JP2006138538A - Flat heat exchanger tube, and multitubular heat exchanger and multitubular heat exchange type egr gas cooling device comprised by incorporating the heat exchanger tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger tube, a multitubular heat exchanger, and a multitubular heat exchange type EGR gas cooling device providing superior cooling efficiency by uniforming distribution and a flow velocity of a fluid in addition to turbulization and an agitating effect to a medium to be cooled or a coolant flowing through a tube, and promoting efficient heat exchange action. <P>SOLUTION: The flat heat exchanger tube, and the multitubular heat exchanger and multitubular heat exchange type EGR gas cooling device comprised by incorporating the heat exchanger tube is comprised by internally providing at least one coil spring comprised by spirally winding a wire and flatly forming a wound cross sectional shape in the tube carrying the medium to be cooled or the coolant. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat transfer tube that is usually installed in a multi-tube heat exchanger and a multi-tube heat exchange type cooling device, and flows through the medium to be cooled or the cooling medium. The fluid to be cooled or the fluid composed of the cooling medium causes a turbulent or vortex stirring action to increase the contact between the heat transfer tube wall surface and the fluid, and the flow velocity of the fluid flowing through the heat transfer tube The present invention relates to a flat heat transfer tube in which excellent heat exchange performance can be obtained by equalizing the flow rate, a multi-tube heat exchanger incorporating the flat heat transfer tube, and a multi-tube heat exchange type EGR gas cooling device.

  In recent years, heat exchangers for various forms of fluids such as EGR coolers for automobile exhaust gas recirculation, liquid-liquid, liquid-gas, gas-gas, etc., such as fuel coolers, oil coolers, and intercoolers have been widely used. However, in the heat transfer tubes through which these fluids flow, various devices have been made to efficiently radiate or absorb the heat held by the fluids. For example, a method of taking a part of exhaust gas from an exhaust system of a diesel engine, returning it to the intake system of the engine again, and adding it to the air-fuel mixture is called EGR (Exhaust Gas Recirculation) and is called NOx (nitrogen oxide) ), Reducing pump loss, reducing heat dissipation loss to the coolant due to lowering of combustion gas temperature, increasing specific heat ratio due to working gas volume / composition change, and accompanying improvement in cycle efficiency Therefore, it is widely adopted as an effective method for purifying exhaust gas from diesel engines and improving thermal efficiency.

However, when the temperature of the EGR gas rises and the amount of EGR gas increases, the durability of the EGR valve decreases due to its thermal action, and there is a risk that it will be damaged at an early stage. There is a need for a structure, and as the intake air temperature rises, the charging efficiency is lowered and the fuel consumption is lowered. In order to avoid such a situation, a device for cooling EGR gas with engine coolant, car air-conditioner refrigerant or cooling air is used, and in particular, gas-liquid that cools EGR gas, which is a gas, with engine coolant. Many heat exchange type EGR gas cooling devices have been proposed, and as means for improving the heat exchange performance, various forms of fins are provided in the pipe through which the EGR gas flows. For example, a double pipe type in which an outer pipe through which a liquid is passed is disposed outside an inner pipe through which a gas passes, and a metal corrugated plate is inserted as a fin in the inner pipe in an exchanger for exchanging heat between the gas and the liquid. A heat exchanger (see, for example, Patent Document 1), an inner pipe for circulating a medium to be cooled inside, an outer pipe provided so as to surround and surround the outer circumference of the inner pipe, and an inside of the inner pipe A double-pipe heat exchanger (for example, refer to Patent Document 2) composed of a radiating fin having a thermal stress relaxation function, an inner pipe for circulating a medium to be cooled, and an outer periphery of the inner pipe A double-pipe heat exchanger (for example, see Patent Document 3) composed of an outer tube provided so as to surround and be separated and a cross fin disposed inside the inner tube has been proposed. Yes.
Japanese Patent Laid-Open No. 11-23181 (pages 1-6, FIGS. 1-2) JP 2000-1111277 A (pages 1 to 12, FIGS. 1 to 12) JP 2003-21478 A (pages 1-8, FIGS. 1-7)

  In each of the above prior arts, in the case of the double-tube type EGR gas cooler disclosed in Patent Documents 1 to 3, the corrugated fins and the cross fins are provided so as to trickle the gas flow and make contact with the fins. In terms of increasing the area, although some results are expected, the inner surface of the pipe constituting the EGR gas flow path has a smooth inner peripheral surface over the entire length. In many cases, the heat transfer near the center of the pipe becomes insufficient, and the gas flow flows straight along the EGR gas pipe, so that the turbulence of the gas flow becomes insufficient and the boundary layer of the heat transfer surface is sufficient. There was a problem that the heat transfer performance was slightly insufficient without being thinned.

 Furthermore, as an example of another heat exchange type cooling device including the EGR gas cooling device, the shell and tube type multi-tube heat exchanger 200 as shown in FIG. 15 is not limited to the EGR gas cooling device recently. Is widely adopted and a plurality of heat transfer tube groups 203 are formed through a tube sheet 205 in a shell 201 through which cooling water flows, and a high temperature introduced from a cooling medium inlet g1 provided in the bonnet 202-1. In the shell 201 through the tube wall of the heat transfer tube forming the heat transfer tube group 203 until the fluid is discharged from the cooled medium outlet g2 provided in the opposite bonnet 202-2. Is cooled to a predetermined temperature by heat exchange with cooling water flowing in a state orthogonal to the flow of the medium to be cooled. Further, by making the individual heat transfer tubes 203-1 forming the heat transfer tube group 203 into flat tubes as shown in FIGS. 16 (a) and (b), the contact area can be increased, A corrugated plate fin 206 having a rectangular cross section in the heat pipe 203-1 and having a free shape in the longitudinal direction is housed, and the flow path of the high-temperature fluid that is the cooling medium is partitioned into a plurality of small flow paths. The plate fin 206 is formed in a waveform as shown in FIG. 16 (c), and the fluid flowing through the small flow path is meandered, thereby further increasing the heat transfer area and improving the heat exchange efficiency. Fin structures for further improvement have been proposed, each achieving initial results.

 However, the heat transfer tube in which the fin structure formed by applying special plastic processing to a plate material made of a single metal thin plate in the flat heat transfer tube is also formed by the fin structure. The pressure loss of the fluid in the small flow path is low, the distribution of the fluid flowing between the small flow paths is not uniform, the flow velocity is unevenly distributed, and it is formed by a single metal sheet Since the small flow paths divided by the plate fins formed independent flow paths for each other and are not in communication with each other, it becomes impossible to eliminate the uneven distribution of the flow velocity once generated, The unsolved problem that the heat exchange efficiency is remarkably lowered due to the uneven flow velocity distribution remains. Further, the non-uniformity of fluid distribution in the small flow path divided in the heat transfer tube makes it impossible to cool to a desired temperature range when an excessive amount of fluid flows, while the fluid flow rate is In the case of less than the design value, although the cooling of the fluid proceeds, the predetermined flow rate is not reached, and as a result, the exchange heat quantity is reduced. That is, even in the fin structure improved to improve the heat exchange efficiency, it is difficult to process and attach it, such as complicated plastic processing, and the performance is sufficient compared to the high cost of the device itself. However, there remains a big problem that further improvement is desired. As a result of various investigations for the purpose of the present invention to solve such problems, a cross-sectional shape obtained by winding a wire rod in a spiral shape instead of a conventional fin structure inserted in a flat heat transfer tube By installing a flat coil spring, a large number of intermittent edge effects occur continuously with respect to the fluid flowing through the flat heat transfer tube, and at the same time, a continuous Karman vortex street is formed. Based on this knowledge, we have developed a flat heat transfer tube with excellent heat exchange efficiency despite its simple structure. By incorporating this flat heat transfer tube, the cooling efficiency has been significantly improved. As well as a multi-tube heat exchange type EGR gas cooling device.

  A flat heat transfer tube according to the present invention for solving the above-described problems is obtained by winding a wire rod in a spiral shape and including at least one coil spring having a flattened cross-sectional shape as a cooling medium or a cooling medium. The gist of the present invention is a flat heat transfer tube that is characterized by being internally provided in a flowing tube.

  Further, in the flat heat transfer tube according to the present invention, the coil spring is wound while maintaining a specific interval between the wires, and the wound cross-sectional shape formed into a flat shape is substantially oval, substantially oval, It is one of substantially rectangular shapes.

  Furthermore, the coil spring according to the present invention is formed by winding a wire rod in a circular spiral shape to form a coil spring, and then pressing the coil spring with a parallel surface to form a flattened cross-sectional shape. It is characterized by.

  In the above-described flat heat transfer tube according to the present invention, the cross-section of the wire forming the coil spring is circular or approximately elliptical, arbitrarily elongated based on the circular shape, substantially elliptical, triangular, square, or arbitrarily based on the square It is preferable to have a cross-sectional shape selected from a substantially rectangular shape, a substantially pentagonal shape, a substantially hexagonal shape, a substantially polygonal shape, a star shape, or the like that is deformed into a shape.

  In the above-described flat heat transfer tube according to the present invention, it is preferable that the cross-sectional shape of the wire forming the coil spring is a rectangle.

  Further, in the above-described flat heat transfer tube according to the present invention, the inner form of the coil spring in the flat heat transfer tube is any one selected from parallel, wavy, vertical, and oblique to the tube axis direction of the flat heat transfer tube. It is characterized in that the interior is configured by arbitrarily combining these forms or these forms.

  Furthermore, the cross-sectional shape of the flat heat transfer tube according to the present invention is substantially oval or substantially rectangular.

  The flat heat transfer tube according to the present invention is characterized in that a concave groove is formed in at least one inner wall surface of the flat heat transfer tube, and the coil spring is fitted into the concave groove. It is.

  In the above-described flat heat transfer tube according to the present invention, it is preferable that the internal means of the coil spring to the flat heat transfer tube is appropriately selected from welding, diffusion bonding, brazing and other bonding means and is integrally bonded. Is.

  Further, in the flat heat transfer tube according to the present invention, it is further preferable that the internal means of the coil spring to the flat heat transfer tube is brazing.

  A multi-tube heat exchanger according to another invention according to the present application is characterized by incorporating at least two flat heat transfer tubes obtained by the above invention.

  In the multitubular heat exchanger according to the invention described above, it is preferable that the medium to be cooled is caused to flow through the flat heat transfer tube to be incorporated.

  In the multitubular heat exchanger according to the invention described above, it is preferable that the medium to be cooled flowing through the flat heat transfer tube is a gas body.

  A multi-tube heat exchange type EGR gas cooling device according to still another invention of the present application is characterized in that EGR gas is allowed to flow as a medium to be cooled in the flat heat transfer tube provided therein. Is.

  According to the flat heat transfer tube according to the present invention, a coil spring having a flat cross-sectional shape wound in the flat heat transfer tube is a fluid composed of a medium to be cooled or a cooling medium flowing through the heat transfer tube. By interposing it in the flow path, a large number of edge portions exist intermittently and without interruption, causing an edge effect on the fluid, and for each wire formed in a spiral shape, A vortex row is continuously formed, and the flow velocity of the fluid in the heat transfer tube is not biased with a large stirring effect. Accordingly, the non-uniform flow velocity distribution is eliminated, and a uniform flow velocity is easily maintained. Therefore, the pressure of the fluid is uniform between the flow paths, the fluid distribution is averaged, the heat transfer performance is dramatically improved, and excellent heat exchange performance is ensured. Further, according to the above flat heat transfer tube having the coil spring according to the present invention, the spirally formed coil spring frequently causes mixing and collision between fluids flowing therethrough, thereby making the working fluid turbulent. The fluid flow is complicated and the laminar flow is separated and effective stirring is repeated, and the fluid flowing through the heat transfer tube repeatedly repeats the heat transfer tube wall surface and coil spring. Effective heat exchange is promoted in contact with.

  In the flat heat transfer tube according to the present invention, if a groove is formed on the inner peripheral wall surface of at least one of the heat transfer tubes, preferably both, and a coil spring is fitted in the groove, it is easy to incorporate. This makes it easier to continuously manufacture by brazing in the furnace, which can greatly reduce the manufacturing cost, improve the vibration resistance of the flat heat transfer tube itself, and improve the vibration resistance. By being attached, the heat transfer from the coil spring to the heat transfer tube wall surface is further improved. Further, by making the cross-sectional shape of the wire forming the coil spring into a flat shape such as an oval, the heat transfer area of the coil spring itself is increased, and the heat transfer performance of the flat heat transfer tube incorporating the coil spring is further improved. . Therefore, the flat heat transfer tube according to the present invention can be suitably installed as a heat transfer tube for a heat exchanger such as a fuel cooler, an oil cooler, or an intercooler as well as a multi-tube heat exchange type cooling device, and at the same time The heat transfer tubes with springs make it possible to reduce the size and weight of these devices due to their excellent heat exchange performance, contributing to the compactness of the devices and enabling easy installation in a limited space. Can be provided relatively inexpensively.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings.
FIG. 1 schematically shows a single flat heat transfer tube according to an embodiment of the present invention, in which (a) is a partially omitted perspective view of the flat heat transfer tube with a coil spring installed therein, and (b) is a single coil spring. FIG. 2 schematically shows a single unit of a flat heat transfer tube according to another embodiment of the present invention, and FIG. 2A is a perspective view with a part omitted of the flat heat transfer tube with a coil spring installed therein. Is a partially omitted perspective view of a single coil spring, FIG. 3 is a partially omitted perspective view schematically showing a flat heat transfer tube according to still another embodiment of the present invention, and FIG. 4 is a perspective view of the coil spring according to the present invention. FIGS. 5A to 5E are front views illustrating a state in which the wound cross-sectional shape is formed flat, and FIG. 5 is a cross-sectional shape of the wire forming the coil spring in the present invention. (A) to (h) are cross-sectional views illustrating the transmission surface shape. FIG. 6 is a two-sided view showing a side surface of a coil spring according to the present invention, in which (a) shows a state where the wires are in close contact with each other, and (b) is a part showing a state where the wires are kept at a specific interval FIG. 7 is an abbreviated side view, FIG. 7 is a partially enlarged plan view schematically showing a state of arrangement of coil springs installed in a flat heat transfer tube, and FIG. 8 is another embodiment according to the present invention. FIG. 9 is a partially enlarged plan view schematically showing the state of arrangement of coil springs installed in a flat heat transfer tube in an example, and FIG. 9 is a coil spring installed in a flat heat transfer tube in still another embodiment of the present invention. (A) is a partially enlarged plan view thereof, (b) is a partially enlarged front view thereof, and FIG. 10 is a still another embodiment according to the present invention. Arrangement of coil springs installed in flat heat transfer tubes FIG. 11 is a partially enlarged plan view schematically showing a situation of arrangement of coil springs installed in a flat heat transfer tube in still another embodiment according to the present invention, FIG. 12 is a partially enlarged plan view schematically showing a state of a combination of coil springs installed in a flat heat transfer tube in one embodiment according to the present invention, and FIG. 13 is a multi-tube heat exchanger according to the present invention. FIG. 14 is a front view schematically showing a state in which a flat heat transfer tube with a coil spring installed therein is assembled. FIG. 14 shows a multi-tube heat exchange type EGR gas cooling device according to the present invention in which a flat heat transfer tube with a coil spring is assembled. FIG.
[Example]

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited thereto, and can be freely modified within the scope of the gist of the present invention.

A wire made of SUS316 austenitic stainless steel with a cross-sectional shape of 0.3 mm thickness and 3 mm width processed into a flat ellipse by cold drawing is prepared, and the wire is wound by applying tight winding to the wire. After the turned cross-sectional shape is formed into a circular coil shape, the flat coil spring 1 having a substantially elliptical cross-sectional shape as shown in FIG. Obtained. On the other hand, after preparing a circular tube made of SUS316 austenitic stainless steel with a thickness of 0.5 mm and applying a pressing process using a mold to form a flat tube having a substantially rectangular cross-sectional shape, a pressing process using a mold is further performed. A flat heat transfer tube 2 having a groove 2-1 formed on the inner peripheral wall surface as shown in FIG. Next, the coil spring 1 is fitted into the concave groove 2-1 of the heat transfer tube 2 so that the wires are kept at a specific interval, and joined together by brazing, and the wound cross-sectional shape according to the present invention is used. A flat heat transfer tube 2 having a flat coil spring 1 was obtained. As a result of preparing eight flat heat transfer tubes 2 obtained in this way and incorporating them into a multi-tube heat exchange type EGR gas cooling device 20 as shown in FIG. 14, the results were provided for a cooling performance test of the EGR gas g. Is shown in Table 1 in comparison with a conventional multi-tube heat exchange type EGR gas cooling device of the same kind. As is apparent from the results shown in Table 1, according to the EGR gas cooling device 20 configured according to the embodiment of the present invention, the high-temperature EGR flowed through the hood 20-3 of the EGR gas g inlet port. The gas g is effectively agitated by the edge effect of the coil spring 1 incorporated in the flat heat transfer tube 2, while the coil spring 1 acts to continuously form a Karman vortex, and the heat transfer While the flow of the EGR gas g flowing through the pipe is turbulent and undergoes a large stirring action, the flow velocity distribution of the EGR gas flow is made uniform, so that the contact with the heat transfer tube wall surface is repeated without deviation, It was confirmed that effective heat exchange was promoted, and excellent cooling performance and high temperature efficiency were obtained.

  SUS316 austenitic stainless steel is used as the wire material for forming the flat heat transfer tube 2 and the coil spring 1 installed in the flat heat transfer tube 2 according to the present embodiment, but has a certain mechanical strength, As long as the material is excellent in corrosion resistance and heat transfer and has good workability, it is not hindered to appropriately select from other metal materials. Furthermore, although the wire forming means in the present embodiment is a wire obtained by cold drawing, a wire obtained by other methods can be used. Further, the flat heat transfer tube 2 is formed by pressing with a mold using a circular tube, but it is also possible to adopt, for example, a middle-matching type (one-sided or two-sided) by sheet metal processing using a flat plate. I do not disturb. On the other hand, the joining means of the coil spring 1 to the flat heat transfer tube 2 is brazed in this embodiment, but the present invention is not limited to this, and welding, diffusion joining and other joining means are appropriately used. In addition, in brazing, at least one of the joining wall surfaces of the coil spring 1 or the flat heat transfer tube 2 may be plated in advance, and a paste, wire, foil Etc. can also be supplied to the joint surface.

  Except that the shape of the flat heat transfer tube 2a is formed as shown in FIG. 2 (a), and the cross-sectional shape of the coil spring 1a wound inside is a substantially rectangular flat shape as shown in FIG. 2 (b). Then, a flat heat transfer tube 2a having a coil spring 1a with a flat cross-sectional shape wound in the same manner as in Example 1 is obtained, and eight flat heat transfer tubes 2a are prepared. As a result of being incorporated in the heat exchange type EGR gas cooling device 20 and subjected to a cooling test under the same conditions as in Example 1, it was confirmed that substantially the same cooling efficiency as in Example 1 could be obtained.

  A plate material made of SUS316 austenitic stainless steel having a thickness of 0.5 mm was prepared and subjected to a mid-process by sheet metal working using a mold to produce a flat heat transfer tube 2b as shown in FIG. On the other hand, the wound cross-sectional shape of the coil spring 1b housed in the flat heat transfer tube 2b is a deformed rectangle as shown in the same figure, and the other windings are as shown in FIG. A flat heat transfer tube 2b having a coil spring 1b with a flat cross-sectional shape was obtained. Next, eight flat heat transfer tubes 2b were prepared and installed in a multi-tube heat exchange type EGR gas cooling device 20 in the same manner as in Example 1 and subjected to a cooling test under the same conditions as in Example 1. It was confirmed that substantially the same cooling efficiency as in Example 1 could be obtained.

  The coil spring incorporated in the flat heat transfer tube in the present invention is not particularly limited as long as the wound cross-sectional shape is formed flat, and for example, a substantially oval shape shown in FIG. The substantially elliptical shape shown in FIG. 6B, the substantially rectangular shape shown in FIG. 10C, the substantially deformed hexagon shown in FIG. 10D, and the substantially deformed rectangular shape shown in FIG. However, other shapes can be freely adopted as long as they meet the object of the present invention. Further, as is clear from the above embodiment, the coil spring according to the present invention is initially formed as a circular tightly wound coil, and when it is installed in a flat heat transfer tube, it is pressed between parallel surfaces using a mold. After being processed, a coil spring having a desired winding cross-sectional shape is formed into a flat coil spring, and the coil spring is installed in the flat heat transfer tube in a tightly wound state as shown in FIG. Although not obstructing, in order to form an effective edge effect and continuous Karman vortex street, and for price and weight, non-contact type with a specific spacing between the wires as shown in FIG. It is desirable that

  The wire material forming the coil spring in the present invention is not particularly limited in cross section as long as it is a wire material capable of forming the coil spring. For example, the wire shown in FIG. A substantially oval shape shown in FIG. 2C, a substantially square shape shown in FIG. 1D, a substantially rectangular shape shown in FIG. 1E, a substantially pentagon shape shown in FIG. ), A substantially star shape shown in FIG. 11 (h), and the like, but other shapes can be freely adopted as long as they meet the object of the present invention. .

  In the present invention, the arrangement method of the coil spring on the flat heat transfer tube is arbitrary and not particularly limited. For example, as shown in FIG. 7, the coil spring is arranged linearly with respect to the flow direction g of the gas to be cooled. 8 can be arranged in a wave shape as shown in FIG. 8, or can be arranged at a right angle as shown in FIG. 9. Further, as shown in FIG. It is also possible to arrange them or to fix them by arranging them in a bellows shape in a flat heat transfer tube as shown in FIG. Further, the above arrangement of the coil springs in the flat heat transfer tube can be provided in combination with each other. For example, as shown in FIG.

  By incorporating a coil spring having a flat cross-sectional shape wound as described above, a flat heat transfer tube according to the present invention can be obtained, and a plurality of the flat heat transfer tubes 2x form a cooling jacket 10-1. The multi-tube heat exchanger 10 of the present invention as shown in FIG. The flat heat transfer tubes to be incorporated do not have to be provided with the same coil springs arranged in the same arrangement. As shown in FIG. 13, the coil springs installed are substantially oval coil springs 1c, The rectangular coil spring 1e can be arbitrarily selected, and the arrangement and combination thereof can be freely selected.

  By incorporating a plurality of the above flat heat transfer tubes according to the present invention, the multi-tube heat exchange type EGR gas cooling device of the present invention shown in FIG. 14 used in the above-described embodiment is constructed. Tube sheets 20-2 are provided at both ends of the main body 20-1 serving as a cooling jacket, and a plurality of flat heat transfer tubes 2x are assembled via the tube sheets. The flat heat transfer tube is internally provided with a coil spring having a flat cross-sectional shape, and hot EGR gas flowing in through the hood 20-3 on the EGR gas inlet side flows through the flat heat transfer tube and passes through the EGR. While it has been confirmed that it is cooled to a temperature level of about 1/3 while flowing out through a bonnet (not shown) on the gas outlet side, it is a flat heat transfer tube that enables such temperature efficiency. It has been confirmed in the above-mentioned embodiment that the factor exists in the edge effect brought about by the coil spring installed in the inner wall and the remarkable improvement in the heat conduction efficiency contributed by the Karman vortex array formed continuously.

  In the present invention, the flat heat transfer tube, the coil spring incorporated in the heat transfer tube, and the materials such as the multi-tube heat exchanger and the EGR gas cooling device are corrosive to the medium to be cooled and the cooling medium flowing through the device. Although it is appropriately selected in consideration of workability, etc., usually austenitic stainless steel, carbon steel as a general steel material, copper, aluminum, titanium, nickel and alloys based on these are exemplified, but certain Austenitic stainless steel is preferably used because it has corrosion resistance and excellent rigidity and can be suitably used for joining such as brazing.

  As is clear from the above embodiment, according to the flat heat transfer tube according to the present invention, a coil spring having a flat cross-sectional shape wound inside the flat heat transfer tube flows through the heat transfer tube. By interposing in the flow path of the medium to be cooled or the fluid consisting of the cooling medium, a large number of edge portions are present intermittently and without interruption, causing an edge effect on the fluid, and in addition, spiral shape For each wire formed, a Karman vortex street is continuously formed, and the flow velocity of the fluid in the heat transfer tube is not biased with a large stirring effect, and accordingly, the uneven flow velocity distribution is eliminated and uniform. The flow rate is easy to maintain. Therefore, the pressure of the fluid is uniform between the flow paths, the fluid distribution is averaged, the heat transfer performance is dramatically improved, and excellent heat exchange performance is ensured. Further, according to the above flat heat transfer tube having the coil spring according to the present invention, the spirally formed coil spring frequently causes mixing and collision between fluids flowing therethrough, thereby making the working fluid turbulent. The fluid flow is complicated and the laminar flow is separated and effective stirring is repeated, and the fluid flowing through the heat transfer tube repeatedly repeats the heat transfer tube wall surface and coil spring. Effective heat exchange is promoted in contact with.

  In the flat heat transfer tube according to the present invention, if a groove is formed on the inner peripheral wall surface of the heat transfer tube and a coil spring is fitted in the groove, the assembly is easy and continuous by brazing in the furnace or the like. Coil springs can be manufactured easily, and the manufacturing cost can be greatly reduced, the vibration resistance is improved by taking into account the reinforcing effect of the flat heat transfer tube itself, and the fixing means is brazed. The heat transfer from the heat transfer tube to the wall surface is further improved. Further, by making the cross-sectional shape of the wire forming the coil spring into a flat shape such as an oval, the heat transfer area of the coil spring itself is increased, and the heat transfer performance of the flat heat transfer tube incorporating the coil spring is further improved. . Therefore, the flat heat transfer tube according to the present invention can be suitably installed as a heat transfer tube for a heat exchanger such as a fuel cooler, an oil cooler, or an intercooler as well as a multi-tube heat exchange type cooling device, and at the same time The heat transfer tubes with springs make it possible to reduce the size and weight of these devices due to their excellent heat exchange performance, contributing to the compactness of the devices and enabling easy installation in a limited space. Since the container can be provided at a relatively low cost, a wide range of applications in the industrial field is expected.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows a single unit of a flat heat transfer tube according to an embodiment of the present invention, in which (a) is a partially omitted perspective view of a flat heat transfer tube with a coil spring installed therein, and (b) is a partially omitted perspective view of a coil spring unit. FIG. The flat heat transfer tube which concerns on the other Example of this invention is shown typically. The (a) is a partially omitted perspective view of the flat heat transfer tube with a coil spring built therein, and (b) is a partially omitted coil spring. It is a perspective view. It is a partially-omission perspective view which shows typically the simple substance of the flat heat exchanger tube which concerns on the further another Example of this invention. The coiled spring which concerns on this invention is shown, and (a)-(e) is each front view which illustrated the state which formed the wound cross-sectional shape flatly. The cross-sectional shape of the wire which forms the said coil spring in this invention is shown, (a)-(h) is each sectional drawing which illustrated this transmission surface shape. It is a 2nd page figure which shows the side surface of the coil spring single-piece | unit in this invention, (a) shows the state which wires contact | adhered, (b) is a partially abbreviated side view which respectively shows the state with which wire materials maintained specific space | interval It is. In one Example which concerns on this invention, it is a partially expanded plan view which shows typically the condition of arrangement | positioning of the coil spring built in a flat heat exchanger tube. In the other Example which concerns on this invention, it is a partially expanded plan view which shows typically the condition of arrangement | positioning of the coil spring built in a flat heat exchanger tube. In the other Example which concerns on this invention, it is a 2nd page figure which shows typically the condition of arrangement | positioning of the coil spring built in a flat heat exchanger tube, (a) is the partially expanded plan view, (b) is the It is a partially expanded front view. In the other Example which concerns on this invention, it is a partially expanded plan view which shows typically the condition of arrangement | positioning of the coil spring internally equipped by a flat heat exchanger tube. In the other Example which concerns on this invention, it is a partially expanded plan view which shows typically the condition of arrangement | positioning of the coil spring internally equipped by a flat heat exchanger tube. In one Example which concerns on this invention, it is a partially expanded plan view which shows typically the condition of the combination of the coil springs with which a flat heat exchanger tube is equipped. In the multi-tube heat exchanger according to the present invention, it is a front view schematically showing a state in which a flat heat transfer tube having a coil spring incorporated therein is incorporated. In the multi-tube heat exchange type EGR gas cooling device according to the present invention, it is a partially omitted side view schematically showing a state in which a flat heat transfer tube having a coil spring incorporated therein is incorporated. It is a typical side view for demonstrating the conventional shell and tube type multi-tube heat exchanger. 2 shows a flat heat transfer tube with a corrugated plate fin having a rectangular cross section mounted on the heat exchanger and a cooling jacket (shell body), (a) is a front view thereof, and (b) is a flat heat transfer tube alone. A front view and (c) are top views of the plate fin built in this flat heat exchanger tube.

Explanation of symbols

1, 1a, 1b, 1c, 1d, 1e, 1f, 1g Coil spring 2, 2a, 2b, 2x Flat heat transfer tube 2-1 Groove 2-2, 2a-2 Inner peripheral wall surface 2b-3 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h Wire material 10 Multi-tube heat exchanger 10-1 Shell (cooling jacket)
20 EGR gas cooling device 20-1 main body 20-2 tube sheet 20-3 bonnet W-1, W-1a Cooling water inlet W-2, cooling water outlet

Claims (14)

A flat wire is formed by winding a wire rod in a spiral shape, and at least one coil spring having a flattened cross-sectional shape is housed in a cooling medium or a pipe through which the cooling medium flows. Heat transfer tube. The coil spring is wound while maintaining a specific interval between wire rods, and the winding cross-sectional shape formed into a flat shape is any one of a substantially oval shape, a substantially oval shape, and a substantially rectangular shape. The flat heat transfer tube according to claim 1. The coil spring is formed by winding a wire rod in a circular spiral shape to form a coil spring, and then pressing the coil spring with a parallel surface so that the wound cross-sectional shape is formed flat. The flat heat exchanger tube according to claim 1 or 2. The cross-section of the wire forming the coil spring is a circle or a substantially oval, a substantially oval, a triangle, a square, or a substantially rectangular or a substantially pentagon that is arbitrarily deformed based on the square. The flat heat transfer tube according to any one of claims 1 to 3, wherein the flat heat transfer tube has a cross-sectional shape selected from a substantially hexagonal shape, a substantially polygonal shape, or a star shape. The flat heat transfer tube according to any one of claims 1 to 4, wherein a cross-sectional shape of a wire forming the coil spring is a rectangle. The interior configuration of the coil spring in the flat heat transfer tube is any one selected from parallel, wavy, vertical, and diagonal with respect to the tube axis direction of the flat heat transfer tube, or any combination thereof. The flat heat transfer tube according to any one of claims 1 to 5, wherein the flat heat transfer tube is internally provided. The flat heat transfer tube according to any one of claims 1 to 6, wherein a cross-sectional shape of the flat heat transfer tube is substantially oval or substantially rectangular. 8. The groove according to claim 1, wherein a concave groove is formed on at least one inner wall surface of the flat heat transfer tube, and the coil spring is fitted into the concave groove. Described in flat heat transfer tube. 9. The interior means of the coil spring to the flat heat transfer tube is appropriately selected from welding, diffusion joining, brazing and other joining means, and joined as a unit. The flat heat transfer tube described in 1. The flat heat transfer tube according to any one of claims 1 to 9, wherein the internal means of the coil spring to the flat heat transfer tube is brazing. A multi-tube heat exchanger comprising at least two flat heat transfer tubes according to any one of claims 1 to 10. The multi-tube heat exchanger according to claim 11, wherein a medium to be cooled is caused to flow through the flat heat transfer tube. The multi-tube heat exchanger according to claim 11 or 12, wherein the medium to be cooled is a gas body. 14. The multi-tube heat exchange type EGR gas cooling device according to claim 11, wherein an EGR gas is allowed to flow as a cooled medium in the flat heat transfer tube.

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