TUBE FOR HEAT EXCHANGER

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2016-0008669, filed on Jan. 25, 2016 and 10-2016-0175285 filed on Dec. 21, 2016 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The following disclosure relates to a tube for a heat exchanger, and more particularly, to a tube for a heat exchanger forming a channel of a heat exchange medium and including a plurality of inner holes having inner spaces separated in a width direction by a plurality of inner walls extending in a longitudinal direction, in which a thickness of outer walls of certain regions at both ends in the width direction of the tube is formed to be thicker than that of the remaining regions, thereby improving heat exchange performance and preventing corrosion.

BACKGROUND

An in-vehicle heat exchanger transfers heat from a high-temperature fluid to a low-temperature fluid to heat or cool the fluid.

The heat transfer is made by conduction and convection phenomena. The heat transfer by the conduction is a phenomenon that heat is transferred when a plurality of objects having different temperatures come into contact with each other, which appears in proportion to a temperature difference between the objects. Further, the heat transfer phenomenon the convection is generated through a gaseous or liquefied fluid, and the fluid continuously contacts a heat transfer surface to exchange heat. Therefore, since a heat transfer amount is getting more increased as a fluid movement is active, efficiency of the heat transfer may be increased by forming a vortex in a flow path of the fluid.

The heat exchanger generally includes a pair of header tanks through which heat exchange medium is introduced and discharged and a tube connecting the header tanks to allow the heat exchange medium to exchange heat while the heat exchange medium flows therein. FIG. 1 illustrates a typical fin-tube type heat exchanger. The heat exchanger 10 includes: a plurality of tubes 40 having a heat exchange medium flowing therein and parallely arranged in a row at regular intervals in parallel with an air blowing direction; an inlet header tank 20 distributing the heat exchange medium introduced through an inlet to the plurality of tubes 40; a radiating fin 50 interposed between the tubes 40 and increasing a heat transfer area with air flowing between the tubes 40; and a discharge header tank 30 haying the heat exchange medium, which flows in the tube 40, collected therein and discharging the collected heat exchange medium through an outlet.

There are various types of heat exchangers such as a plate type and a pin-tube type. Generally, the fin-tube type heat exchanger as described above is the most commonly used.

The heat transfer process of the fin-tube heat exchanger is as follows. A working fluid flows into one of the tanks 20 and into the header 30 and passes through a multi-stage tube 40. The multi-stage tube 40 which receives heat from the working fluid conducts heat to fins 50 provided between the tubes 40. At this point, as air introduced from the outside flows through the plurality of fins 50, the heat transfer by the convection phenomenon is made between the fins 50 and the introduced air.

As a patent on fin-tube heat exchanger, there is Korean Patent Laid-Open Publication No. 10-2013-0016982 open Publication Date: 2014 Aug. 27, Title: “Fin-tube Heat Exchanger”)

As illustrated in FIG. 1, the tube generally has a flat shape, and an outer side thereof is brazed to a fin by a brazing scheme. At this time, in order to improve the heat exchange performance, an inner channel shape of the tube is formed in a squared or circular shape depending on performance requirements of the heat exchanger and an operation pressure of the system.

For a high-performance extrusion tube, it is necessary to increase a cross sectional area over which a refrigerant may flow while increasing an inner refrigerant contact length. In order to achieve this, it is preferable to make a thickness of an inner wall and an outer wall thin.

However, it is preferable to make the thickness of the inner wall and the outer wall as thin as possible in terms of the performance. However, since the thickness of the inner wall has to consider pressure resistance performance along with extrudability and manufacturing performance and the thickness of the outer wall has Lo consider the extrudability, the manufacturing performance, and corrosion performance, the tube needs to be developed on the basis of a multilateral analysis.

RELATED ART DOCUMENT
Patent Document

Korean Patent Laid-Open Publication No. 10-2013-0016982 (Laid-open Publication Date: 2014 Aug. 27, Title: “Fin-tube Heat Exchanger”)

SUMMARY

An embodiment of the present invention is directed to providing a tube for a heat exchanger forming a heat exchange medium and including a plurality of inner holes having inner spaces separated in a width direction by a plurality of inner walls and extending in a longitudinal direction, in which a thickness of outer walls of certain regions at both ends in the width direction of the tube is formed to be thicker than that of the remaining regions, thereby improving heat exchange performance and preventing corrosion.

In one general aspect, there is provided a tube 100 for a heat exchanger provided in plural and forming a channel a a heat exchange medium that is circulated in the heat exchanger, and including a plurality of inner holes 120 having inner spaces separated in a width direction by a plurality of inner walls 110 and extending in a longitudinal direction, in which a thickness of outer walls located at both ends in a width direction may be differently formed from that of the remaining regions.

The tube 100 may include first reinforcing portion 132 in which a thickness of outer walls of regions located on both surfaces in a thickness direction among regions located at both ends in the width direction is formed to be thicker than that of the remaining regions.

A thickness of the first reinforcing portion 132 may range from 0.2 to 0.25 mm and the thickness of the remaining regions may range from 0.18 to 0.23 mm.

The first reinforcing portion 132 may be formed at both ends, respectively, as much as a length of 10 to 25% of an entire length in the width direction of the tube 100.

When a width of the tube 100 is N (8 mm≦N≦20 mm), the number H_numof inner holes 120 may be 1.5N≦H_num≦3N.

A thickness of the inner wall 110 may range from 0.1 to 0.15 mm and a width of the inner hole 120 may range from 0.25 to 0.5 mm.

One side or both sides of the tube 100 may contact the fin 200 interposed between adjacent tubes 100 in the thickness direction and may be formed flat in the width direction of the contact surface.

The tube 100 and the fin 200 may be formed so that lengths of the contacting surfaces are equal to each other.

A thickness T1 of surfaces located at both ends in the width direction may be thicker than a thickness T2 of surfaces located at both sides in the thickness direction.

The tube 100 may include a second reinforcing portion 140 in which the inner surfaces of surfaces located at both ends in a width direction is protrudedly formed inwardly.

A protruding al of the second reinforcing portion 140 may be equal to or greater than distances a1 and a3 from each edge to both ends in the width direction of the second reinforcing portion 140.

The tube 100 may be an extruding tube.

A hydraulic diameter may range from 0.40 to 0.65 mm.

A cross sectional ratio (cross sectional area of inner hole/entire tube area) of a passage may range from 42 to 55%.

The tube 100 may have a protrusion 150 inwardly protruding on inner surfaces of both sides in the thickness direction.

The protrusion 150 may be further formed on the inner wall 110.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view illustrating a typical heat exchanger.

FIG. 2 is a front view illustrating a tube for a heat exchanger according to an exemplary embodiment of the present invention.

FIG. 3 is a front view illustrating a tube for a heat exchanger according to another exemplary embodiment of the present invention.

FIGS. 4 and 5 are front views illustrating a tube for a heat exchanger according to still another exemplary embodiment of the present invention.

FIG. 6 is a front view illustrating a state in which a fin is interposed between the tubes for a heat exchanger of FIG. 3.

FIG. 7 is a front view illustrating a state in which a fin is interposed between the tubes for a heat exchanger of FIG. 2.

FIGS. 8 and 9 are enlarged front views of a region in which a second reinforcing portion is formed, in the tube for a heat exchanger.

DETAILED DESCRIPTION OF EMBODIMENTS

Hereinafter, a tube for a heat exchanger according to exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 2 to 5 are front views illustrating a tube for a heat exchanger according to various exemplary embodiments of the present invention, FIG. 6 is a front view illustrating a state in which a fin is interposed between the tubes for a heat exchanger of FIG. 3, FIG. 7 is a front view illustrating a state in which a fin is interposed between the tubes for a heat exchanger of FIG. 2, and FIGS. 8 and 9 are enlarged front views of a region in which a second reinforcing portion is formed, in the tube for a heat exchanger.

A tube 100 for a heat exchanger according to an exemplary embodiment of the present invention is manufactured by extrusion molding and is provided in plural to form a channel of a heat exchange medium circulated in the heat exchanger and includes a plurality of inner holes 120 having inner spaces separated in a width direction by a plurality of inner walls 110 and extending in a longitudinal direction, and in particular, a thickness of outer walls of certain regions at both ends of the tube in the width direction of the tube is differently formed from that of the remaining regions.

At this point, the tube 100 according to the exemplary embodiment of the present invention includes a first reinforcing portion 132 in which a thickness of outer walls of certain regions at both ends in the width direction is formed to be thicker than that of the remaining regions.

That is, as illustrated in FIG. 2, the tube 100 according to the exemplary embodiment of the present invention includes a first reinforcing portion 132 in which a thickness of outer walls located at both sides in a thickness direction is formed to be thicker than a thickness of an outer wall 131 of a region located at a central part in certain region at both ends in the width direction.

The region in which the first reinforcing portion 132 is located is a region that most comes in contact with running wind, and actually is a region that is vulnerable to corrosion due to corrosive substances penetrated in an air flow direction.

In the past, the outer wall has been formed to be thicker over the entire region to prevent a water leakage due to such corrosion. In this case, a total weight of the tube increases and a cross sectional area of the tube in which a refrigerant may flow is decreased as the thickness of the outer wall is thick, thereby causing the problem in which the heat exchange performance deteriorates.

Therefore, according to the exemplary embodiment of the present invention, only the outer wall 131 located in the region most vulnerable to the corrosion is formed to be thick, and the first reinforcing portion 132 is formed at both ends in width direction for easiness of assembly at the time of manufacturing.

That is, according to the exemplary embodiment of the present invention, the first reinforcing portion 132 for preventing the corrosion is formed, and the remaining regions are formed to have a minimum thickness of outer wall 131 to secure the heat exchange performance. For this purpose, by experiments, values of each part of the tube 100 were optimized as described below.

The tube 100 according to the exemplary embodiment of the present invention is designed so that a thickness Tr of the first reinforcing portion 132 ranges from 0.2 to 0.25 mm and a thickness To of the remaining regions ranges from 0.18 to 0.23 mm, and is based on the condition in which a thickness Tr of the first reinforcing portion 132 is formed to be thicker than the thickness To of the remaining regions.

As illustrated in FIG. 2, the first reinforcing portion 132 is formed up to a region in which about three inner holes 120 are located at both ends in the width direction of the tube 100, but the number of inner holes 120 is not limited thereto and therefore may also be two or four.

As described above, in order for the tube 100 to secure the cross sectional area over which the refrigerant may flow as well as to secure the water leakage preventing effect due to the corrosion to a certain level or more, it is preferable to maintain a length including a width W_holeof the inner hole 120 and a thickness T_inthe inner wall 110 corresponding to region in which the first reinforcing portion 132 is formed and thicknesses of both ends in the width direction of the tube at a certain level.

The following Table 1 shows the detailed example in which when the width of the tube is 12 T, the thicknesses of both ends in the width direction, the thickness T_inof the inner wall 110, a width W_holeof the inner hole 120, and the number A (descending) of inner holes depending thereon are calculated.

TABLE 1

The

Second reinforcing
Inner
Width of
number of

Width of tube
portion
wall
inner hole
inner holes

12T
0.4
0.10
0.30
28

0.6
0.15
0.50
16

Further, the following Table 2 shows an example of a length Lr of the first reinforcing portion 132 and a ratio of the fir at reinforcing portion 132 to an entire width depending on the number of inner holes, when the width of the tube is 12 T.

TABLE 2

Two inner holes + inner wall
Three inner holes + inner wall

Length
Ratio
Length
Ratio

1.20
10.0
1.60
13.3

1.90
15.8
2.55
21.3

Considering the number of inner holes, the thickness of the inner wall, or the like as described above, the length Lr of the first reinforcing portion 132 is preferably set at both ends, respectively, as much as a length of 10 to 25% of the entire length in the width direction of the tube 100.

Meanwhile, the width of the tube 100 is generally designed to be about 8 to 20 mm.

According to the exemplary embodiment of the present invention, the entire size of the tube is maintained while the width of the tube 100 is maintained, but the number of inner holes 120 is increased and the thickness T_inof the inner wall 110 is decreased, such that the pressure resistance performance over a certain level may be satisfied.

In more detail, representing the relationship of the number of the inner holes 120 depending on the width of the tube 100 by the following Equation, when the width of the tube 100 is N mm, the number H_numof the inner holes 120 may be 1.5N≦H_num≦3N.

At this point, in the tube 100 according to the exemplary embodiment of the present invention, the thickness T_inof the inner wall 110 may be formed to be thin as 0.1 to 0.15 mm and the width of the inner hole 120 may range from 0.25 to 0.5 mm.

The following Table 3 shows an example of the number of inner holes 120 depending on the width of the tube 100 in the tube 100 having the above-mentioned characteristics, in which the number of inner holes 120 is not necessarily limited as shown in the following Table and therefore may be changed within the range of 1.5N≦H_num≦3N without any limitation.

At this point, it is preferable that a hydraulic diameter of the tube 100 is equal to or less than 0.65 mm and a cross sectional area (cross sectional area of inner hole/entire tube area) ratio of a passage is equal to or more than 42%.

The hydraulic diameter and the passage cross sectional area ratio are areas that have a difficulty in being achieved by the existing folded and extruded tubes, and when the tube 100 according to the exemplary embodiment of the present invention is manufactured as a high-performance extrusion tube having the hydraulic diameter and the passage cross sectional area and thus applied to a condenser, the heat exchange performance of the condenser and a coefficient of performance (COP) of a refrigeration cycle may be improved.

Here, the hydraulic diameter of the tube 100 is a hydraulic diameter Dh=4*channel area/perimeter for the channel divided by the inner wall 110 in the tube 100 of FIG. 2, in which the channel area indicates the cross sectional area of the inner hole of the tube 100 and the water contact length indicates a circumferential length of the channel.

TABLE 3

12T Tube
16T Tube

The number of
23
30

inner holes

Hydraulic
0.54
0.58

diameter

Passage cross
48%
51%

sectional area

ratio

In the above examples, when the width of the tube 100 is 12 mm, the first reinforcing portion 132 may be approximately formed from both ends to a region where about three inner holes 120 and three inner walls 110 are located and when the width of the tube 100 is changed, the region where the first reinforcing portion 132 is formed may be appropriately adjusted to meet the conditions as described above.

As described above, the tube 100 according to the exemplary embodiment of the present invention has a predetermined number or more of inner holes 120 and minimizes the thickness of the inner wall 110 and the outer wall 131 of the central part to sufficiently secure the cross sectional area over which the refrigerant may flow, thereby improving the pressure resistance performance while maintaining the heat exchange performance at a certain level or higher and at the same time.

As another example, as illustrated in FIG. 5, the tube 100 may include protrusions 150 protruding inwardly on inner surfaces of both sides in the thickness direction. The protrusion 150 increases a contact area between the refrigerant and the tube 100, thereby increasing the hydraulic diameter and improving the heat exchange efficiency.

At this point, the protrusion 150 may be protrudedly formed on the inner surfaces of both sides in the thickness direction as illustrated in FIG. 5, may protrude from the inner wall 110, or may be formed thereon in plural.

Meanwhile, the fin 200 of the heat exchanger is interposed between the tubes 100 and thus the exchange between the heat exchange medium and air is made in the region contacting the tube 100.

At this point, the heat transfer area increases as the contact area between the fin 200 and the tube 100 increases, and as a result the larger the contact area between the fin 200 and the tube 100, the better the heat exchange performance.

To this end, the tube 100 for a heat exchanger according to the exemplary embodiment of the present invention may be formed flat in the width direction of the surface contacting the fin 200.

At this point, as illustrated in FIG. 7, the tube 100 for a heat exchanger according to the exemplary embodiment of the present invention has a substantially rectangular cross section, in which it is preferable that each edge is minimally rounded to coincide with a contact area with tips of the fins 200.

That is, since the lengths of the surfaces contacting the fins 200 are the same, the tube 100 has more increased heat transfer area and heat exchange performance, compared to the existing tube 100 having an outer round.

Further, as illustrated in FIG. 6, the tube 100 for a heat exchanger of the present invention may be formed in a shape having circular rounds at both end but is not necessarily limited to a squared or circular shape.

Further, in the tube 100, a thickness T1 of surfaces located at both sides in the width direction may be equal to a thickness T2 of surfaces located at both sides in the thickness direction or as illustrated in FIG. 8, the thickness T1 of the surfaces located at both sides in the thickness direction may be formed to be thicker than the thickness T2 of surfaces located at both sides in the thickness direction.

In particular, since the tube 100 for a heat exchanger according to the present invention includes the first reinforcing portion 132 whose thickness of the outer walls at both ends in the width direction is formed to thicker than that of the remaining regions, even if the thickness T1 of the surfaces located at both sides in the width direction is equal to the thickness T2 of the surfaces located at both sides in the thickness direction, the tube 100 is thicker than the existing tube 100, thereby having a certain level of corrosion prevention function.

At this point, in the tube 100, the thickness T1 of the surfaces located at both sides in the width direction is formed to be smaller than distances a1 and a3 from each of the outer edges to each of the inner edges.

FIG. 8 illustrates the example in which the thickness of the surfaces located at both sides in the width direction is formed to be thick constantly and FIG. 9 illustrates the tube 100 including a second reinforcing portion 140 having inner surfaces of the surfaces located at both sides in the width direction protrudedly formed inwardly.

At this point, is preferable that a protruding height a2 of the second reinforcing portion 140 is equal to or greater than the distances a1 and a3 reaching both ends of the second reinforcing portion 140 an the thickness direction from each edge of the tube 100 and is formed to be at least 0.4 mm or more.

Therefore, the region that easily comes into contact with corrosive substances or foreign matters while all the tubes 100 are traveling formed to be thicker than other regions, and therefore the tube 100 may minimize the problem in which the water leakage occurs due to the damage caused by the corrosive substances or the foreign matters and contribute to the improvement in durability.

Describing it once more, according to the tube 100 for a heat exchanger in accordance with the exemplary embodiments of the present invention, the thickness of the outer walls of certain regions at both ends in the width direction of the tube 100 may be formed to be thicker than the remaining region, thereby improving the durability of the portion where the water leakage is liable to occur due to the damage by corrosive substances or foreign matters and the remaining region may be formed to be thin to secure the area of the region through which the refrigerant passes, thereby maintaining the heat exchange performance at the predetermined level or more.

Further, according to the tube 100 for a heat exchanger in accordance with the exemplary embodiments of the present invention, the thickness of the inner wall 110 and the number of inner holes 120 formed by the inner wall 110 may be optimized to satisfy the extrudability, the manufacturing performance, and the pressure resistance performance.

In addition, according to the tube 100 for a heat exchanger in accordance with the exemplary embodiments of the present invention, one side or both sides of the tube comes into contact with the fin 200 in the thickness direction and the surface from one end portion to the other end portion of the tube 100 may be formed flat in the width direction of the contacting surface to more increase the heat transfer area than that of the existing tube 100 having the outer round, thereby improving the heat exchange performance.

According to the tube for a heat exchanger in accordance with the exemplary embodiments of the present invention, the thickness of the outer walls of certain regions at both ends in the width direction of the tube may be formed to be thicker than that of the remaining regions, thereby improving the durability of the portion where the water leakage is liable to occur due to the damage by corrosive substances or foreign matters and the remaining regions may be formed to be thin to secure the area of the region through which the refrigerant passes, thereby maintaining the heat exchange performance at the predetermined level or more.

Further, according to the tube for a heat exchanger in accordance with the exemplary embodiments of the present invention, the thickness of the inner wall and the number of inner holes formed by the inner wall may be optimized to satisfy the extrudability, manufacturing performance, and the pressure resistance performance.

In addition, according to the tube for a heat exchanger in accordance with the exemplary embodiments of the present invention, one side or both sides of the tube comes into contact with the fin in the thickness direction and the surface from one end portion to the other end portion of the tube may be formed flat in the width direction of the contacting surface to more increase the heat transfer area than that of the existing tube having the outer round, thereby improving the heat exchange performance.

The present invention is not limited to the above-mentioned embodiments but may be variously applied, and may be variously modified by those skilled in the art to which the present invention pertains without departing from the gist of the present invention claimed in the claims.

Number	Date	Country	Kind
10-2016-0008669	Jan 2016	KR	national
10-2016-0175285	Dec 2016	KR	national

TUBE FOR HEAT EXCHANGER

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