JPH06185885A - Flat multi-holed condensing and heat transfer pipe - Google Patents

Abstract

PURPOSE:To provide a flat multi-holed condensing and heat transfer pipe of small diameter which is used in a car cooler and other small-sized condensors and has a higher heat transfer performance without increasing a pressure loss. CONSTITUTION:In a flat type heat transfer pipe having a plurality of independent flat refrigerant flow passages arranged in a width direction and continuous in a length-wise direction, a height (h) of the heat transfer pipe is set to be 2.0mm or less. The refrigerant flow passage has a height (h) of 1.2mm or less and a ratio of a width (w1) in respect to the height (h1) of a range of 1.8 to 6.0, respectively. An inner wall surface of the refrigerant passage is formed with a plurality of continuous projections extending along a longitudinal direction and at the same time grooves adjacent to the projections are formed in the flat smooth bottom surface. In addition, a ratio of the height (h2) of the projection in respect to the height (h1) of the refrigerant flow passage is set in a range of 0.055 to 0.25. It is preferable that a pitch (p) of the projection is in a range of 0.25 to 0.6mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a flat multi-hole condensing heat transfer tube, and more specifically, to a small heat exchanger (condenser) such as a car cooler. The present invention relates to a condensation heat transfer tube suitable for.

[0002]

2. Description of the Related Art For example, Japanese Patent Laid-Open No. 62-175588 and US Pat. No. 4,998,580 relating to the first patent application in the United States propose a condenser as shown in FIG. This condenser is composed of a pair of header tubes 8 and 9 facing each other at regular intervals, a large number of parallel flat multi-hole condensing heat transfer tubes 7 connected to opposite sides of the header tubes 8 and 9, and a header. It comprises upper and lower parts 5, 6 connected to tubes 8, 9. A corrugated radiating fin 70 is fixed between the condensing heat transfer tubes 7. One header tube 8 acts as a steam supply side, and has a steam supply port 80 attached to one end and a lid 81 attached to the other end. Also, the other header tube 9
Acts as the discharge side of the condensate, and has a conduit 9 at one end.
A condensate outlet 90 for communicating with 2 is attached,
A lid 91 is attached to the other end. The inside of the flat multi-hole condensing heat transfer tube 7 used in the condenser is shown in FIG.
As enlarged and shown in FIG.
Is inserted and fixed, a plurality of independent refrigerant channels 72 having a substantially triangular cross section are formed along the length direction.

In this type of condenser, the heat transfer coefficient with respect to the outside air of the radiation fins 70 is much smaller than the condensation heat transfer coefficient of the vapor in the condensation heat transfer tube 7. Therefore, the heat transfer tube 7 of the condenser relatively increases the heat dissipation area of the heat dissipation fins 70 by reducing the steam inflow cross-sectional area to the extent that the pressure loss in the refrigerant flow path 72 does not become so large. The fluid diameter of each refrigerant passage 72 in the heat transfer tube 7 (the cross-sectional area of the refrigerant passage multiplied by 4 and this divided by the wet perimeter of the refrigerant passage) is 0.015 to 0.040 inches (about The range is 0.4 to 1.0 mm).

[0004]

When the diameter of the fluid in the refrigerant passage is reduced as in the condensation heat transfer tube 7 described above, the heat dissipation area of the heat dissipation fins 70 is relatively increased, so that the heat transfer performance is improved. By the way, in recent years, particularly in the field of car coolers and other small heat exchangers, there has been a demand for the development of a more compact condenser having a higher level of heat transfer performance.
In order to meet such a demand, the inventors have proposed a conventional multi-hole condensing heat transfer tube 7 as described above, in which a refrigerant flow path has a fluid diameter of 1.0 mm or less and a protrusion is formed on the inner wall surface of the refrigerant flow path. When various prototypes of heat transfer tubes that did not exist were subjected to performance tests, it was found that this heat transfer tube was impractical because of its extremely large pressure loss, regardless of its heat transfer performance.

That is, the inventors have conducted various experiments on a flat condensing heat transfer tube having a plurality of refrigerant passages having a fluid diameter of 1 mm or less, and as a result, have found the following points to be improved and found the present invention. Has been completed. One of them is the most important point.In the conventional flat multi-hole condensing heat transfer tube, some of the partition walls separating the adjacent refrigerant flow passages are deleted to remove each refrigerant flow. By making the width of the passage larger than the internal height by a certain amount or more and forming a continuous projection along the length direction in place of the deleted partition wall, the pressure loss of the refrigerant flow passage becomes smaller, and at the same time, the transmission loss increases. It was found that the thermal performance is further improved.
The other one has found that when the ratio of the height of the protrusion to the internal height of the refrigerant channel is within a certain range, the heat transfer performance of the condensation heat transfer tube becomes a higher level. That is. Still another is that when the groove adjacent to the protrusion has a smooth bottom surface (preferably when the shape of the groove is an inverted trapezoid), the heat transfer performance of the condensation heat transfer tube becomes higher. I have found that. Still another is to find out that the heat transfer performance becomes even higher when the pitch between the protrusions formed in the refrigerant flow path is within a certain range.

The object of the present invention is to reduce the pressure loss in the refrigerant flow path as compared with the above-described conventional flat multi-hole condensing heat transfer tube and to further improve the heat transfer performance. It is to provide a condensing heat transfer tube. Another object of the present invention is to provide a flat multi-hole condensing heat transfer tube capable of further miniaturizing a car cooler or other small condenser.

[0007]

According to the present invention, in a flat heat transfer tube having a plurality of independent flat refrigerant passages arranged in the width direction and continuous in the length direction, the height of the flat heat transfer tube is increased. The height of the flat refrigerant passage is set to 1.2 mm or less and the width-to-height ratio is set to a range of 1.8 to 6.0. A plurality of projections that are continuous along the length direction are formed on the inner wall surface of the flat refrigerant passage, and the bottom surface of the groove adjacent to each projection is formed to be smooth, with respect to the internal height of the flat refrigerant passage. Provided is a flat multi-hole condensing heat transfer tube in which the height ratio of the protrusions is set to 0.055 to 0.25. The inner wall surface of the flat refrigerant flow passage means a wall surface in the upper and lower width directions and a wall surface in the height direction.

In the flat multi-hole condensing heat transfer tube according to the present invention, the pitch of the protrusions is preferably 0.25 to 0.6 mm. The cross-sectional shape of the groove between the protrusions is preferably substantially inverted trapezoidal, for example, by forming the cross-sectional shape of the protrusion into a triangle. The fluid diameter of the flat refrigerant passage is preferably 0.7 to 1.5 mm.

[0009]

The flat multi-hole condensing heat transfer tube according to the present invention is used by incorporating it into a condenser in a horizontally elongated state. When the condensation heat transfer tube according to the present invention is compared with the above-described conventional flat multi-hole condensation heat transfer tube, the width of each refrigerant passage is larger than the height, and the inner wall surface of each refrigerant passage is continuous in the length direction. Since the protrusion is formed and the groove adjacent to the protrusion has a smooth bottom surface, the vapor of the refrigerant contacting the surface of the protrusion is efficiently condensed, and the condensed refrigerant is more quickly distributed along the groove. Move in a certain direction. Therefore, the pressure loss in the pipe is relatively small, and the heat transfer performance is further improved.

The reason why the height (total thickness) of the condensation heat transfer tube according to the present invention is set to 2.0 mm or less and the height of the refrigerant passage is set to 1.2 mm or less is that these values are not less than these values. In some cases, the ratio of the surface area of the radiating fins attached to the surface of the condensing heat transfer tube becomes relatively small with respect to the heat transfer area of the refrigerant flow path, which lowers the heat transfer performance of the heat exchanger. This is because it becomes impossible to reduce the size of the exchanger. Further, the reason why the ratio of the width to the height of each refrigerant channel is set to 1.8 to 6.0 is that if the ratio of both is set to 1.8 or less, the pressure loss of the refrigerant channel increases and both of them are increased. This is because if the ratio is set to 6.0 or more, the pressure resistance of the heat transfer tube against the internal pressure when the refrigerant passes through the inside is significantly reduced. Other functions of the condensation heat transfer tube according to the present invention are:
A detailed example will be described below.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the condensing heat transfer tube according to the present invention will be described with reference to FIGS. FIG. 1 is an enlarged sectional view showing a first embodiment of a condensation heat transfer tube according to the present invention,
2 is an enlarged cross-sectional view of the protrusions in the refrigerant flow path of the condensation heat transfer tube of FIG. 1, FIG. 3 is a partially enlarged cross-sectional view showing a second embodiment of the condensation heat transfer tube according to the present invention, and FIG. 4 is the condensation transfer tube of FIG. FIG. 5 is an enlarged cross-sectional view showing a protrusion in the refrigerant passage in the heat pipe, FIG. 5 is an enlarged sectional view showing a modified example of the protrusion in the refrigerant passage, and FIG. 6 is a partially enlarged cross-section showing a fifth embodiment of the condensation heat transfer pipe according to the present invention. Figure, Figure 7
Is a partially enlarged sectional view showing a sixth embodiment of the condensation heat transfer tube according to the present invention, FIG. 8 is a partially enlarged sectional view showing a seventh embodiment of the condensation heat transfer tube according to the present invention, and FIG. 9 is a condensation heat transfer tube according to the present invention. FIG. 10 is a partially enlarged cross-sectional view showing an eighth embodiment, FIG. 10 is a partially enlarged cross-sectional view showing a ninth embodiment of the condensing heat transfer tube according to the present invention, and FIG. 11 is an enlarged cross-sectional view showing another modified example of the protrusion in the refrigerant passage. FIG. 12 is a partially enlarged cross-sectional view showing a comparative example with respect to the embodiment of the condensation heat transfer tube according to the present invention, and FIG. 13 is a partially enlarged cross-sectional view showing another comparative example with respect to the embodiment of the condensation heat transfer tube according to the present invention. Is a bar graph comparing the heat transfer coefficients in the tubes of the condensing heat transfer tubes of some examples according to the present invention and the condensing heat transfer tubes of the comparative examples of FIGS. 12 and 13, and FIG. 15 is a bar graph of some examples of the present invention. Condensation heat transfer tube and FIGS. 12 and 1
3 is a bar graph showing the pressure loss ratio with the condensation heat transfer tube of the comparative example of FIG. 3, FIG. 16 is a line graph showing the relationship between the projection pitch and the heat transfer coefficient in the tube in the embodiment of the condensation heat transfer tube according to the present invention, and FIG. In the embodiment of the condensation heat transfer tube according to the present invention, a line graph showing the relationship between the projection height and the heat transfer coefficient in the tube,
FIG. 18 is a partially exploded perspective view of a conventional condenser using a flat multi-hole condensing heat transfer tube, and FIG. 19 is an enlarged sectional view of the flat multi-hole condensing heat transfer tube in the condenser of FIG.

First Embodiment The condensing heat transfer tube 1 of the first embodiment illustrated in FIG. 1 is a flat tube made of aluminum alloy and manufactured by conform extrusion (precision extrusion). In this condensing heat transfer tube 1, flat independent refrigerant passages 10, 10, 11, 11 each having a width w1 larger than a height h1 are arranged in the width direction via a partition wall 14 and in the length direction. It is formed so as to be continuous along. Each refrigerant channel 1
A large number of protrusions 12 are formed on the upper and lower inner wall surfaces of 0 and 11 so as to be continuous in the length direction at substantially uniform pitches. Since the cross-sectional shape of the protrusion 12 is substantially triangular as shown in FIG. 2, each groove 13 between the protrusions 12 has a substantially inverted trapezoidal cross-sectional shape. Therefore, each groove 13 has a smooth bottom surface.

The size of the condensation heat transfer tube 1 in FIG. 1 is as follows. Length = 850 mm Width w = 17 mm Height h = 1.8 mm Wall thickness t = 0.45 mm Width w1 of the central refrigerant passage 10 = 3.87 mm Width of both sides of the refrigerant passage 11 w1 = 3.755 mm Refrigerant Height of flow paths 10 and 11 = 0.9 mm Thickness of partition wall t1 = 0.25 mm Height of protrusion 12 h2 = 0.15 mm Width of protrusion 12 w2 = 0.15 mm Pitch of protrusion 12 p = 0. 48 mm Smooth bottom width of groove 13 w3 = 0.33 mm Ratio of width w1 to height h1 of refrigerant channel 10 = 4.3 Ratio of width w1 to height h1 of refrigerant channel 11≈4.2 Ratio of height h2 of protrusion 12 to height h1≈0.
17 Refrigerant channel 10 fluid diameter ≈ 1.06 mm Refrigerant channel 11 fluid diameter ≈ 1.14 mm Protrusion 12 apex angle θ (Fig. 2) = about 54 ° The condensation heat transfer tube of the first embodiment will be described later. It is sample No. 1 of performance test-1.

According to the condensing heat transfer tube of the first embodiment, FIG.
When it is used by being incorporated in the condenser as described above, the vapor of the refrigerant flowing in a certain direction in the refrigerant flow paths 10 and 11 comes into contact with the surfaces of the protrusions 12 and efficiently condenses as shown in FIG. The condensed liquid 4 rapidly moves in a fixed direction along the groove 13 in a state as shown in FIG. 2, although not always.

Second Embodiment The condensation heat transfer tube 1 of the second embodiment illustrated in FIGS. 3 and 4 is
It is manufactured by the same material and the same method as the condensing heat transfer tube of the first embodiment. The projections 12a on the inner wall surfaces of the refrigerant flow passages 10 and 11 have their tops R = 0.1 as shown in FIG.
It is formed in an arc shape of mm. The size of the condensing heat transfer tube 1 is as follows, and the sizes of parts not described next are the same as those of the condensing heat transfer tube of the first embodiment. Width w2 of the projection 12a = 0.25 mm Pitch of the projection 12a p = 1.03 mm Smooth bottom width w3 of the groove 13 = 0.78 mm Fluid diameter of the refrigerant channels 10 and 11≈1.21 mm Condensation of the second embodiment The heat transfer tube is Sample No. 2 of Performance Test-1 described later.

Third Embodiment Instead of the projections 12a of the condensing heat transfer tube 1 of FIG. 3, the inner wall surface of the refrigerant passage has a height h2 = 0.15 mm and a width w2 = 0.25 mm as shown in FIG. A condensing heat transfer tube having a protrusion 12b having a quadrangular cross section was manufactured, and this heat transfer tube was designated as Sample No. 3 of Performance Test-1 described later. The condensing heat transfer tube of Sample No. 3 has a fluid diameter of the refrigerant flow path of 1.24 mm, and the size of the other parts of this condensing heat transfer tube is the same as the condensing heat transfer tube of the second embodiment.

Fourth Embodiment Instead of the projections 12a of the condensing heat transfer tube 1 of FIG. 3, a height h2 = 0.15 mm and a width w2 are formed on the inner wall surface of the refrigerant passage as shown in FIG.
A condensing heat transfer tube having a protrusion 12 having a triangular cross section of 0.15 mm was manufactured, and this heat transfer tube was designated as Sample No. 4 of Performance Test-1 described later. The condensing heat transfer tube of Sample No. 4 has a fluid diameter of the refrigerant passage ≈1.28 mm, and the size of the other parts of this condensing heat transfer tube is the same as the condensing heat transfer tube of the second embodiment.

Fifth Embodiment The condensing heat transfer tube 1 of the fifth embodiment illustrated in FIG. 6 is similar to that of FIG. 4 only in one width surface (upper width surface in use) of each of the refrigerant passages 10 and 11. Protrusion 12 with various cross-sectional shapes
a is formed, and the other width faces of the refrigerant channels 10 and 11 are smooth. The condensing heat transfer tube 1 of this embodiment is the same in material and manufacturing method as the condensing heat transfer tube of the first embodiment. Further, the fluid diameter of the refrigerant passages 10 and 11 is approximately 1.33 mm, and the size of the other portions is the same as that of the condensation heat transfer tube of the second embodiment. The condensing heat transfer tube of the fifth embodiment is sample No. 5 of the performance test described later.

Sixth Embodiment A condensing heat transfer tube 1 of a sixth embodiment illustrated in FIG.
8 parallel refrigerant flow paths 10 and 11 are formed through the holes, and each of the refrigerant flow paths 10 and 11 is formed in the center of both width surfaces of the refrigerant flow paths 10 and 11 as shown in FIG.
A protrusion 12a having a cross-sectional shape similar to that is formed. This condensation heat transfer tube 1 is a partition wall 1 of a condensation heat transfer tube 3 shown in FIG.
This is a structure in which every other 4 is replaced by a protrusion 12a. The condensing heat transfer tube 1 of the sixth embodiment has the first material and the first manufacturing method.
This is the same as the condensation heat transfer tube of the embodiment. The size and the like are as follows, and the sizes of the parts not described next are the same as those of the condensing heat transfer tube of the second embodiment. Width w1 of the refrigerant channels 10 and 11 = 1.81 Fluid diameter of the refrigerant channels 10 and 11 ≈1.07 Channel width w1 / height h1 ≈2.0 The condensation heat transfer tube of the sixth embodiment will be described later. It is sample No. 6 of the performance test of.

Comparative Example-1 The condensation heat transfer tube 2 of FIG. 12 is a condensation heat transfer tube of a comparative example for comparison with the condensation heat transfer tube 1 of each of the above-mentioned embodiments. Sample No.7 in -1
And Eight refrigerant flow paths 20 are formed in the condensing heat transfer tube 2 so as to be aligned in the width direction via the vertical partition walls 14, and no projection is formed on the inner wall surface of each refrigerant flow path 20. Each refrigerant passage 20 has a fluid diameter of ≈1.20 mm, and the size of the other parts of this heat transfer tube 2 is the same as the condensation heat transfer tube of FIG. 7.

Comparative Example-2 The condensing heat transfer tube 3 of FIG. 13 is a condensing heat transfer tube of another comparative example for comparison with the condensing heat transfer tube 1 of each of the above-mentioned embodiments, and this condensing heat transfer tube 3 will be described later. Performance test-1 sample
No.8 The condensing heat transfer tube 3 is formed so that the sixteen refrigerant passages 30 are arranged side by side in the width direction via the partition walls 14, and no protrusion is formed on the inner wall surface of each refrigerant passage 30. The condensing heat transfer tube 3 has a width w1 = 0.
78, the fluid diameter of the refrigerant channel 30 ≈ 0.84 mm
It is included in the range of the condensation heat transfer tube described in No. 2-175588. ), The flow path width w1 / the internal height h1≈0.87, and the sizes of the other parts are the same as those of the condensation heat transfer tube in FIG.

Performance test-1 Using aluminum alloy, the flat multi-hole condensing heat transfer tubes of sample No. 1 to sample No. 8 described above were prototyped by conform hot extrusion, and each sample No. 1 to No. Regarding No. 8, the steam (134a) inflow temperature was 40 ° C and the outside temperature was 3
The average heat transfer coefficient and the pressure loss inside the tube were measured at 0 ° C. respectively, and the results were as shown in FIGS. 14 and 15. In addition, FIG. 15 shows the pressure loss of the No. 8 condensing heat transfer tube 3 as 1
Shows the pressure loss ratio.

According to the result of FIG. 14, the condensing heat transfer tube of sample No. 8 manufactured with the same specifications as the conventional condensing heat transfer tube was
In terms of heat transfer performance, the fluid diameter of the refrigerant channel is about 1.2.
It is slightly better than the condensing heat transfer tube of Sample No. 7 which is 0 mm. However, condensing heat transfer tube 3 of sample No. 8
Is every other partition wall 1 of the partition walls 14 of the heat transfer tube 3.
Sample No. 6 in which 4 is replaced by the protrusion 12a (sixth embodiment)
The heat transfer performance is inferior to the condensation heat transfer tube of
The difference in heat transfer performance from the No. 1 to No. 5 condensation heat transfer tubes is even greater.

According to the results shown in FIG. 15, the condensation heat transfer tube of Sample No. 6 is slightly inferior to the condensation heat transfer tube of No. 7 in terms of pressure loss, but is far superior to the condensation heat transfer tube of Sample No. 8. It is excellent, and the pressure loss of the condensing heat transfer tubes of samples No.1 to No.5 is even smaller than that of sample No.8.

According to the results of performance test-1, the purpose of further improving the thermal performance without increasing the pressure loss can be achieved by reducing the fluid diameter of the refrigerant passage in the condensation heat transfer tube. Rather, it is better achieved by forming a small protrusion on the inner wall surface of the flat refrigerant passage having a width wider than the internal height, like the condensation heat transfer tube of the embodiment according to the present invention described above. Is. In particular, the condensing heat transfer tube of Sample No. 1 is far superior in both pressure loss and heat transfer coefficient to the condensing heat transfer tube of Sample No. 8.

Performance test-2 The width w, the length, the height h, the height h1 and the width w1 of the refrigerant passages 10 and 11 are the same as those of the condensation heat transfer tube of the first embodiment (FIG. 1), and the protrusions 2 and 4 and 5, respectively, and the projection pitch p is within the range of 0.23 to 1.94 mm. Prototypes were made by extrusion, and the average heat transfer coefficient in tubes was measured for these prototypes in the same manner as in Performance Test-1. The result was as shown in FIG. In FIG. 16, the heat transfer tubes whose protrusions have a triangular cross-sectional shape (FIG. 2) are solid lines,
A heat transfer tube having a quadrangular protrusion (FIG. 5) has a dashed-dotted line, and a heat transfer tube having a protrusion having a circular arc shape (FIG. 4) has a dashed-two dotted line.
In addition, in these condensation heat transfer tubes, the fluid diameter of each refrigerant flow path is in the range of 0.7 to 1.5. Also, the pressure loss of these condensation heat transfer tubes is
When the pressure loss of the condensing heat transfer tube of 0.8 was set to 1, it was in the range of 0.55 to 0.6 (the magnitude of the pressure loss is inversely proportional to the magnitude of the projection pitch p).

According to this performance test-2, the condensation heat transfer tubes having the projection pitch p within the range of 0.25 to 0.6 mm in the refrigerant passage have relatively small pressure loss in the refrigerant passage. It has been revealed that it exhibits a higher level of heat transfer performance. Further, according to the experiment, when the protrusion in the refrigerant flow path in the condensation heat transfer tube has a triangular cross section, the apex angle is 30 to
Most preferably, it is 60 °.

Performance test-3 The width w, the length, the height h, the height h1 and the width w1 of the refrigerant passages 10 and 11 are the same as those of the condensation heat transfer tube of the first embodiment (FIG. 1), and the protrusions 2 has the same cross-sectional shape and size (the cross section of the protrusion is triangular, and the height of the triangle is the same as the base), and the height of the protrusion is within the range of 0.05 to 0.3 mm (the height of the protrusion). h2 / height of refrigerant flow path h1 = 0,0.0
55 to 0.33) aluminum alloy condensation heat transfer tubes were prototyped by conform hot extrusion, and the average heat transfer coefficient in tubes was measured for these prototypes in the same manner as in Performance Test-1. . The results are shown in FIG. In addition, in these condensation heat transfer tubes, the fluid diameter of each refrigerant flow path is in the range of 0.7 to 1.5.

According to this performance test-3, the ratio of the protrusion height h2 to the internal height h1 of the refrigerant passage is 0.055.
It has been revealed that the condensation heat transfer tube having the range of 0.25 has a relatively small pressure loss in the refrigerant flow path and exhibits a higher level of heat transfer performance. In addition, the pressure loss of the condensation heat transfer tube in which the height h1 of the refrigerant flow path with respect to the protrusion height h2 is within the range of 0.055 to 0.25, the pressure loss of the condensation heat transfer tube of Sample No. 8 is 1 If done, 0.55-0.7
Within the range (the magnitude of the pressure loss is proportional to the magnitude of the protrusion height h2).

In the condensing heat transfer tube according to the present invention, like the condensing heat transfer tube 1 of the seventh embodiment shown in FIG. 8, the projections 12 (12a, 12) on the upper and lower width surfaces of the refrigerant flow passage 10 (11).
b) It can be configured such that they are staggered horizontally. That is, in the condensing heat transfer tube 1 of the seventh embodiment, the projections 12 formed on the upper width surface of the refrigerant channel 10 (11) and the projections 12 formed on the lower width surface thereof do not face each other on the same vertical surface. It is in a state. In the condensing heat transfer tube 1 of the seventh embodiment, the number of protrusions on the upper width surface of the refrigerant flow passage 10 (11) and the number of protrusions on the lower width surface are different, but the width surface above the refrigerant flow passage 10 (11) in use. The number of protrusions in
It is preferably larger than the number of protrusions on the lower width surface.

Further, in the condensing heat transfer tube according to the present invention, as in the condensing heat transfer tube 1 of the eighth embodiment shown in FIG. 9, the projections 1 are formed on the upper and lower width surfaces in the refrigerant flow passages 10 and 11 of the condensing heat transfer tube 1.
In addition to forming 2 (12a, 12b), the protrusion 12 (12a, 12b) can be formed on the partition wall 14 or the inner wall surface of the side portion.

Further, like the condensing heat transfer tube of the ninth embodiment shown in FIG. 10, by forming the projection 12 in the condensing heat transfer tube 1 to have a triangular cross section and forming the base of the partition wall 14 into a tapered shape, The cross-sectional shape of the groove 13 adjacent to the partition wall 14 may be an inverted trapezoid.
Further, in the condensation heat transfer tube 1 of each of the above-described embodiments,
As shown by 1, a protrusion 12c having a trapezoidal cross section may be formed.

[0033]

According to the flat multi-hole condensing heat transfer tube of the present invention, it is possible to provide a condensing heat transfer tube which has a relatively small pressure loss in the refrigerant passage and exhibits a higher level of heat transfer performance. Therefore, it is possible to manufacture a further downsized condenser.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing a first embodiment of a condensing heat transfer tube according to the present invention.

FIG. 2 is an enlarged cross-sectional view of a protrusion in a refrigerant passage in the condensation heat transfer tube of FIG.

FIG. 3 is a partially enlarged sectional view showing a second embodiment of the condensation heat transfer tube according to the present invention.

FIG. 4 is an enlarged cross-sectional view of a protrusion in a refrigerant flow path in the condensation heat transfer tube of FIG.

FIG. 5 is an enlarged cross-sectional view showing a modified example of protrusions in the coolant channel.

FIG. 6 is a partially enlarged sectional view showing a fifth embodiment of the condensation heat transfer tube according to the present invention.

FIG. 7 is a partially enlarged sectional view showing a sixth embodiment of the condensation heat transfer tube according to the present invention.

FIG. 8 is a partially enlarged sectional view showing a seventh embodiment of the condensation heat transfer tube according to the present invention.

FIG. 9 is a partially enlarged sectional view showing an eighth embodiment of the condensation heat transfer tube according to the present invention.

FIG. 10 is a partially enlarged sectional view showing a ninth embodiment of the condensation heat transfer tube according to the present invention.

FIG. 11 is an enlarged cross-sectional view showing another modified example of the protrusion in the coolant channel.

FIG. 12 is a partially enlarged cross-sectional view showing a comparative example with respect to the embodiment of the condensation heat transfer tube according to the present invention.

FIG. 13 is a partially enlarged sectional view showing another comparative example with respect to the embodiment of the condensation heat transfer tube according to the present invention.

FIG. 14 is a bar graph comparing in-tube heat transfer coefficients of the condensation heat transfer tubes of some examples according to the present invention and the condensation heat transfer tubes of the comparative examples of FIGS. 12 and 13.

FIG. 15 is a bar graph showing the pressure loss ratios of the condensation heat transfer tubes of some examples according to the present invention and the condensation heat transfer tubes of the comparative examples of FIGS. 12 and 13.

FIG. 16 shows an embodiment of a condensing heat transfer tube according to the present invention,
It is a line graph which shows the relationship between a protrusion pitch and a heat transfer coefficient in a pipe.

FIG. 17 shows an embodiment of a condensing heat transfer tube according to the present invention,
It is a line graph which shows the relationship between projection height and heat transfer coefficient in a pipe.

FIG. 18 is a partial exploded perspective view of a heat exchanger using a conventional flat multi-hole condensing heat transfer tube.

19 is an enlarged sectional view of a flat multi-hole condensing heat transfer tube in the heat exchanger of FIG. 1,2,3 Condensation heat transfer tube 10,11,20,3072 Refrigerant flow path 12,12a, 12b, 12c Protrusion 13 Groove 14,71 Partition wall 4 Refrigerant condensate 5,6 Upper and lower parts 70 Radiating fin 8,9 Header Tube 80 Steam supply port 81, 91 Lid 90 Condensate discharge port 92 Conduit h Height of heat transfer tube h1 Internal height of refrigerant passage h2 Height of protrusion w Width of heat transfer tube w1 Inner width of refrigerant passage w2 Width of protrusion

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuya Nagata 3-4-1, Okubo, Shinjuku-ku, Tokyo Department of Mechanical Engineering, Waseda University (72) Masafumi Katsuda 3-4-1 Okubo, Shinjuku-ku, Tokyo Waseda University Faculty of Science and Engineering Department of Mechanical Engineering

Claims (5)

[Claims] 1. A flat heat transfer tube having a plurality of independent flat refrigerant passages arranged in the width direction and continuous in the length direction, wherein the flat heat transfer tube has a height h of 2.0 mm or less, The flat refrigerant passage has a height h1 of 1.2 mm or less, and a ratio of the width w1 to the height h1 is set within a range of 1.8 to 6.0, and the flat refrigerant passage has an inner wall surface. Has a plurality of projections continuous along the length direction, and the groove adjacent to the projections has a smooth bottom surface, and the ratio of the height h2 of the projections to the height h1 of the flat refrigerant passage is A flat multi-hole condensing heat transfer tube, which is in the range of 0.055 to 0.25. 2. The pitch p of the protrusions is 0.25 to 0.6.
The flat multi-hole condensing heat transfer tube according to claim 1, having a size of mm. 3. The flat multi-hole condensing heat transfer tube according to claim 1, wherein the cross-sectional shape of the groove between the protrusions is an inverted trapezoid. 4. The flat multi-hole condensing heat transfer tube according to claim 3, wherein the protrusion has a substantially triangular cross-sectional shape. 5. The fluid diameter of the flat refrigerant channel is 0.7.
The flat multi-hole condensing heat transfer tube according to any one of claims 1 to 3, which has a diameter of ~ 1.5 mm.