JP2016161250A - Heat exchanger tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger tube which can largely improve performance more than before when employed to a heat exchanger such as an EGR cooler.SOLUTION: In a heat exchanger tube, a flat tube main body 14 is employed which has such a shape that a plurality of pieces of circular pipes are made to approximate each other, aligned in a plane shape, and connected to each other with an approximating region between the circular pipes as a communication part 13, swirl flow formation protrusions 16 are formed at internal peripheral faces of circuit pipe parts 15 equivalent to the circular pipes of the flat tube main body 14 so as to progress along spiral trajectories which are coaxial with center axes O of the circular pipe parts 15, and swirl flows of an exhaust gas 10 can be individually formed at the respective circular pipe parts 15. A partitioning wall 17 is formed at least at a part of the communication part 13 at a latter half of the flat tube main body 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat exchanger tube that can be used in a heat exchanger such as an EGR cooler.

  Conventionally, an EGR device that reduces the generation of nitrogen oxides by recirculating a part of exhaust gas of an engine of an automobile or the like to the engine is known. In such an EGR device, the exhaust gas recirculated to the engine is known. When the engine is cooled, the temperature of the exhaust gas is reduced and the volume of the exhaust gas is reduced, so that the combustion temperature can be lowered and the generation of nitrogen oxides can be effectively reduced without significantly reducing the output of the engine. Some engines are equipped with an EGR cooler for cooling the exhaust gas in the middle of the line for recirculating the exhaust gas to the engine.

  FIG. 3 is a cross-sectional view showing an example of the EGR cooler. In FIG. 3, reference numeral 1 denotes a shell formed in a cylindrical shape, and a plate so as to close the end surface of the shell 1 at both ends in the axial center direction of the shell 1. 2 and 2 are fixed, and both ends of a large number of tubes 3 are fixed to the respective plates 2 and 2 in a penetrating state. The large numbers of tubes 3 extend in the axial direction inside the shell 1. Yes.

  A cooling water inlet pipe 4 is attached from the outside near one end of the shell 1, and a cooling water outlet pipe 5 is attached from the outside near the other end of the shell 1. 9 is supplied from the cooling water inlet pipe 4 to the inside of the shell 1, flows outside the tube 3, and is discharged from the cooling water outlet pipe 5 to the outside of the shell 1.

  Further, bonnets 6, 6 formed in a bowl shape are fixed to the opposite shell 1 side of each plate 2, 2 so as to enclose the end faces of the respective plates 2, 2, and in the center of one bonnet 6. Is provided with an exhaust gas inlet 7 and an exhaust gas outlet 8 at the center of the other bonnet 6. The exhaust gas 10 of the engine enters the inside of one bonnet 6 from the exhaust gas inlet 7, and a plurality of tubes 3. After being cooled by heat exchange with the cooling water 9 flowing outside the tube 3, it is discharged into the other bonnet 6 and recirculated from the exhaust gas outlet 8 to the engine.

  In the figure, reference numeral 11 denotes a bypass outlet pipe provided at a position facing the cooling water inlet pipe 4 in the diameter direction of the shell 1. By extracting a part of the cooling water 9 from the bypass outlet pipe 11, The stagnation of the cooling water 9 is prevented from occurring at a location facing the inlet pipe 4.

  In such a conventional EGR cooler, since the exhaust gas 10 flows straight through the tube 3 and the exhaust gas 10 does not sufficiently contact the inner peripheral surface of the tube 3, the heat exchange efficiency is not so good. 4, the spiral protrusion 12 is formed on the inner peripheral surface of the tube 3 (the spiral protrusion 12 is formed on the inner peripheral surface side as an inverted shape by denting the outer peripheral surface side of the tube 3 as a spiral groove). It has already been proposed to improve the heat exchange efficiency of the EGR cooler by using the exhaust gas 10 flowing inside as a swirling flow, thereby increasing the contact frequency and contact distance of the exhaust gas 10 with respect to the inner peripheral surface of the tube 3.

  On the other hand, in such a structure in which a plurality of tubes 3 are arranged in parallel and accommodated in the shell 1, the heat exchanger per unit volume is small, so the overall structure of the heat exchanger becomes large, and the mounting property to equipment is improved. As shown in an example in FIG. 5, the flat tube main body has a shape in which a plurality of circular tubes are arranged close to each other and arranged in a planar shape and adjacent portions thereof are connected as communication portions 13, as shown in FIG. 5. The swirl flow forming projection 16 is formed on the inner peripheral surface of the circular tube portion 15 corresponding to the circular tube of the flat tube body 14 so as to follow a spiral orbit concentric with the central axis O of the circular tube portion 15. (The swirl flow forming projections 16 are formed in an inverted shape by recessing the outer peripheral surface side of each circular pipe portion 15 into a groove shape), and the swirl flow of the exhaust gas 10 can be individually formed in each circular pipe portion 15. The heat exchanger tube And it started to be considered that (see Patent Document 1, etc. below).

  That is, when the heat exchanger tube is configured in this way, when the exhaust gas 10 flows through each circular pipe portion 15 of the flat tube main body 14, the swirl flow forming projections 16 on the inner peripheral surface of each circular pipe portion 15 The flow is guided in the direction along the spiral trajectory, and as a result, the swirling flow of the exhaust gas 10 is individually formed in each circular pipe portion 15. As a result, the contact frequency of the exhaust gas 10 with respect to the inner peripheral surface in each circular pipe portion 15. In addition, the heat exchange efficiency is increased by increasing the contact distance, and the circular pipe parts 15 are in communication with each other via the communication part 13 so that the exhaust gas 10 flows. Since a large road cross-sectional area is ensured, an excellent effect is obtained that the amount of exchange heat per unit volume is increased and the pressure loss is reduced.

JP 2013-79779 A

  However, it is considered that exhaust gas regulations aimed at combating global warming will be strengthened in the future, and this is the case when a heat exchanger tube comprising a flat tube body 14 as shown in FIG. 5 is used in an EGR cooler. However, there is a demand for improvement efforts to further improve performance.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a tube for a heat exchanger that can realize a significant performance improvement as compared with the conventional case when employed in a heat exchanger such as an EGR cooler.

  The present invention comprises a flat tube body having a shape such that a plurality of circular tubes are arranged close to each other in a plane and connected to each other as a communicating portion, and corresponds to the circular tube of the flat tube body. The swirl flow forming protrusions can be formed on the inner peripheral surface of the circular tube portion along the spiral orbit concentric with the central axis of the circular tube portion, and the swirl flow of the heat medium can be individually formed in each circular tube portion. In the heat exchanger tube configured as described above, a partition wall is formed in at least a part of the communication portion in the latter half of the flat tube body.

  Thus, if the heat exchanger tube is configured in this way, the heat medium flows through each circular pipe part of the flat tube body while forming a swirl flow, and the temperature of the heat medium in which heat exchange has proceeded in the latter half part. Even if the temperature difference with the refrigerant outside the flat tube body decreases and the heat transfer area in the latter half of the flat tube body increases by the amount of the partition wall, the heat medium and the refrigerant The amount of exchange heat that should decrease due to the reduction in the temperature difference between the two is compensated by the increase in the heat transfer area, and a significant performance improvement is realized when it is adopted in a heat exchanger such as an EGR cooler.

  Here, in the latter half of the flat tube body, heat exchange proceeds and the volume of the heat medium is smaller than that in the first half. The increase in the flow rate of the heat transfer medium reduces the thickness of the boundary layer with the heat transfer surface and improves the heat transfer coefficient. The amount of heat exchanged in the latter half of this increases, thereby improving the performance.

  Further, in the present invention, it is preferable that the direction of the swirl flow forming projections of adjacent circular pipe portions is formed so as to be along mutually opposite spiral trajectories, and in this way, adjacent circular pipe portions The swirl flows in the same direction flow in the same direction and accelerate each other, and even if there is a communication part between each circular pipe part, it is possible to more reliably form the heat medium as a swirl flow Become.

  Furthermore, in the present invention, it is preferable that the partition wall is partially formed so as to sandwich the unprocessed communication portion in the arrangement direction of the circular pipe portions and to be intermittently scattered in the longitudinal direction of the circular pipe portions, In this way, excessive reduction of the cross-sectional area of the flow path is avoided, and a significant increase in pressure loss can be more reliably prevented.

  According to the above-described heat exchanger tube of the present invention, the following various excellent effects can be obtained.

  (I) According to the invention described in claim 1 of the present invention, even if heat exchange proceeds in the latter half of the flat tube main body and the temperature difference between the heat medium and the refrigerant becomes small, in the latter half of the flat tube main body. The heat transfer area can be increased by forming the partition wall, and the partition wall is formed in the latter half where the volume of the heat medium is reduced compared to the first half, while avoiding a significant increase in pressure loss. Since the heat transfer coefficient can be improved by increasing the flow rate of the medium, the exchange heat quantity in the latter half of the flat tube body can be effectively increased and used in heat exchangers such as EGR coolers. Can be realized.

  (II) According to the invention described in claim 2 of the present invention, the swirl flows can be accelerated in the same direction at the communicating portions of the adjacent circular pipe portions, and each circular pipe portion can be accelerated. The formation of the swirling flow can be made more reliable.

  (III) According to the invention described in claim 3 of the present invention, the partition wall is arranged so that the unprocessed communication portion is sandwiched in the arrangement direction of the circular pipe portions and is intermittently scattered in the longitudinal direction of the circular pipe portions. By partially forming the, it is possible to avoid excessive reduction in the cross-sectional area of the flow path and more reliably prevent a significant increase in pressure loss.

It is sectional drawing which shows an example of the form which implements this invention. It is a top view of the flat tube main body of FIG. It is sectional drawing which shows an example of a common EGR cooler. It is a perspective view which shows a prior art example. It is a perspective view which shows another prior art example.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 and 2 show an example of an embodiment for implementing a heat exchanger tube according to the present invention, and show a case where it is applied to an EGR cooler (heat exchanger) as in the case of the conventional example described above. The part which attached | subjected the code | symbol same as FIGS. 3-5 represents the same thing.

  As shown in FIG. 1 and FIG. 2, in the heat exchanger tube of this embodiment, as in the case of the conventional example of FIG. A flat tube body 14 having a shape such that adjacent portions are connected as communication portions 13, and the central axis of the circular tube portion 15 is formed on the inner peripheral surface of the circular tube portion 15 corresponding to the circular tube of the flat tube body 14. A swirl flow forming protrusion 16 is formed along a spiral orbit concentric with O (the swirl flow forming protrusion 16 is formed in an inverted shape by denting the outer peripheral surface side of each circular tube portion 15 in a groove shape: FIG. For the sake of convenience, only a part is shown), and the swirl flow of the exhaust gas 10 can be individually formed in each of the circular pipe portions 15, but the latter half of the flat tube main body 14 (the exhaust gas 10). Downstream of the middle in the flow direction It is characterized in where the partition wall 17 at least a portion of the communicating portion 13 is formed in.

  More specifically, the partition wall 17 is partially formed so as to sandwich the unprocessed communicating portions 13 one by one in the arrangement direction of the circular pipe portions 15 and to be intermittently scattered in the longitudinal direction of the circular pipe portions 15. In addition, the direction of the swirl flow forming protrusions 16 of the adjacent circular pipe portions 15 is formed so as to follow the spiral trajectories opposite to each other (see the illustration of the swirl flow forming protrusions 16 in FIG. 2). It is devised so that the swirl flows are made to flow in the same direction at the communicating part 13 of the matching circular pipe part 15 so that the mutual flows do not cancel each other (the swirl flow of the exhaust gas 10 shown by the arrow in FIG. 1). See orientation).

  Furthermore, when manufacturing the flat tube body 14, for example, a pair of halved parts that are divided into an upper part and a lower part are manufactured by pressing, and the halved parts are overlapped vertically and welded on both sides. In the press working, the outer peripheral surface side of each circular tube portion 15 is recessed into a groove shape, and the swirl flow forming protrusion 16 is raised as an inverted shape on the inner peripheral surface side, and the flat tube body In the range corresponding to the latter half part 14, a dividing wall part obtained by dividing the partition wall 17 into two parts in the vertical direction is formed in advance in each of the half parts, and brazing or welding is performed in a state where the divided wall parts are in contact with each other. What is necessary is just to complete | finish as the division wall 17 by joining.

  In addition, when utilizing the side part of this flat tube main body 14 for joining at the time of manufacture of such a flat tube main body 14, considering the workability at the time of the joining operation, the swirl flow formation protrusion 16 of the said side part is provided. The processing (groove processing from the outer peripheral surface side: see FIG. 2) may be partially omitted, and even if the partial swirl flow forming protrusion 16 is omitted here, the swirl flow formation is greatly affected. The inventors of the present application have confirmed that it is not necessary to provide this.

  Thus, when the heat exchanger tube is configured in this way, the exhaust gas 10 flows through each circular pipe portion 15 of the flat tube main body 14 while forming a swirl flow, and the exhaust gas in which heat exchange has proceeded in the latter half portion. Even if the temperature of the gas 10 decreases and the temperature difference from the cooling water 9 outside the flat tube main body 14 decreases, the heat transfer area in the latter half of the flat tube main body 14 increases by the amount of the partition wall 17 formed. Therefore, the amount of exchange heat that would otherwise be reduced by reducing the temperature difference between the exhaust gas 10 and the cooling water 9 is compensated by the increase in the heat transfer area, and a significant improvement in performance when used in an EGR cooler is realized. Will be.

  Here, in the latter half portion of the flat tube main body 14, heat exchange proceeds and the volume of the exhaust gas 10 is smaller than that in the first half portion. The increase in the flow rate of the exhaust gas 10 increases the boundary layer thickness with the heat transfer surface, thereby improving the heat transfer coefficient. However, the amount of heat exchanged in the latter half of the flat tube main body 14 is increased, thereby improving the performance.

  Therefore, according to the above embodiment, even if heat exchange proceeds in the latter half of the flat tube main body 14 and the temperature difference between the exhaust gas 10 and the cooling water 9 becomes small, the heat transfer area in the latter half of the flat tube main body 14 is reduced. Can be increased by forming the partition wall 17, and the partition wall 17 is formed in the latter half portion where the volume of the exhaust gas 10 is reduced from the first half portion, thereby avoiding a significant increase in pressure loss. Since the heat transfer coefficient can be improved by increasing the flow rate of the gas 10, it is possible to effectively increase the exchange heat amount in the latter half of the flat tube body 14 and realize a significant performance improvement when it is used in an EGR cooler. Can do.

  Further, particularly in the present embodiment, the direction of the swirl flow forming projections 16 of the adjacent circular pipe portions 15 is formed so as to follow the spiral trajectories that are opposite to each other. In FIG. 13, the swirl flows can be accelerated in the same direction as each other, and the formation of the swirl flow in each circular pipe portion 15 can be made more reliable.

  Further, by forming the partition wall 17 so as to sandwich the unprocessed communication portion 13 in the direction in which the circular pipe portions 15 are arranged and to be intermittently scattered in the longitudinal direction of the circular pipe portion 15, excessive flow path disconnection is achieved. A reduction in area can be avoided, and a significant increase in pressure loss can be prevented more reliably.

  In addition, the tube for heat exchangers of this invention is not limited only to the above-mentioned form example, You may apply to heat exchangers other than an EGR cooler, In addition, in the range which does not deviate from the summary of this invention. Of course, various changes can be made.

9 Cooling water (refrigerant)
10 Exhaust gas (heat medium)
13 Communication part 14 Flat tube main body 15 Circular pipe part 16 Swirling flow formation protrusion 17 Partition wall O Center axis

Claims (3)

  A circular tube portion corresponding to the circular tube of the flat tube body, which is formed of a flat tube body having a shape in which a plurality of circular tubes are arranged close to each other and arranged in a plane and connected to each other as a communicating portion. A swirl flow forming projection is formed on the inner peripheral surface of the circular pipe portion so as to follow a spiral orbit concentric with the central axis of the circular pipe portion, and a swirl flow of the heat medium can be individually formed in each circular pipe portion. A heat exchanger tube, wherein a partition wall is formed in at least a part of the communication portion in the latter half of the flat tube main body.   2. The heat exchanger tube according to claim 1, wherein the swirl flow forming projections of adjacent circular pipe portions are formed so as to be along mutually opposite spiral trajectories.   The partition wall is partially formed so as to sandwich an unprocessed communication portion in the direction in which the circular pipe portions are arranged and to be intermittently scattered in the longitudinal direction of the circular pipe portions. The tube for a heat exchanger as described.

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