JP2013139978A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger capable of maintaining heat exchange performance, even if frost deposition occurs.SOLUTION: A fin tube heat exchanger 11 comprises a plurality of plate fins 20 and a tube 10 which penetrates a tube hole 21 formed at each of the plate fins 20 in the thickness direction, and with a refrigerant flowing therethrough. The plate fins 20 have easy-to-pass parts 231 with air easily passing therethrough, and difficult-to-pass parts 232 in which air is more difficult to pass than the easy-to-pass parts 231. The whole of the plate fins 20 including the easy-to-pass parts 231 and the difficult-to-pass parts 232 forms a continuous face, and is formed symmetric with a center line C1 for dividing an air flow flowing between and among the plate fins 20 into an upstream side and a downstream side. The easy-to-pass parts 231 are arranged at the upstream side and the downstream side rather than the tube 10. The difficult-to-pass parts 232 are arranged at the upstream side and the downstream side rather than an intermediate region 220 gripped by the tube 10 which is aligned in a direction perpendicular to the air flow.

Description

  The present invention relates to a fin tube type heat exchanger including plate fins and tubes.

Fin tube type heat exchangers are known as heat exchangers used in air conditioners and refrigerators. The finned tube heat exchanger includes plate-like fins that are stacked at intervals and a tube that penetrates the plate fins in the stacking direction. And heat exchange is performed between the air which passes between plate fins, and the refrigerant | coolant which flows through the inside of a tube.
Furthermore, since the finned tube heat exchanger used in the outdoor unit acts as an evaporator during heating operation, if the outside air temperature is low, frosting occurs on the plate fins, the air flow path is blocked, and the air volume is reduced. As a result, there is a concern that the performance deteriorates. Therefore, in the fin tube type heat exchanger used for the outdoor unit, generally, the plate fin is not cut and raised. This is because the cut-and-raised piece having a high heat transfer coefficient with air is likely to form frost.
In order to increase the efficiency (performance) of this type of heat exchanger, the plate fins are corrugated or provided with ridges. For example, in Patent Document 1, peak portions protruding from the plate surface are formed on the plate fin on the upstream side and the downstream side of the air flow (hereinafter sometimes simply referred to as the upstream side and the downstream side), respectively. Furthermore, peaks are also formed in the region between the tubes arranged in a direction orthogonal to the direction of air flow.
Further, in Patent Document 2 in which the plate fins are corrugated, in response to the problem of clogging between the fins due to the formation of frost from the upstream edge of the plate fin during heating operation, The tube is arranged downstream from the center of the plate fin in the direction of. If it does so, since the tube hole which lets a tube pass will be arrange | positioned in the position eccentric with respect to the centerline of a plate fin, a plate fin will become an asymmetrical shape about the centerline which bisects to an upstream and downstream.

Japanese Patent Laid-Open No. 2008-128569 JP 2000-193389 A

As is well known, the heat exchanger of an outdoor unit that functions as an evaporator during heating operation is located upstream of the plate fins, particularly upstream of the plate fins having a high heat transfer coefficient with air, when the outside air temperature is low. Frost is likely to occur at the peak portion.
When the air flow path between the plate fins becomes narrow due to frost formation, the air volume passing between the plate fins decreases, so that the heat exchange performance deteriorates.
In addition to the above, if the plate fin is formed asymmetrically as in Patent Document 2, the plate fin may be twisted because the internal stress of the plate fin is not symmetric when the plate fin is pressed.

  An object of the present invention is to provide a heat exchanger that can maintain high heat exchange performance even when frost is formed and has excellent workability based on the above-described problems.

  Since it is difficult to eliminate frost formation on the heat exchanger, the present inventor has studied to suppress a decrease in the amount of air that passes between the plate fins even when frost formation occurs. In other words, air passes between the tubes, and the position of the tube and the vicinity thereof hardly function as an air flow path. Therefore, by guiding the air toward the tube on the upstream side of the air, the tube and its tube The idea was to preferentially frost the neighborhood.

The heat exchanger according to the present invention based on the above idea passes through a plurality of plate fins arranged at intervals from each other and tube holes formed in each of the plurality of plate fins in the thickness direction, and a refrigerant is contained inside. A flowing tube.
The plate fin includes an easy-to-pass portion through which an air flow flowing between the plate fins easily passes, and a difficult-to-pass portion through which the air flow does not pass easily compared to the easy-to-pass portions. The entire plate fin including the easy passage portion and the difficult passage portion forms a continuous surface and is formed symmetrically with respect to a center line that bisects the upstream side and the downstream side of the air flow.
The easy-to-pass portions are respectively arranged on the upstream side and the downstream side of the tube.
The difficult-to-pass portions are arranged on the upstream side and the downstream side of the intermediate region sandwiched between the tubes arranged in the direction orthogonal to the air flow.

According to the heat exchanger of the present invention, when the outside air temperature is low and frosting occurs by allowing air to flow from the easily passing portion with a relatively large air volume, Promotes frost. If it does so, the amount of frost formation to the intermediate region between the difficult passage part and the tube located downstream rather than it will reduce.
Here, even if frost is formed on the easy-to-pass portion and its vicinity, the portion has a small influence on securing the entire air volume because the tube originally becomes a barrier and it is difficult for air to flow. If frost formation on the difficult-to-pass portion and the intermediate region is suppressed, it is difficult for the air flow path to be blocked. In other words, even if frost formation occurs, the air volume reduction associated therewith can be avoided, so that the heat exchange performance can be maintained.
And the whole plate fin including the easy passage part and the difficult passage part has comprised the continuous surface. The easy-to-pass part and the difficult-to-pass part are formed, for example, by deforming the plate fins in the thickness direction to make irregularities. The present invention can also contribute to the suppression of frost formation in that a cut-and-raised piece in which a discontinuous portion is formed at one end is not formed on the plate fin.
In addition, since the easy-to-pass part and the difficult-to-pass part are formed on the downstream side, the air flowing in from the upstream side escapes from the easy-to-pass part. By guiding the air toward the easily passing portion in this way, the dead water area formed on the downstream side of the tube is reduced, so that the heat transfer area where heat exchange is effectively performed increases. Thereby, high heat exchange performance is realizable.
Furthermore, since the plate fins have a symmetrical shape, the residual stress generated when the plate fins are formed by press working becomes symmetric, and the plate fins can be easily manufactured because they are difficult to twist during processing.

The easy passage portion and the difficult passage portion in the present invention can be configured as various specific forms as follows. In the present invention, since the entire plate fin including the easy passage portion and the difficult passage portion forms a continuous surface, a part of the plate fin is cut up and compared with a configuration in which a discontinuous portion is generated at one end of the cut and raised piece. Thus, various forms of the easy passage portion and the difficult passage portion that control the air flow can be easily realized.
As a 1st form, a difficult passage part is made into the convex part which protrudes from the surface of a plate fin, and the easy passage part has a height lower than a difficult passage part.
In the 1st form, the height of the easy passage part can be made the same height as the surface of a plate fin.
As a 2nd form, the dimension in the direction of an air flow is narrower than the difficulty passage part in the easy passage part.

In any of the first and second embodiments described above, by providing the easy-to-pass part and the difficult-to-pass part on the upstream side, the effect of maintaining the heat exchange performance even when frost is formed can be obtained as described above. .
In addition to this, by providing the easy passage portion and the difficult passage portion on the downstream side, as described above, high heat exchange performance can be realized by reducing the dead water area.

In the present invention, if the dimension of the easy-to-pass portion in the direction orthogonal to the air flow direction is length L, the diameter of the tube holes is D, and the pitch between the tube holes in the orthogonal direction is Dp, L / D is It is preferable to satisfy the following formula.

Further, in the present invention, the easy-to-pass portion protrudes toward the tube in a plan view on the upstream side, and the difficult-to-pass portion protrudes toward the opposite side to the intermediate region in the plan view on the upstream side. It is preferable that an inclined portion that is inclined with respect to a direction orthogonal to the air flow is provided between the first and second difficult passage portions.
In this invention, since the air that has reached the difficult-to-pass portion is guided to the easy-to-pass portion by the inclined portion, the effect of inducing air toward the tube is promoted. For this reason, the effect of frosting on the tube and the vicinity thereof is further remarkable.

And in this invention, it is preferable that a plate fin has the peak part which protrudes from the surface of a plate fin in an intermediate | middle area | region, and a peak part has a slope which goes down toward a tube.
Where turbulent flow exists between the plate fins due to the collision of the air flow with the tube, in the present invention, air is guided along the slope of the mountain portion in a direction orthogonal to the flow of the original air flow, Promotes. In this way, heat transfer is promoted, so that the heat exchange performance can be improved.
Further, since the slope of the mountain portion is lowered toward the tube, the air flowing into the intermediate region is guided toward the side surface of the tube by this slope. Thereby, since the air volume which goes around to the downstream side of a tube increases and a dead water area is reduced more, it can contribute to the further improvement of heat exchange performance.

  According to the heat exchanger of the present invention, even if frost formation occurs, high heat exchange performance can be maintained and workability is also excellent.

It is a perspective view showing a schematic structure of a fin tube type heat exchanger concerning a 1st embodiment. It is a top view of the plate fin of a 1st embodiment. (A) is a 3A-3A arrow directional view of FIG. 2, (B) is a 3B-3B arrow directional view of FIG. FIG. 4 is a view taken along line 4-4 in FIG. 2. It is a figure for demonstrating the effect | action by the easy passage part and the difficult passage part of a plate fin. It is a figure which shows the dead water area in a plate fin. It is a graph which shows a heat exchange performance ratio. It is a top view of the plate fin of a 2nd embodiment. It is a graph which shows a heat exchange performance ratio. It is a top view of the plate fin of a 3rd embodiment. It is a top view of the plate fin of a 4th embodiment.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
In the following description, the same components as those described above are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[First Embodiment]
The finned-tube heat exchanger 1 of 1st Embodiment shown in FIG. 1 is mounted in the outdoor unit of an air conditioner. The heat exchanger 1 includes plate fins 20 that are stacked many times at intervals, and a tube 10 made of metal such as copper that penetrates the plate fins 20 in the thickness direction. The outer diameter of the tube 10 is preferably 5 to 8 mm, for example, and the pitch between the overlapping plate fins 20 is preferably 1.0 mm to 1.6 mm, for example.

The tube 10 includes a large number of hairpin tubes 11 that penetrate the plate fins 20 from one end 202 in the stacking direction, and a U bend 12 that connects the ends of the adjacent hairpin tubes 11 at the other end 201 in the stacking direction. It is configured. In the tube 10, a refrigerant (not shown) is introduced from one end portion 10 </ b> A and led out from the other end portion 10 </ b> B.
Two or more tubes 10 can be provided in the heat exchanger 1.

  As shown in a specific shape in FIG. 2, the plate fins 20 are orthogonal to the direction of the air flow (X direction in FIG. 2, hereinafter referred to as the width direction) guided by a blower fan (not shown) between the plate fins 20. It is formed in a strip shape elongated in the longitudinal direction (Y direction in FIG. 2). A plurality of tube holes 21 through which the tube 10 is passed are formed in the plate fin 20. A plurality of plate fins 20 are arranged according to the required heat exchange capacity.

A collar 21 </ b> A rising from the surface of the plate fin 20 is formed at the periphery of the tube hole 21. The outer periphery of the tube 10 (FIG. 1) is in close contact with the inner peripheral surface of the collar 21A.
Further, the tube holes 21 are arranged in the longitudinal direction Y at the same pitch Dp. Here, between the plate fins 20 adjacent in the width direction X, the formation positions of the tube holes 21 are shifted from each other by (Dp / 2).

Each plate fin 20 has, on one surface (surface) side, a plurality of ridges 22, a plurality of first protrusions 23 located on the upstream side of the air flow, and a plurality of first protrusions located on the downstream side of the air flow. 2 convex portions 24.
The peak portion 22 is formed in an intermediate region 220 that is a region between the tube holes 21 adjacent in the longitudinal direction Y. In the present embodiment, two peak portions 22 are formed side by side in the width direction X in one intermediate region 220.
The height of the peak portion 22 is preferably, for example, 40 to 70% of the pitch between the overlapping plate fins 20.
The mountain portion 22 has a slope that goes down in the width direction X and a slope that goes down in the longitudinal direction Y with the apex 22A as the center (FIGS. 3A and 3B). That is, the peak portion 22 has a quadrangular pyramid shape. The vertex 22A coincides with the midpoint between the hole centers of the tube holes 21 adjacent in the longitudinal direction Y.
Such ridges 22 are formed such that their hems are slightly separated from the collar 21A, and an annular flat portion 210 (FIG. 3A) having no gradient is formed on the outer periphery of the base end of the collar 21A. ing. The height of the flat portion 210 is a reference height for the plate fin 20.
Note that the slope of the mountain portion 22 is not limited to a flat surface, and may be a curved surface. The same applies to the first convex portion 23 and the second convex portion 24.

The first convex portion 23 is provided on the upstream side of the peak portion 22, and similarly to the peak portion 22, a slope (FIG. 3 (B)) with a vertex 26 as a center and descending in the width direction X and a longitudinal direction. It has a mountain shape with a slope (FIG. 4) descending in the direction Y. Note that the vertex 26 has a position in the longitudinal direction Y that coincides with the vertex 22A and is lower than the vertex 22A.
Further, in the present embodiment, the terminal end 27 (FIG. 4) of the gradient of the first convex portion 23 has reached the position that hangs on the tube hole 21 (next to the hole center of the tube hole 21). At the terminal end 27, the height from the surface of the plate fin 20 (flat portion 210) may be “0”.
The 2nd convex part 24 is provided in the downstream rather than the peak part 22, and like the 1st convex part 23, it is the slope (FIG. 3 (B)) which goes down in the width direction X centering | focusing on the vertex 26. And an angled shape having a slope (FIG. 4) descending in the longitudinal direction Y.

As described above, the first convex portion 23, the two peak portions 22, and the second convex portion 24 are sequentially arranged on the plate fin 20 from the upstream side to the downstream side of the air flow. Here, only the bottom (end 27) of the first convex portion 23 reaches the upstream side of the tube 10. Therefore, the resistance on the upstream side of the tube 10 is smaller with respect to the air guided toward the plate fins 20 than in the region where the first protrusions 23 are provided. Then, the air guided from the blower fan flows into the plate fin 20 from the upstream side of the tube 10 rather than over the first convex portion 23. That is, the upstream side of the tube 20 is an easy-to-pass part 231 through which air easily passes, and conversely, the first convex part 23 functions as a difficult-to-pass part 232 through which air hardly passes.
Since the second convex part 24 similar to the first convex part 23 is formed, the downstream side of the tube 20 becomes the easy passage part 241, and the second convex part 24 functions as the difficult passage part 242. The easy passage portions 231 and 241 face each other with the tube 10 interposed therebetween. Further, the difficult passage portions 232 and 242 face each other with the intermediate region 220 interposed therebetween.

  The heights of the first and second convex portions 23 and 24 are both lower than the heights of the two peak portions 22 and 22 of the intermediate region 220 as shown in FIG. The height of the vertex 26 of the first and second convex portions 23 and 24 is preferably, for example, 40 to 60% of the height of the vertex 22A of the peak portion 22. As a result, the air that has flowed in between the plate fins 20 gets over the first convex part 23 and circulates to the mountain parts 22, 22, and gets over the second convex part 24 and flows into the adjacent plate fins 20.

  As shown in FIG. 2, the plate fin 20 configured as described above is symmetrical with respect to the center line C1 that bisects the plate fin 20 into the upstream end 20A side and the downstream end 20B side (symmetric in plan view). ). Further, as shown in FIG. 3B, their cross-sectional shapes are also formed symmetrically with respect to a center line C2 that is equally divided into the upstream end 20A side and the downstream end 20B side.

During operation of the air conditioner, as shown in FIG. 1, air (outside air) is guided from the blower fan toward the plate fins 20. Heat exchange is performed between this air and the refrigerant flowing in the tube 10.
In the present embodiment, the peak portion 22 and the first and second convex portions 23 and 24 are formed, and air collides with them to obtain a heat transfer acceleration effect, so that the heat exchange performance is improved.

  The air flowing between the plate fins 20 flows from the upstream end 20A toward the downstream end 20B, and flows from the downstream end 20B to the upstream end 20A of the adjacent plate fin 20. By shifting the position of the tube hole 21 between adjacent plate fins 20 by Dp / 2, the air flow is easily sewn between the tubes 10.

During the heating operation, if the outside air temperature is low, the temperature of the refrigerant that exchanges heat with the air also decreases, and the temperature of the plate fin 20 becomes 0 ° C. or less, so the moisture contained in the air flowing between the plate fins 20, 20 Is deposited as frost on the surface of the plate fin 20. In particular, frost formation is likely to occur at the upstream end 20A having a high heat transfer coefficient with air.
Among the upstream end portion 20A, frost formation is likely to occur particularly in the vicinity of the tube 10 where the temperature decreases to near the refrigerant temperature.
Further, the side surfaces of the collar 21 </ b> A and the tube 10 have high heat transfer rates due to collision of air, so that frost formation is likely to occur.

  In view of the above points, by providing the easy-to-pass part 231 and the difficult-to-pass part 232 on the upstream side of the airflow, the air flowing into the heat exchanger 1 is guided to the easy-to-pass part 231. If it does so, frosting arises preferentially in the side surface of the collar 21A and the tube 10 which are located in the passage easy part 231 and its downstream side. On the other hand, since the amount of air passing through the difficult-to-pass portion 232 is relatively reduced, the amount of frost on the difficult-to-pass portion 232 and the intermediate region 220 located on the downstream side can be reduced.

  Here, even if frosting is remarkably generated in the vicinity of the easy-to-pass portion 231, the air hardly flows due to the presence of the collar 21A or the side surface of the tube 10 from the beginning. Therefore, the influence on the entire air volume flowing between the plate fins 20 is small. Since the frost formation on the intermediate region 220 having the largest contribution to the heat exchange between the refrigerant and the air and the vicinity thereof is suppressed, the air flow path can be prevented from being blocked. That is, according to this embodiment, even if frosting occurs, a decrease in the air volume due to the frost formation can be avoided.

  In addition, according to the present embodiment, the amount of air passing through the first convex portion 23, that is, the difficult passage portion 232 is reduced by a part of the air flow flowing into the heat exchanger 1 being guided to the easy passage portion 231. The amount of decrease is limited, and the entire air volume flowing between the plate fins 20 is sufficiently secured.

The above is the operation and effect at the upstream end 20A of the plate fin 20. However, according to the present embodiment, the following operation and effect can be obtained at the downstream end 20B of the plate fin 20 as well.
An easy-to-pass portion 241 having low air resistance is also formed on the second convex portion 24 that faces the first convex portion 23 with the tube 10 interposed therebetween. For this reason, as shown in FIG. 5, the air that has flowed in from the easy-to-pass portion 231 of the first convex portion 23 wraps downstream of the tube 10 along the outer periphery of the tube 10.
Thereby, as schematically shown in FIG. 6, since the dead water area 253 is reduced as shown in FIG. 6B (dead water area 252), the heat transfer area where heat exchange is effectively performed increases, and the plate The heat exchange performance of the entire fin 20 is improved. The dead water area refers to an area that has a low heat transfer rate due to a slow air flow and does not function effectively as a heat transfer area.
Here, the heat transfer area increases even if the height of the peak portion 22 or the first convex portion 23 is increased, but in this case, the pressure loss (pneumatic loss) increases, so the equivalent heat exchange performance is achieved. In order to obtain, the input of a ventilation fan increases. On the other hand, if the dead water area is reduced, the heat exchange performance can be improved without increasing the input of the blower fan.

FIG. 7 shows the result of calculating the heat exchange performance ratio when the heights of the easy passage portions 231 and 241 are changed. In this embodiment, the height here is the height from the surface of the plate fin 20 at the terminal ends 27 (FIG. 4) of the first and second convex portions 23 and 24.
The horizontal axis of FIG. 7 indicates the height of the easy passage portions 231 and 241 when the height of the difficult passage portions 232 and 242 is 1.0. Moreover, the vertical axis | shaft of FIG. 7 has shown the heat exchange performance ratio when heat traffic wind power is made constant. Here, the heat traffic wind power is the product of the air pressure loss and the air volume, and corresponds to the input of the blower fan to the heat exchanger 1.
When the height of the easy passage portions 231 and 241 is lower than the height of the difficult passage portions 232 and 242, the heat exchange performance is gradually improved. This is because the effect of reducing the air pressure loss due to the lower easy passage portions 231 and 241 is combined with the effect of increasing the effective heat transfer area due to the reduction of the dead water area.
As described above, by reducing the height of the easy-to-pass portions 231 and 241, the heat exchange performance with respect to the blower fan input to the heat exchanger 1 can be improved.

In addition to the above effects, according to the present embodiment, the following effects can be obtained.
The plate fin 20 has a symmetrical shape on the upstream end 20A side and the downstream end 20B side. Therefore, since the residual stress generated when the plate fin 20 is pressed is also symmetric, it is difficult to twist during the processing, and the labor for correcting it can be saved.

Further, the peak portion 22 has a slope in the longitudinal direction Y. In the airflow flowing between the plate fins 20, turbulent flow is generated by collision with the collar 21 </ b> A and the tube 10, but the turbulent flow is promoted by the flow along the slope in the longitudinal direction Y. Thereby, heat transfer is accelerated | stimulated and heat exchange performance improves.
In addition to this, since the slope of the peak portion 22 is lowered toward the tube 10, the air flowing into the intermediate region 220 is guided toward the tube 10 by this slope. Thereby, since the air volume which goes around to the downstream side of the tube 10 increases and a dead water area is reduced more, it can contribute to the further improvement of heat exchange performance.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In FIG. 8, the illustration of the peak portion 22 formed in the intermediate region 220 is omitted. The same applies to the drawings of the following embodiments.

A plurality of first convex portions 332 are formed at equal intervals in the longitudinal direction Y at the upstream end portion 30 </ b> A of the plate fin 30. The first convex portion 332 protrudes from the surface of the plate fin 30 at a certain height (for example, the same height as the vertex 26 in the first embodiment), and functions as a difficult passage portion. The first convex portion 332 is provided on the upstream side of the intermediate region 220. The 1st convex part 332 is formed similarly to the 1st convex part 23 of a 1st embodiment except for the point formed with fixed height.
And the area | region between the 1st convex parts 332 adjacent in the longitudinal direction Y is the easy passage part 331 formed in 20 A of upstream ends.

A second convex portion 342 similar to the first convex portion 332 is also formed at the downstream end portion 30B of the plate fin 30, and a region between the adjacent second convex portions 342 is formed at the downstream end portion 30B. The passage easy portion 341 is used.
The easy passage portions 331 and 341 have the same height as the surface of the plate fin 20, but may be protrusions shorter than the first convex portions 332 and 342. Moreover, although the upper end of the 1st convex part 332,342 is made into the flat surface, you may make it step shape. The same applies to the following embodiments.

  As will be described later with reference to FIG. 9, the plurality of tube holes 21 are arranged at a predetermined pitch Dp in the longitudinal direction Y. The diameter of the tube hole 21 is D, and the dimension in the longitudinal direction Y of the easy-to-pass portion 331 (the same for the easy-to-pass portion 341) is the length L. The length L is equal to the distance between the adjacent first protrusions 33 (or the distance between the second protrusions 34).

Also according to the present embodiment configured as described above, the same effects as those of the first embodiment can be obtained. That is, frost formation is likely to occur in the easy-to-pass portion 331 and the vicinity thereof, while frost formation is suppressed in the first convex portion 332 and the vicinity thereof, so that a reduction in the air volume accompanying the frost formation can be avoided.
In addition, the dead water area is reduced by increasing the amount of air flowing around the downstream side of the tube 10 by the easy passage portion 341 of the downstream end 30B (see FIG. 6). This improves the heat exchange performance. Therefore, even if frost formation occurs, high heat exchange performance can be realized.

Now, it is shown in FIG. 9 that the heat exchange performance ratio varies depending on the length distribution in the longitudinal direction Y between the easy-to-pass portions 331 and 341 and the first and second convex portions 332 and 342 that are difficult to pass portions. It is confirmed by the calculation result.
The horizontal axis in FIG. 9 is (L / D), that is, the length of the easy-to-pass portions 331 and 341 with respect to the diameter D of the tube hole 21. And the vertical axis | shaft has shown the heat exchange performance ratio when heat traffic wind power is made constant like FIG. The broken line and the solid line indicate the characteristics when Dp is relatively large and small, respectively.

  Here, it can be seen that the increase rate of the heat exchange performance ratio increases when the length L is equal to or greater than the diameter D (L / D ≧ 1) in both the broken line and solid line characteristics. If the length L is smaller than the diameter D (L / D <1), the collar 21A and the tube 10 serve as an air flow barrier, and the amount of air passing through the easy passage portion 341 cannot be increased so much, so that the dead water area is greatly reduced. The contribution to improving heat exchange performance is small. That is, L / D is preferably 1 or more.

  On the other hand, in both the broken line and the solid line, the heat exchange performance ratio starts decreasing at a certain point. Therefore, it is desirable to consider this point when determining the dimensions of the first and second convex portions 332 and 342.

The lengths of the first and second convex portions 332 and 342 are represented by (Dp−L). The first convex portion 332 and the tube 10 provide a flow path on the upstream end 30A side so that the air volume is minimized. When the first and second convex portions 332 and 342 are arranged so as to close and close the flow path on the downstream end 30B side with the second convex portion 342 and the tube 10, the first and second convex portions 332 are disposed. , 342 is represented by (Dp-D).
Here, whether the first and second convex portions 332 and 342 provide a sufficient heat transfer acceleration effect depends on the length (Dp−L) of the first and second convex portions 332 and 342 ( A point that is ½ of Dp−D) is a branch point, and in order to obtain a sufficient heat transfer enhancement effect, it is necessary that (Dp−L) is ½ or more of (Dp−D). This is expressed by the following formula (1). When this is deformed, a suitable upper limit of L / D that can realize a high heat exchange performance ratio is obtained, and if shown together with the above lower limit, Equation (2) is obtained. According to the range indicated by the formula (2) (the ranges indicated by the broken line and the solid line in FIG. 9), the heat exchange performance can be improved more reliably.

  Here, the same calculation results as shown in FIG. 9 are obtained regardless of the shapes of the first embodiment and the later-described embodiments, such as the easy passage portion and the difficult passage portion. Since the heat exchange performance ratio varies depending on the length distribution in the longitudinal direction Y with the difficult-to-pass portion, L / D is preferably in the range of the formula (2).

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
The upstream end portion 50A of the plate fin 50 is continuous from one end to the other end in the longitudinal direction Y, and a first convex portion 53 is formed. The first convex portion 53 has a narrow width on the upstream side of the tube 20 and a wide width on the upstream side of the intermediate region 220. The portion where the width of the first convex portion 53 is narrow has less air resistance than the thick portion, and therefore air easily passes therethrough. For this reason, the narrow portion is the easy passage portion 531 and the thick portion is the difficult passage portion 532.

A second convex portion 54 formed in the same manner as the first convex portion 53 is also formed in the downstream end portion 50B. The second convex portion 54 includes an easy passage portion 541 that faces the easy passage portion 531 across the tube hole 21, and a difficult passage portion 542 that faces the difficult passage portion 532 across the intermediate region 220.
Also according to this embodiment, the same operational effects as those of the first embodiment can be obtained.

  As described above, according to the first to third embodiments, several methods of forming the easy passage portion and the difficult passage portion are illustrated on the upstream side and the downstream side of the plate fin, respectively, but two or more methods are combined. In addition, an easy-to-pass part and a difficult-to-pass part can be formed.

  FIG. 2 shows an example in which four rows of plate fins 20 are individually press-molded. However, a plurality of plate fins 20 can be formed by press-molding a material having a size corresponding to the required number of plate fins 20. Can also be formed integrally.

[Fourth Embodiment]
The air induction effect toward the tube 10 on the upstream side of the plate fin described in each of the above embodiments is configured by including an inclined portion that is inclined with respect to the longitudinal direction Y between the easy passage portion and the difficult passage portion. Can be promoted.
For example, when the inclined portion is applied to the configuration described in the first embodiment, the configuration shown in FIG. 11 is obtained.
The upstream end portion 40A of the plate fin 40 is formed with a first convex portion 43 that is continuous from one end to the other end in the longitudinal direction Y and meanders in a wavy shape in plan view.
The first convex portion 43 has a height gradient similar to the first convex portion 23 shown in FIG. 4, whereby an easy-to-pass portion 431 is formed on the upstream side of the tube 10, and the intermediate region A difficult passage portion 432 is formed on the upstream side of 220.
The easy-to-pass portion 431 is curved so as to be convex toward the downstream side (tube 10), and the difficult-to-pass portion 432 is convex toward the upstream side (the side opposite to the intermediate region 220). Is curved. An inclined portion R is formed between the easy passage portion 431 and the difficult passage portion 432.

On the other hand, in the downstream end portion 40B, a second convex portion 44 meandering like a wave is formed similarly to the first convex portion 43. The first and second convex portions 43 and 44 are formed symmetrically with respect to the center line C1.
Similarly to the first convex portion 43, the second convex portion 44 has a gradient in height, thereby forming an easy passage portion 441 on the downstream side of the tube 10, and downstream of the intermediate region 220. The passage difficult part 442 is formed.
The first convex portion 43 and the second convex portion 44 are formed with a constant width. Note that the first convex portion 43 and the second convex portion 44 may have a gradient in the width direction X as shown in FIG.

The air that is about to flow in from the upstream end 40A is guided to the easy-to-pass part 431 by the inclined part R even as it reaches the difficult-to-pass part 432, so that more air from the easy-to-pass part 431 than the difficult to pass part 432 Flows in downstream. As described above, since the effect of inducing air toward the tube 10 is promoted, the effect of frosting the tube 10 and the vicinity thereof is further remarkable.
In addition, the structure provided with the inclination part R which inclines with respect to the longitudinal direction Y between an easy passage part and a difficult passage part is applicable also to 2nd Embodiment or 3rd Embodiment.

  In addition to those described above, the configurations described in the above embodiments can be selected or modified as appropriate to other configurations without departing from the gist of the present invention.

1 Fin Tube Heat Exchanger 10 Tube 20, 30, 40, 50 Plate Fin 20A, 30A, 40A, 50A Upstream End 20B, 30B, 40B, 50B Downstream End 21 Tube Hole 21A Collar 22 Mountain 22A Vertex 23 First Convex part 24 Convex part 26 Vertex 27 Terminal part 43 First convex part 44 Second convex part 53 First convex part 54 Second convex part 210 Flat part 220 Middle area 231 Easy passage part 232 Difficult part 241 Easy part 242 Passing difficulty part 252, 253 Dead water area 331 Easy passing part 332 First convex part 341 Easy passing part 342 Second convex part 431 Easy passing part 432 Difficult part 441 Easy passing part 442 Easy passing part 531 Easy passing part 532 Easy passing part 541 Easy passage portion 542 Difficult passage portion R Inclined portion

Claims (7)

A plurality of plate fins spaced apart from each other;
A tube that penetrates the tube hole formed in each of the plurality of plate fins in the thickness direction, and the refrigerant flows through the inside.
The plate fin is
An easy-to-pass part through which the air flow flowing between the plate fins easily passes, and a difficult-to-pass part through which the air flow is less likely to pass than the easy-to-pass part. The whole forms a continuous surface and is formed symmetrically with respect to a center line that bisects the plate fin into an upstream side and a downstream side of the air flow,
The easy-to-pass portions are respectively disposed on the upstream side and the downstream side of the tube,
The difficult passage portion is disposed on the upstream side and the downstream side of an intermediate region sandwiched between the tubes arranged in a direction orthogonal to the air flow.
A heat exchanger characterized by that. The passage difficult portion is a convex portion protruding from the surface of the plate fin,
The easy passage part has a height lower than the difficult passage part,
The heat exchanger according to claim 1. The height of the easy passage portion is the same as the surface of the plate fin.
The heat exchanger according to claim 2. The dimension of the easy passage part in a direction orthogonal to the direction of the air flow is a length L,
The diameter of the tube hole is D,
When the pitch between the tube holes in the orthogonal direction is Dp,
L / D satisfies the following formula:
The heat exchanger according to any one of claims 1 to 3.

  The heat exchanger according to any one of claims 1 to 4, wherein the easy-to-pass part has a dimension in the air flow direction that is narrower than the difficult-to-pass part. The easy-to-pass portion protrudes toward the tube in a plan view on the upstream side,
The difficult-to-pass portion protrudes toward the opposite side of the intermediate region in plan view on the upstream side;
Between the easy-to-pass part and the difficult-to-pass part, an inclined part that is inclined with respect to a direction orthogonal to the air flow is provided,
The heat exchanger according to any one of claims 1 to 5. The plate fin has a peak portion protruding from the surface of the plate fin in the intermediate region,
The said peak part is a heat exchanger as described in any one of Claim 1 to 6 which has a slope which goes down toward the said tube.

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