JP2004340516A - Heat exchanger tube and heat exchanger incorporating the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove soot deposited on the inner face of a heat exchanger tube without stopping the cooling operation of the heat exchanger tube while eliminating the possibility of lowering the primary heat transfer efficiency of the heat exchanger tube, and to minimize the lowering of heat transfer efficiency of the heat exchanger tube due to the soot by removing the soot within a time when it is less deposited on the inner face of the heat exchanger tube. <P>SOLUTION: On an inner peripheral face 6 of an element tube 3 which has a fluid introduction port 4 and a fluid delivery port 5 at one axial end and at the other axial end, respectively, a plurality of metal wires 7 are annularly arranged in parallel to the axial direction of the element tube 3 in spaced relation. At least one end portion 8 of each metal wire 7 is fixed to the side of the fluid introduction port 4 of the element tube 3 and the metal wire 7 has strength enough for oscillation in random amplitude with the introduction of fluid into the fluid introduction port 4. Soot deposited on the inner peripheral face 6 of the element tube 3 is separated therefrom with the oscillation of the metal wires 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Industrial applications]
The present invention relates to a heat exchanger for cooling water, cooling air, a refrigerant for a car air conditioner, and other cooling media, and a combustion exhaust gas containing EGR gas and soot in a multi-tube heat exchanger such as an EGR gas cooling device. The present invention relates to a heat transfer tube used for performing an exchange and a heat exchanger to which the heat transfer tube is assembled.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. H11-108578 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-227413
Conventionally, in an engine of an automobile, an EGR system in which a part of exhaust gas is taken out from an exhaust gas system, returned to an intake system of the engine, and added to an air-fuel mixture or intake air has been used for both a gasoline engine and a diesel engine. . An EGR system, particularly a cooled EGR system of a diesel engine with a high EGR rate, reduces NOx in exhaust gas to prevent deterioration of fuel efficiency and also prevents deterioration of EGR valve function and durability due to excessive temperature rise. For this purpose, a device for cooling the high-temperature EGR gas with cooling water, cooling air, a refrigerant, or another cooling medium is provided.
[0004]
In this EGR gas cooling device, as shown in FIG. 5, a plurality of small-diameter heat transfer tubes (1) through which the EGR gas can flow are arranged, and cooling water or cooling water is provided outside the heat transfer tubes (1). The heat exchange between the EGR gas and the cooling medium is performed through the heat transfer tube (1) by circulating a cooling medium such as a wind or a refrigerant.
[0005]
As such a heat transfer tube, the invention described in Patent Document 1 and the invention described in Patent Document 2 are known. In these conventionally known heat transfer tubes, since the inner peripheral surface through which the fluid flows is smooth, soot (2) contained in the flowing exhaust gas easily accumulates as shown in FIG. When the soot (2) adheres and accumulates on the inner surface of the heat transfer tube (1), the soot (2) causes an adiabatic action to reduce the amount of exchanged heat, thereby lowering the performance as the heat transfer tube (1). Absent. Therefore, conventionally, as a method of removing the soot (2) from the inner surface of the heat transfer tube (1), after using the heat transfer tube (1) for a certain period of time, the heat transfer tube (1) is scraped off with a brush-like material or the heat transfer tube (1). The soot (2) is incinerated and removed by making the heat transfer tube (1) high temperature by stopping the cooling operation of the soot.
[0006]
[Problems to be solved by the invention]
However, the soot (2) adhered to the inner surface of the heat transfer tube (1) may be scraped off with a brush, or the cooling operation of the heat transfer tube (1) may be stopped to raise the temperature of the heat transfer tube (1). The method of incinerating the soot (2) not only requires a lot of trouble but also requires the cooling operation of the heat transfer tube (1) to be stopped, which significantly reduces the work efficiency of the heat transfer tube (1). ing. In order to prevent such a defect and prevent soot (2) from adhering to the inner surface of the heat transfer tube (1), a coating having a low surface energy such as fluororesin is applied to the inner surface of the heat transfer tube (1). Has also been done. However, this method of applying a coating having a low surface energy to the inner surface of a heat transfer tube is based on a heat exchanger because a coating having a low surface energy, such as a fluororesin, has a low heat conductivity and a poor heat conductivity as compared with a metal. The heat transfer efficiency of a certain heat transfer tube (1) is reduced.
[0007]
The present invention is intended to solve the above-described problems, and does not reduce the heat transfer efficiency, which is the original purpose of the heat transfer tube (1), and does not stop the cooling operation of the heat transfer tube. It is possible to automatically remove soot (2) attached to the inner surface of the heat transfer tube (1). Also, by removing the soot (2) while the amount of the soot (2) adhered to the inner surface of the heat transfer tube (1) is small, the decrease in the heat transfer efficiency of the heat transfer tube due to the soot (2) is minimized. It is something to try.
[0008]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION In order to solve the above-described problems, the first invention is directed to a method in which a fluid inlet is provided at one end in an axial direction and a fluid outlet is provided at the other end in the axial direction. A plurality of metal wires are arranged annularly at intervals with being parallel to the axial direction of the metal wire, and at least one end of the metal wire is fixed to the fluid inlet side of the raw tube, and the metal wire is connected to the fluid inlet. A heat transfer tube according to the present invention is characterized in that it has a strength capable of swinging with the introduction of a fluid, and soot attached to the inner peripheral surface of the raw tube can be peeled off by swinging a metal wire.
[0009]
Further, the second invention provides a method for manufacturing a plurality of metal plates parallel to the axial direction of a base tube on an inner peripheral surface of the base tube having a fluid inlet at one end in the axial direction and a fluid outlet at the other end in the axial direction. The wires are arranged annularly at intervals, and at least one end of the metal wire is fixed to the fluid inlet side of the raw tube, and the metal wire can be swung with the introduction of the fluid into the fluid inlet. The present invention relates to a heat exchanger to which a heat transfer tube has been attached, wherein the heat transfer tube has a strength and is capable of separating soot adhering to the inner peripheral surface of the raw tube by swinging a metal wire.
[0010]
Further, the metal wire is arranged continuously over the entire length from the fluid inlet to the fluid outlet of the raw tube, with one end fixed to the fluid inlet and the other end fixed to the fluid outlet. Is also good.
[0011]
In addition, the base tube is formed by fixing a fixed ring at an interval from the fluid inlet side to the inner surface of the fluid outlet side, and fixing one end of a metal wire to each of the plurality of fixed rings on the fluid inlet side. It may be what you did.
[0012]
[Action]
In the configuration described above, when a fluid such as EGR gas or soot-containing combustion exhaust gas is introduced from the fluid inlet of the raw pipe, the fluid flows in the direction of the fluid outlet and the soot flows into the inner surface of the fluid. At the same time, the metal wire is vibrated by the flow energy of the fluid, and is swung up and down and right and left at random with respect to the axial direction. This swing is particularly likely to occur when the speed of the fluid flowing in the heat transfer tube changes, or when vibration occurs in the EGR system. Due to this swing, the metal wire comes into contact with the inner peripheral surface of the raw tube and rubs, so that the soot adhering to the inner peripheral surface can be separated from the inner peripheral surface of the raw tube in the initial stage of adhesion. Become. Then, the soot separated from the inner peripheral surface of the raw tube flows out downstream with the fluid.
[0013]
The metal wire has no technical effect when formed to a strength that does not cause oscillation due to the fluid. And As for the strength, if the metal wire is shortened, the swing hardly occurs, and if the metal wire is long, the swing easily occurs. In addition, if the diameter of the metal wire is increased, the strength is increased and it is difficult for the metal wire to oscillate.
[0014]
Further, the metal wire may be continuously arranged over the entire length from the fluid inlet to the fluid outlet of the raw tube. In this case, one end of the metal tube is connected to the fluid inlet, and the other end is connected to the fluid inlet. It is formed fixed to the outlet.
[0015]
Further, as described above, the metal wire may be one metal tube arranged continuously over the entire length from the fluid inlet to the fluid outlet of the raw tube, but a plurality of metal tubes may be arranged in the axial direction of the raw tube. A metal wire may be arranged. In this case, a fixed ring is fixed at a distance from the fluid inlet side to the inner surface on the fluid outlet side, and one end of each metal wire is fixed to the fluid inlet side of the plurality of fixed rings. It is.
[0016]
【Example】
Hereinafter, an embodiment of the heat transfer tube of the present invention will be described with reference to the drawings. (1) is a heat transfer tube, and a fluid introduction port (1) is provided at one axial end of a raw tube (3) through which fluid can flow. 4) is provided, and a fluid outlet (5) is formed at the other end in the axial direction. A plurality of metal wires (7) are annularly arranged on the inner peripheral surface (6) of the raw tube (3) at a desired interval in parallel with the axial direction of the raw tube (3). At least one end (8) of the metal wire (7) is engaged and fixed to the opening edge (10) of the fluid inlet (4) of the raw tube (3). In one embodiment, the metal wire (7) extends over the entire length from the fluid inlet (4) to the fluid outlet (5) of the raw pipe (3) as shown in FIGS. And one end (8) is bent and engaged with the opening edge (10) of the fluid inlet (4), and the other end (11) is connected to the other opening edge (12) of the fluid outlet (5). ) To be engaged and fixed.
[0017]
The metal wire (7) is formed of a corrosion-resistant metal such as SUS or Inconel, and has a diameter in the range of 50 μm to 250 μm. If the diameter of the metal wire (7) is smaller than 50 μm, the strength is weakened, and breakage during use or the like is not preferred. Further, when the diameter of the metal wire (7) is larger than 250 μm, the strength of the metal wire (7) increases, so that the introduction of the fluid into the raw pipe (3) causes little or no oscillation. As a result, the soot (2) adhered to the inner surface of the raw tube (3) cannot be effectively separated. As described above, the metal wire (7) has a strength capable of swinging at a random amplitude with the introduction of the fluid into the fluid introduction port (4), and adheres to the inner peripheral surface (6) of the raw tube (3). The soot (2) to be removed can be separated by the swing of the metal wire (7).
[0018]
Further, in the above embodiment, one metal wire (7) is arranged over the entire length from the fluid inlet (4) to the fluid outlet (5) of the raw pipe (3), and one end (8) is connected. The other end (11) is bent and engaged with the other opening edge (12) of the fluid outlet (5) while being bent and engaged with the opening edge (10) of the fluid introduction port (4). I have. However, in another different second embodiment, as shown in FIG. 4, a plurality of metal wires (7) may be arranged in the axial direction of the raw pipe (3). In this case, the fixed rings (13) are fixed at desired intervals in the axial direction on the inner surface from the fluid inlet (4) side to the fluid outlet (5) side. The fixed ring (13) has an insertion interval (14) for the metal wire (7) between the fixed ring (13) and the inner peripheral surface (6) of the raw tube (3). One end (8) of (7) is inserted and bent and engaged with the fixed ring (13). The engagement and fixing of the metal wire (7) to the plurality of fixing rings (13) is performed by fixing the one end (8) such that the engagement fixing position of the one end (8) is arranged on the fluid introduction port (4) side. Things.
[0019]
FIG. 5 shows a heat exchanger which is an EGR gas cooling device (15) using the heat transfer tube (1) as described above. The EGR gas cooling device (15), which is a heat exchanger, has a pair of tube sheets (17) connected near both ends of a cylindrical body tube (16) so that the inside can be hermetically sealed. A plurality of heat transfer tubes (1) of this embodiment are connected and arranged between the pair of tube sheets (17) through the tube sheet (17). A bonnet (21) having an EGR gas inlet (18) and an outlet (20) is connected to both ends of the body tube (16).
[0020]
Further, by providing an inlet (22) and an outlet (23) for a cooling medium such as engine cooling water, cooling air, or a refrigerant for a car air conditioner on the outer periphery of the body tube (16), a pair of tube sheets (17) is provided. The inside of the air-tight space partitioned by ()) is a cooling unit (24) through which a cooling medium can flow. Preferably, a plurality of support plates (25) are joined and arranged in the cooling section (24), and the heat transfer tube (1) is inserted through the insertion hole (26) provided in the support plate (25). Thereby, the heat transfer tube (1) is stably supported as a baffle plate, and the flow of the cooling medium flowing in the cooling unit (24) is meandered.
[0021]
In the EGR gas cooling device (15) as described above, when high-temperature EGR gas is introduced into the body tube (16) from the introduction port (18), a plurality of EGR gases are arranged in the body tube (16). Flows into the heat transfer tube (1). In the cooling section (24) in which the heat transfer tube (1) is arranged, a cooling medium such as engine cooling water flows in advance outside the heat transfer tube (1), so that the cooling medium flows through both the inner and outer surfaces of the heat transfer tube (1). Thus, heat exchange is performed between the EGR gas and the cooling medium.
[0022]
In the above heat exchange, when the fluid flowing inside the heat transfer tube (1) contains soot (2) or the like in the fluid, such as exhaust gas of a diesel engine, the inner periphery of the heat transfer tube (1) is used. The soot (2) is deposited on the surface. However, in the embodiment of the present invention, when a fluid such as an EGR gas or a combustion exhaust gas containing soot (2) is introduced from the fluid inlet (4) of the raw pipe (3), the fluid is discharged from the fluid outlet. In the process of flowing in the direction (5), the soot (2) is attached to the inner surface of the heat transfer tube (1), and the metal wire (7) is vibrated by the flow energy of the fluid as shown in FIG. Swings at random amplitudes up, down, left and right. By this swing, the metal wire (7) causes the soot (2) adhering to the inner peripheral surface of the raw tube (3) to separate from the inner peripheral surface (6) of the raw tube (3) at the initial stage of the adhesion. It becomes possible. Then, the soot (2) separated from the inner peripheral surface (6) of the raw tube (3) flows out downstream with the fluid.
[0023]
Therefore, as in the prior art, after using the heat transfer tube (1) for a certain period of time, the heat transfer tube (1) can be scraped off with a brush, or the cooling operation of the heat transfer tube (1) can be stopped to raise the temperature of the heat transfer tube (1). It is not necessary to take a removing means such as burning and removing the soot (2). In the present invention, since the adhesion of soot (2) to the inner surface of the heat transfer tube (1) is automatically removed, no trouble is required, and the use of the heat transfer tube (1) for removing the soot (2) is not required. Will not be interrupted.
[0024]
【The invention's effect】
Since the present invention is configured as described above, it does not lower the heat transfer efficiency, which is the original purpose of the heat transfer tube, and adheres to the inner surface of the heat transfer tube without stopping the cooling operation of the heat transfer tube. Soot can be automatically removed. Further, the removal of the soot can be performed while the amount of the soot adhering to the inner surface of the heat transfer tube is small, and a decrease in the heat transfer efficiency of the heat transfer tube due to the soot can be minimized.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a first embodiment of the present invention.
FIG. 2 is a partially omitted enlarged end view showing a relationship between a metal wire and a raw pipe.
FIG. 3 is an enlarged sectional view showing a soot removal state by a metal wire.
FIG. 4 is an enlarged sectional view of a second embodiment.
FIG. 5 is a cross-sectional view showing an example of an EGR gas cooling device in which a heat transfer tube is assembled.
FIG. 6 is an enlarged sectional view showing an example of adhesion of soot to a heat transfer tube according to a conventional example.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 heat transfer tube 2 soot 3 element tube 4 fluid inlet 5 fluid outlet 6 inner peripheral surface 7 metal wire 8 one end 11 other end 13 fixed ring 15 gas cooling device

Claims (6)

A fluid introduction port is provided at one end in the axial direction, and a plurality of metal wires are provided in parallel with the axial direction of the raw pipe at intervals on an inner peripheral surface of the raw pipe provided with a fluid outlet at the other axial end. At least one end of the metal wire is fixed to the fluid introduction port side of the raw tube, and the metal wire has a strength capable of swinging with the introduction of fluid into the fluid introduction port, A heat transfer tube characterized in that soot adhering to a surface can be separated by swinging a metal wire. A fluid introduction port is provided at one end in the axial direction, and a plurality of metal wires are provided in parallel with the axial direction of the raw pipe at intervals on an inner peripheral surface of the raw pipe provided with a fluid outlet at the other axial end. At least one end of the metal wire is fixed to the fluid introduction port side of the raw tube, and the metal wire has a strength capable of swinging with the introduction of fluid into the fluid introduction port, A heat exchanger to which a heat transfer tube is attached, wherein a heat transfer tube capable of removing soot adhering to a surface by swinging a metal wire is attached. The metal wire is disposed continuously over the entire length from the fluid inlet to the fluid outlet of the raw tube, and one end is fixed to the fluid inlet and the other end is fixed to the fluid outlet. Item 1. The heat transfer tube according to Item 1. The metal wire is disposed continuously over the entire length from the fluid inlet to the fluid outlet of the raw tube, and one end is fixed to the fluid inlet and the other end is fixed to the fluid outlet. Item 2. A heat exchanger to which the heat transfer tube according to Item 2 is assembled. The base tube is formed by fixing a fixed ring at a distance from the fluid inlet side to the inner surface of the fluid outlet side and fixing one end of a metal wire to each of the plurality of fixed rings at the fluid inlet side. The heat transfer tube according to claim 1, wherein: The base tube is formed by fixing a fixed ring at a distance from the fluid inlet side to the inner surface of the fluid outlet side and fixing one end of a metal wire to each of the plurality of fixed rings at the fluid inlet side. A heat exchanger to which the heat transfer tube according to claim 2 is assembled.

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