 1 or embodiment 2 will be omitted, and parts that are the same as or equivalent to embodiment 1 and embodiment 2 will be assigned the same reference numerals.

[0054] At least one drainage slit 23 is formed in the fin portion 24 at a central portion 1C of the width of the plurality of flat heat transfer tubes 1 in the air flow direction Y, extending in the tube arrangement direction X. The drainage slit 23 allows condensation water 4 on the upper surfaces of the fin portion 24 to fall and be drained. The drainage slit 23 is an opening formed in the fin portion 24 and is a through-hole. The number of drainage slits 23 may be one or more. The drainage slit 23 only needs to be formed in 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 position of the drainage slit 23 may be biased toward the leading edge portion 2b or the trailing edge portion 2c with respect to the central portion 1C.

[0055] [Effects of Heat Exchanger 10] At least one drainage slit 23 that allows condensation water 4 on the upper surfaces of the fin portion 24 to fall and be drained is formed in the fin portion 24 at a position at the center 1C of the width of the flat heat transfer tubes 1 in the air flow direction Y, and extends in the tube arrangement direction X. The heat exchanger 10 according to the third embodiment efficiently drains the condensation water 4 on the surfaces of the fin portion 24 near the center of the fin portion 24, thereby preventing the condensation water 4 from being guided to the remaining frost 4a on the leading edge portion 2b and reducing frost growth due to outside wind.

[0056] Fourth Embodiment. Fig. 12 is a schematic plan view of a portion of a heat exchanger 10 according to a fourth embodiment. 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 the fourth embodiment, cut in the air flow direction Y. The fourth embodiment further specifies the configuration of the leading edge protrusion 2a. The outline 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 condensed water 4 flows. The fourth embodiment will be described below, but descriptions of parts that overlap with the first to third embodiments will be omitted, and the same reference numerals will be used to refer to the same or corresponding parts as those in the first to third embodiments.

[0057] The leading edge protrusion 2a of the heat exchanger 10 according to the fourth embodiment includes a first folded edge portion 2a1 that is folded toward the upper surface of the fin portion 24 and overlaps the flat plate portion 21. In FIG. 12 , the hatched portion indicates the first folded edge portion 2a1. The edge of the first folded edge portion 2a1 forms a step 2a2 with respect to the flat plate portion 21. The first folded edge portion 2a1 is a portion where the plate-like member constituting the fin portion 24 overlaps the flat plate portion 21 above. The corrugated fin 2 has the first folded edge portion 2a1 at its end on the leading edge portion 2b side in the air flow direction Y. The folded portion of the first folded edge portion 2a1 forms the leading edge portion 2b of the fin portion 24. The edge portion of the first folded edge portion 2a1 facing inward of the heat exchanger 10 forms the step 2a2. The step 2a2 forms a wall extending in the tube axis direction Z and the tube arrangement direction X, preventing condensation water 4 from migrating toward the leading edge portion 2b.

[0058] [Effects of the Heat Exchanger 10] The leading edge protrusion 2a of the heat exchanger 10 according to the fourth embodiment includes a first folded edge portion 2a1 that is folded toward the upper surface of the fin portion 24 and overlaps the flat plate portion 21. The edge of the first folded edge portion 2a1 forms a step 2a2 with respect to the flat plate portion 21. The heat exchanger 10 according to the fourth embodiment includes the first folded edge portion 2a1 and forms the step 2a2 on the leading edge protrusion 2a, thereby preventing condensation water 4 from being guided to the leading edge portion 2b and reducing the growth of frost due to external wind. Furthermore, the heat exchanger 10 according to the fourth embodiment forms the first folded edge portion 2a1 by folding the edge of the fin portion 24, and by increasing the thickness of the fin portion 24 on the leading edge portion 2b side, the thermal conductivity is increased, making it easier to melt frost on the leading edge portion 2b side. Therefore, by having the first edge folded portion 2a1, the heat exchanger 10 of embodiment 4 can improve frost resistance while suppressing remaining ice at the fin tips even during defrosting operation, thereby improving low-temperature heating capacity.

[0059] The heat exchanger 10 according to the fourth embodiment includes the first folded edge portion 2a1, which improves the fin strength of the leading edge protrusion 2a compared to a heat exchanger without the first folded edge portion 2a1. Furthermore, the heat exchanger 10 includes the first folded edge portion 2a1, which increases the thickness of the fin material and improves the strength of the fin tip portion. This makes the corrugated fin 2 less likely to collapse when manufacturing a structure in which the fin portion 24 protrudes upstream, thereby improving manufacturability.

[0060] Fifth Embodiment. Figure 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 the fifth embodiment, cut in the air flow direction Y. The fifth embodiment further specifies the configuration of the leading edge protrusion 2a. The outline arrows in Figure 14 indicate the direction of air flow. The dashed arrows in Figure 14 indicate an example of the direction of condensed water 4 flow. Below, the fifth embodiment will be described, but descriptions of parts that overlap with the first to fourth embodiments will be omitted, and parts that are the same as or equivalent to the first to fourth embodiments will be designated by the same reference numerals.

[0061] The leading edge protrusion 2a of the heat exchanger 10 according to the fifth embodiment includes a second folded edge portion 2a3 that is folded toward the underside of the fin portion 24 and overlaps the flat plate portion 21. The edge of the second folded edge portion 2a3 forms a step 2a2 with respect to the flat plate portion 21. The second folded edge portion 2a3 is a portion where the plate-like member that constitutes the fin portion 24 overlaps the lower side of the flat plate portion 21. The corrugated fin 2 has the second folded edge portion 2a3 at the end on the leading edge portion 2b side in the air flow direction Y. The folded portion of the second folded edge portion 2a3 constitutes the leading edge portion 2b of the fin portion 24. The edge portion of the second folded edge portion 2a3 that faces inward of the heat exchanger 10 forms the step 2a2.

[0062] 14, the corrugated fin 2 has first folded portions 2a1 and second folded portions 2a3 alternately formed in the tube axis direction Z. That is, the corrugated fin 2 includes the first folded portions 2a1 and the second folded portions 2a3.

[0063] [Effects of Heat Exchanger 10] The leading edge protrusion 2a of the heat exchanger 10 according to the fifth embodiment includes a second folded edge portion 2a3 that is folded toward the underside of the fin portion 24 and overlaps the flat plate portion 21. By including the second folded edge portion 2a3, the heat exchanger 10 according to the fifth embodiment can improve the fin strength of the leading edge protrusion 2a compared to a heat exchanger that does not have this configuration.

[0064] Furthermore, the leading edge protrusion 2a of the heat exchanger 10 according to the fifth embodiment includes a first folded edge portion 2a1 that is folded toward the upper surface of the fin portion 24 and overlaps the flat plate portion 21. Therefore, similar to the heat exchanger 10 according to the fourth embodiment, the heat exchanger 10 has the first folded edge portion 2a1, which improves frost resistance and suppresses ice remaining at the fin tips during defrosting operation, thereby improving low-temperature heating capacity. The heat exchanger 10 according to the fifth embodiment has the first folded edge portion 2a1 and the second folded edge portion 2a3, which improves the fin strength of the leading edge protrusion 2a compared to a heat exchanger not having this configuration.

[0065] Sixth Embodiment Figure 15 is a schematic plan view of a portion of a heat exchanger 10 according to a sixth embodiment. In the sixth embodiment, the position of the drainage slits 23 is specified, and the drainage slits 23 are formed in a different position than in the third embodiment. In Figure 15, the hatched portion indicates the leading edge protrusion 2a. The outline arrow in Figure 15 indicates the direction of air flow. Below, the sixth embodiment will be described, but explanations of parts that overlap with the first to fifth embodiments will be omitted, and the same reference numerals will be used to denote the same or corresponding parts as in the first to fifth embodiments.

[0066] The leading edge protrusion 2a of the heat exchanger 10 according to the sixth embodiment is formed with at least one drainage slit 23 extending in the pipe arrangement direction X, which allows condensation water 4 (see FIG. 2 ) on the upper surface of the fin portion 24 to fall and be drained. The drainage slit 23 is an opening formed in the fin portion 24 and is a through-hole. The number of drainage slits 23 may be one or more. The drainage slit 23 is an opening with a long width extending along the pipe arrangement direction X. At least a portion of the drainage slit 23 is formed upwind of the position of the windwardest brazed portion 10a. In other words, at least a portion of the drainage slit 23 is formed in the fin portion 24 between the position of the leading edge 2b and the position of the windwardest brazed portion 10a.

[0067] [Effects of the Heat Exchanger 10] At least one drainage slit 23 extending in the pipe arrangement direction X is formed in the leading edge protrusion 2a of the heat exchanger 10, allowing condensation water 4 (see FIG. 2 ) on the upper surface of the fin portion 24 to fall and be drained. By providing the drainage slit 23 in the leading edge protrusion 2a, the heat exchanger 10 can prevent the condensation water 4 from being guided to the leading edge portion 2b and suppress the growth of frost due to outside wind. In other words, by providing the drainage slit 23 in the leading edge protrusion 2a, the heat exchanger 10 can prevent the condensation water 4 from being guided to the residual frost and refreezing, thereby suppressing the growth of the residual frost.

[0068] Seventh Embodiment. FIG. 16 is a schematic plan view of a first example of a portion of a heat exchanger 10 according to the seventh embodiment. FIG. 17 is a schematic cross-sectional view of the first example of a flat portion 21 of a corrugated fin 2 of a heat exchanger 10 according to the seventh embodiment, cut in the air flow direction Y. FIG. 18 is a schematic plan view of a second example of a portion of a heat exchanger 10 according to the seventh embodiment. FIG. 19 is a schematic cross-sectional view of the second example of a flat portion 21 of a corrugated fin 2 of a heat exchanger 10 according to the seventh embodiment, cut in the air flow direction Y. The seventh embodiment further specifies the configuration of the leading edge protrusion 2a. In FIGS. 16 and 18, the hatched portion indicates the leading edge protrusion 2a. The white arrows in FIGS. 16 to 19 indicate the air flow direction. Below, the seventh embodiment will be described. Explanations of parts that overlap with those of the first to sixth embodiments will be omitted, and the same or corresponding parts as those of the first to sixth embodiments will be denoted by the same reference numerals.

[0069] 16 and 17 , the leading edge protruding portion 2 a of the heat exchanger 10 according to the seventh embodiment is provided with a convex portion 25 that forms a wall that protrudes upward from the flat plate portion 21 and extends in the tube arrangement direction X. Alternatively, as shown in FIGS. 18 and 19 , the leading edge protruding portion 2 a of the heat exchanger 10 according to the seventh embodiment is provided with a concave portion 26 that is a recessed wall formed on the upper surface of the flat plate portion 21 and extends in the tube arrangement direction.

[0070] The protrusion 25 is a rib provided on the upper surface of the leading edge protrusion 2a. The protrusion 25 protrudes upward from the surface of the flat plate portion 21. Note that the protrusion 25 may also be provided on the lower surface of the leading edge protrusion 2a. The recess 26 is a depression or groove provided on the upper surface of the leading edge protrusion 2a. The recess 26 is recessed downward from the upper surface of the flat plate portion 21. The number of protrusions 25 and recesses 26 may be one or more. The protrusion 25 and recess 26 are formed on the windward side of the position of the windward-most brazed portion 10a. In other words, the protrusion 25 and recess 26 are formed on the fin portion 24 between the position of the leading edge portion 2b and the position of the windward-most brazed portion 10a. The protrusion 25 is a wall that prevents the movement of condensed water 4. The recess 26 prevents the movement of condensed water 4 by allowing condensed water to flow into it.

[0071] [Effects of the Heat Exchanger 10] The leading edge protrusion 2a of the heat exchanger 10 according to the seventh embodiment has a protrusion 25 or a recess 26 extending in the tube arrangement direction X. The provision of the protrusion 25 on the leading edge protrusion 2a of the heat exchanger 10 prevents the condensation water 4 from being guided toward the tip of the fin portion 24, thereby preventing frost regrowth due to outside wind. The provision of the recess 26 on the leading edge protrusion 2a of the heat exchanger 10 prevents the condensation water 4 from being guided toward the tip of the fin portion 24, thereby preventing frost regrowth due to outside wind. That is, the provision of the protrusion 25 or the recess 26 on the leading edge protrusion 2a of the heat exchanger 10 prevents the condensation water 4 from flowing toward the tip of the fin portion 24, thereby preventing the formation of residual frost and improving frost resistance. Furthermore, the provision of the protrusion 25 or the recess 26 on the leading edge protrusion 2a of the heat exchanger 10 improves the fin strength of the leading edge protrusion 2a compared to a heat exchanger without such a configuration.

[0072] Eighth Embodiment. Figure 20 is a schematic side view of a heat exchanger 10 according to an eighth embodiment. Figure 21 is a schematic plan view of a portion of an end portion of a heat exchanger 10 according to an eighth embodiment in the tube axis direction Z. Figure 22 is a schematic plan view of a portion of a central portion of a heat exchanger 10 according to an eighth embodiment in the tube axis direction Z. The eighth embodiment further specifies the relationship between the corrugated fins 2 and the flat heat transfer tubes 1. Figure 20 shows the heat exchanger 10 as viewed in the tube arrangement direction X. In Figures 21 and 22, the hatched areas indicate the leading edge protrusions 2a. The white arrows in Figures 20 to 22 indicate the air flow direction. The eighth embodiment will be described below, but descriptions of parts that overlap with those of the first to seventh embodiments will be omitted, and the same reference numerals will be used to designate the same or corresponding parts as those of the first to seventh embodiments.

[0073] When viewed in the tube juxtaposition direction X, the flat heat transfer tubes 1 are curved in the air flow direction Y so that the central portions 10c in the tube axis direction Z protrude relative to both end portions 10c1. That is, when viewed in the tube juxtaposition direction X, the flat heat transfer tubes 1 are curved relative to the vertical direction. Here, the length by which the corrugated fins 2 protrude from the flat heat transfer tubes 1 in the air flow direction Y when viewed in the tube juxtaposition direction X is defined as a protrusion length δ. The corrugated fins 2 are formed to protrude in the upwind direction from the tips of the flat heat transfer tubes 1. When viewed in the tube juxtaposition direction X, the protrusion length δ is the distance between the tube front end portions 1c, which are the tips of the flat heat transfer tubes 1 of the heat exchanger 10 on the upwind side in the air flow direction Y, and the leading edge portions 2b of the corrugated fins 2. The portion that constitutes the protrusion length δ is included in the leading edge protrusion portion 2a.

[0074] The protrusion length δ of the corrugated fin 2 in the windward direction varies depending on the position of the heat exchanger 10 in the tube axis direction Z. As shown in Figures 20 and 21 , in the heat exchanger 10, the protrusion length δ of the corrugated fin 2 near the lower end 10b in the tube axis direction Z is １ As shown in Figures 20 and 22, in the heat exchanger 10, the protrusion length δ of the central portion of the corrugated fin 2 in the tube axis direction Z is defined as the central protrusion length δ ２ As shown in FIG. 20 , the heat exchanger 10 has a lower protrusion length δ of the corrugated fin 2 in the vicinity of the lower end 10 b in the tube axis direction Z. １ is the central protrusion length δ at the central portion of the corrugated fin 2 in the pipe axis direction Z. ２ The lower protrusion length δ is configured to be smaller than １ The portion 10b near the lower end of the heat exchanger 10 constituting the heat exchanger 10 is closer to the lower end 10c11 than the central portion 10c in the tube axis direction Z, and is the portion near the first header 3A.

[0075] [Effects of Heat Exchanger 10] The heat exchanger 10 according to the eighth embodiment has a lower protrusion length δ of the corrugated fin 2 in the vicinity of the lower end 10b in the tube axis direction Z. １ is the central protrusion length δ at the central portion of the corrugated fin 2 in the pipe axis direction Z. ２With this configuration, the heat exchanger 10 according to the eighth embodiment can suppress residual frost at the tip of the leading edge protruding portion 2 a by reducing the protruding length δ of the fin portion 24 near the lower end portion 10 b where condensation water is more likely to occur and residual frost is more likely to remain than in the central portion 10 c.

[0076] Ninth Embodiment Figure 23 is a schematic plan view of a portion of an end portion in the tube axis direction Z of a heat exchanger 10 according to a ninth embodiment. This figure further specifies the configuration of the corrugated fins 2. The outline arrows in Figure 23 indicate the direction of air flow. Below, we will explain the ninth embodiment, but explanations of parts that overlap with those of the first to eighth embodiments will be omitted, and parts that are the same as or equivalent to those of the first to eighth embodiments will be given the same reference numerals.

[0077] The corrugated fin 2 has a trailing edge portion 2c, which is the tip of the corrugated fin 2 on the downwind side with respect to the flow of air flowing between adjacent flat heat transfer tubes 1 among the multiple flat heat transfer tubes 1 in the air flow direction Y.

[0078] Each of the plurality of flat heat transfer tubes 1 has a tube rear end 1d that is the tip of the plurality of flat heat transfer tubes 1 on the downwind side with respect to the flow of air that flows 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 a rear edge 2c is positioned on the downwind side of the tube rear end 1d with respect to the flow of air that flows between adjacent flat heat transfer tubes 1 among the plurality of flat heat transfer tubes 1 in the air flow direction Y.

[0079] The fin portion 24 includes a trailing edge protrusion 2e that extends downwind from the brazed portion 10d at the most downwind portion between the flat heat transfer tubes 1 and the corrugated fin 2. In Fig. 23, the hatched portion on the leading edge 2b side indicates the leading edge protrusion 2a, and the hatched portion on the trailing edge 2c side indicates the trailing edge protrusion 2e. The trailing edge protrusion 2e forms a portion between the brazed portion 10d and the trailing edge 2c in the air flow direction Y. In other words, the trailing edge protrusion 2e forms a portion that protrudes outward from the flat heat transfer tubes 1 in the air flow direction Y.

[0080] [Effects of the Heat Exchanger 10] The fin portion 24 includes a trailing edge protrusion 2e that extends downwind from the brazed portion 10d at the most downwind portion between the flat heat transfer tubes 1 and the corrugated fin 2. When the extension length of the leading edge protrusion 2a must be reduced due to residual frost, the heat exchanger 10 has this configuration, extending the portion on the trailing edge 2c side, thereby increasing the heat transfer area and improving the heating low-temperature capacity while suppressing residual frost. The heat exchanger 10 has this configuration, and by extending the fin portion 24 downstream, the surface area can be increased and the frost resistance can be improved.

[0081] Tenth Embodiment. FIG. 24 is a schematic plan view of a portion of a heat exchanger 10 according to a tenth embodiment. 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 the tenth embodiment, cut along the airflow direction Y. The tenth embodiment further specifies the configuration of the trailing edge protrusion 2e. The outline arrows in FIGS. 24 and 25 indicate the air flow direction. The dashed arrows in FIGS. 24 and 25 indicate an example of the direction of condensation water 4 flow. Note that in FIG. 25, the fin portion 24 includes a first folded edge portion 2a1 on the leading edge portion 2b side. However, the fin portion 24 may include a second folded edge portion 2a3 (see FIG. 14) instead of the first folded edge portion 2a1, or may not include either the first folded edge portion 2a1 or the second folded edge portion 2a3. The tenth embodiment will be described below. Explanations of parts overlapping with those of the first to ninth embodiments will be omitted, and the same reference numerals will be used to designate parts that are the same as or correspond to those of the first to ninth embodiments.

[0082] The trailing edge protrusion 2e of the heat exchanger 10 according to embodiment 10 includes a third edge folded portion 2e1 that is folded toward the upper surface of the fin portion 24 and overlaps the flat plate portion 21. In FIG. 24 , the hatched portion indicates the third edge folded portion 2e1. The edge of the third edge folded portion 2e1 forms a step 2e2 with respect to the flat plate portion 21. The third edge folded portion 2e1 is a portion where the plate-like member that constitutes the fin portion 24 overlaps the flat plate portion 21 above. The corrugated fin 2 has the third edge folded portion 2e1 at its end on the trailing edge portion 2c side in the air flow direction Y. The folded portion of the third edge folded portion 2e1 constitutes the trailing edge portion 2c of the fin portion 24. The edge portion of the third edge folded portion 2e1 facing inward of the heat exchanger 10 forms the step 2e2. The step 2e2 forms a wall extending in the tube axis direction Z and the tube arrangement direction X, and prevents the condensed water 4 from moving toward the rear edge portion 2c.

[0083] [Effects of the Heat Exchanger 10] The trailing edge protrusion 2e of the heat exchanger 10 according to the tenth embodiment includes a third folded edge portion 2e1 that is folded toward the upper surface of the fin portion 24 and overlaps the flat plate portion 21. The edge of the third folded edge portion 2e1 forms a step 2e2 with respect to the flat plate portion 21. The heat exchanger 10 according to the tenth embodiment includes the third folded edge portion 2e1 and forms the step 2e2 on the trailing edge protrusion 2e, thereby suppressing the condensation water 4 from being guided to the trailing edge portion 2c and reducing the growth of frost due to external wind. Furthermore, the heat exchanger 10 according to the tenth embodiment forms the third folded edge portion 2e1 by folding the edge of the fin portion 24, and by increasing the thickness of the fin portion 24 on the trailing edge portion 2c side, the thermal conductivity is increased, making it easier to melt frost on the trailing edge portion 2c side. Therefore, the heat exchanger 10 of embodiment 10 has the third edge folded portion 2e1, which improves frost resistance while suppressing remaining ice at the rear end of the fins even during defrosting operation, thereby improving low-temperature heating capacity.

[0084] The heat exchanger 10 according to the tenth embodiment includes the third folded edge portion 2e1, which improves the fin strength of the trailing edge protrusion 2e compared to a heat exchanger without the third folded edge portion 2e1. Furthermore, the third folded edge portion 2e1 of the heat exchanger 10 increases the thickness of the fin material and improves the strength of the fin tip portion. This reduces the tendency of the corrugated fin 2 to collapse during manufacturing of a structure in which the fin portion 24 protrudes downstream, thereby improving manufacturability. Furthermore, the heat exchanger 10 can further improve the above-described effects by including both the first folded edge portion 2a1 or the second folded edge portion 2a3 (see FIG. 14 ) and the third folded edge portion 2e1.

[0085] Eleventh Embodiment. Figure 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 the eleventh embodiment, cut in the air flow direction Y. The eleventh embodiment further specifies the configuration of the trailing edge protrusion 2e. The outline arrows in Figure 26 indicate the air flow direction. The dashed arrows in Figure 26 indicate an example of the direction of condensation water 4 flow. Note that in Figure 26, the fin portion 24 includes the first folded edge portion 2a1 and the second folded edge portion 2a3 on the leading edge portion 2b side, but the first folded edge portion 2a1 and the second folded edge portion 2a3 are not required. The eleventh embodiment will be described below. Explanations of parts that overlap with the first to tenth embodiments will be omitted, and parts that are the same as or correspond to the first to tenth embodiments will be denoted by the same reference numerals.

[0086] The rear edge protrusion 2e of the heat exchanger 10 according to embodiment 11 includes a fourth edge folded portion 2e3 that is folded toward the underside of the fin portion 24 and overlaps the flat plate portion 21. The edge of the fourth edge folded portion 2e3 forms a step 2e2 with respect to the flat plate portion 21. The fourth edge folded portion 2e3 is a portion where the plate-like member that constitutes the fin portion 24 overlaps the lower side of the flat plate portion 21. The corrugated fin 2 has the fourth edge folded portion 2e3 at its end on the rear edge portion 2c side in the air flow direction Y. The folded portion of the fourth edge folded portion 2e3 constitutes the rear edge portion 2c of the fin portion 24. The edge portion of the fourth edge folded portion 2e3 facing inward of the heat exchanger 10 forms a step 2a2.

[0087] 26 , the corrugated fin 2 has third folded portions 2e1 and fourth folded portions 2e3 formed alternately in the tube axis direction Z. That is, the corrugated fin 2 includes the third folded portions 2e1 and the fourth folded portions 2e3.

[0088] [Effects of the Heat Exchanger 10] The trailing edge protrusion 2e of the heat exchanger 10 according to the eleventh embodiment includes a fourth folded edge 2e3 bent toward the underside of the fin portion 24 and overlapping the flat plate portion 21. The inclusion of the fourth folded edge 2e3 in the heat exchanger 10 according to the eleventh embodiment improves the fin strength of the trailing edge protrusion 2e compared to a heat exchanger without this configuration. The inclusion of the fourth folded edge 2e3 in the heat exchanger 10 increases the thickness of the fin material and improves the strength of the fin tip. This reduces the tendency of the corrugated fin 2 to collapse during manufacturing of a structure in which the fin portion 24 protrudes downstream, thereby improving manufacturability. Furthermore, the heat exchanger 10 can further improve the above-described effects by including both the first folded edge 2a1 or the second folded edge 2a3 (see FIG. 14 ) and the fourth folded edge 2e3.

[0089] Furthermore, the trailing edge protrusion 2e of the heat exchanger 10 according to embodiment 11 includes a third folded edge portion 2e1 bent toward the upper surface of the fin portion 24 and overlapping the flat plate portion 21. Therefore, similar to the heat exchanger 10 according to embodiment 10, the third folded edge portion 2e1 of the heat exchanger 10 improves frost resistance and suppresses ice remaining at the fin tips during defrosting operation, thereby improving low-temperature heating capacity. The heat exchanger 10 according to embodiment 11 includes the third folded edge portion 2e1 and the fourth folded edge portion 2e3, thereby improving the fin strength of the trailing edge protrusion 2e compared to a heat exchanger that does not have this configuration. Furthermore, the heat exchanger 10 can further enhance the above-described effects by including both the first folded edge portion 2a1 and the second folded edge portion 2a3 (see FIG. 14 ) and the third folded edge portion 2e1 and the fourth folded edge portion 2e3.

[0090] Twelfth Embodiment. Figure 27 is a schematic plan view of a portion of a heat exchanger 10 according to a twelfth embodiment. The twelfth embodiment further specifies the configuration of the fin portion 24. The outline arrows in Figure 27 indicate the direction of air flow. In Figure 27, the hatched area on the leading edge 2b side indicates a leading edge-side folded portion 2f, which will be described later, and the hatched area on the trailing edge 2c side indicates a trailing edge-side folded portion 2g. The twelfth embodiment will be described below, but explanations of parts that overlap with those of the first to eleventh embodiments will be omitted, and parts that are the same as or correspond to those of the first to eleventh embodiments will be denoted by the same reference numerals.

[0091] The corrugated fin 2 protrudes so that a trailing edge 2c, which is the tip of the corrugated fin 2 on the leeward side, is positioned further downwind than the tube rear ends 1d, which are the tips of the flat heat transfer tubes 1 on the leeward side, with respect to the flow of air flowing between adjacent flat heat transfer tubes 1. The fin portion 24 includes a trailing edge protrusion 2e that forms a portion extending further downwind than the brazed portion 10d at the most downwind position between the flat heat transfer tubes 1 and the corrugated fin 2.

[0092] The leading edge protrusion 2a includes a leading edge side edge folded portion 2f folded toward the upper surface or lower surface of the fin portion 24 and overlapped on the flat plate portion 21. The leading edge side edge folded portion 2f folded toward the upper surface of the fin portion 24 and overlapped on the flat plate portion 21 is the above-mentioned first edge folded portion 2a1 (see FIG. 26 ). The leading edge side edge folded portion 2f folded toward the lower surface of the fin portion 24 and overlapped on the flat plate portion 21 is the above-mentioned second edge folded portion 2a3 (see FIG. 26 ). The edge of the leading edge side edge folded portion 2f forms a step 2a2 with respect to the flat plate portion 21.

[0093] The trailing edge protrusion 2e includes a trailing edge side edge folded portion 2g folded toward the upper or lower surface of the fin portion 24 and overlapped with the flat plate portion 21. The trailing edge side edge folded portion 2g folded toward the upper surface of the fin portion 24 and overlapped with the flat plate portion 21 is the above-mentioned third edge folded portion 2e1 (see FIG. 26). The trailing edge side edge folded portion 2g folded toward the lower surface of the fin portion 24 and overlapped with the flat plate portion 21 is the above-mentioned fourth edge folded portion 2e3 (see FIG. 26). The edge of the trailing edge side edge folded portion 2g forms a step 2e2 with respect to the flat plate portion 21.

[0094] The fin portion 24 is configured such that, when viewed in the tube axis direction Z, the area S1 of the trailing edge side bent portion 2g is larger than the area S2 of the leading edge side bent portion 2f.

[0095] The length L1 of the trailing edge projection 2e in the air flow direction Y is longer than the length L2 of the leading edge projection 2a. The length L1 of the trailing edge projection 2e is the length between the brazed portion 10d and the trailing edge 2c in the air flow direction Y. The length L2 of the leading edge projection 2a is the length between the brazed portion 10d and the leading edge 2b in the air flow direction Y. The trailing edge projection 2e protrudes further from the flattened heat transfer tube 1 than the leading edge projection 2a.

[0096] The heat exchanger 10 is not limited to one in which the trailing edge projection 2e protrudes more from the flat heat transfer tube 1 than the leading edge projection 2a. The heat exchanger 10 may have the trailing edge projection 2e and the leading edge projection 2a protrude by the same amount, or the leading edge projection 2a may protrude by a greater amount than the trailing edge projection 2e. When the length L1 of the trailing edge projection 2e in the air flow direction Y is longer than the length L2 of the leading edge projection 2a, the heat exchanger 10 protrudes also downstream of the fin portion 24, thereby increasing the surface area and improving frost resistance.

[0097] [Effects of the Heat Exchanger 10] The fin portion 24 is configured such that the area S1 of the trailing edge folded portion 2g is larger than the area S2 of the leading edge folded portion 2f when viewed in the tube axis direction Z. By configuring the heat exchanger 10 in this manner, when the protruding length of the fin portion 24 on the trailing edge 2c side is longer than that on the leading edge 2b side, the strength of the fin portion 24 can be improved compared to when the heat exchanger 10 does not have this configuration.

[0098] Embodiment 13. Figure 28 is a diagram showing the configuration of an air conditioning apparatus 90 according to embodiment 13. Embodiment 13 relates to an air conditioning apparatus 90 as an example of a refrigeration cycle apparatus equipped with the heat exchanger 10 according to embodiments 1 to 12. The air conditioning apparatus 90 uses the heat exchanger 10 according to embodiments 1 to 12 as an outdoor heat exchanger 230.

[0099] As shown in Figure 28, an air conditioner 90 configures a refrigerant circuit by connecting an outdoor unit 200 and an indoor unit 100 with gas refrigerant piping 300 and liquid refrigerant piping 400. The outdoor unit 200 has a compressor 210, a four-way valve 220, an outdoor heat exchanger 230, and an outdoor fan 240. The air conditioner of embodiment 13 is configured such that one outdoor unit 200 and one indoor unit 100 are connected with piping, although the number of units is arbitrary.

[0100] The compressor 210 compresses the drawn refrigerant and discharges it. Although not particularly limited, the compressor 210 can change the capacity of the compressor 210 by arbitrarily changing the operating frequency using, for example, an inverter circuit. The four-way valve 220 is a valve that switches the flow of refrigerant depending on whether the operation is cooling or heating.

[0101] The outdoor heat exchanger 230 exchanges heat between the refrigerant and outdoor air. During heating operation, the outdoor heat exchanger 230 functions as an evaporator, evaporating and vaporizing the refrigerant. During cooling operation, the outdoor heat exchanger 230 functions as a condenser, condensing and liquefying the refrigerant. The outdoor fan 240 sends outdoor air to the outdoor heat exchanger 230 to promote heat exchange in the outdoor heat exchanger 230.

[0102] On the other hand, the indoor unit 100 has an indoor heat exchanger 110, a pressure reducing device 120, and an indoor fan 130. The indoor heat exchanger 110 exchanges heat between the refrigerant and the indoor air to be air-conditioned. During heating operation, the indoor heat exchanger 110 functions as a condenser, condensing and liquefying the refrigerant. During cooling operation, the indoor heat exchanger 110 functions as an evaporator, evaporating and vaporizing the refrigerant.

[0103] The pressure reducing device 120 reduces the pressure of the refrigerant to expand it. The pressure reducing device 120 is configured, for example, by an electronic expansion valve. When the pressure reducing device 120 is configured by an electronic expansion valve, the pressure reducing device 120 adjusts its opening degree based on instructions from a control device (not shown) or the like. The indoor fan 130 passes indoor air through the indoor heat exchanger 110 and supplies the air that has passed through the indoor heat exchanger 110 into the room.

[0104] Next, the operation of each component of the air conditioner 90 will be described based on the flow of refrigerant. First, heating operation will be described. During heating operation, the four-way valve 220 is switched to the dotted line side in FIG. 28 . High-temperature, 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 flows into the indoor heat exchanger 110 condenses and liquefies by exchanging heat with the air in the space to be air-conditioned. The liquefied refrigerant is depressurized by the pressure reducing device 120 to a two-phase gas-liquid state, and then flows into the outdoor heat exchanger 230. The refrigerant that flows into the outdoor heat exchanger 230 evaporates and gasifies by exchanging heat with outdoor air sent from the outdoor fan 240. The gasified refrigerant passes through the four-way valve 220 and is drawn back into the compressor 210. By circulating the refrigerant in this manner, the air conditioner 90 performs air conditioning related to heating.

[0105] Next, cooling operation will be described. During cooling operation, the four-way valve 220 is switched to the solid line side in FIG. 28 . High-temperature, 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 flows into the outdoor heat exchanger 230 condenses and liquefies by exchanging heat with outdoor air supplied by the outdoor fan 240. The liquefied refrigerant is decompressed by the pressure reducing device 120 to a two-phase gas-liquid state, and then flows into the indoor heat exchanger 110. The refrigerant that flows into the indoor heat exchanger 110 evaporates and gasifies by exchanging heat with the air in the space to be air-conditioned. The gasified refrigerant passes through the four-way valve 220 and is drawn back into the compressor 210. By circulating the refrigerant in this manner, the air conditioner 90 performs air conditioning related to cooling.

[0106] Next, the defrosting operation will be described. When heating operation is performed in a low-temperature environment where the surface temperatures of the flat heat transfer tubes 1 (see FIG. 1) and the corrugated fins 2 (see FIG. 1) are below 0°C, frost forms 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, causing a decrease in the performance of the outdoor heat exchanger 230 and a decrease in heating performance. Therefore, when heating performance decreases, the air conditioning apparatus 90 performs a defrosting operation to melt the frost on the surface of the outdoor heat exchanger 230.

[0107] During defrosting operation, the outdoor fan 240 is stopped, the four-way valve 220 is switched to the same state as during cooling operation, and high-temperature, high-pressure gas refrigerant flows into the outdoor heat exchanger 230. This melts frost adhering to the flat heat transfer tubes 1 and the corrugated fins 2. When defrosting operation begins, the high-temperature, high-pressure gas refrigerant flows into the flat heat transfer tubes 1 via the header 3 (see FIG. 1 ). The high-temperature refrigerant flowing into the flat heat transfer tubes 1 melts the frost adhering to the flat heat transfer tubes 1 and the corrugated fins 2, turning them into water. The water produced by the melted frost is drained below the outdoor heat exchanger 230 along the flat heat transfer tubes 1 or the corrugated fins 2. When the frost melts, the air conditioning device 90 terminates the defrosting operation and resumes heating operation. The timing for terminating the defrosting operation and resuming heating operation can be determined using a known method. For example, the defrosting operation may be terminated and the heating operation may be resumed when the temperature detected by a temperature sensor (not shown) reaches a predetermined temperature, or when the defrosting operation has been performed for a certain period of time.

[0108] [Effects of Air Conditioning Apparatus 90] The air conditioning apparatus 90 of embodiment 13 includes the heat exchanger 10 of embodiments 1 to 12, and can therefore achieve the same effects as the heat exchanger 10. For example, the air conditioning apparatus 90 can achieve both improved frost resistance and reduced generation of residual ice during defrosting operation, and can suppress a decrease in defrosting performance.

[0109] The first to thirteenth embodiments described above can be implemented in combination with one another. For example, the trailing edge protrusion 2e may be formed with a drainage slit 23. The trailing edge protrusion 2e may also have a convex portion 25 or a concave portion 26. The configurations described in the above embodiments are merely examples, and may be combined with other known techniques, and some of the configurations may be omitted or modified without departing from the spirit of the invention.

[0110] 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 protrusion portion, 2a1 first edge folded portion, 2a2 step, 2a3 second edge folded portion, 2b leading edge portion, 2c trailing edge portion, 2e trailing edge protrusion portion, 2e1 third edge folded portion, 2e2 step, 2e3 fourth edge folded portion, 2f leading edge side edge folded portion, 2g trailing edge side edge folded portion, 3 header, 3A first header, 3B second header, 4 condensation water, 4a residual frost, 10 heat exchanger, 10L heat exchanger, 10M heat exchanger, 10a brazed portion, 10b near lower end portion, 10c central portion, 10c1 both ends, 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 drainage slit, 24 fin portion, 25 convex portion, 26 concave portion, 90 air conditioning apparatus, 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 piping, 400 liquid refrigerant piping.

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, vertically arranged 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 connected 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 portion on the windward side of the corrugated fin, protrudes to be located more on the windward side than the tube front end portion, which is the tip portion on the windward side of the plurality of flat heat transfer tubes. The fin portion includes a leading edge protruding portion that constitutes a portion extending more on the windward side than the brazing portion of the portion located most on the windward side of the plurality of flat heat transfer tubes and the corrugated fin, 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 . When 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, it is a heat exchanger configured as such.

2. The relationship of L in the fin part and the plurality of flat heat transfer tubes ｔ / L Ｆ is such that 0.06 < L ｔ / L Ｆ < 0.22, and the heat exchanger according to claim 1 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 most upstream position has an inclined surface for guiding the condensed water adhering to the fin portion to the trailing edge portion side of the corrugated fin on the side opposite to the leading edge portion in the air flow direction. The heat exchanger according to claim 1 or 2.

4. At least one drainage slit for draining the condensed water on the upper surface of the fin portion by dropping it is formed in the fin portion so as to extend in the tube juxtaposition 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 any one of claims 1 to 3.

5. At least one drainage slit for draining the condensed water on the upper surface of the fin portion by dropping it is formed in the leading edge protruding portion so as to extend in the tube juxtaposition direction. The heat exchanger according to any one of claims 1 to 3.

6. In the leading edge protruding portion, a convex portion constituting a wall protruding upward from the flat plate portion or a concave portion which is a recessed wall formed on the upper surface of the flat plate portion is provided so as to extend in the tube juxtaposition direction. The heat exchanger according to any one of claims 1 to 5.

7. When viewed in the direction in which the plurality of flat heat transfer tubes are arranged side by side, the central portion in the tube axis direction is curved in the air flow direction so as to protrude with respect to both end portions. 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 the protruding length δ, the lower protruding length δ in the vicinity of the lower end portion of the corrugated fins in the tube axis direction １ is configured to be smaller than the central protruding length δ at the central portion of the corrugated fins in the tube axis direction. The heat exchanger according to any one of claims 1 to 6 ２ is configured as described above.

8. The leading edge protruding portion includes a first edge folding portion bent to the upper surface side of the fin portion and overlapped with the flat plate portion, and the edge of the first edge folding portion forms a step with respect to the flat plate portion. The heat exchanger according to any one of claims 1 to 7.

9. The leading edge protruding portion includes a second edge folding portion bent to the lower surface side of the fin portion and overlapped with the flat plate portion, and the edge of the second edge folding portion forms a step with respect to the flat plate portion. In the tube axis direction, the corrugated fin has the first edge folding portion and the second edge folding portion alternately formed. The heat exchanger according to claim 8.

10. In the air flow direction, for the air flow flowing between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, the trailing edge portion which is the tip portion on the downstream side of the corrugated fin protrudes so as to be located on the downstream side of the tube trailing end portion which is the tip portion on the downstream side of the plurality of flat heat transfer tubes. The fin portion includes a trailing edge protruding portion which constitutes a portion extending downstream of the brazed portion of the portion located most downstream of the plurality of flat heat transfer tubes and the corrugated fin. The heat exchanger according to any one of claims 1 to 9.

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

12. The trailing edge protrusion includes a fourth edge-folded portion that is bent to the lower surface side of the fin portion and overlapped with the flat plate portion, and an edge of the fourth edge-folded portion forms a step with respect to the flat plate portion. In the corrugated fin, in the tube axis direction, the third edge-folded portion and the fourth edge-folded portion are alternately formed. The heat exchanger according to claim 11.

13. In the air flow direction of the corrugated fin, a trailing edge portion, which is a tip portion on the leeward side of the corrugated fin with respect to the air flow flowing between adjacent flat heat transfer tubes among the plurality of flat heat transfer tubes, protrudes to be located on the leeward side of a tube trailing end portion, which is a tip portion on the leeward side of the plurality of flat heat transfer tubes. The fin portion includes a trailing edge protrusion that constitutes a portion extending to the leeward side of a brazed portion of a portion located most leeward among the plurality of flat heat transfer tubes and the corrugated fin. The leading edge protrusion includes a leading edge side edge-folded portion that is bent to the upper surface side or the lower surface side of the fin portion and overlapped with the flat plate portion, and an edge of the leading edge side edge-folded portion forms a step with respect to the flat plate portion. The trailing edge protrusion includes a trailing edge side edge-folded portion that is bent to the upper surface side or the lower surface side of the fin portion and overlapped with the flat plate portion, and an edge of the trailing edge side edge-folded portion forms a step with respect to the flat plate portion. The fin portion is configured such that, when viewed in the tube axis direction, an area of the trailing edge side edge-folded portion is larger than an area of the leading edge side edge-folded portion. The heat exchanger according to any one of claims 1 to 7.

14. An air conditioner having the heat exchanger according to any one of claims 1 to 13.

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