Heat exchanger
A heat exchanger has tubes defining refrigerant passages therein and fins disposed between the tubes. The tubes have tube main walls opposed to each other. The fins are joined to the tube main walls. The tube main walls have projections that project inside of the tubes and define recesses on outer sides of the tubes. Each of the tubes has an outer dimension, in a direction perpendicular to the tube main walls, in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm.
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This application is based on Japanese Patent Application No. 2006-103093 filed on Apr. 4, 2006, the disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTIONThe present invention relates to a heat exchanger, which is for example used as a refrigerant radiator for cooling a refrigerant flowing in tubes.
BACKGROUND OF THE INVENTIONU.S. Pat. No. 6,595,273 B2 (JP-A-2004-3787) discloses a heat exchanger having flat tubes, as a refrigerant radiator. The flat tubes have recesses on flat walls (tube main walls) thereof for allowing air to flow, thereby to improve the efficiency of heat exchange. The recesses are defined by projections formed on the tube main walls.
The projections have serpentine side walls such that air flows in the recesses in a serpentine or meandering manner. Because the flow of air adjacent to outer surfaces of the tube main walls is disturbed, development of a temperature boundary layer adjacent to the outer surfaces of the tube main walls is reduced. Thus, a coefficient of heat transfer of the air improves.
The recesses are formed by pressing the outer surfaces of the tube main walls in an inward direction of the tubes. Therefore, inside of the flat tubes, the refrigerant flows over the inward projections in a serpentine manner, and hence the flow of refrigerant is disturbed. Because development of a temperature boundary layer adjacent to inner surfaces of the tube main walls is reduced, a coefficient of heat transfer of the refrigerant improves. Accordingly, in this heat exchanger, the coefficient of heat transfer of both of the air and the refrigerant is improved by disturbing the flows of air and refrigerant, thereby improving the efficiency of heat exchange.
However, since the refrigerant flows in the serpentine manner, resistance to flow of the refrigerant increases, resulting in pressure loss of the refrigerant. If the temperature of the refrigerant reduces due to the pressure loss of the refrigerant, the temperature difference between the refrigerant and the air reduces. Further, this will affect the efficiency of heat exchange.
SUMMARY OF THE INVENTIONThe present invention is made in view of the foregoing matter, and it is an object of the present invention to provide a heat exchanger having tubes with projections for disturbing flows of an internal fluid and an external fluid, which is capable of sufficiently maintaining or improving efficiency of heat exchange.
According to an aspect of the present invention, a heat exchanger has tubes and fins. The tubes define passages therein through which a refrigerant as an internal fluid flows. The tubes have tube main walls opposed to each other. The fins are disposed between the tubes and joined to the tube main walls. The tube main walls have projections projecting inside of the tubes and defining recesses outside of the tubes for allowing an external fluid to flow. Each of the tubes has a tube outer dimension (tube height), in a direction perpendicular to the tube main walls, in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm.
As the tube outer dimension increases, a passage area of a refrigerant passage increases and resistance to flow of the refrigerant reduces. Therefore, pressure loss of the refrigerant is reduced and hence the decrease of efficiency of heat exchange may be suppressed. However, if the tube outer dimension is increased more than necessarily, the resistance to flow of the refrigerant is reduced excessively. In this case, although the refrigerant flows smoothly, disturbing effect of the refrigerant is reduced.
Accordingly, the tube outer dimension is set in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm. When the tube outer dimension is in this range, the pressure loss of the refrigerant is reduced while the disturbing effect of the refrigerant is maintained. Therefore, the efficiency of heat exchange is sufficiently provided.
Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which like parts are designated by like reference numbers and in which:
A first embodiment will be described with reference to
The heat exchanger 10 has a generally rectangular outline and includes a heat exchanging part 13 and tanks 14, 15. The heat exchanging part 13 includes flat tubes and fins 12. The flat tubes 11 define refrigerant passages therein through which a refrigerant flows. The fins 12 are for example corrugated fins. The heat exchanging part 13 performs heat exchange between the refrigerant and air flowing outside of the flat tubes 11.
The tanks 14, 15 are coupled to opposite longitudinal ends of the tubes 11. The refrigerant is distributed into the flat tubes 11 from one of the tanks 14, 15 (e.g., a left tank in
The tanks 14, 15 are made of metal such as aluminum alloy, and in the form of cylindrical container. The tanks 14, 15 are formed with slits (not shown), and the slits are arranged at predetermined intervals in a longitudinal direction of the tanks 14, 15. The longitudinal ends of the tubes 11 are inserted in the slits to make communication with the tanks 14, 15.
The tanks 14, 15 are provided with connecting blocks 14a, 15a. For example, a first connecting block 14a is brazed to the left tank 14 at a position adjacent to one end (e.g., lower end in
Also, a second connecting block 15a is brazed with the right tank 15 at a position adjacent to an opposite end (e.g., upper end in
Further, the tanks 14, 15 are provided with engaging projections 14b, 15b at ends thereof (lower ends in
Next, a structure of the heat exchanging part 13 will be described with reference to
Each of the tubes 11 has generally flat walls 20, 21 (hereafter, referred to as tube main walls) opposed to each other. The tube main walls 20, 21 extend substantially parallel to a general flow direction Ar1 of the air. The tubes 11 and the fins 12 are stacked in a direction perpendicular to the tube main walls 20, 21, thereby to construct the heat exchanging part 13. The tubes 11 are joined to the fins 12 through the tube main walls 20, 21.
Here, each tube 11 has an outer dimension (hereafter, referred to as a tube height) H in a direction perpendicular to the tube main walls 20, 21. The tube height H is in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm. Also, each fin 12 has a height (hereafter, referred to as a fin height) F in the direction perpendicular to the tube main walls 20, 21. The fin height F is in a range between equal to or greater than 2.0 mm and equal to or less than 9.0 mm.
Each of the tube main walls 20 has projections 22 projecting inside of the tube 11. For example, the projections 22 are formed by pressing or embossing corresponding portions of the tube main wall 20 from the outer side to the inner side. Thus, the projections 22 define recesses 20a on a tube outer side for allowing air to pass through as shown by an arrow Ar2. Similarly, the tube main walls 21 have projections 23 that define recesses 21 a on the tube outer side.
Specifically, each of the projections 22, 23 (recesses 20a, 21a) extends in a serpentine or meandering manner with a constant width along the tube main wall 20, 21. Also, the projection 22, 23 extends entirely from an air upstream end to an air downstream end of the tube 11 with respect to the air general flow direction Ar1. In this embodiment, the projections 22 of the tube main wall 20 and the projections 23 of the tube main wall have the same shape.
Each projection 22, 23 has an end wall, which corresponds to a bottom of each recess 20a, 21a, and side walls. The end wall defines a substantially flat wall. The side walls connect to the outer surfaces of the tube main wall, but form rounded corners with the outer surface of the tube main wall. Namely, corners 22a, 23a between the side walls of the projection 22, 23 and the outer surfaces of the tube main wall are chamfered in an arc shape.
The projections 22, 23 are arranged at predetermined intervals (pitch) P with respect to a general flow direction Rf1 of the refrigerant, i.e., a longitudinal direction of the tube 11. Here, the pitch P is within a range between equal to or greater than 1.0 mm and equal to or less than 6.5 mm.
The end walls of the projections 22, 23 have first depressed portions 22b, 23b at positions corresponding to apexes or most curved portions of the meandering recesses 20a, 21a. The first depressed portions 22b, 23b are further recessed inside of the tube 11 from the end walls of the projections 22, 23 in stepwise.
The projections 22 of the tube main wall 20 and the projections 23 of the tube main wall 21 are staggered with respect to the refrigerant general flow direction Rf1. Further, the projection 22 of the tube main wall 20 and the projection 23 of the tube main wall 21 overlap with each other at the first depressed portions 22b, 23b. Also, the tube main walls 20, 21 are in contact with and joined to each other at the first depressed portions 22b, 23b.
Also, the end wall of the projections 22, 23 have second depressed portions 22c, 23c at positions corresponding to upstream and downstream ends of the projections 22, 23 with respect to the air general flow direction Ar1. The second depressed portions 22c, 23c are further recessed from the end walls of the projections 22, 23 inside of the tube 11, similar to the first depressed portions 22b, 23b. Thus, the second depressed portions 22c, 23c are in contact with and joined to each other. In this embodiment, the dimension of the first and second depressed portions 22b, 23b, 22c, 23c from the outer surfaces of the tube main walls 20, 21 in the direction perpendicular to the tube main walls 20, 21 is 0.65 mm, for example.
In this embodiment, the projections 22, 23 of the tube main walls 20, 21 have the same shape. Thus, the first tube member 11a and the second tube member 11b are shaped into the same shape. That is, the first tube member and the second tube member 11a, 11b are provided by the same members. Therefore, productivity of the tubes 11 improves, and hence manufacturing costs of the tubes 11 reduces.
As shown in
Specifically, since inner surfaces of the first depressed portions 22b, 23b of the projections 22, 23 are in contact with each other, the refrigerant passages are divided over the first depressed portions 22b, 23b and then merged together. The flows of the refrigerant repeat the divergence and mergence while flowing along the tube main walls 20, 21 in the meandering manner.
The fins 12 are for example corrugated fins. Each of the fins 12 is formed by bending a thin plate member, which is for example made of aluminum alloy, into a corrugated shape. The fin 12 has joining walls (first walls) 12a, 12b to be joined to the outer surfaces of the tube main walls 20, 21.
Also, the fin 12 has connecting walls (second walls) 12c, 12d extending perpendicular to the joining walls 12a, 12b. The connecting walls 12c, 12d are formed with louvers 12e, 12f. The louvers 12e, 12f are formed by cutting out from the flat walls 12c, 12d and bending relative to the connecting walls 12c, 12d so as to oppose a flow of air passing through the connecting walls 12c, 12d (arrow Ar3).
Next, an operation of the heat exchanger 10 will be briefly described. The high temperature, high pressure refrigerant, which has been discharged from the compressor (not shown), flows into the left tank 14 of heat exchanger 10 through the first connector block 14a. The refrigerant is distributed into the tubes 11 from the left tank 14.
While the refrigerant flowing in the tubes 11, heat of the refrigerant is transferred to the air flowing outside of the tubes 11 through entire surfaces of the tubes 11 and the fins 12. Thus, the refrigerant is condensed into the liquid-phase. The liquid-phase refrigerant is collected in the right tank 15 and discharged from the heat exchanger 10 through the second connecting block 15a. Then, the refrigerant is introduced into the expansion valve (not shown), for example.
Next, an effect of heat exchange between the refrigerant and the air in the heat exchanging part 13 will be described. As shown by the arrows Rf2 in
On the other hand, the air that flows at positions separated from the tube main walls 20, 21 flows along the fins 12, as shown by the arrow Ar3 in
Also, the air flowing adjacent to the tube main walls receives heat from the tubes 11 and is discharged from the heat exchanging part 13 after cooling the tube 11. In this case, as the air flows through the recesses 20a, 21a in the meandering manner, as shown by the arrows Ar2, the flow of this air is disturbed. As such, the coefficient of heat transfer of the air improves.
In addition, as the air is contracted when flowing into the recesses 20a, 21a, the coefficient of heat transfer of the air improves. Further, because the surface of heat transfer is increased by the recesses 20a, 21a, the amount of heat radiation from the tube 11 to the air is increased.
Q=φ·Cp·ρ·Wa(Tr−Ta) (1)
Here, φ represents temperature efficiency of the heat exchanger 10; Cp represents specific heat of air; ρ represents density of air; Wa represents the volume of air; Tr represents temperature of refrigerant; and Ta represents inlet temperature of air.
In
As shown by the solid line L1 in
On the other hand, as the tube height H increases larger than 1.3 mm, the passage area inside of the tube 11 increases. Although the refrigerant flows smoothly, the disturbing effect of the refrigerant reduces. Thus, the coefficient of heat transfer of the refrigerant reduces. With the decrease of the coefficient of heat transfer of the refrigerant, the temperature efficiency φ of the heat exchanger 10 reduces. Accordingly, the efficiency Q reduces.
In the case that the tube height H is in a range between equal to or greater than 0.8 mm and equal to or less than 1.9 mm, the pressure loss of the refrigerant is reduced while maintaining the disturbing effect of the refrigerant. As such, the decrease of the efficiency Q due to the pressure loss of the refrigerant is suppressed. That is, when the tube height H is in the above range, the efficiency Q is provided sufficiently.
Also, in the case that the tube height H is in a range between equal to or greater than 1.0 mm and equal to or less than 1.6 mm, the decrease of the efficiency Q due to the pressure loss of the refrigerant is further suppressed.
Further, in the case that the tube height H is in a range between equal to or greater than 1.2 mm and equal to or less than 1.4 mm, the decrease of the efficiency Q due to the pressure loss of the refrigerant is further effectively suppressed.
In
Accordingly, the efficiency Q of this embodiment having the projections 22, 23 improves, as compared with the comparative example without having the projections 22, 23. Also, in this embodiment, the tube height H where the efficiency Q is at the maximum level is greater than that of the comparative example. Namely, in the comparative example, the efficiency Q is at the maximum level when the tube height H is 1.0 mm. On the other hand, in this embodiment, the efficiency Q is at the maximum level when the tube height H is 1.3 mm.
In this embodiment, the flow of the refrigerant is disturbed by the projections 22, 23. Therefore, the pressure loss of the refrigerant of this embodiment is larger than the pressure loss of the refrigerant of the comparative example even when the tube height H is the same between this embodiment and the comparative example.
In
A graph of
As shown in
On the other hand, as the projection pitch P increases from 3.6 mm, the number of the projections 22, 23 of the tubes 10 reduces. Therefore, the disturbing effect of the flow of the refrigerant reduces, and hence the flow of the refrigerant becomes close to a natural convection current. As a result, the coefficient of heat transfer of the refrigerant reduces. Thus, the temperature efficiency φ reduces, and hence the efficiency Q reduces.
Accordingly, when the projection pitch P is in a range between equal to or greater than 1.0 mm and equal to or less than 6.5 mm, the efficiency Q is improved by effectively providing the disturbing effect of the refrigerant.
Also, when the projection pitch P is in a range between equal to or greater than 1.6 mm and equal to or less than 5.7 mm, the efficiency Q is improved by providing the disturbing effect of the refrigerant further effectively.
Further, when the projection pitch P is in a range between equal to or greater than 2.3 mm and equal to or less than 5.0 mm, the disturbing effect of the refrigerant is further effectively improved. Thus, the efficiency Q is improved.
In
In this embodiment, the end walls of the projections 22, 23 have the first and second depressed portions 22b, 23b, 22c, 23c that are further projected inside of the tube 11 in a stepwise manner. Therefore, the flows of air in the recesses 20a, 21a are further disturbed. As such, the coefficient of heat transfer of the air is further improved.
A graph of
As shown in
On the other hand, as the fin height F increases greater than 5.0 mm, the heat transfer area excessively increases. As a result, because the fin efficiency reduces, the temperature efficiency φ reduces. Therefore, the efficiency Q reduces.
Accordingly, when the fin height F is in a range between equal to or greater than 2.0 mm and equal to or less than 9.0 mm, heat radiation is effectively performed by the fin 12. As such, the efficiency Q improves.
Also, when the fin height F is in a range between equal to or greater than 3.0 mm and equal to or less than 7.3 mm, the heat radiation is further effectively performed by the fin 12. As such, the efficiency Q improves.
Further, when the fin height F is in a range between equal to or greater than 4.0 mm and equal to or less than 6.0 mm, the heat radiation is much further effectively performed by the fin 12. As such, the efficiency Q further improves.
In
Since the projections 20, 21 extend continuously from the air upstream end to the air downstream end of the tube 11, the flow of air is introduced by the projections 20, 21 (recesses 20a, 21a). Thus, the disturbing effect of the air improves, and the efficiency of heat transfer improves. Further, the projections 20, 21 extend in the serpentine or curved manner, the disturbing effect of the air improves.
Second EmbodimentA second embodiment will be described with reference to
In the heat exchanger 10 of the second embodiment, because the efficiency of heat radiation of the fins 12 slightly reduces due to elimination of the louvers 12e, 12f, the efficiency Q slightly reduces as compared with the efficiency Q of the first embodiment. However, the tubes. 11 have the similar structure as the first embodiment. Therefore, effects substantially similar to the effects of the first embodiment are provided in the second embodiment.
Accordingly, the relationships between the efficiency Q and the tube height H, projection pitch P and fin height F have the similar trends as those of the first embodiment, though the efficiency Q is slightly reduced in this embodiment.
Third EmbodimentA third embodiment will be described with reference to
In the second embodiment, the corners 22a, 23a are chamfered into the arc shape. In the third embodiment, on the other hand, the corners 22a, 23a are not chamfered. Instead, the side walls of the projections 22, 23 and the outer surfaces of the tube main walls 20, 21 form edged corners, as shown in
Also in this case, the effects similar to the second embodiment are provided. Therefore, the relationships between the efficiency Q and the tube height H, projection pitch P and fin height F have the similar trends as those of the second embodiment.
Fourth EmbodimentA fourth embodiment will be described with reference to
As shown in
On the other hand, the air flowing adjacent to the tubes 11 are biased and disturbed by the recesses 20a, 21a. Therefore, the coefficient of heat transfer of the air improves.
Accordingly, even when the projections 22, 23 are formed to extend straight in the oblique direction relative to the general air flow direction Ar1, the effects similar to the third embodiment are provided. Therefore, the relationships between the efficiency Q and the tube height H, projection pitch P and fin height F have the similar trends as those of the third embodiment.
Fifth EmbodimentA fifth embodiment will be described with reference to
Also in this case, the projections 22 of the tube main wall 20 and the projections 23 of the tube main wall 21 have the same V-shape, but are arranged in opposite directions with respect to the refrigerant general flow direction Rf1. The diverged ends of the V-shaped projection 22 are opposed to the diverged ends of the V-shaped projection 23. Therefore, the projections 22, 23 intersect with each other at the predetermined angle. Accordingly, the refrigerant passages are formed inside of the tubes 11 in complexly serpentine manner.
On the other hand, the air flowing adjacent to the tube main walls 20, 21 are biased and disturbed by the recesses 20a, 21a. Therefore, the coefficient of heat transfer of the air improves.
Accordingly, even when the projections 22, 23 are formed in the V-shape diverging in the refrigerant general flow direction Rf1, the effects similar to the third embodiment will be provided. Further, the relationships between the efficiency Q and the tube height H, projection pitch P and fin height F have the similar trends as those of the third embodiment.
Sixth EmbodimentA sixth embodiment will be described with reference to
In the example of
Also in this embodiment, the projections 22, 23 provide the disturbing effect of the flows of the refrigerant and air, similar to the third embodiment. Accordingly, the similar effects as the third embodiment are provided. Also, the relationships between the efficiency Q and the tube height H, projection pitch P and fin height F have the similar trends as those of the third embodiment.
Seventh EmbodimentA seventh embodiment will be described with reference to
Also in this embodiment, the refrigerant passages are formed inside of the tube 11 in the complexly serpentine manner. On the outside of the tube 11, the recesses 20a, 21a are formed as mesh. Thus, the air flows in the recesses 20a, 21a while diverging and merging repetitively, and is disturbed sufficiently. Therefore, the coefficient of heat transfer of the air improves.
Accordingly, even when the projections 22, 23 have the meshed shape, the similar effects as the third embodiment are provided. Also, the relationships between the tube height H, projection pitch P and fin height F and the efficiency Q have the similar trends as those of the third embodiment.
Eighth EmbodimentAn eighth embodiment will be described with reference to
As shown in
In this embodiment, the projections 22, 23 have the serpentine shape, similar to the projections 22, 23 of the third embodiment. However, the end walls of the projections 22, 23 do not have the first and second depressed portions 22b, 23b, 22c, 23c.
In the tube 11 formed in the above-described manner, the effects similar to the third embodiment will be provided. Therefore, the relationships between the tube height H, projection pitch P and fin height F and the efficiency Q have the similar trends as those of the third embodiments. Also, since the separation walls 31 are integrally formed into the tube 11, strength of the tube 11 against pressure improves.
Ninth EmbodimentA ninth embodiment will be described with reference to
Also in this case, the similar effects as the eighth embodiment will be provided. Thus, the relationships between the tube height H, projection pitch P and fin height F and the efficiency Q have the similar trends as those of the eighth embodiments.
Further, since the tube 11 has the separation walls 31 therein, the strength of the tube 11 against pressure improves, similar to the eighth embodiment. The shape of the projections 22, 23 can be changed into any other shapes as the above first to seventh embodiments.
Other EmbodimentsIn the above embodiments, the projections 22, 23 have the constant width. However, it is not always necessary that the projections 22, 23 have the constant width. The width of the projections 22, 23 can be changed or varied appropriately.
In the third to ninth embodiments, the fins 12 do not have the louvers 12e, 12f. However, the fins 12 may have the louvers 12e, 12f in the third to ninth embodiments. Also, the heat exchanger 10 may be implemented by any combinations of the above first to ninth embodiments.
In the above embodiments, the heat exchanger 10 is exemplary employed as the refrigerant condenser. However, the heat exchanger 10 can be employed as a refrigerant radiator of a supercritical refrigerating cycle in which the pressure of a refrigerant exceeds a critical pressure at a high pressure side. Further, use of the heat exchanger 10 may not be limited to the above.
The example embodiments of the present invention are described above. However, the present invention is not limited to the above example embodiment, but may be implemented in other ways without departing from the spirit of the invention.
Claims
1. A heat exchanger for performing heat exchange between a refrigerant and an external fluid, comprising:
- tubes defining passages therein for allowing the refrigerant to flow, the tubes having tube main walls opposed to each other; and
- fins disposed between the tubes and joined with the tube main walls, wherein
- the tube main walls have projections that project inside of the tubes and define recesses outside of the tubes for allowing the external fluid to flow, and
- each of the tubes has a tube outer dimension in a range between at least 0.8 mm and at most 1.9 mm, in a direction perpendicular to the tube main walls.
2. The heat exchanger according to claim 1, wherein
- the tube outer dimension is in a range between at least 1.0 mm and at most 1.6 mm.
3. The heat exchanger according to claim 2, wherein
- the tube outer dimension is in a range between at least 1.2 mm and at most 1.4 mm.
4. The heat exchanger according to claim 1, wherein
- the projections are arranged at a predetermined pitch with respect to a longitudinal direction of the tube, and
- the predetermined pitch is in a range between at least 1.0 mm and at most 6.5 mm.
5. The heat exchanger according to claim 4, wherein
- the predetermined pitch is in a range between at least 1.6 mm and at most 5.7 mm.
6. The heat exchanger according to claim 5, wherein
- the predetermined pitch is in a range between at least 2.3 mm and at most 5.0 mm.
7. The heat exchanger according to claim 1, wherein
- each of the fins has a fin outer dimension in a range between at least 2.0 mm and at most 9.0 mm, in the direction perpendicular to the tube main walls.
8. The heat exchanger according to claim 7, wherein
- the fin outer dimension is in a range between at least 3.0 mm and at most 7.3 mm.
9. The heat exchanger according to claim 8, wherein
- the fin outer dimension is in a range between at least 4.0 mm and at most 6.0 mm.
10. The heat exchanger according to claim 1, wherein
- the projections extend continuously from upstream ends to downstream ends of the tubes with respect to a flow direction of the external fluid flowing outside of the tubes.
11. The heat exchanger according to claim 1, wherein
- each of the tubes has a first tube member and a second tube member joined with the first tube member, and the tube main walls of each tube are included in the first and second tube members.
12. The heat exchanger according to claim 11, wherein
- the first tube member and the second tube member have an identical shape.
13. The heat exchanger according to claim 1 wherein
- each of the tubes has a separation wall for separating an inner space of the tube into a plurality of spaces in a direction perpendicular to a longitudinal direction of the tube, and
- the separation wall is integrated with the tube main walls.
14. The heat exchanger according to claim 1, wherein
- the projections have curved shapes extending along the tube main walls in a meandering manner in a direction perpendicular to a longitudinal direction of the tubes.
15. The heat exchanger according to claim 1, wherein
- the projections have straight shapes extending along the tube main walls and obliquely with respect to a longitudinal direction of the tubes.
16. The heat exchanger according to claim 1, wherein
- the projections have V-shapes that extend along the tube main walls and diverging in a longitudinal direction of the tubes.
17. The heat exchanger according to claim 1, wherein
- the projections are meshed along the tube main walls.
18. The heat exchanger according to claim 1, wherein
- the projections have side walls extending perpendicular to outer surfaces of the tube main walls, and
- the side walls define edged corners with the outer surfaces of the tube main walls.
19. The heat exchanger according to claim 1, wherein
- the projections have side walls extending perpendicular to outer surfaces of the tube main walls, and
- the side walls define curved corners with the outer surfaces of the tube main walls.
20. The heat exchanger according to claim 1, wherein
- the fins are corrugated fins including first fin walls and second fin walls connecting the first fin walls, and
- the first fin walls are flat and joined with outer surfaces of the tube main walls.
21. The heat exchanger according to claim 20, wherein
- the second fin walls have louvers that are angled with respect to a flow direction of the external fluid flowing through the fins.
22. The heat exchanger according to claim 1, wherein the external fluid is air for cooling the refrigerant.
Type: Application
Filed: Apr 2, 2007
Publication Date: Oct 4, 2007
Applicant: DENSO Corporation (Kariya-city)
Inventors: Masahiro Shimoya (Kariya-city), Akira Itoh (Kariya-city)
Application Number: 11/732,097
International Classification: F28D 1/02 (20060101);