The present invention relates to a heat exchanger that exchanges heat between a refrigerant and air.
Conventionally, heat exchangers for exchanging heat between a refrigerant and air are used in air conditioners and the like. For example, Patent Literature 1 discloses a heat exchanger including flat tubes in which a refrigerant flows and corrugated members disposed between the flat tubes. The corrugated members each have flat portions arranged in a direction in which the flat tubes extend and raised portions arranged between the flat portions to join them, and form flow passages for allowing the air to flow therethrough.
Patent Literature 1: JP 2004-317002 A
SUMMARY OF INVENTION
In the heat exchanger of Patent Literature 1, the flat portions are arranged at a constant pitch. Therefore, in the case where this heat exchanger is used as an outdoor heat exchanger for an air conditioner, if frost forms thereon during heating operation, the frost blocks all the air flow passages between the flat portions simultaneously, which may make it impossible to continue heat exchange between the refrigerant and air.
Under these circumstances, it is an object of the present invention to provide a heat exchanger capable of performing heat exchange between a refrigerant and air continuously even if frost forms thereon.
In order to solve the above problem, the heat exchanger of the present invention is a heat exchanger that exchanges heat between a refrigerant and air and includes: a plurality of heat transfer tubes extending in an internal flow direction in which the refrigerant flows; and a corrugated member having a corrugated shape. The corrugated member includes: a plurality of fins that are arranged at at least two different pitches, a relatively large first pitch and a relatively small second pitch, in the internal flow direction; and a plurality of folded portions that are bonded alternately in the internal flow direction to the heat transfer tubes that are adjacent to each other.
In the configuration described above, the fins are arranged at irregular pitches. Therefore, for example, even if frost forms on the outdoor heat exchanger during heating operation and narrower air flow passages formed between the fins with a smaller pitch are blocked, wider air flow passages formed between the fins with a larger pitch are less likely to be blocked. Rather, when the narrower air flow passages formed between the fins with the smaller pitch are blocked, the flow rate of the air increases between the fins arranged at the larger pitch, which makes the blockage of the wider air flow passages less likely to occur. This is because the frost is removed from the air flow passages by the air flowing therein at a high flow rate before the frost grows thick enough. Therefore, the heat exchanger can perform heat exchange between the refrigerant and the air continuously.
A first aspect of the present disclosure provides a heat exchanger that exchanges heat between a refrigerant and air, including: a plurality of heat transfer tubes extending in an internal flow direction in which the refrigerant flows; and a corrugated member having a corrugated shape. The corrugated member includes: a plurality of fins that are arranged at at least two different pitches, a relatively large first pitch and a relatively small second pitch, in the internal flow direction; and a plurality of folded portions that are bonded alternately in the internal flow direction to the heat transfer tubes that are adjacent to each other.
A second aspect of the present disclosure provides the heat exchanger as set forth in the first aspect, wherein each of the fins includes a plurality of flat portions that are arranged in a staggered or stepped manner in an external flow direction perpendicular to the internal flow direction and a direction in which the heat transfer tubes are arranged, and slits opening in the external flow direction are formed between the flat portions. According to the second aspect, water resulting from melting of frost runs down through the slits formed between the flat portions. Therefore, the water is well drained.
A third aspect of the present disclosure provides the heat exchanger as set forth in the second aspect, wherein the fins are arranged in such a manner that the fins coincide with each other by parallel displacement in the internal flow direction. According to the third aspect, between the two adjacent fins, the flat portions of one of the fins and the counterpart flat portions of the other fin face each other in the internal flow direction such that the distance between these facing flat portions in the internal direction is kept constant at any position in the external flow direction. In addition, since the air is likely to flow at a constant rate in the air passage, a less turbulent air flow can be formed. Furthermore, such a corrugated member can be produced easily.
A fourth aspect of the present disclosure provides the heat exchanger as set forth in the second aspect or the third aspect, wherein widths of the flat portions are equal in the external flow direction. According to the fourth aspect, the ratio between the surface area and the volume of each of the flat portions is constant. Therefore, the heat transfer efficiency of the fins is optimized.
A fifth aspect of the present disclosure provides the heat exchanger as set forth in any one of the second to fourth aspects, wherein the flat portions are first flat portions and second flat portions that are arranged in a staggered manner in the external flow direction. According to the fifth aspect, a relatively large slit can be formed between the first flat portion and the second flat portion. In addition, an air flow passage extending straight in the external flow direction can be formed. Furthermore, since the upper and lower edges of the fins are in direct contact with the heat transfer tubes, these fins can achieve a higher fin efficiency than louvered fins and the like.
A sixth aspect of the present disclosure provides the heat exchanger as set forth in the fifth aspect, wherein the slits are formed between the first flat portions and the second flat portions, and a dimension of each of the slits in the internal flow direction is one half or less of the second pitch. According to the sixth aspect, the largest possible air passages can be obtained.
A seventh aspect of the present disclosure provides the heat exchanger as set forth in any one of the second to fourth aspects, wherein the flat portions form a series of steps descending in a direction inclined with respect to the external flow direction and the internal flow direction. According to the seventh aspect, drainage of meltwater resulting from melting of frost can be facilitated.
An eighth aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to seventh aspects, wherein the fins are arranged so that the second pitch appears before and after the first pitch. According to the eighth aspect, spread of frost in the internal flow direction can be inhibited.
A ninth aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to seventh aspects, wherein the first pitch and the second pitch appear alternately. According to the ninth aspect, spread of frost in the internal flow direction can be inhibited.
A tenth aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to seventh aspects, wherein when an odd number of the fins are arranged in series from above in the internal flow direction, and odd-numbered fins are defined as first fins and even-numbered fins are defined as second fins, a total sum of the pitches between the first fins and the fins adjacent to and below the first fins is equal to a total sum of the pitches between the second fins and the fins adjacent to and below the second fins. According to the tenth aspect, the total sum of the areas of bonding between one of the two adjacent heat transfer tubes and the corrugated member is equal or almost equal to the total sum of the areas of bonding between the other one of the adjacent heat transfer tubes and the corrugated member. Therefore, the adjacent heat transfer tubes have the same or almost the same area for heat transfer to/from the corrugated member.
An eleventh aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to tenth aspects, wherein the first pitch is 1.2 times or more and 3.0 times or less the second pitch. According to the eleventh aspect, it is possible to allow the corrugated member to have a sufficiently large heat transfer area as a whole while inhibiting blockage of the air flow passages due to frost formation.
A twelfth aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to eleventh aspects, wherein the plurality of heat transfer tubes includes at least four of the heat transfer tubes, and a pair of the corrugated members having the same shape are bonded to both sides of each of the heat transfer tubes interposed between the two adjacent heat transfer tubes in such a manner that the corrugated members coincide with each other by parallel displacement in an arbitrary direction. According to the twelfth aspect, in the heat transfer tubes interposed between the two adjacent heat transfer tubes, the total sums of the areas of bonding to the corrugated members are equal or almost equal to each other. Therefore, these heat transfer tubes have the same or almost the same area for heat transfer to/from the corrugated members.
A thirteenth aspect of the present disclosure provides the heat exchanger as set forth in any one of the first to twelfth aspects, wherein the adjacent heat transfer tubes are flat tubes that are parallel to each other.
Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following description of the present invention is merely exemplary and is not intended to limit the present invention.
Specifically, the heat exchanger 1 includes a plurality of heat transfer tubes 3 in which the refrigerant flows and a pair of headers 2 to which both ends of each of the heat transfer tubes 3 are connected. The heat transfer tubes 3 extend in a specific direction, and are arranged in a direction perpendicular to the specific direction. Here, the refrigerant flows in the specific direction in the heat transfer tubes 3. The pair of headers 2 extend in the arrangement direction of the heat transfer tubes 3. Hereinafter, in order to simplify the description, the specific direction (an internal flow direction of the present invention), the arrangement direction of the heat transfer tubes 3, and the direction perpendicular to these directions (an external flow direction of the present invention) are referred to as an X direction, a Y direction, and a Z direction, respectively.
In this embodiment, the Y direction and the Z direction are the horizontal directions, and the X direction is the vertical direction. In other words, the pair of headers 2 extend in the horizontal direction, and the heat transfer tubes 3 disposed between the headers 2 extend in the vertical direction. The heat transfer tubes 3 do not necessarily have to extend in the vertical direction, and may extend in an oblique direction or in the horizontal direction. The pair of headers 2 do not necessarily have to extend in the horizontal direction, and may extend in the vertical direction.
As shown in
As shown in
The fins 5 are arranged at at least two different pitches, a relatively large first pitch P1 and a relatively small second pitch P2, in the X direction. As shown in
The first pitch P1 and the second pitch 2 are defined by the X-direction dimensions of the folded portions 6 that join the adjacent fins 5. In this embodiment, as shown in
In the heat exchanger 1 of this embodiment, the fins 5 are arranged at irregular pitches. Therefore, as shown in
Preferably, the first pitch P1 is 1.2 times or more and 3.0 times or less the second pitch P2. When the ratio P1/P2 is 1.2 or more, the likelihood of blockage of the wider air flow passages 41 due to frost formation can be reduced sufficiently. When the ratio of P1/P2 is 3.0 or less, the corrugated members 4 are allowed to have a sufficiently large heat transfer area as a whole. In view of these, it is preferable that the ratio P1/P2 satisfy 1.5≦P1/P2≦1.8.
As shown in
The two corrugated members 4 having the same shape only have to be bonded to both sides of the heat transfer tube 3 interposed between the two adjacent heat transfer tubes 3 in such a manner that these corrugated members 4 coincide with each other by parallel displacement in an arbitrary direction. For example, the two corrugated members 4 having the same shape may be bonded to both sides of the heat transfer tube 3 interposed between the two adjacent heat transfer tubes 3 in such a manner that these corrugated members 4 coincide with each other by parallel displacement in the X and Y directions. Instead, the two corrugated members 4 having the same shape may be bonded to both sides of the heat transfer tube 3 interposed between the two adjacent heat transfer tubes 3 in such a manner that these corrugated members 4 coincide with each other by parallel displacement in the Y and Z directions. Furthermore, the two corrugated members 4 having the same shape may be bonded to both sides of the heat transfer tube 3 interposed between the two adjacent heat transfer tubes 3 in such a manner that these corrugated members 4 coincide with each other by parallel displacement in the X, Y and Z directions. In any of these configurations, the heat transfer tubes 3 interposed between the two adjacent heat transfer tubes 3 have the same or almost the same area for heat transfer to/from the corrugated members 4. Therefore, the refrigerant flowing in each of the heat transfer tubes 3 is uniformly heated by the air.
The heat exchanger 1 of the first embodiment can be modified from various points of view. For example, each of the fins 5 may be provided with louvers that are inclined with respect to the fin 5 and arranged in the Z direction.
The fins 5 do not have to be arranged so that the second pitch P2 appears before and after the first pitch P1. In order to inhibit blockage of the air flow passages when frost forms, the fins 5 have to be arranged so that at least one first pitch P1 appears.
The first pitch P1 and the second pitch P2 do not necessarily have to appear alternately. A series of the second pitches may appear either before or after the first pitch or before and after the first pitch. For example, the fins 5 may be arranged as shown in
The fins 5 do not necessarily have to be arranged at two different pitches, and they may be arranged at three or more different pitches. For example, in the case where the fins 5 are arranged at three different pitches, the smallest pitch may be regarded as the second pitch as defined in this embodiment, and the medium or largest pitch may be regarded as the first pitch as defined in this embodiment. Instead, the medium pitch may be regarded as the second pitch as defined in this embodiment, and the largest pitch may be regarded as the first pitch as defined this embodiment.
The corrugated members 4 having the fins 5 that are arranged at irregular pitches do not have to be disposed between all pairs of heat transfer tubes 3, and they may be disposed between at least one pair of adjacent heat transfer tubes 3. For example, the heat exchanger may be configured such that the corrugated member having the fins 5 that are arranged at a constant pitch is disposed between a pair of heat transfer tubes 3 in a region where the air flows at the highest rate in the heat exchanger (for example, the central region of the heat exchanger) and the corrugated members 4 having the fins 5 that are arranged at irregular pitches are disposed between the other pairs of heat transfer tubes 3.
Next, a second embodiment of the present invention is described. The second embodiment can be configured in the same manner as in the first embodiment, unless otherwise stated. The same or corresponding components are denoted by the same reference numerals as in the first embodiment, and the description thereof may be omitted.
As shown in
As shown in
The corrugated member 4 configured as described above can be produced by making cuts in a flat metal plate (for example, an aluminum plate) to form the first flat portions 51 and the second flat portions 52 and then pressing the metal plate into shape or passing the metal plate through a pair of transfer rollers. In the corrugated member 4 produced in this manner, the thickness of the first flat portions 51 and the second flat portions 52 is almost equal to the thickness of the folded portions 6.
Also in this embodiment, the fins 5 are arranged at irregular pitches. Therefore, for example, even if frost forms on the outdoor heat exchanger during heating operation and the narrower air flow passages 42 are blocked, the wider air flow passages 41 are less likely to be blocked. Rather, when the narrower air flow passages 42 are blocked, the flow rate of the air increases in the wider air flow passages 41, which makes the blockage thereof less likely to occur. Therefore, the heat exchanger can perform heat exchange between the refrigerant and the air continuously.
In addition, in this embodiment, each of the fins 5 is composed of the first flat portions 51 and the second flat portions 52, and the slits 53 are formed between them. Therefore, as shown in
From the viewpoint of maximizing the area of the narrower air flow passages 42, the X-direction dimension L of the slit 53 formed between the first flat portion 51 and the second flat portion 52 (see
The heat exchanger 1 of the second embodiment can be modified from various points of view. For example, it can be modified based on the viewpoint described as the modification in the first embodiment.
In each of the fins, the plurality of flat portions may be arranged in the form of at least two steps in the Z direction. For example, as shown in
In this modification, the center of the fin 5 is located at the intermediate position between the upper flat portion 53 and the lower flat portion 55 and coincides with the center line of the middle flat portion 54 in its thickness direction. Also in this modification, as shown in
Furthermore, as shown in
In this modification, the center of the fin 5 is the reference line located at the midpoint between the flat portion 51A disposed on the inlet side of the air flow passage 41 or 42 and the flat portion 51F disposed on the outlet side of the air flow passage 41 or 42. As shown in
Number | Date | Country | Kind |
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2011-229764 | Oct 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/006689 | 10/18/2012 | WO | 00 | 10/29/2013 |