Heat exchanger

Abstract

A heat exchanger (1) includes a plurality of fins (11) and a plurality of heat transfer tubes (12) having a flat cross-sectional shape, and is configured such that the heat transfer tubes (12) are arranged in a vertical direction. each fin (11) includes, between the vertically aligned heat transfer tubes (12), an opening (112) that extends in the vertical direction. The opening (112) is formed in a portion of a water retention region (R) of the fin (11) located between the vertically aligned heat transfer tubes (12), where a first virtual plane, a second virtual plane, and a third virtual plane overlap. The first virtual plane has upper and lower boundaries defined by a lower surface (12b) of an upper, first heat transfer tube (12), and a first virtual line (VL1) extending in the transverse direction of the heat transfer tubes (12) at a position intermediate between a lower, second heat transfer tube (12) and the first heat transfer tube (12). The second virtual plane is bounded by a second virtual line (VL2) connecting the front edge portions (12f) of the heat transfer tubes (12), and extends in a direction away from the front edge portions (12f). The third virtual plane is bounded by a third virtual line (VL3) connecting intermediate portions in the transverse direction of the heat transfer tubes (12), and extends in a direction toward the front edge portions (12f).

Description

Technical Field

[0001] Embodiments of the present invention relate to a heat exchanger.Background Art

[0002] There exists a type of fin-tube heat exchanger provided with a plurality of fins arranged at intervals and a plurality of heat transfer tubes. These tubes extend in a direction in which the fins are aligned, penetrate each fin in its thickness direction, and are spaced apart from each other in a direction perpendicular to the fin alignment. The heat transfer tubes have a flattened cross-sectional shape.Prior Art DocumentsPatent Documents

[0003] Patent Document 1: Japanese Patent No. 6710205Summary of the InventionProblems to be Solved by the Invention

[0004] During operation of a heat exchanger, water generated by condensation and adhering to the surfaces of the fins and heat transfer tubes must be appropriately discharged from the heat exchanger. Heat transfer tubes having a flattened cross-sectional shape (hereinafter sometimes referred to as "flattened tubes") offer superior heat transfer performance compared to circular heat transfer tubes (hereinafter sometimes referred to as "circular tubes").

[0005] However, the cross-sectional shape of the flattened tubes tends to hinder smooth drainage, as compared to tubes with a circular cross-section. A related phenomenon has been observed in which water accumulated in the region between vertically aligned heat transfer tubes (hereinafter sometimes referred to as the "water retention region") is obstructed from flowing out by the lower heat transfer tube, and water that has passed over the front edge portion of the upper heat transfer tube enters the water retention region, thereby hindering prompt drainage.

[0006] Patent Document 1 discloses a technique in which slit-like or louver-like raised portions are formed in the fins between vertically aligned heat transfer tubes. Capillary action occurring in the gaps between these raised portions and adjacent fins promotes the movement of water from the vicinity of the lower surface of the upper tube to the vicinity of the upper surface of the lower tube within the water retention region.

[0007] This technique facilitates the discharge of water formed near the lower surface of the upper tube by guiding it along the raised portion and then to the lower tube, effectively repeating inflow and outflow of water into the water retention region. However, it does not aim to suppress the ingress of water into the water retention region. In other words, it differs from techniques that seek to accelerate drainage by forming a water flow path outside the water retention region.

[0008] In view of the above, it is an object of the present invention to provide a heat exchanger that achieves high heat exchange efficiency with flattened heat transfer tubes, while also ensuring enhanced drainage performance.Means for Solving the Problem

[0009] A heat exchanger in one aspect of the present invention includes a plurality of fins spaced apart from each other in a thickness direction, a plurality of heat transfer tubes having a flat cross-sectional shape, which extend through the respective fins in the thickness direction and are arranged with spacing in a direction perpendicular to the thickness direction.

[0010] In this aspect, the heat exchanger is configured such that the plurality of heat transfer tubes are arranged in a vertical direction, and airflow passes between the vertically aligned heat transfer tubes in a transverse direction corresponding to the minor axis of the tubes.

[0011] Each of the plurality of fins includes an opening between the vertically aligned heat transfer tubes, which extends in the vertical direction and penetrates the fin in the thickness direction.

[0012] The opening is formed in a portion of a water retention region of the fin located between the vertically aligned heat transfer tubes, where a first virtual plane, a second virtual plane, and a third virtual plane overlap with each other.

[0013] The first virtual plane has upper and lower boundaries defined by a lower surface of a first heat transfer tube as an upper tube of the vertically aligned tubes, and a first virtual line extending in the transverse direction of the heat transfer tubes at a position intermediate between an upper surface of a second heat transfer tube as a lower tube of the vertically aligned tubes and the lower surface of the first heat transfer tube.

[0014] The second virtual plane extends in a direction from front edge portions of the first and second heat transfer tubes toward their opposite rear edge portions, with a boundary defined by a second virtual line connecting the respective front edge portions of the first and second heat transfer tubes.

[0015] The third virtual plane extends in a direction toward the front edge portions, with a boundary defined by a third virtual line connecting intermediate portions in the transverse direction of the first and second heat transfer tubes.

[0016] The opening may be formed in the fin by punching in the thickness direction and include a through-hole penetrating the fin.

[0017] The opening may be formed by lancing the fin in the thickness direction, and include a protruding portion that protrudes from a surface of the fin and covers the through-hole on one side of the fin in the thickness direction.

[0018] The distance between the opening and the second virtual line may be between 1 mm and 4 mm.

[0019] The distance between the opening and the lower surface of the first heat transfer tube may be between 0.5 mm and 2 mm.

[0020] The heat exchanger may be further provided with a ridge or groove extending in the vertical direction in a portion of the water retention region other than the overlapping portion.

[0021] In another aspect of the present invention, a heat exchanger includes a plurality of fins spaced apart from each other in a thickness direction, and a plurality of heat transfer tubes having a flat cross-sectional shape, which extend through the respective fins in the thickness direction and are arranged with spacing in a direction perpendicular to the thickness direction.

[0022] The heat exchanger is configured such that the plurality of heat transfer tubes are arranged in a vertical direction, and airflow passes between the vertically aligned heat transfer tubes in a transverse direction corresponding to the minor axis of the tubes.

[0023] Each of the plurality of fins includes an opening in a water retention region defined between the vertically aligned heat transfer tubes, which penetrates the fin in the thickness direction and extends in the vertical direction along a virtual line connecting the front edge portions of the heat transfer tubes.

[0024] The heat exchanger is configured such that water flowing down from above a first heat transfer tube as an upper tube of the vertically aligned tubes and passing over the front edge portion of the first heat transfer tube flows downward along the edge of the opening located near the front edge portion, merges with water discharged from the water retention region, and flows downward below a second heat transfer tube as a lower tube of the vertically aligned tubes.Effects of the Invention

[0025] According to one aspect of the present invention, during operation of the heat exchanger, water generated by condensation adheres to the surfaces of the fins and heat transfer tubes, and flows along the surface of the fins while repeatedly coalescing and migrating toward the upper surfaces of the heat transfer tubes.

[0026] This condensate water then travels along the upper surface of the heat transfer tube, flows over the front edge portion of the heat transfer tube, and wraps around to the underside of the heat transfer tube.

[0027] In this process, since an opening is formed in a portion of the water retention region of the fin where a first virtual plane, a second virtual plane, and a third virtual plane overlap with each other, the condensate water that has flowed over the front edge portion of the heat transfer tube is inhibited from entering the water retention region due to surface tension acting at the periphery of the opening, and instead flows downward along the opening.

[0028] Subsequently, the condensate water merges with water discharged from the water retention region, and as the influence of gravity becomes relatively dominant, the flow is accelerated by its own weight and is promptly discharged from the heat exchanger.

[0029] As described above, the opening suppresses the ingress of water descending over the front edge portion of the upper heat transfer tube into the water retention region, thereby promoting the flow of water along the exterior of the water retention region.

[0030] Accordingly, it becomes possible to provide a heat exchanger that achieves high heat exchange efficiency through the use of flattened heat transfer tubes, while also ensuring enhanced drainage performance.

[0031] By forming the opening through punching in the thickness direction of the fin and providing a through-hole that penetrates the fin, water discharge can be effectively promoted, thereby improving drainage performance.

[0032] By forming the opening through lancing the fin in the thickness direction, and additionally providing a protruding portion that protrudes from the surface of the fin and covers the through-hole, it is possible to enhance the heat transfer characteristics of the fin while promoting water discharge, thereby achieving both high heat exchange efficiency and improved drainage.

[0033] By setting the distance between the opening and the second virtual plane to be between 1 mm and 4 mm, a favorable water flow along the opening can be formed, thereby improving drainage performance.

[0034] By setting the distance between the opening and the lower surface of the first heat transfer tube to be between 0.5 mm and 2 mm, ingress of water into the opening can be effectively suppressed.

[0035] By providing a ridge or groove extending in the vertical direction in a portion of the water retention region other than the aforementioned portion, a downward flow of water present in the water retention region can be actively formed, thereby facilitating smooth water discharge from the water retention region.

[0036] By forming, in the water retention region, the opening that extends along a virtual line connecting the front edge portions of the respective heat transfer tubes and penetrates the fin in the thickness direction, and configuring the structure such that condensate water descending over the front edge portion of the first heat transfer tube as an upper tube of the vertically aligned heat transfer tubes from above the first heat transfer tube flows downward along the edge of the opening near the front edge portions, merges with water discharged from the water retention region, and flows downward to the second heat transfer tube as a lower tube of the vertically aligned heat transfer tubes, it becomes possible to provide a heat exchanger that achieves high heat exchange efficiency through the use of flattened heat transfer tubes, while also ensuring enhanced drainage performance.Brief Description of the Drawings

[0037] Fig. 1 is a schematic diagram illustrating the configuration of a refrigeration cycle apparatus including a heat exchanger according to one embodiment of the present invention. FIG. 2 is a front view showing the structure of the heat exchanger. FIG. 3 is a schematic diagram illustrating the configuration of a fin-tube assembly provided in the heat exchanger. FIG. 4 is a schematic diagram showing the structure of an opening formed in a fin of the heat exchanger. FIG. 5 is a schematic diagram illustrating an example arrangement of the openings in the fin. FIG. 6 is a schematic diagram showing the drainage behavior from the heat exchanger. FIG. 7 is a schematic diagram illustrating the configuration of a fin-tube assembly provided in a heat exchanger according to another embodiment of the present invention. Description of Embodiments

[0038] Referring now to the drawings, embodiments of the present invention will be described in detail.(Configuration of Refrigeration Cycle Apparatus)

[0039] FIG. 1 is a schematic diagram illustrating the configuration of a refrigeration cycle apparatus C including a heat exchanger 1 according to one embodiment of the present invention.

[0040] In this embodiment, the heat exchanger 1 is configured as an outdoor heat exchanger and is disposed outdoors.

[0041] The refrigeration cycle apparatus C is configured as an air conditioning system and includes, in addition to the heat exchanger 1, a compressor 2, a four-way valve 3, an expansion valve 4, and an indoor heat exchanger 5. These refrigeration cycle components are connected via refrigerant piping 6 (including segments 6a to 6f). The heat exchanger 1 is provided with an outdoor fan 1', which introduces outdoor air, or ambient air, into the heat exchanger 1. The indoor heat exchanger 5 is provided with an indoor fan 5', which introduces indoor air into the indoor heat exchanger 5.

[0042] The compressor 2 includes a compressor body 2a and an accumulator 2b. The accumulator 2b separates the refrigerant into gas and liquid phases and supplies the separated gas refrigerant to the compressor body 2a. The compressor body 2a compresses the supplied gas refrigerant and discharges it as a high-temperature, high-pressure gas refrigerant.

[0043] The operation of the refrigeration cycle apparatus C can be switched between cooling and heating modes by changing the flow path in the four-way valve 3.(Cooling Operation)

[0044] FIG. 1 shows the flow of refrigerant during cooling operation by solid arrows A1.

[0045] During cooling operation, the refrigerant flows through the refrigerant piping 6 in the following order: from the compressor 2, through the four-way valve 3, the heat exchanger 1, the expansion valve 4, and then to the indoor heat exchanger 5. The high-pressure gas refrigerant compressed by the compressor 2 is cooled and condensed through heat exchange with outdoor air as passing through the heat exchanger 1. The resulting gas-liquid mixed refrigerant passes through the expansion valve 4, where its pressure is reduced, and is supplied as low-pressure liquid refrigerant to the indoor heat exchanger 5. In the indoor heat exchanger 5, the liquid refrigerant is heated and evaporated through heat exchange with indoor air. The evaporated gas-liquid mixed refrigerant then returns to the compressor 2 via the four-way valve 3.(Heating Operation)

[0046] FIG. 1 shows the flow of refrigerant during heating operation by dashed arrows A2.

[0047] During heating operation, the refrigerant flows through the refrigerant piping 6 in the following order: from the compressor 2, through the four-way valve 3, the indoor heat exchanger 5, the expansion valve 4, and then to the heat exchanger 1. The high-pressure gas refrigerant compressed by the compressor 2 is cooled as it passes through the indoor heat exchanger 5 by exchanging heat with indoor air, that is, by releasing heat to the indoor air and thereby condensing. The resulting gas-liquid mixed refrigerant passes through the expansion valve 4, where its pressure is reduced, resulting in a low-pressure liquid refrigerant that is supplies to the heat exchanger 1. As the liquid refrigerant enters the heat exchanger 1, it is heated by exchanging heat with outdoor air, that is, by absorbing heat from the outdoor air and thereby evaporating. The evaporated gas-liquid mixed refrigerant then returns to the compressor 2 via the four-way valve 3.(Defrost Operation)

[0048] During heating operation, when the refrigerant evaporates in the heat exchanger 1, heat is absorbed from the outdoor air, causing water vapor in the outdoor air to condense and form water droplets that adhere to heat exchange components (e.g., plate-like fins 11) inside the heat exchanger 1. If the outdoor temperature is low, the adhered moisture may freeze and form frost. Such frost can hinder heat exchange and reduce heat exchange efficiency, necessitating a defrost operation for removing the adhered frost.

[0049] During defrost operation, the four-way valve 3 is set to the same state as in cooling operation, and the refrigerant flows in the same sequence as in cooling mode. However, both the outdoor fan 1' and the indoor fan 5' are stopped. The heat exchange components of the heat exchanger 1 are heated by the high-temperature, high-pressure gas refrigerant discharged from the compressor 2, thereby melting the frost. The resulting water is drained from the heat exchanger 1.(Basic Configuration of Outdoor Heat Exchanger)

[0050] FIG. 2 is a front view illustrating the configuration of the heat exchanger 1.

[0051] The heat exchanger 1 is a so-called fin-tube type heat exchanger and includes a heat exchanger core composed of a fin-tube assembly in which plate-like fins 11 are assembled with heat transfer tubes 12. FIG. 2 shows the configuration of the heat exchanger core with the housing 1a being removed from the heat exchanger 1. In FIG. 2, the two-dot chain line schematically indicates the outer contour of the housing 1a.

[0052] In the heat exchanger 1 shown in FIG. 2, the refrigerant flows in the lateral direction relative to the plane of the drawing. Among the flow directions, the direction indicated by arrow X, from right to left in the drawing, is defined as the X-direction. In this embodiment, the X-direction corresponds to both the stacking direction of the plate-like fins 11 and the extending direction of the heat transfer tubes 12.

[0053] Meanwhile, outdoor air passing through the heat exchanger 1 flows in a direction perpendicular to the drawing plane, from front to back. The direction indicated by arrow Z, which is a flow direction of outdoor air, is defined as the Z-direction. That is, the outdoor air flows in the direction of arrow Z and passes through the heat exchanger 1. The downstream side corresponds to the tip direction of arrow Z, and the upstream side corresponds to the base direction.

[0054] Furthermore, the direction indicated by arrow Y, from top to bottom in the drawing, is defined as the Y-direction. Arrow Y represents the vertical downward direction, i.e., the direction of gravity, and coincides with the arrangement direction of the heat transfer tubes 12.

[0055] The heat exchanger 1 includes a plurality of plate-like fins 11, a plurality of heat transfer tubes 12, headers 13, 14, a gas-side fitting 15, and a liquid-side fitting 16. In this embodiment, the plate-like fins 11 are generally rectangular in shape. The headers 13, 14 are cylindrical and have their upper and lower ends in the Y-direction sealed with sealing members.

[0056] The gas-side fitting 15 is connected to the refrigerant piping 6, 6b leading to the four-way valve 3, and the liquid-side fitting 16 is connected to the refrigerant piping 6, 6c leading to the expansion valve 4.

[0057] The refrigerant flowing into the heat exchanger 1 from the refrigerant piping 6 enters one of the headers 13 or 14 via the gas-side fitting 15 or the liquid-side fitting 16, and is distributed to each of the heat transfer tubes 12. While flowing through the heat transfer tubes 12, the refrigerant exchanges heat with outdoor air flowing between the plate-like fins 11, and condenses or evaporates depending on the operating mode of the heat exchanger 1.

[0058] The condensed or evaporated refrigerant is collected in the other header 14 or 13 and discharged to the refrigerant piping 6 via the liquid-side fitting 16 or the gas-side fitting 15.(Detailed Configuration of Fin-Tube Assembly)

[0059] FIG. 3 is a schematic enlarged view illustrating the configuration of the fin-tube assembly provided in the heat exchanger 1.

[0060] FIG. 3(a) is a side view of the fin-tube assembly shown in FIG. 2, as viewed along the stacking direction of the plate-like fins 11, i.e., the X-direction in which the plurality of plate-like fins 11 are aligned.

[0061] FIG. 3(b) is a rear view of the fin-tube assembly shown in FIG. 2, as seen from the downstream side with respect to the flow direction of outdoor air, i.e., in the direction opposite to the Z-direction (reverse Z-direction).

[0062] FIG. 3(c) is a cross-sectional view of the fin-tube assembly shown in FIG. 2 taken along line A-A in FIG. 3(a).

[0063] In this embodiment, the fin-tube assembly includes a plurality of plate-like fins 11 spaced apart in the thickness direction of the fins 11, and a plurality of heat transfer tubes 12 arranged to extend in a direction perpendicular to the surface of the plate-like fins 11, i.e., in the stacking direction of the fins 11, and penetrate each plate-like fin 11 in the thickness direction of the fins 11.

[0064] The plurality of heat transfer tubes 12 are arranged with spacing between them in a direction perpendicular to their extending direction, i.e., to the thickness direction of the plate-like fins 11.

[0065] In actual use, the heat exchanger 1 is installed such that the Y-direction, in which the heat transfer tubes 12 are arranged, aligns with the vertical direction, as shown in FIG. 2. In other words, the heat exchanger 1 is installed with the plate-like fins 11 being arranged horizontally and the heat transfer tubes 12 being arranged vertically.

[0066] Each heat transfer tube 12 has a flattened cross-sectional shape, such as an approximately elliptical or oval shape, and includes a plurality of internal passages 121 formed in parallel for refrigerant flow.

[0067] The internal passages 121 extend inside the heat transfer tube 12 in the X-direction which is the extending direction of the heat transfer tube 12 and are arranged in the Z-direction, i.e., the flow direction of outdoor air. Each end of the heat transfer tube 12 in the X-direction is connected to the headers 13, 14, and each internal passage 121 communicates with one of the headers 13 at one end and with the other header 14 at the other end.

[0068] The heat transfer tubes 12 are inserted into tube insertion portions n formed in each plate-like fin 11, and are fixed to the plate-like fins 11 by brazing or similar means, thereby being assembled into the fins 11. FIG. 3(a) shows a state in which some of the heat transfer tubes 12 are removed to clearly illustrate the tube insertion portions n.

[0069] The tube insertion portions n are formed along the cross-sectional shape or outer contour of the heat transfer tubes 12, and have a shape elongated in the Z-direction.

[0070] In this embodiment, each tube insertion portion n is formed as a notch in the plate-like fin 11, opening at one edge 11a of the fin 11 in the Z-direction which is the flow direction of outdoor air, and closed at the opposite edge 11b.

[0071] That is, the tube insertion portion n terminates between the two edges 11a, 11b, and in this embodiment is in a state where it is open on the downstream side and closed on the upstream side.

[0072] In this embodiment, each heat transfer tube 12 has a width dimension defined in the Z-direction, i.e., the transverse direction, that is smaller than the width dimension of the plate-like fins 11 defined in the same Z-direction. The plate-like fins 11 are formed such that their length dimension, defined in the Y-direction in which the heat transfer tubes 12 are arranged, is greater than their width dimension.

[0073] Assuming that the dimension of the plate-like fins 11 defined in the X-direction, which corresponds to the extending direction of the heat transfer tubes 12, is referred to as the thickness dimension, the thickness of each plate-like fin 11 is smaller than both its width and length dimensions.

[0074] The tube insertion portion n can be formed, for example, by punching the plate-like fin 11 in the X-direction at a location where the tube insertion portion n is to be provided, prior to assembly. Upon formation of the tube insertion portion n, a collar 111 is formed around its peripheral edge, protruding in the punching direction.

[0075] The collar 111 serves to guide the insertion of the heat transfer tube 12 into the tube insertion portion n, and also supports the heat transfer tube 12 after insertion.(Configuration and Arrangement of Opening)

[0076] In this embodiment, each plate-like fin 11 includes an opening 112 that penetrates through the fin 11 in the thickness direction, and is located between vertically aligned heat transfer tubes 12. The opening 112 has a rectangular shape that is elongated in the Y-direction, in which the heat transfer tubes 12 are arranged, and shorter in the Z-direction, which corresponds to the transverse direction of the heat transfer tubes 12.

[0077] The opening 112 is formed in a portion of the water retention region R of the plate-like fin 11, which is located between the vertically aligned heat transfer tubes 12. The water retention region R is vertically bounded between a horizontal plane including the lower surface 12b of a first heat transfer tube 12, 12u, which is the upper one of a pair of the vertically aligned heat transfer tubes 12, and a horizontal plane including the upper surface 12t of a second heat transfer tube 12, 12l, which is the lower one of the pair. The front and rear boundaries, corresponding respectively to the windward and leeward sides, are defined by a vertical plane connecting the front edge portions 12f of the pair of heat transfer tubes 12, 12u, 12l on the windward side, and a vertical plane connecting the rear edge portions 12r on the leeward side.

[0078] Here, three virtual straight lines (hereinafter referred to as "virtual lines") are defined with respect to the plate-like fin 11, namely, a first virtual line VL1, a second virtual line VL2, and a third virtual line VL3. In this embodiment, the first virtual line VL1 is defined as a straight line extending in the horizontal direction, or in the Z-direction, at an intermediate position in the Y-direction between the upper surface 12t of the second heat transfer tube 12l and the lower surface 12b of the first heat transfer tube 12u. The second virtual line VL2 is defined as a straight line extending in the vertical direction, or in the Y-direction, and connecting the front edge portions 12f of the first and second heat transfer tubes 12u and 12l. The third virtual line VL3 is defined as a straight line extending in the vertical direction, or in the Y-direction, and connecting the intermediate portions in the Z-direction of the first and second heat transfer tubes 12u and 12l.

[0079] The opening 112 is formed in a portion of the water retention region R where the following three virtual planes overlap with each other: a first virtual plane, whose upper and lower boundaries are defined by the lower surface 12b of the first heat transfer tube 12u and the first virtual line VL1; a second virtual plane extending from the second virtual line VL2, which serves as the windward-side boundary, in a direction away from the front edge portions 12f, i.e., toward the rear edge portions 12r; and a third virtual plane extending from the third virtual line VL3, which serves as the leeward-side boundary, in a direction approaching the front edge portions 12f.

[0080] In other words, assuming that the width of the heat transfer tube 12 is denoted as Dwf, and the vertical distance between the lower surface 12b of the first heat transfer tube 12u and the upper surface 12t of the second heat transfer tube 12l is denoted as Ddf, the opening 112 is located within a region extending from the front edge portion 12f of the first heat transfer tube 12u in the flow direction of outdoor air up to a distance of Dwf / 2, and extending vertically downward from the lower surface 12b of the first heat transfer tube 12u up to a distance of Ddf / 2.

[0081] Furthermore, the distance Dga between the opening 112 and the second virtual line VL2, specifically the distance between the windward-side edge of the opening 112 and the second virtual line VL2, is preferably between 1 mm and 4 mm. The distance Dgb between the opening 112 and the first heat transfer tube 12u, specifically the distance between the upper edge of the opening 112 and the lower surface 12b of the first heat transfer tube 12u, is preferably between 0.5 mm and 2 mm.

[0082] FIG. 4 is a schematic diagram showing specific examples of the opening 112 applicable to the plate-like fin 11 of the heat exchanger 1 according to this embodiment.

[0083] FIG. 4(a) illustrates an example in which a through-hole 112a is formed by punching the plate-like fin 11 in the thickness direction, thereby forming the opening 112 with the through-hole 112a itself. For illustrative purposes, the through-hole 112a is shown with hatching in FIGS. 4(a)-(c). In the example illustrated in FIG. 4(a), the opening 112 does not include a corresponding configuration to the protrusion portion 112b described below. The projection of the periphery of the opening 112 onto a plane perpendicular to the flow direction of outdoor air (Z-direction) has a dimension, in the thickness direction (X-direction) of the plate-like fin 11, that is equal to the thickness of the plate-like fin 11.

[0084] As shown in FIGS. 4(b) and 4(c), the opening 112 may also be formed by lancing, in other words partially shearing and forming, the plate-like fin 11 in the thickness direction (X-direction). In this case, the opening 112 includes a through-hole 112a that penetrates the plate-like fin 11 in the thickness direction, and a protruding portion 112b that protrudes from the surface of the plate-like fin 11 and covers the through-hole 112a on one side of the fin 11 in the thickness direction.

[0085] FIGS. 4(b) and 4(c) show specific examples of openings 112 with protruding portions 112b. FIG. 4(b) illustrates a slit-type opening 112, while FIG. 4(c) illustrates a louver-type opening 112.

[0086] The slit-type opening 112 is configured to open the through-hole 112a toward both the front and rear edge portions 12f, 12r of the heat transfer tube 12, i.e., in this embodiment, both in the upstream and downstream directions of airflow.

[0087] In contrast, the louver-type opening 112 is configured to open the through-hole 112a only toward the front edge portion 12f of the heat transfer tube 12, i.e., in the upstream direction of airflow, while the through-hole 112a is closed toward the rear edge portion 12r of the heat transfer tube 12, i.e., in the downstream direction, by means of the protruding portion 112b.

[0088] FIG. 5 is a schematic diagram showing examples of the arrangement of the opening 112 in the plate-like fin 11.

[0089] FIG. 5(a) illustrates an example in which a single opening 112 is arranged vertically, i.e., with its longitudinal axis aligned with the vertical or gravitational direction, perpendicular to the flow direction of outdoor air.

[0090] FIG. 5(b) illustrates an example in which the opening 112 is arranged obliquely with respect to the airflow direction. The number of openings 112 is not limited to one and may be plural.

[0091] FIG. 5(c) illustrates an example in which multiple openings 112 are arranged. The openings 112 are aligned in the airflow direction and may be arranged either parallel to each other or at an angle.(Description of Operational Effects)

[0092] The heat exchanger 1 according to this embodiment has the configuration described above. The effects obtained by this embodiment will be explained below.

[0093] FIG. 6 is a schematic diagram illustrating the drainage behavior of water from the water retention region R of the heat exchanger 1. FIG. 6(a) shows a case in which the opening 112 formed in a louvered shape is provided, while FIG. 6(b) shows a comparative example in which no opening 112 is provided, i.e., the surface of the water retention region R is formed as a continuous single plane.

[0094] During operation of the heat exchanger 1, water generated by condensation and adhering to the surfaces of the plate-like fins 11 and heat transfer tubes 12 must be appropriately discharged from the heat exchanger 1. The heat transfer tubes 12 having a flattened cross-sectional shape is advantageous for achieving superior heat transfer performance and high heat exchange efficiency. However, due to its cross-sectional geometry, it presents a drawback in that drainage does not proceed smoothly.

[0095] Focusing on the two vertically aligned heat transfer tubes 12, the upper first heat transfer tube 12u and the lower second heat transfer tube 12l, and the water retention region R between them, water generated in the water retention region R and adhering to the surfaces of the plate-like fins 11 and heat transfer tubes 12 flows downward under the influence of gravity and repeatedly coalesces while moving toward the upper surfaces of the heat transfer tubes 12 and their vicinity (see arrow a1).

[0096] FIGS. 6(a) and 6(b) schematically show the water accumulated near the upper surfaces of the heat transfer tubes 12 using frames W1 and W2 of two-dot chain lines.

[0097] Furthermore, the water W1 and W2 flows along the upper surfaces of the heat transfer tubes 12 toward the front edge portions 12f and rear edge portions 12r, i.e., toward the windward and leeward sides. Water flowing toward the leeward side reaches the rear edge portion 12r and separates from the heat transfer tube 12, being dispersed by the external airflow.

[0098] In the comparative example illustrated in FIG. 6(b), the water flowing toward the windward side as indicated by arrow a2 passes over the front edge portion 12f of the first heat transfer tube 12u, and then flows along the lower surface of the first heat transfer tube 12u. Subsequently, the water wraps around to the underside of the first heat transfer tube 12u and infiltrates into the water retention region R located directly beneath it as indicated by arrows a31 and a32.

[0099] The infiltrated water merges with water W2 present in the water retention region R, forming a larger water mass, which then flows out from the water retention region R as indicated by arrow a4.

[0100] In this manner, in the comparative example, water arriving over the front edge portion 12f of the first heat transfer tube 12u enters the water retention region R, thereby hindering smooth drainage from the water retention region R.

[0101] In contrast, in this embodiment, as shown in FIG. 6(a), the opening 112 is formed along the front edge portion of the water retention region R, i.e., along the second virtual line VL2 connecting the front edge portions 12f of the vertically aligned heat transfer tubes 12.

[0102] Accordingly, for the water that has passed over the front edge portion 12f of the heat transfer tube on the upper side, namely the first heat transfer tube 12u, surface tension acts effectively at the periphery of the opening 112, particularly at the windward-side edge located near the front edge portion 12f (hereinafter sometimes referred to as the "long-side portion of the opening").

[0103] As a result of this surface tension, the lateral movement of the water across the opening 112 in the flow direction of outdoor air is suppressed. Instead, the water flows downward along the opening 112 and moves downward toward the heat transfer tube on the lower side, namely the second heat transfer tube 12l as indicated by arrow a5.

[0104] The water then merges with the water flowing out from the water retention region R as indicated by arrow a4 below the opening 112 or near the lower end portion of the opening 112, forming a larger water mass that is significantly affected by gravity and flows outside the water retention region R.

[0105] Thus, according to this embodiment, the infiltration of water into the water retention region R, which arrives after passing over the front edge portion 12f of the upper heat transfer tube (i.e., the first heat transfer tube 12u), is suppressed by the opening 112. As a result, the flow of water is promoted outside the water retention region R, namely along the outer side of the second virtual line VL2 relative to the water retention region R.

[0106] Accordingly, the heat exchanger 1 can achieve both high heat exchange efficiency through the use of flattened heat transfer tubes 12 and excellent drainage performance.

[0107] This effect is not limited to defrosting operation of the refrigeration cycle apparatus C, but can also be obtained during normal heating operation when the outdoor fan 1' is operating. The formation of the opening 112 facilitates the discharge of water adhering to the surfaces of the plate-like fins 11 or heat transfer tubes 12 during heating operation.

[0108] Here, in the water retention region R, the opening 112 is formed within a portion where the following three virtual planes overlap. A first virtual plane is defined vertically between the lower surface of the upper heat transfer tube 12 (first heat transfer tube 12u) and the first virtual line VL1 extending in the horizontal direction (Z-direction) at a position intermediate between a pair of vertically aligned heat transfer tubes 12. A second virtual plane is bounded by the second virtual line VL2 defined vertically (in the Y-direction) so as to connect the front edge portions 12f of the pair of heat transfer tubes 12, and extends in a direction from the front edge portions 12f toward the rear edge portions 12r on the opposite side. A third virtual plane is bounded by a third virtual line VL3 defined vertically so as to connect intermediate portions in the transverse direction (Z-direction) of the pair of heat transfer tubes 12, and extends toward the front edge portions 12f. By forming the opening 112 in the portion where these three virtual planes overlap, drainage performance can be effectively improved.

[0109] By setting the region in which the opening 112 is formed above the first virtual line VL1, it is possible to suppress situations in which water present in the water retention region R is prevented from flowing out, thereby avoiding excessive retention of water near the upper surface 12t of the heat transfer tube 12 and achieving higher drainage performance.

[0110] Furthermore, by limiting the region in which the opening 112 is formed, it is possible to suppress degradation in the heat transfer characteristics of the plate-like fin 11, which may otherwise be adversely affected due to interference with heat conduction caused by the opening 112.

[0111] In the explanation of FIG. 6, the opening 112 formed in a louvered shape as shown in FIG. 4(c) is used. However, the opening 112 is not limited to this configuration and may be a simple through-hole 112a as shown in FIG. 4(a), or a through-hole 112a covered by a protrusion 112b having a slit or other shape as shown in FIG. 4(b). This allows for improved heat transfer characteristics of the plate-like fin 11 while maintaining drainage performance. In the example shown in FIG. 4(a), airflow resistance can be suppressed, promoting smooth flow of outdoor air.

[0112] The opening 112 may be formed with its longitudinal direction aligned with the vertical or gravitational direction, as shown in FIG. 5(a), or may be formed diagonally, as shown in FIG. 5(b). This enables the water flowing along the opening 112 to acquire a flow velocity component directed away from the water retention region R, thereby actively promoting drainage from the water retention region R.

[0113] Furthermore, as shown in FIG. 5(c), by arranging multiple openings 112 in the transverse direction of the heat transfer tubes 12, i.e., in the Z-direction which corresponds to the flow direction of outdoor air in this embodiment, water that has entered the water retention region R beyond one opening 112 can be suppressed from further intrusion by another opening 112, thereby promoting discharge from the water retention region R.

[0114] Preferably, the opening 112 is formed with an appropriate distance Dga from the second virtual line VL2. This allows for optimization of the surface tension acting on water at the periphery of the opening 112, particularly at the long-side portion near the front edge portion 12f. The distance Dga is preferably between 1 mm and 4 mm.

[0115] Additionally, the opening 112 is preferably formed with an appropriate distance Dgb from the lower surface 12b of the upper heat transfer tube 12u. This suppresses the entry of water generated near the lower surface 12b into the opening 112 and promotes the movement of water along the periphery of the opening 112, particularly along the long-side portion near the front edge portion 12f. The distance Dgb is preferably between 0.5 mm and 2 mm.(Other Embodiments)

[0116] In the water retention region R, in addition to forming the opening 112, it is also possible to form ridges or grooves extending in the vertical direction.

[0117] FIG. 7 illustrates a schematic view illustrating the configuration of the fin-tube assembly according to another embodiment of the present invention, in which a recessed-and-protruded portion 113 is formed on the plate-like fin 11 in addition to the opening 112.

[0118] As shown in FIG. 7, the recessed-and-protruded portion 113 is provided such that a plurality of ridges 113a and 113b are formed in a raw in the flow direction of outdoor air, or the transverse direction of the heat transfer tubes 12, and to extend in a direction perpendicular to the airflow.

[0119] The ridges formed by the recessed-and-protruded portion 113 include a first ridge 113a which is relatively short in the vertical direction, and a second ridge 113b which is longer in the vertical direction than the first ridge 113a.

[0120] The first ridge 113a is formed below the opening 112, i.e., between the upper surface 12t of the lower heat transfer tube 12 and the first virtual line VL1.

[0121] The second ridge 113b is formed on the opposite side of the second virtual line VL2 with respect to the opening 112, or in this embodiment, on the leeward side of the opening 112 and between the second virtual line VL2 and the third virtual line VL3.

[0122] In addition to the ridges 113a and 113b, the recessed-and-protruded portion 113 also includes grooves extending in the vertical direction, which are formed between adjacent first ridges 113a, 113a and between the first ridge 113a and the second ridge 113b, respectively.

[0123] By forming the recessed-and-protruded portion 113 in the water retention region R in addition to the opening 112, it is possible to suppress the entry of water that has passed over the front edge portion 12f of the upper heat transfer tube 12 into the water retention region R.

[0124] Moreover, the recessed-and-protruded portion 113 can promote the downward movement of water present in the water retention region R due to its own weight, i.e., flow toward the upper surface 12t of the lower heat transfer tube 12, thereby facilitating drainage from the water retention region R.

[0125] As a result, further improvement in drainage performance can be achieved.

[0126] In the above description, the headers 13 and 14 are illustrated as cylindrical headers. However, the headers 13 and 14 are not limited to this configuration and may alternatively be laminated-type headers formed by stacking plate-like members.

[0127] The plate-like fin 11 is not limited to a flat shape except for the opening 112 and the recessed-and-protruded portion 113. For example, in the region outside the water retention region R, specifically the region on the windward side of the second virtual line VL2 in this embodiment, the fin 11 may include a stepped portion extending in the Y-direction, in which the heat transfer tubes 12 are aligned.

[0128] Furthermore, the direction of airflow between the plate-like fins 11 is not limited to the Z-direction and may alternatively be in the reverse Z-direction.

[0129] In such a case, the outdoor air passes through the water retention region R from the rear edge portion 12r toward the front edge portion 12f of the heat transfer tubes 12.

[0130] In this configuration, in association with the definition of a region where the opening 112 is formed, the downstream edge of the second virtual plane is defined by the second virtual line VL2, and the upstream edge of the third virtual plane is defined by the third virtual line VL3.

[0131] Additionally, in the louver-shaped opening 112, the direction in which the through-hole 112a opens is not limited to the direction toward the front edge portion 12f of the heat transfer tubes 12, and may alternatively be toward the rear edge portion 12r.

[0132] In other words, the louver-shaped opening 112 may be configured such that the through-hole 112a opens toward the rear edge portion 12r of the heat transfer tube 12 while being closed in the direction toward the front edge portion 12f.

[0133] A number of embodiments of the present invention have thus been described; however, those embodiments are presented as examples and are not intended to limit the scope of the invention. It is possible to carry out the novel embodiments in other various modes and to apply various omissions, substitutions, and changes thereto without departing from the gist of the invention. The embodiments and modifications thereof are included in the scope and the gist of the invention, and are also included in the scope of the invention set forth in the claims and equivalents thereof.Reference Signs List

[0134] C: refrigeration cycle apparatus, 1: heat exchanger (outdoor heat exchanger), 1a: housing, 1': outdoor fan, 2: compressor, 2a: compressor body, 2b: accumulator, 3: four-way valve, 4: expansion valve, 5: indoor heat exchanger, 5': indoor fan, 6, 6a-6f: refrigerant piping, 11: plate-like fin, 111: collar, 12: heat transfer tube, 121: internal passage, 13, 14: header, 15: gas-side fitting, 16: liquid-side fitting, X: thickness direction of plate-like fin, extending direction of heat transfer tube, Y: direction in which heat transfer tubes are aligned, Z: flow direction of outdoor air, R: water retention region, VL1: first virtual line, VL2: second virtual line, VL3: third virtual line.

Claims

1. A heat exchanger comprising: a plurality of fins spaced apart from each other in a thickness direction; and a plurality of heat transfer tubes having a flat cross-sectional shape, which extend through the respective fins in the thickness direction and are arranged with spacing in a direction perpendicular to the thickness direction, the heat exchanger being configured such that the plurality of heat transfer tubes are arranged in a vertical direction, and airflow passes between the vertically aligned heat transfer tubes in a transverse direction corresponding to the minor axis of the tubes, wherein each of the plurality of fins includes, between the vertically aligned heat transfer tubes, an opening that extends in the vertical direction and penetrating the fin in the thickness direction, and wherein the opening is formed in a portion of a water retention region of the fin located between the vertically aligned heat transfer tubes, where a first virtual plane, a second virtual plane, and a third virtual plane overlap with each other, the first virtual plane having upper and lower boundaries defined by a lower surface of a first heat transfer tube which is an upper one of the vertically aligned heat transfer tubes, and a first virtual line extending in the transverse direction of the heat transfer tubes at a position intermediate between an upper surface of a second heat transfer tube which is a lower one of the vertically aligned heat transfer tubes and the lower surface of the first heat transfer tube, the second virtual plane extending in a direction from front edge portions of the first and second heat transfer tubes toward their opposite rear edge portions, with a boundary defined by a second virtual line connecting the respective front edge portions of the first and second heat transfer tubes; and the third virtual plane extending in a direction toward the front edge portions, with a boundary defined by a third virtual line connecting intermediate portions in the transverse direction of the first and second heat transfer tubes.

2. The heat exchanger according to claim 1, wherein the opening is formed in the fin by punching in the thickness direction and includes a through-hole penetrating the fin.

3. The heat exchanger according to claim 2, wherein the opening is formed by lancing the fin in the thickness direction, and includes a protruding portion that protrudes from a surface of the fin and covers the through-hole on one side of the fin in the thickness direction.

4. The heat exchanger according to claim 1, wherein a distance between the opening and the second virtual line is between 1 mm and 4 mm.

5. The heat exchanger according to claim 1, wherein a distance between the opening and the lower surface of the first heat transfer tube is between 0.5 mm and 2 mm.

6. The heat exchanger according to any one of claim 1 to claim 5, further comprising a ridge or groove extending in the vertical direction in a portion of the water retention region other than the overlapping portion.

7. A heat exchanger comprising: a plurality of fins spaced apart from each other in a thickness direction; and a plurality of heat transfer tubes having a flat cross-sectional shape, which extend through the respective fins in the thickness direction and are arranged with spacing in a direction perpendicular to the thickness direction, the heat exchanger being configured such that the plurality of heat transfer tubes are arranged in a vertical direction, and airflow passes between the vertically aligned heat transfer tubes in a transverse direction corresponding to the minor axis of the tubes, wherein each of the plurality of fins includes an opening in a water retention region defined between the vertically aligned heat transfer tubes, which penetrates the fin in the thickness direction and extends in the vertical direction along a virtual line connecting the front edge portions of the heat transfer tubes, and wherein water flowing down from above a first heat transfer tube which is an upper one of the vertically aligned heat transfer tubes and passing over the front edge portion of the first heat transfer tube flows downward along the edge of the opening located near the front edge portion, merges with water discharged from the water retention region, and flows downward below a second heat transfer tube which is a lower one of the vertically aligned heat transfer tubes.

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