HEAT EXCHANGER, REFRIGERATION CYCLE APPARATUS, AND METHOD FOR MANUFACTURING HEAT EXCHANGER

Abstract

The purpose of the present disclosure is to achieve a heat exchanger, a refrigeration cycle device, and a heat exchanger manufacturing method which enable improvement in draining properties and frost-proofing of corrugated fins. A heat exchanger according to the present disclosure is provided with: a plurality of flat heat transfer tubes that are arranged in parallel to one another with the outer surfaces opposed to one another; and corrugated fins that are wave-shaped and that are disposed between the plurality of flat heat transfer tubes opposed to one another. Top portions of the wave shape of the corrugated fins are joined to the outer surfaces of the plurality of flat heat transfer tubes, and the fins connecting the top portions are arranged in parallel to one another along the axial direction of the plurality of flat heat transfer tubes. When the direction in which the plurality of flat heat transfer tubes are arranged in parallel is defined as a parallel direction and the longer axis direction of the plurality of flat heat transfer tubes in the cross-sectional shape is defined as a depth direction, the fins have a plurality of heat-transfer accelerating parts which are arranged along the depth direction, and the plurality of heat-transfer accelerating parts each have a heat-transfer accelerating projection projecting from the surface of the corresponding fin, and an opening that is open in the surface of the fin. Between the plurality of heat-transfer accelerating parts, frost growing regions each having a width in the depth direction are provided, and the frost growing regions each have a through-hole formed contiguous with the opening of the corresponding heat-transfer accelerating part.

Description

Heat exchanger, refrigeration cycle device, and method of manufacturing heat exchanger

[0001] The present disclosure relates to a heat exchanger configured by combining corrugated fins and flat heat transfer tubes, a refrigeration cycle device, and a method for manufacturing the heat exchanger.

[0002] A common prior art technology is a corrugated fin tube heat exchanger, in which corrugated fins are arranged between the flat portions of a plurality of flat heat transfer tubes connected between a pair of headers through which a refrigerant passes. Gas flows between the flat heat transfer tubes with the corrugated fins. In such a heat exchanger, the surface temperature of at least one of the flat heat transfer tubes and the corrugated fins may fall below freezing. When the surface temperature drops, moisture in the air near the surface precipitates and turns into water. When the temperature drops further below freezing, the water freezes. Therefore, to allow water to drain, the heat exchanger has slits in the fin section to serve as voids, and the water precipitated on the surface is discharged through the slits (see, for example, Patent Document 1).

[0003] JP 2015-183908 A

[0004] Conventional heat exchangers have slits, which are structures that allow water that precipitates on the surface of the corrugated fins to drain. The slits are formed by partially cutting the plate material that makes up the corrugated fins and creating cuts that penetrate the plate material. However, the slits are narrow, making it difficult to drain water or frost that accumulates between the slits. The accumulated water or frost creates resistance for air passing through the heat exchanger, reducing the heat transfer performance of the corrugated fins.

[0005] In order to solve the above-mentioned problems, the present disclosure aims to provide a heat exchanger, a refrigeration cycle device, and a method for manufacturing a heat exchanger in which the drainage performance and frost resistance of the corrugated fins are improved.

[0006] The heat exchanger of the present disclosure comprises a plurality of flat heat transfer tubes arranged in parallel with their outer surfaces facing each other, and a corrugated fin having a wave shape and arranged between the plurality of opposing flat heat transfer tubes, wherein the corrugated fins have peaks of the wave shape joined to the outer surfaces of the plurality of flat heat transfer tubes, and fins connecting the peaks are arranged in parallel in the axial direction of the plurality of flat heat transfer tubes, and when the direction in which the plurality of flat heat transfer tubes are arranged in parallel is defined as the parallel direction and the longitudinal direction of the cross-sectional shapes of the plurality of flat heat transfer tubes is defined as the depth direction, the fin has a plurality of heat transfer promotion portions arranged in the depth direction, and each of the plurality of heat transfer promotion portions has a heat transfer promotion protrusion formed protruding from the surface of the fin and an opening portion opened in the surface of the fin, and a frost growth region having a width in the depth direction between the plurality of heat transfer promotion portions, and the frost growth region has a through hole formed continuous with the opening portion of each of the plurality of heat transfer promotion portions.

[0007] The present disclosure also provides a refrigeration cycle device including the heat exchanger described above.

[0008] In addition, the method for manufacturing a heat exchanger disclosed herein is the same as the method for manufacturing the heat exchanger described above, and includes the steps of forming the corrugated fins from flat plate material and joining the tops of the corrugated fins to the flat heat transfer tubes, and the step of forming the corrugated fins includes the steps of drilling the through holes in the plate material, deforming at least one flat portion of the edge of the through hole so as to move it perpendicular to the surface of the plate material to form the heat transfer promotion portion, bending the plate material with the through holes and the heat transfer promotion portion formed into a corrugated shape, and cutting the plate material to a predetermined length after the bending step.

[0009] According to the present disclosure, the upper fins of the corrugated fins of a heat exchanger are configured to pass through the frost growth area adjacent to the heat transfer promotion section and drain water to the lower fins. This prevents water from accumulating on the fins and freezing, further improving the heat transfer performance of the corrugated fins. Furthermore, the provision of a frost space extends the time that the air passage between the fins is blocked when frost grows, improving frost resistance.

[0010] 1 is a front view illustrating the structure of a heat exchanger 10 according to a first embodiment. FIG. 2 is a diagram illustrating the configuration of a refrigeration cycle apparatus according to a first embodiment. FIG. 3 is an enlarged perspective view illustrating the structure of a plurality of flat heat transfer tubes 1 and a corrugated fin 2 of the heat exchanger 10 according to the first embodiment. FIG. 4 is a top view of a corrugated fin 2 according to the first embodiment. FIG. 5 is a top view of a modified example of a fin 21 of the corrugated fin 2 according to the first embodiment. FIG. 6 is a top view of a modified example of a corrugated fin 2 according to the first embodiment. FIG. 7 is a top view of a modified example of a fin 21 of the corrugated fin 2 according to the first embodiment. FIG. 8 is an explanatory diagram of a cross-sectional structure of a fin 21 according to the first embodiment. FIG. 9 is an explanatory diagram of a cross-sectional structure of a fin 121 that is a comparative example of the fin 21 according to the first embodiment. FIG. 10 is a diagram illustrating the relationship between the width of a frost growth region and drainage performance in the heat exchanger 10 according to the first embodiment. FIG. 11 is an example of the structure of a fin 21 according to a second embodiment. FIG. 12 is an example of a fin 21 according to a third embodiment. FIG. 13 is an explanatory diagram illustrating an example of a cross-sectional shape of a fin 21 according to a fourth embodiment. FIG. 14 is an explanatory diagram of the structure of an apparatus for manufacturing a corrugated fin 2 according to a fifth embodiment. FIG. 15 is an example of a flow chart of a processing process for a corrugated fin 2 according to the fifth embodiment. 10 is an explanatory diagram of a processing step of the corrugated fin 2 according to the fifth embodiment. FIG.

[0011] A heat exchanger, a refrigeration cycle apparatus, and a method for manufacturing a heat exchanger according to embodiments will be described below with reference to the accompanying drawings. In the following drawings, components designated by 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 will be referred to as the "lower side." Furthermore, for ease of understanding, directional terms (e.g., "right," "left," "front," "rear," etc.) will be used as appropriate, but these terms are for illustrative purposes only and are not intended to limit the scope of the present invention. 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 those in reality.

[0012] First Embodiment. FIG. 1 is a front view illustrating the structure of a heat exchanger 10 according to the first embodiment. The heat exchanger 10 of the first embodiment is a parallel-pipe type corrugated fin tube heat exchanger. The heat exchanger 10 includes a plurality of flat heat transfer tubes 1 with their tube axes oriented in the vertical direction, a plurality of corrugated fins 2, and a pair of headers 3. The headers 3 include a header 3A located below the plurality of flat heat transfer tubes 1 and a header 3B located above them. Hereinafter, the vertical direction in FIG. 1 will be referred to as the tube axis direction, and the left-right direction will be referred to as the parallel direction. The direction perpendicular to the plane of the page in FIG. 1 will be referred to as the depth direction. The depth direction is the direction in which air flows through the heat exchanger 10. In the first embodiment, the tube axes of the plurality of flat heat transfer tubes 1 are arranged along the direction of gravity, i.e., the height direction. However, the tube axes do not necessarily need to be parallel to the direction of gravity and may be arranged at an angle.

[0013] (Heat Exchanger 10) The headers 3A and 3B are each connected to other devices constituting the refrigeration cycle system 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. A plurality of flat heat transfer tubes 1 are arranged between the two headers 3A and 3B with their tube axes oriented perpendicular to each header 3A and parallel to each other. In the heat exchanger 10 of the first embodiment, the two headers 3A and 3B are arranged separately above and below. Here, the header 3A through which liquid refrigerant passes is located on the lower side, and the header 3B through which gaseous refrigerant passes is located on the upper side. The refrigerant flows in through the lower header 3A, branches into the plurality of flat heat transfer tubes 1, merges in the upper header 3B, and flows out of the heat exchanger 10.

[0014] (Refrigeration cycle apparatus) Fig. 2 is a diagram showing the configuration of a refrigeration cycle apparatus according to embodiment 1. In embodiment 1, an air conditioning apparatus 1000 will be described as an example of a refrigeration cycle apparatus. In the air conditioning apparatus 1000 shown in Fig. 2, the heat exchanger 10 is used as the outdoor heat exchanger 203. However, the heat exchanger 10 is not limited to being used as the outdoor heat exchanger 203, and may also be used as the indoor heat exchanger 110, or may be used as both the outdoor heat exchanger 203 and the indoor heat exchanger 110.

[0015] As shown in Figure 2, the air conditioning apparatus 1000 has a refrigerant circuit formed by connecting the outdoor unit 200 and the indoor unit 100 via gas refrigerant piping 300 and liquid refrigerant piping 400. The outdoor unit 200 has a compressor 201, a four-way valve 202, an outdoor heat exchanger 203, and an outdoor fan 204. The air conditioning apparatus of embodiment 1 has one outdoor unit 200 and one indoor unit 100 connected via piping.

[0016] Compressor 201 compresses and discharges the drawn refrigerant. Although not particularly limited, compressor 201 can change the capacity of compressor 201 by arbitrarily changing the operating frequency using, for example, an inverter circuit. Four-way valve 202 is a valve that switches the flow of refrigerant depending on, for example, whether the operation is cooling or heating.

[0017] The outdoor heat exchanger 203 exchanges heat between the refrigerant and the outdoor air. For example, during heating operation, it functions as an evaporator, evaporating and vaporizing the refrigerant. During cooling operation, it functions as a condenser, condensing and liquefying the refrigerant. The outdoor fan 204 sends outdoor air to the outdoor heat exchanger 203 to promote heat exchange in the outdoor heat exchanger 203.

[0018] Meanwhile, the indoor unit 100 has an indoor heat exchanger 110, an expansion valve 120, and an indoor fan 130. The expansion valve 120, such as a throttling device, reduces the pressure of the refrigerant and expands it. For example, if configured as an electronic expansion valve, its opening degree is adjusted based on instructions from a control device (not shown). The indoor heat exchanger 110 exchanges heat between the refrigerant and the indoor air in the space to be air-conditioned. For example, during heating operation, it functions as a condenser, condensing and liquefying the refrigerant. During cooling operation, it functions as an evaporator, evaporating and vaporizing the refrigerant. 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.

[0019] Next, the operation of each device in the air conditioner 1000 will be described based on the flow of refrigerant. First, the operation of each device in the refrigerant circuit during heating operation will be described based on the flow of refrigerant. High-temperature, high-pressure gas refrigerant compressed and discharged by the compressor 201 passes through the four-way valve 202 and flows into the indoor heat exchanger 110. That is, during heating operation, the refrigerant flows along the path indicated by the dotted line in the four-way valve 202 in FIG. 2 . While passing through the indoor heat exchanger 110, the gas refrigerant condenses and liquefies by exchanging heat with, for example, the air in the space to be air-conditioned. The condensed and liquefied refrigerant passes through the expansion valve 120. The refrigerant is decompressed as it passes through the expansion valve 120. The refrigerant, which has been decompressed by the expansion valve 120 and is now in a two-phase gas-liquid state, passes through the outdoor heat exchanger 203. In the outdoor heat exchanger 203, the refrigerant evaporates by exchanging heat with outdoor air sent from the outdoor fan 204. The gasified refrigerant passes through the four-way valve 202 and is again drawn into the compressor 201. In this manner, the refrigerant in the air conditioner circulates to perform air conditioning related to heating.

[0020] Next, cooling operation will be described. High-temperature, high-pressure gas refrigerant compressed and discharged by compressor 201 passes through four-way valve 202 and flows into outdoor heat exchanger 203. That is, during cooling operation, the refrigerant flows along the path indicated by the solid line in four-way valve 202 in FIG. 2 . The refrigerant then passes through outdoor heat exchanger 203 and condenses by exchanging heat with outdoor air supplied by outdoor fan 204. The liquefied refrigerant then passes through expansion valve 120. The refrigerant is decompressed as it passes through expansion valve 120. The refrigerant, which has been decompressed by expansion valve 120 and is now in a gas-liquid two-phase state, passes through indoor heat exchanger 110. The refrigerant then evaporates in indoor heat exchanger 110 by exchanging heat with, for example, air in the space to be air-conditioned. The gasified refrigerant then passes through four-way valve 202 and is drawn back into compressor 201. In this manner, the refrigerant in the air conditioner circulates to perform air conditioning for cooling.

[0021] (Flat Heat Transfer Tubes 1) FIG. 3 is an enlarged perspective view illustrating the structure of the flat heat transfer tubes 1 and the corrugated fins 2 of the heat exchanger 10 according to the first embodiment. In FIG. 3, the flat heat transfer tubes 1 are partially shown, showing their cross-sectional structure perpendicular to the tube axis, and the corrugated fins 2 are also partially shown with a zigzag shape to illustrate the structure of the fins 21. The flat heat transfer tubes 1 have a flat cross-section perpendicular to the tube axis, and are arranged with their longitudinal direction oriented along the depth direction, which is the air flow direction. The flat heat transfer tubes 1 have an outer surface 1A that is a plane along the longitudinal direction of the cross-sectional shape. Furthermore, the short-side surfaces of the flat heat transfer tubes 1 that are perpendicular to the longitudinal direction, i.e., the longitudinal end faces of the cross-sectional shape of the flat heat transfer tubes 1, are configured to be curved.

[0022] The flat heat transfer tube 1 is a multi-hole flat heat transfer tube having a plurality of holes 1B therein that serve as refrigerant flow paths. In the first embodiment, the holes 1B of the flat heat transfer tube 1 serve as flow paths connecting the headers 3A and 3B. Therefore, the holes 1B are formed to extend in the height direction. The plurality of flat heat transfer tubes 1 are arranged in parallel at equal intervals in a direction perpendicular to the tube axis direction, with their outer surfaces 1A along the longitudinal direction facing each other.

[0023] When manufacturing the heat exchanger 10 according to the first embodiment, each flat heat transfer tube 1 is inserted into an insertion hole (not shown) of each header 3 and joined by brazing. A brazing filler metal containing aluminum, for example, is used for the brazing.

[0024] When the heat exchanger 10 is used as a condenser in a refrigeration cycle device, a high-temperature, high-pressure refrigerant flows through the refrigerant flow paths in the flat heat transfer tubes 1. When the heat exchanger 10 is used as an evaporator, a low-temperature, low-pressure refrigerant flows through the refrigerant flow paths in the flat heat transfer tubes 1. The heat exchanger 10 is used as the indoor heat exchanger 110 or the outdoor heat exchanger 203 shown in FIG. 2 .

[0025] The refrigerant flows into one of the headers 3 through piping (not shown) that supplies the refrigerant to the heat exchanger 10 from devices constituting the refrigeration cycle, such as the four-way valve 202 or expansion valve 120, that constitute the air conditioning apparatus 1000. The refrigerant that flows into one of the headers 3 is distributed and passes through each of the flat heat transfer tubes 1. The flat heat transfer tubes 1 exchange heat between the refrigerant passing through the tubes and the outside air, i.e., the ambient air, passing outside the tubes. During this process, the refrigerant radiates heat to or absorbs heat from the outside air while passing through the flat heat transfer tubes 1. If the temperature of the refrigerant is higher than the temperature of the outside air, the refrigerant radiates its own heat to the outside air. If the temperature of the refrigerant is lower than the temperature of the outside air, the refrigerant absorbs heat from the outside air. The refrigerant that has passed through the flat heat transfer tubes 1 and exchanged heat flows into the other header 3 and merges. The refrigerant then flows back to an external device through piping connected to the other header 3.

[0026] (Corrugated Fins 2) Corrugated fins 2 are arranged between the opposing outer surfaces 1A of the flat heat transfer tubes 1 arranged in a row. The corrugated fins 2 are installed to increase the heat transfer area between the refrigerant in the heat exchanger 10 and the outside air. The corrugated fins 2 are formed by corrugating a plate material and folding it into a zigzag shape with repeated mountain folds and valley folds. In other words, in the front view shown in FIG. 1 , the corrugated fins 2 have a wave or bellows shape. Here, the folded portions of the corrugated fins 2 form the crests of the wave shapes. In the first embodiment, the crests of the corrugated fins 2 are arranged in a row in the tube axial direction along the outer surface 1A of the flat heat transfer tube 1.

[0027] 3, the corrugated fin 2 has a front edge 2B, which is one end portion that protrudes upstream in the air flow direction from between the outer surfaces 1A of the opposing flat heat transfer tubes 1, and the corrugated fin 2 has a crest 2A in contact with the outer surface 1A of the flat heat transfer tube 1. The contact portion between the crest 2A and the outer surface 1A is brazed and joined with a brazing material.

[0028] The plate material constituting the corrugated fin 2 is made of, for example, an aluminum alloy. The surface of the plate material is clad with a brazing filler metal layer. The clad brazing filler metal layer is based on, for example, an aluminum-silicon based brazing filler metal containing aluminum, and the brazing filler metal layer is approximately 30 μm to 200 μm thick.

[0029] The flanks between the peaks 2A of the corrugated fin 2, i.e., the portions connecting the peaks 2A, are called fins 21. Each fin 21 has a heat transfer promotion portion 22, which is a protrusion protruding upward from the surface, and a frost growth region 23. Multiple heat transfer promotion portions 22 are arranged in each fin 21 in the depth direction, which is the air flow direction.

[0030] The heat transfer promotion section 22 has a heat transfer promotion protrusion 22A protruding from the fin 21 in the tube axial direction and an opening 22B through which air or condensed water passes. The opening 22B is an opening formed directly below the heat transfer promotion protrusion 22A. In each fin 21, a frost growth region 23 is located adjacent to the heat transfer promotion section 22 in the depth direction. The frost growth region 23 is a hole penetrating the fin 21 and, from a perspective perpendicular to the surface of the fin 21, is a rectangular hole extending elongated in the parallel arrangement direction of the flat heat transfer tubes 1. The frost growth region 23 is sandwiched between the heat transfer promotion section 22 and the flat section 24 and is located adjacent to the heat transfer promotion section 22 and the flat section 24. In other words, the fin 21 has a structure in which the upper part of each of the multiple openings is partially covered by the heat transfer promotion protrusion 22A. The multiple openings are located adjacent to the flat section 24. The plurality of openings are arranged in parallel in the depth direction of the heat exchanger 10 .

[0031] (Function of the heat transfer promotion section 22 and the frost growth region 23) When the heat exchanger 10 functions as an evaporator, the surfaces of the flat heat transfer tubes 1 and the corrugated fins 2 are at a temperature lower than the air passing through the heat exchanger 10. As a result, moisture in the air condenses on the surfaces of the flat heat transfer tubes 1 and the corrugated fins 2, and condensed water 4 precipitates. Furthermore, when the air temperature is even lower, the surface temperature of the corrugated fins 2 drops below freezing, and the condensed water 4 remaining on the surfaces of the corrugated fins 2 freezes to form frost, which grows and blocks the air passage. As a result, the ventilation resistance of the heat exchanger 10 increases, and the amount of air flowing through the heat exchanger 10 decreases, which may result in a decrease in the performance of the heat exchanger 10.

[0032] In the first embodiment, condensed water 4 condensed on the surfaces of each fin 21 of the corrugated fin 2 flows into the openings 22B of the heat transfer acceleration section 22 and the frost growth region 23, and then flows downward to the lower fin 21. The frost growth region 23 and the openings 22B of the heat transfer acceleration section 22 are connected and continuously arranged, thereby increasing the opening area. This reduces the amount of condensed water 4 retained by the fin 21 due to surface tension and improves the drainage rate. Furthermore, each fin 21 of the corrugated fin 2 is arranged at an incline, rather than parallel to the arrangement direction of the flattened heat transfer tubes 1. Therefore, when condensed water is discharged, it flows downward from the frost growth region 23 along the inclined surfaces of the fins 21. As a result, the heat exchanger 10 reduces the amount of condensed water 4 retained on the corrugated fins 2, leading to improved drainage rate.

[0033] Under low-temperature conditions where the surface temperature of the corrugated fin 2 is below freezing, moisture adhering to the surface of the fin 21 freezes and grows as frost. Frost growth is particularly pronounced near the leading edge 2B of the fin 21, which is located upstream of the air flowing into the heat exchanger 10, due to its high heat transfer coefficient. Consequently, frost growth on the leading edge 2B blocks the airflow path and reduces the performance of the heat exchanger. However, in the first embodiment, the frost growth region 23 is located adjacent to the leading edge 2B, where frost is likely to grow, and is also located contiguous with the heat transfer acceleration section 22, where frost is likely to grow. This delays airflow path blockage and suppresses degradation of heat exchanger performance. In other words, the provision of the frost growth region 23 improves the heat exchanger 10's frost resistance. In particular, the temperature difference between the air and the fin surface is greater at the heat transfer acceleration section 22 located at the windward side of the heat exchanger 10 than at the heat transfer acceleration section 22 on the downwind side, resulting in a greater amount of frost formation. Therefore, by ensuring the frost growth area 23 as in the fins 21 of the heat exchanger 10 according to the first embodiment, the decrease in the drainage speed can be suppressed and the blockage of the air passage can be delayed more effectively.

[0034] FIG. 4 is a top view of the corrugated fin 2 according to the first embodiment. FIG. 4 is a view of the flat heat transfer tubes 1 as viewed from the tube axis direction. A-A in FIG. 4 indicates the center of the flat heat transfer tubes 1 in the depth direction. Also, B-B in FIG. 4 indicates the center between two flat heat transfer tubes 1 sandwiching the corrugated fin 2. As described above, the frost growth regions 23 are provided to sandwich the heat transfer promotion section 22. This promotes drainage by draining water downward from the frost growth regions 23 located on both sides of the heat transfer promotion section 22, where condensation is likely to occur. Furthermore, under low-temperature conditions, frost grows in the frost growth regions 23, which are the spaces on both sides of the heat transfer promotion section 22. This prevents impairing ventilation between the flat heat transfer tubes 1, improving the frost resistance of the heat exchanger 10.

[0035] Figure 5 is a top view showing a modified example of the fin 21 of the corrugated fin 2 according to the first embodiment. Frost growth is most pronounced on the leading edge 2B side of the heat transfer acceleration section 22, which is located upstream of the air flow and has a high heat transfer coefficient. Therefore, for example, as shown in Figure 5, the frost growth region 23 may be provided only on the upwind side of the heat transfer acceleration sections 22. In this case, the frost growth region 23, which is a hole opened in the fin 21 in top view, is formed only upstream of the heat transfer acceleration sections 22, thereby suppressing a reduction in the heat transfer area and improving frost resistance.

[0036] Fig. 6 is a top view showing a modified example of the corrugated fin 2 according to the first embodiment. In the fin 21 shown in Figs. 4 and 5, the heat transfer promotion portions 22 and the frost growth regions 23 have the same width and position in the parallel arrangement direction of the flattened heat transfer tubes 1, but this is not limiting. For example, the width of the frost growth regions 23 may be different from that of the heat transfer promotion portions 22. In other words, the frost growth regions 23 and the heat transfer promotion portions 22 may only partially overlap in the depth direction. Furthermore, adjacent heat transfer promotion portions 22 may be arranged with their centers offset in the parallel arrangement direction.

[0037] In manufacturing, forming the corrugated fin 2 requires a process for forming through-holes 27 (see FIG. 16 ) that become the frost growth regions 23 and a process for forming the heat transfer promotion protrusions 22A of the heat transfer promotion portions 22 so that they protrude from the surface of the fin 21. In the case of the fin 21 structure shown in FIG. 6 , the die for punching out the frost growth regions 23 and the die for forming the heat transfer promotion portions 22 must be pressed against the fin 21 at positions offset in the width direction to apply force. If the frost growth regions 23 and the heat transfer promotion portions 22 are positioned so that they only partially overlap in the depth direction, the die for forming the frost growth regions 23 and the die for forming the heat transfer promotion portions 22 are pressed against the fin 21 with an offset in the parallel direction of the flattened heat transfer tube 1. If the two dies are misaligned, the fin 21 is likely to warp during molding. However, if the horizontal centers of the frost growth regions 23 and the heat transfer promotion portions 22 are aligned, warping of the fin 21 is more likely to be suppressed during the shape formation process.

[0038] FIG. 7 is a top view showing a modified example of the fin 21 of the corrugated fin 2 according to the first embodiment. In the first embodiment, the shape of the frost growth region 23 is rectangular as shown in FIGS. 4 to 6 , but is not limited to a rectangular shape. For example, taking into account the frost growth distribution revealed by the inventors' analysis and experiments, the frost growth region 23 is configured so that the opening width in the depth direction decreases with increasing distance from each of the two flat heat transfer tubes 1, as shown in FIG. 7 . The shape of the frost growth region 23 shown in FIG. 7 results in a narrower opening width in the depth direction and a smaller opening area in regions with lower heat exchange efficiency through the fin 21. Therefore, the frost resistance can be efficiently increased while suppressing a decrease in the heat transfer area in regions farther from the two flat heat transfer tubes 1.

[0039] 8 is an explanatory diagram of the cross-sectional structure of the fin 21 according to the first embodiment. Fig. 8 shows a cross section perpendicular to the fin 21, and illustrates an outline of the shape pattern of the fin 21 in a cross section corresponding to the section B-B in Fig. 4. As described above, the heat transfer promotion portions 22 protrude from the surfaces of the fins 21 and are provided so as to protrude into the air path of the outside air passing through the heat exchanger 10. Formed in this manner, the heat transfer promotion portions 22 promote heat transfer by disrupting the temperature boundary layer of the air in the air path between the two flattened heat transfer tubes 1.

[0040] The frost growth region 23 is arranged upstream of the heat transfer promotion section 22 or both upstream and downstream of the air flow. The frost growth region 23 is a hole that penetrates the fin 21. A flat section 24 is arranged downstream of the frost growth region 23. And another frost growth region 23 is arranged downstream of the flat section 24. In other words, frost growth regions 23 are arranged both upstream and downstream of the flat section 24.

[0041] The frost growth region 23 is a hole opened in the surface of the fin 21, and is arranged adjacent to at least the upstream side of the heat transfer promotion portion 22. The heat transfer promotion portion 22 has a heat transfer promotion protrusion 22A formed by deforming a portion of the fin 21 by lifting it upward relative to the flat portion 24. An opening portion 22B is formed below the heat transfer promotion protrusion 22A. The frost growth region 23 forms an integral opening that is continuous with the opening portion 22B below the heat transfer promotion portion 22. In other words, the heat transfer promotion protrusion 22A is arranged so as to straddle above the opening provided in the fin 21.

[0042] FIG. 9 is an explanatory diagram of the cross-sectional structure of a fin 121, which is a comparative example of the fin 21 according to the first embodiment. In a conventional heat exchanger, louvers 122 are formed by cutting and raising portions of the fin 121. The conventional louvers 122 are formed by forming cuts 125 in the plate material constituting the fin 21, and then raising the flat plate surface by press working, thereby extending the cuts 125 perpendicular to the plate surface of the fin 21. Therefore, an opening 122B is formed perpendicular to the flat portion 121a between the leading edge 122a located on the windward side of the louver 122 and the flat portion 121a. However, in the conventional louvers 122, when viewed perpendicular to the flat portion 121a, the opening 122B is not visible, or if it is visible, it appears as only a tiny gap.

[0043] In contrast, in the heat exchanger 10 according to the first embodiment, as shown in Figures 4 to 7, the frost growth regions 23, which are openings, can be seen when viewed perpendicularly to the surfaces of the fins 21. These openings are, for example, 0.5 mm wide, preferably 1 mm or wider, in the depth direction when viewed perpendicularly to the surfaces of the fins 21, and are located at least upstream of the heat transfer promotion sections 22. In other words, in the first embodiment, the surfaces of the fins 21 are not cut out, but the heat transfer promotion protrusions 22A of the heat transfer promotion sections 22 and the holes serving as the frost growth regions 23 are arranged in parallel in the depth direction. Therefore, when viewed in the axial direction, the frost growth regions 23 of the fins 21 can be seen as holes.

[0044] As shown in FIG. 8, the length L of the frost growth region in the ventilation direction, i.e., the depth direction, Ｓ The distance between the centers of the heat transfer promotion portion 22 and the frost growth region 23 is L Ｐ , the length L of the heat transfer promotion portion 22 Ｌ , the length L of the flat portion 24 Ｆ , fin total length L Ｔ It is defined as:

[0045] In the fins 21 of the heat exchanger 10 shown in FIG. 8, in order to improve the frost resistance and the drainage performance during defrosting operation, it is desirable to make the frost growth region 23 somewhat larger than the heat transfer promotion portion 22. Specifically, L Ｓ >L Ｌ / 7, preferably L Ｓ >L Ｌ The length L of the frost growth region 23 is preferably set to / 6. Ｓ and the length L of the heat transfer promotion portion 22 Ｌ By setting these parameters so as to satisfy this relationship, the frost resistance is improved while increasing the drainage performance in the frost growth region 23. As a result, when the heat exchanger 10 functions as an evaporator at low temperatures, the frost resistance is improved, and the low-temperature heating capacity of the air conditioning apparatus 1000 is improved.

[0046] FIG. 10 is a diagram showing the relationship between the width of the frost growth region and the drainage performance in the heat exchanger 10 according to the first embodiment. Ｓ L Ｆ / 5-L Ｆ This graph shows the drainage performance when the temperature is set to a range of 1 / 7, and shows the results of a three-dimensional two-phase flow analysis developed by the inventors. The drainage performance of the heat exchanger 10 was measured by immersing the heat exchanger 10 in a water tank and then comparing the results of calculating the amount of water retained in the heat exchanger 10 at any given time when the heat exchanger 10 was pulled out. In other words, Figure 10 shows that the greater the drainage performance, the faster the drainage speed.

[0047] As shown in FIG. 10, the depth direction length S of the frost growth region 23 Ｌ is the depth direction length L of the heat transfer promotion portion 22 Ｌ By increasing the relative size of L Ｓ >L Ｌ This is because the drainage performance is improved rapidly at the length L of the frost growth region 23. Ｓ This is thought to be because when the surface tension of water between the flat portion 24 and the heat transfer promotion portion 22 increases to a certain extent, the formation of a bridge between the flat portion 24 and the heat transfer promotion portion 22 due to the surface tension of water is suppressed.

[0048] The depth direction length L of the frost growth region 23 Ｓ is preferably L Ｌ It is preferable that the length L of the frost growth region 23 is set to be equal to or greater than 1 / 6. In addition, in order to roll-form the fin 21, the plate material constituting the fin 21 must have a certain degree of rigidity and strength. In the corrugated fin 2 according to the first embodiment, in order to satisfy this requirement, the length L of the frost growth region 23 is set to be equal to or greater than 1 / 6. Ｓ is the length L of the flat portion 24Ｆ Therefore, in the first embodiment, the dimensional relationship of the fin 21 is as follows: L Ｓ ≦L Ｆ That is, the length of the frost growth region 23 in the depth direction is preferably L Ｌ / 7<L Ｓ ≦L Ｆ It is set so that:

[0049] Furthermore, in the heat exchanger 10 according to the first embodiment, in order to improve the frost resistance, the length L in the depth direction of the flat portion 24 of the frost growth region is Ｆ A certain size is required for L Ｓ ≧L Ｆ / 4, preferably L Ｓ ≧L Ｆ It is better to use / 3.

[0050] In the first embodiment, the fin 21 has the frost growth region 23, so the flat portion length L Ｆ and the length of the heat transfer promotion section L Ｌ The sum of the total fin length L Ｔ That is, when the heat transfer promotion portion 22 is virtually set to the same height as the flat portion 24, the fin total length L Ｔ The length L of the plurality of frost growth regions 23 Ｓ The length of the fin 21 is shortened by the sum of the above.

[0051] Embodiment 2 A heat exchanger 10 according to embodiment 2 will be described. The heat exchanger 10 according to embodiment 2 is different from the heat exchanger 10 according to embodiment 1 in that the shape of the heat transfer promotion portion 22 is changed. In embodiment 2, the changes from embodiment 1 will be mainly described.

[0052] 11 shows an example of the structure of the fin 21 according to the second embodiment. In the second embodiment, the heat transfer promotion portion 22 has a heat transfer promotion protrusion 222A protruding from the surface of the fin 21. The tip end surface of the heat transfer promotion protrusion 222A is not flat, but has a curved surface with a convex central portion in a cross section perpendicular to the parallel direction. This shape prevents condensed water 4 from accumulating on the upper surface of the heat transfer promotion protrusion 222A of the heat transfer promotion portion 22, improving drainage. Furthermore, when air passing through the heat exchanger 10 passes over the curved surface formed on the upper surface of the heat transfer promotion protrusion 22A, turbulence is promoted, improving heat exchange performance.

[0053] Embodiment 3 A heat exchanger 10 according to embodiment 3 will be described. The heat exchanger 10 according to embodiment 3 is different from the heat exchanger 10 according to embodiment 1 in that the shape of the heat transfer promotion portion 22 is changed. In embodiment 3, the changes from embodiment 1 will be mainly described.

[0054] FIG. 12 shows an example of a fin 21 according to a third embodiment. In the third embodiment, adjacent heat transfer promotion portions 22 are formed offset in the parallel arrangement direction of the flat heat transfer tubes 1, as shown in the heat transfer promotion portions 22p and 22q in FIG. 12. This configuration enhances the leading edge effect of the heat transfer promotion portions 22. In other words, the heat exchange efficiency of the fin 21 is high on the upstream side of the airflow, making frost formation more likely. However, the heat transfer promotion portions 22 have high drainage properties on the leading edge side, so ventilation is less likely to be impaired even if frost forms. This reduces pressure loss and improves the performance of the heat exchanger. Furthermore, the frost growth region 23 is more effectively improved in the case of the third embodiment, where the leading edge effect is large.

[0055] Embodiment 4 A heat exchanger 10 according to embodiment 4 will be described. The heat exchanger 10 according to embodiment 4 is different from the heat exchanger 10 according to embodiment 1 in that the shape of the heat transfer promotion portion 22 is changed. In embodiment 4, the changes from embodiment 1 will be mainly described.

[0056] 13 is an explanatory diagram showing an example of the cross-sectional shape of the fin 21 according to the fourth embodiment. In the fourth embodiment, the heat transfer promotion portion 22 and the flat portion 24 have inclined surfaces, forming a so-called louvered shape. That is, in the fourth embodiment, the heat transfer protrusion 422A of the heat transfer promotion portion 422 is inclined, with one end 422a located above the surface of the flat portion 24 in the depth direction and the other end 422b located below the surface of the flat portion 24. Alternatively, the ends 422a and 422b of the heat transfer protrusion 422A may be at the same height as the flat portion 24.

[0057] Frost growth areas 423 are arranged upstream and downstream of the heat transfer promotion section 422, and similar to the frost growth areas 23 in the fins 21 of embodiments 1 to 3, an opening having a width of 0.5 mm in the depth direction, preferably 1 mm or more, is secured when viewed from a direction perpendicular to the surface of the fin 21.

[0058] 9, in conventional corrugated fins, louvers 122 are formed by forming cuts 125 in fins 121, whereas in fin 21 according to embodiment 4, frost growth regions 423 are formed as holes in fin 21, thereby increasing the spacing between heat transfer protrusions 422A of heat transfer promotion section 422. This allows for a larger space between the louvers, improving condensate drainage and frost resistance while promoting heat transfer.

[0059] In particular, in the fins 121 having louvers 122 with a high heat transfer promoting effect, frost growth becomes noticeable at the front edge 122a between adjacent louvers 122, i.e., at the upstream side of the louvers 122. This causes air passage blockage and leads to a decrease in the performance of the heat exchanger under low temperature conditions. However, the heat exchanger 410 according to the fourth embodiment is provided with a frost growth region 423, and this frost growth region 423 has a length L in the depth direction in the cross section shown in FIG. Ｓ The distance in the depth direction between one upstream end 422a and the other downstream end 422b of the two heat transfer promotion portions 422 arranged in the depth direction is L ＳThis provides a large space for frost to grow at the upstream end 422a of the heat transfer acceleration section 422 where frost growth is most noticeable, thereby preventing air passage blockage.

[0060] A flat portion 24 may be provided near the center of the fin 21 in the depth direction. A frost growth region 423A for improving drainage is provided on the upstream or downstream side of the flat portion 24, and has a length L in the depth direction. Ｓ Since the frost growth region 423A is also formed in the center of the depth direction of the fin 21, the drainage performance is further improved.

[0061] In the fin 21 according to the fourth embodiment, the heat transfer promotion portion 422 is inclined. When the louver angle is virtually set to 0°, the total length L of the fin 21 in the depth direction is Ｔ - Depth length L of the frost growth region 23 Ｓ (total of the length of the inclined portion L Ｌ Sum of + length of flat part L Ｆ The heat transfer acceleration parts 422, which are louvers, are arranged symmetrically with respect to the center in the depth direction. The heat transfer acceleration parts 422 are formed to face each other across the frost growth region 423A of the flat part 24 near the center.

[0062] 13, when an imaginary line P is defined as an extension of the centerline in the plate thickness direction of the heat transfer acceleration portions 422 arranged symmetrically with respect to the center portion, the heat transfer acceleration portions 422 are oriented so that the imaginary line P intersects with the imaginary line P below the fin 21. With this configuration, condensed water collects in the central portion of the fin 21 along the heat transfer acceleration portions 422, so that condensed water collects in the central portion of each of the multiple fins 21 arranged in the vertical direction, and can be efficiently guided to the frost growth region 423A around the flat portion 24. This improves the drainage performance of the heat exchanger 10. In the fourth embodiment, a case where multiple flat portions 24 and frost growth regions 423A are provided has been described, but the number and shape of the flat portions 24 and frost growth regions 423A are not limited.

[0063] The flat portion 24 arranged adjacent to the heat transfer acceleration portion 422 across the frost growth region 423 may have an inclined portion 424a at the end on the frost growth region 423 side. The inclined portion 424a is preferably formed at the same angle and in the same direction as the inclination of the heat transfer acceleration portion 422.

[0064] Fifth Embodiment A heat exchanger 10 according to a fifth embodiment will be described. In the fifth embodiment, an example of a method for manufacturing the fins 21 of the heat exchangers 10 according to the first to fourth embodiments will be described.

[0065] FIG. 14 is an explanatory diagram of the structure of an apparatus for manufacturing a corrugated fin 2 according to embodiment 5. Specifically, the drawing shows an example of a perforating roller 500 for manufacturing the corrugated fins 2 according to embodiments 1 to 4. The perforating roller 500 forms frost growth regions 23 by drilling through holes 27 (see FIG. 16) in a plate material 521 (see FIG. 16) that will become the corrugated fin 2. When the plate material 521 that will become the corrugated fin 2 is fed between a first roller cutter 501 and a second roller cutter 502 that are arranged vertically, the engagement between the rollers forms through holes 27 that will become the frost growth regions 23 in parts of the plate material 521.

[0066] The first roller cutter 501 and the second roller cutter 502 have parallel rotation axes and have cutters 501a and 502a on their outer peripheries that process the plate material 521. The first roller cutter 501 and the second roller cutter 502 have a predetermined distance between their rotation axes, and the plate material 521 is punched or bent by passing between the cutters 501a and 502a. As an example, the first roller cutter 501 and the second roller cutter 502 shown in Figure 14 form the frost growth region 23 by punching.

[0067] The first roller cutter 501 and the second roller cutter 502 can form frost growth regions 23 with different horizontal spacing in the processed plate material by changing the spacing in the rotational direction of their respective cutters 501a and 502a. In this case, one rotation of the first roller cutter 501 and the second roller cutter 502 constitutes one cycle, and the spacing of the formed through holes 27 changes periodically and uniformly.

[0068] For example, by making the circumferential length of the roller longer than the length of the corrugated fin 2, it is possible to process the corrugated fin 2 so that the intervals between the frost growth regions 23 formed thereon are all different. By using the perforating roller 500 to form the frost growth regions 23 on the corrugated fin 2 in this way, the processing speed when manufacturing the corrugated fin 2 can be faster than that of normal press processing. As shown in FIG. 14 , the apparatus for manufacturing the corrugated fin 2 includes a control device 590. The control device 590 controls processing conditions such as the rotation speeds of the first roller cutter 501 and the second roller cutter 502 and the feed speed of the plate material 521.

[0069] FIG. 15 shows an example of a flow chart of the processing steps for the corrugated fin 2 according to the fifth embodiment. First, through holes 27 are formed in the plate material 521 that constitutes the corrugated fin 2 (step S01). The through holes 27 are formed, for example, by a perforation roller 500 shown in FIG. 14. This process is called the perforation process. Starting from this point, the heat transfer promotion portions 422 are formed by applying convex or louvered molding to the flat portions sandwiched between the frost growth regions 23 (step S02). This process is called the heat transfer promotion portion forming process. Next, the plate material that constitutes the corrugated fin 2 is bent into a wave shape (step S03). This process is called the folding process. The plate material is then cut to the desired length (step S04).

[0070] 16 is an explanatory diagram of a processing step for a corrugated fin 2 according to the fifth embodiment. In step S01, elongated rectangular or approximately rectangular through-holes 27 that will become frost growth regions 23 are punched into a flat plate material 521 that constitutes the corrugated fin 2. In FIG. 16, the plate material 521 is a long, strip-shaped metal plate extending along the outline arrow in the figure. The through-holes 27 are formed in the plate material 521 for each group of through-holes 527 that are aligned longitudinally, and are formed sequentially and continuously in the longitudinal direction of the plate material 521 (the direction of the outline arrow in FIG. 16).

[0071] In step S02, at least one of the flat portions 28 forming the long sides of the elongated rectangular through-holes 27 is moved from its original position 29 in a direction perpendicular to the surface of the plate material 521, and deformed to form the heat transfer promotion portion 22 having the cross-sectional structure shown in Fig. 9 or 10. That is, the flat portions 28 between the parallel through-holes 27 are deformed into a bridge shape (also called a bridge lance) so as to rise in a direction perpendicular to the surface of the plate material 521. Alternatively, the flat portions forming the long sides of the slits may be deformed so as to be inclined from their original positions 29, and formed into a louver-like structure like the heat transfer promotion portion 22 shown in Fig. 13.

[0072] The forming in step S02 may be performed by rollers as shown in Fig. 13, and the plate material 521 having the through holes 27 formed therein may be passed between two rollers to form the heat transfer promotion portion 22. The rollers that form the heat transfer promotion portion 22 may be arranged, for example, downstream of the perforating rollers 500 in Fig. 14, so that the plate material 521 that has passed through the perforating rollers 500 in Fig. 14 is continuously supplied.

[0073] Alternatively, the step of punching through holes 27 (step S01) and the step of vertically raising flat portions 28 between through holes 27 to form a bridge shape (step S02) may be performed in a single step. For example, the through holes 27 and the heat transfer promotion portions 22 may be formed simultaneously using a perforation roller 500 shown in FIG.

[0074] After the plate material 521 is drilled and deformed in steps S01 and S02, the plate material 521 is bent along the line m shown in Fig. 16(a). The plate material 521 is fed in the direction of the outline arrow in Fig. 16(a) and is bent sequentially along the line m, which is an imaginary line between the rows of through holes 27 (step S03). The bent plate material 521 is then cut to a predetermined length to form the corrugated fin 2 (step S04).

[0075] The corrugated fins 2 formed as described above are sandwiched between the flat heat transfer tubes 1, and the corrugated fins 2 are joined to the outer surfaces 1A of the flat heat transfer tubes by brazing or the like. Both ends of the flat heat transfer tubes 1 are inserted into insertion holes provided in the headers 3A, 3B and brazed to each other. In this way, the heat exchanger 10 is completed.

[0076] According to the manufacturing method of the heat exchanger 10 of embodiment 5, the corrugated fin 2 can be molded continuously and with high precision to form the through holes 27 and the heat transfer promotion portions 22, so that the corrugated fin 2 shown in embodiments 1 to 4 can be manufactured easily and quickly.

[0077] In the past, it was difficult to form the through holes 27 and the heat transfer promotion portions 22 consecutively. For example, as in the fin 121 of the comparative example, louvers 122 were formed by cutting incisions 125 into a plate material and opening the incisions 125 perpendicular to the surface of the plate material to form the openings 122B. This resulted in poor drainage and frost resistance of the corrugated fin 2 having the fin 121. However, according to the manufacturing method of the heat exchanger 10 of the fifth embodiment, the through holes 27 and the heat transfer promotion portions 22 are formed in a synchronized manner with high precision, thereby enabling the frost growth region 23 to be formed adjacent to at least one end of the heat transfer promotion portions 22 in the airflow direction of the corrugated fin 2. This makes it possible to realize the fin 21 structure having the frost growth region 23 of the first to fourth embodiments.

[0078] One example of a synchronization method involves using an imaging device 580 such as a CCD camera shown in FIG. 14 to monitor the formation positions of the through holes 27 and the variation in their formation positions while performing image processing on the images obtained from the CCD camera. While determining the formation positions of the through holes 27 and the variation in their formation positions, the material feed rate and the rotation speed of the roller 500 are adjusted so that the through holes 27 and the heat transfer promotion portions 22 are formed continuously. Alternatively, the timing for adjusting the processing conditions, such as the material feed rate and the rotation speed of the roller 500, can be optimized by machine learning using AI, using as training data information on the formation positions of the through holes 27 obtained from the images, processing conditions such as the material feed rate and the rotation speed of the roller 500, and a data set of the accuracy of the shape of the heat transfer promotion portions 22.

[0079] In the manufacturing method of the heat exchanger 10, the hole drilling process and the heat transfer promotion portion forming process are performed consecutively. Therefore, depending on the variation in the material feed speed and the rotation speed of the roller 500, it is possible that the position of the through holes 27 may be shifted in the hole drilling process, and that the position of the heat transfer promotion portions 22 may vary in the heat transfer promotion portion forming process, resulting in the heat transfer promotion portions 22 being formed offset relative to the through holes 27. In particular, because the material is fed to the next process in one direction at a set speed, the position of the through holes 27 and the shape and position of the processed heat transfer promotion portions 22 may vary in the material feed direction.

[0080] For example, a CCD camera is placed between the hole drilling process and the heat transfer promotion portion forming process to photograph the surface of the material in which the through holes 27 are formed. Alternatively, a CCD camera is placed after the heat transfer promotion portion forming process to photograph the surface of the material in which the heat transfer promotion portions 22 are formed. These CCD camera images are subjected to image processing to determine positional accuracy data, such as the amount of deviation between the positions of the through holes 27 and the formation positions of the heat transfer promotion portions 22. This data, along with information on processing conditions such as the material feed rate and the rotation speed of the roller 500, is used as labeled data for machine learning in a model. Furthermore, information on processing conditions other than the material feed rate and the rotation speed of the roller 500, such as the temperature and the thickness of the plate material 521, may be added to the labeled data for machine learning of the model.

[0081] Furthermore, in the hole drilling process and the heat transfer promotion portion forming process, the model grasps the amount of deviation between the position of the through hole 27 and the formation position of the heat transfer promotion portion 22 from actual images from the CCD camera, and adjusts processing conditions such as the material feed speed and the rotation speed of the roller 500 based on the amount of deviation. The adjustment content is determined by AI using the above-mentioned machine learning. Note that the machine learning may feed back to the model processing accuracy data and processing conditions based on images obtained while performing the hole drilling process and the heat transfer promotion portion forming process, and reflect them simultaneously with processing.

[0082] The model may be implemented, for example, in the control device 590 of the apparatus for manufacturing the corrugated fin 2, or may be implemented in a computer connected to the apparatus. The model determines appropriate processing conditions based on the actual processing conditions during the hole drilling process and the heat transfer promotion portion forming process, as well as data such as images. Information on the processing conditions determined to be optimal by the model is sent from the control device 590 to the rollers 500 of the apparatus for manufacturing the corrugated fin 2 and the apparatus performing the heat transfer promotion portion forming process, and instructions are sent to control the processing conditions. The control device 590 may receive the results of the model's determination of the optimal processing conditions and continuously monitor and control the processing conditions, or may modify the processing conditions at predetermined time intervals.

[0083] As described above, the first to fifth embodiments of the present disclosure have been described, but the first to fifth embodiments are merely examples of the heat exchanger 10, the refrigeration cycle device, and the method for manufacturing the heat exchanger, and they can be combined with other known techniques. Furthermore, the heat exchanger 10 can be modified or part of its configuration can be omitted without departing from the scope of the present disclosure.

[0084] In the heat exchanger 10 described in the first to fifth embodiments, it is desirable that the frost growth regions 23 and the heat transfer promotion portions 22 provided on the fins 21 are positioned symmetrically with respect to the center in the direction of air flow of the fins 21, i.e., the depth direction. In other words, it is desirable that the fins 21 have a shape symmetrical with respect to the line A-A shown in Figures 4 to 7 and 12. By positioning the frost growth regions 23 and the heat transfer promotion portions 22 so that they are bilaterally symmetric with respect to the center line, it becomes easier to supply the plate material 521 straight during the hole drilling process and the heat transfer promotion portion forming process, and the through holes 27 and the heat transfer promotion portions 22 can be formed with high precision without the plate material 521 being misaligned to the left or right with respect to the material feed direction.

[0085] 1 Flat heat transfer tube, 1A outer surface, 1B hole, 2 Corrugated fin, 2A top, 2B front edge, 3 Header, 3A Header, 3B Header, 4 Condensed water, 10 Heat exchanger, 21 Fin, 21A Surface, 22 Heat transfer promotion portion, 22A Heat transfer promotion convex portion, 22B Opening portion, 22p Heat transfer promotion portion, 22q Heat transfer promotion portion, 23 Frost growth area, 24 Flat portion, 27 Through hole, 28 Flat portion, 100 Indoor unit, 110 Indoor heat exchanger, 120 Expansion valve, 121 Fin, 121a Flat portion, 122 Louver, 122B Opening, 122a Front edge, 125 Notch, 130 Indoor fan, 200 Outdoor unit, 201 Compressor, 202 Four-way valve, 203 Outdoor heat exchanger, 204 Outdoor fan, 210 Heat exchanger, 222A Heat transfer promotion convex portion, 300 Gas refrigerant piping, 310 Heat exchanger, 400 Liquid refrigerant piping, 410 Heat exchanger, 422 Heat transfer promotion portion, 422A Heat transfer convex portion, 422a Upstream end portion, 422b Downstream end portion, 422c End portion, 422d (other) end portion, 423 Frost growth region, 423A Frost growth region, 500 Roller, 501 First roller cutter, 501a Cutter, 502 Second roller cutter, 502a Cutter, 510 Heat exchanger, 521 Plate material, 527 Through hole group, 580 Imaging device, 590 Control device, 1000 Air conditioning device.

Claims

1. A heat exchanger comprising: a plurality of flat heat transfer tubes arranged in parallel with their outer surfaces facing each other; and corrugated fins having a wave shape and arranged between the plurality of opposing flat heat transfer tubes, wherein the corrugated fins have peaks of the wave shape joined to the outer surfaces of the plurality of flat heat transfer tubes, and fins connecting the peaks are arranged in parallel in the axial direction of the plurality of flat heat transfer tubes, and when the direction in which the plurality of flat heat transfer tubes are arranged in parallel is defined as the parallel direction and the long axis direction of the cross-sectional shapes of the plurality of flat heat transfer tubes is defined as the depth direction, the fin has a plurality of heat transfer promotion portions arranged in the depth direction, and each of the plurality of heat transfer promotion portions has a heat transfer promotion protrusion formed by protruding from the surface of the fin and an opening portion opened in the surface of the fin, and a frost growth region having a width in the depth direction between the plurality of heat transfer promotion portions, and the frost growth region has through holes formed contiguous with the opening portion of each of the plurality of heat transfer promotion portions.

2. A heat exchanger as described in claim 1, wherein the plurality of heat transfer promotion portions have tip surfaces located at the tips of the portions protruding from the surface of the fins, and the tip surfaces have curved surfaces formed so that the central portions are convex in the depth direction.

3. A heat exchanger as described in claim 1, wherein the plurality of heat transfer promotion portions have tip surfaces located at the tips of the portions protruding from the surface of the fins, and the tip surfaces are inclined with respect to the surface of the fins.

4. A heat exchanger as described in claim 3, wherein one of the plurality of heat transfer promotion sections has a flat section arranged adjacent to the frost growth region, and the flat section has an inclined section inclined at the same angle and in the same direction as the tip surfaces of the plurality of heat transfer promotion sections.

5. A heat exchanger according to any one of claims 1 to 4, wherein two adjacent heat transfer promotion parts among the plurality of heat transfer promotion parts are arranged offset from each other in the parallel direction.

6. The fin has a length of the frost growth area in the depth direction of L Ｓ , the length of the heat transfer promotion portion is L Ｌ When this is done, L Ｌ / 7<L Ｓ The heat exchanger according to any one of claims 1 to 5, which satisfies the relationship:

7. A heat exchanger according to any one of claims 1 to 6, which has a flat portion between two adjacent heat transfer promotion portions among the plurality of heat transfer promotion portions.

8. The fin has a length of the frost growth area in the depth direction of L Ｓ , the length of the heat transfer promotion portion is L Ｌ , the length of the flat portion is L Ｆ When this is done, L Ｌ / 7<L Ｓ ≦L Ｆ The heat exchanger according to claim 7, which satisfies the relationship:

9. A refrigeration cycle device comprising the heat exchanger according to any one of claims 1 to 8.

10. A method for manufacturing a heat exchanger as defined in any one of claims 1 to 8, comprising the steps of: forming the corrugated fins from a flat plate; and joining the tops of the corrugated fins to the flat heat transfer tubes, wherein the step of forming the corrugated fins comprises: a drilling step of forming the through holes in the plate; a heat transfer promotion portion forming step of deforming at least one flat portion of the edge of the through hole so as to move it in a direction perpendicular to the surface of the plate, thereby forming the heat transfer promotion portion; a bending step of bending the plate, with the through holes and the heat transfer promotion portions formed in it, into a corrugated shape; and a step of cutting the plate to a predetermined length after the bending step.

11. A method for manufacturing a heat exchanger as described in claim 10, wherein the hole-making step is performed by passing the plate material between two roller cutters having cutters and parallel rotation axes, and the heat transfer promotion portion forming step is performed after the hole-making step by passing the plate material between two rollers having parallel rotation axes.

12. A method for manufacturing a heat exchanger as described in claim 11, wherein the positional accuracy of the through holes during the drilling process is monitored based on an image of the surface of the plate material taken by an imaging device, and processing conditions including the rotational speed of the roller cutter and the feed speed of the plate material are varied based on the positional accuracy data of the through holes obtained from the image.

Images