JPH1047883A - Heat exchanger - Google Patents

Abstract

(57) [Problem] To improve the heat exchange rate by uniformly exchanging the internal fluid of a heat exchanger with an external fluid. SOLUTION: Inside a tube 21 through which an internal fluid 22 passes,
Inner fins are intermittently arranged at predetermined intervals in the longitudinal direction of the tube 21, and the inner fluid 22 flowing out of the outlet of the upstream inner fin 25a is mixed between these inner fins to form a downstream inner fin. A chamber 27 for feeding the fins 25b is provided so that the internal fluid 22 uniformly exchanges heat with the external fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger used for changing a fluid temperature to a required temperature.
In particular, the present invention relates to a heat exchanger in which inner fins are provided in a tube through which an internal fluid passes for the purpose of improving a heat transfer coefficient.

[0002]

2. Description of the Related Art Conventionally, as this type of heat exchanger, for example, as shown in FIG. 6, a plurality of flat tubes 1 are arranged in parallel with a gap 2 therebetween, and both ends thereof are headers 3a, 3b. Are connected to each other, and an inner fin 4 is provided in each tube 1 and an outer fin 5 is provided between each tube 1. In this case, as shown in FIGS. 7 and 8, the tube 1 and each of the fins 4 and 5 are formed of a clad material 8 in which a low melting point metal layer 6 is bonded to both surfaces of a base material 7. The tube 1 is formed by fitting the cladding material 8 into a tube shape, the inner fin 4 is inserted therein, and the outer fin 5 is arranged outside, and brazing is performed by the low melting point metal layer 6 of each cladding material 8. It is produced by doing.

[0003] The inner fins 4 are arranged so that the longitudinal direction thereof coincides with the longitudinal direction of the tube 1.
Provided between the header 3a and the header 3b,
The inner fin is provided continuously without interruption from the entrance to the exit. Then, while the internal fluid 9 passes through the inner fins 4 provided in the tube 1,
As the external fluid 10 passes through the gaps 2 between the tubes, heat is exchanged between the internal fluid 9 and the external fluid 10.

[0004]

However, in the conventional heat exchanger, since the external fluid 10 does not uniformly contact the entire surface of the tube 1, the internal fluid 9 passing through the tube 1 is uniformly exchanged with the external fluid 10. For this reason, the heat exchange rate was reduced.

That is, as shown in FIG.
Of the internal fluid 9 diverted by the inner fins 4 installed therein, sufficient heat exchange is performed with respect to the internal fluid 9a that passes on the upstream side with respect to the direction of flow of the external fluid 10, but the downstream side does not. The internal fluid 9b passing therethrough did not perform sufficient heat exchange as compared with the internal fluid 9a on the upstream side, and thus caused a problem that the heat exchange rate was reduced.

[0006] As shown in FIG. 7, the joining portion 11 of the clad material 6 protruding from the outer surface of the tube 1 is connected to an external fluid 10.
Due to the resistance at the time of passage, the smooth flow of the external fluid 10 on the surface of the tube 1 was impeded, and this also led to a decrease in the heat exchange rate.

The present invention has been made in view of the above circumstances, and provides a heat exchanger capable of improving a heat exchange rate by uniformly exchanging heat with an external fluid in an entire internal fluid. With the goal.

[0008]

According to the heat exchanger of the present invention, inner fins are intermittently arranged at predetermined intervals in the longitudinal direction of a tube in a tube through which an internal fluid passes. A chamber is provided between the fins for mixing the internal fluid flowing out from the outlet of the upstream inner fin and sending the mixed fluid to the downstream inner fin.

In the heat exchanger of the present invention, the flow path in the tube is narrowed by the inner fin at the portion where the inner fin is provided, whereas the flow path in the tube is narrowed by the inner fin. The flow path cross-sectional area is large. For this reason, the pressure is increased when the internal fluid flowing in the tube passes through the upstream inner fin having a small channel cross-sectional area. The internal fluid, which was almost laminar, was changed to turbulent near the outlet of the inner fin, and the internal fluid was swirled by the expansion and turbulence of the fluid at that time. Mix in the chamber. Therefore, the internal fluid flowing on the upstream side and the internal fluid flowing on the downstream side in the direction of the flow of the external fluid are mixed in the chamber, and the entire internal fluid is uniformly heat-exchanged with the external fluid. .

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG.
Reference numeral 21 denotes a tube through which an internal fluid 22, which is a heat exchange fluid, passes. The tube 21 is manufactured by extrusion molding of aluminum or an aluminum alloy, has a flat shape, is arranged in parallel with a gap 23 therebetween, and both ends thereof are connected to headers 24a and 24b, respectively.

Inner fins 25a and 25b having a corrugated section are provided in each tube 21 so that the longitudinal direction thereof coincides with the longitudinal direction of the tube 21, and the gap 23 of each tube has a corrugated section. The outer fin 26 is provided to be orthogonal to the inner fins 25a and 25b.
Further, a plurality of inner fins 25a, 25b are provided intermittently from the header 24a to the header 24b,
A chamber 27 in which no inner fin is provided is formed between the inner fins 25a and 25b.

The material of the tube 21 is desirably made of JIS standard A3000 series aluminum alloy or pure aluminum having high thermal conductivity in order to improve the heat transfer coefficient. As shown in FIG. 3, the inner fins 25a, 25b and the outer fins 26 are joined to the inner or outer peripheral surface of the tube, respectively. An alloy or pure aluminum is used as a base material 29, and a three-layer clad material is used on both surfaces of which a low-melting metal layer 30 made of an aluminum alloy of JIS standard A4000 series having a lower melting point than the base material is used. It is joined to the tube 21 by brazing with a layer 30.

In the heat exchanger configured as described above, the internal fluid 22 exchanges heat with the external fluid 28 as follows. First, as shown in FIG. 1, after passing through the header 24a, the internal fluid 22 flowing into the heat exchanger is introduced into each of the tubes 21 arranged vertically in parallel. Next, the internal fluid 22 introduced into each tube 21 is diverted to each flow path 31a partitioned by the upstream inner fin 25a, and when passing through the inner fin 25a, heat is exchanged by the external fluid 28. You.

Here, of the internal fluids passing through the inner fins 25a, the internal fluids passing on the upstream side with respect to the flow direction of the external fluid 28 are in the vicinity of the side surface of the tube 21 where the external fluid 28 is in direct contact , The heat exchange rate with the external fluid is high. On the other hand, the internal fluid passing on the downstream side in the flow direction of the external fluid 28 is the external fluid 28
Is separated from the side of the tube 21 that is in direct contact,
Low heat exchange rate. Therefore, the upstream inner fin 25a
At the time of passing, a temperature gradient occurs in the direction of the flow of the external fluid 28.

When this internal fluid flows out of the inner fin 25a into the chamber 27, as shown in FIG. 2, the section where the inner fin 25a is installed has a narrower flow path cross-sectional area, whereas the inner fin 25a has a smaller cross-sectional area. Since the cross-sectional area of the flow passage is large in the portion 27, the upstream inner fin 25a
The internal fluid 22 that has increased in pressure when passing through the inner fin 25a expands due to a decrease in pressure due to a sudden change in the cross-sectional area from the inner fin 25a to the chamber 27, and the internal fluid that has been substantially laminar flows into the inner fin 25a. A turbulent flow is formed near the outlet of the internal fluid 22, and the internal fluid 22 is mixed in the chamber 27 by the stirring action of the fluid expansion and turbulent flow at that time. further,
The internal fluid mixed in the chamber 27 is sent to the downstream inner fin 25b, and after heat exchange, is sent to a chamber located further downstream to be mixed by the agitating action.

As described above, the internal fluid flowing on the upstream side and the internal fluid flowing on the downstream side with respect to the flow direction of the external fluid are mixed each time when passing through the chamber. The whole can be uniformly and heat-exchanged with the external fluid, and the heat exchange rate can be improved.

Conventionally, as shown in FIG. 8, a clad material was also used for the tube 1. However, since this was manufactured by extrusion molding, the outer peripheral surface of the tube 21 was brazed as shown in FIG. The outer fluid 28 is formed smoothly without forming a joint portion, and there is no resistance when the external fluid 28 passes, so that the external fluid flows smoothly. Furthermore, by eliminating the joining part as extrusion molding,
Brazing is no longer required in the manufacture of the tube,
Instead of brazing material, it is possible to use JIS standard A3000 series aluminum alloy or pure aluminum having high thermal conductivity, and from this point, it is possible to improve the heat exchange rate.

The heat exchanger of the present invention may have the following embodiments. Inner fins 25a, 2
5b and the outer fin 26 have a corrugated cross section, but since each fin is provided for the purpose of improving the heat transfer coefficient between the internal fluid 22 and the external fluid 28, a large surface area is secured in a small space. Other cross-sectional shapes may be used as long as they can be formed.

Although the inner fins are shown as having the same fin pitch from the upstream side to the downstream side,
Like the inner fins 32a and the inner fins 32b shown in FIG. 5, fins with different fin pitches may be arranged, and even those with the same pitch are shifted by a half pitch between the upstream side and the downstream side of the chamber. You may make it.

With such a configuration, the flow paths 33a and 33b defined by the inner fins 32a and 32b are not linearly arranged between the upstream inner fin 32a and the downstream inner fin 32b, so that the When the internal fluid is introduced into the inner fin 32b, the branch flow as indicated by the dashed arrow is effectively repeated, and the mixing effect in the chamber 27 described above can be further enhanced.

[0021]

As described above, according to the present invention,
In the tube through which the internal fluid passes, the inner fin is
A chamber is provided intermittently at predetermined intervals in the longitudinal direction of the tube, and a chamber for mixing the internal fluid flowing out from the outlet of the upstream inner fin and sending it to the downstream inner fin is provided between these inner fins. Because of the provision of the internal fluid, the pressure of which is increased when passing through the upstream inner fin having a small cross-sectional area of the flow path, when flowing into the chamber having a large cross-sectional area of the flow path, As the pressure drops due to the change and expands,
The substantially laminar internal fluid changes to a turbulent flow near the outlet of the inner fin, and the internal fluid is mixed in the chamber by the stirring action of the fluid expansion and turbulent flow at that time.
Therefore, the internal fluid flowing on the upstream side and the internal fluid flowing on the downstream side in the direction of the flow of the external fluid are mixed in the chamber, and the entire internal fluid is uniformly exchanged with the external fluid for heat. Thus, the heat exchange rate can be improved.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view showing an example of an embodiment of a heat exchanger according to the present invention.

FIG. 2 is a cross-sectional plan view of the tube, showing a state in which an internal fluid passes through the tube of the heat exchanger.

FIG. 3 is a sectional view showing a tube of the heat exchanger.

FIG. 4 is an enlarged view of a cross section of a joint between a tube and an inner fin or an outer fin of the heat exchanger.

FIG. 5 is a plan cross-sectional view of a tube showing a state in which an internal fluid passes through a tube of a heat exchanger according to another embodiment of the present invention.

FIG. 6 is a perspective view showing a conventional heat exchanger.

FIG. 7 is a sectional view showing a tube of the heat exchanger.

FIG. 8 is an enlarged view of a cross section of a joint between a tube and an inner fin or an outer fin of the heat exchanger.

[Explanation of symbols]

 21 Tube 22 Internal fluid 25a Upstream inner fin 25b Downstream inner fin 27 Chamber 28 External fluid

Claims (1)

[Claims] 1. A heat exchanger in which heat is exchanged between an internal fluid passing through tubes arranged in parallel at a predetermined interval and an external fluid passing between the tubes, wherein a heat exchanger is provided inside the tubes through which the internal fluid passes. The inner fins are intermittently arranged at predetermined intervals in the longitudinal direction of the tube, and the inner fluid flowing out of the outlet of the upstream inner fin is mixed between these inner fins to form the downstream inner fin. A heat exchanger provided with a chamber for feeding into the heat exchanger.