JP4201642B2 - Heat transfer tube and heat exchanger assembled with this heat transfer tube - Google Patents

Description

[0001]
[Industrial application fields]
The present invention is a multi-tube heat exchanger such as an EGR gas cooling device, and heat of cooling water, cooling air, refrigerant for car air conditioner, other cooling medium, combustion exhaust gas containing EGR gas, soot, etc. The present invention relates to a heat exchanger tube used for exchanging and a heat exchanger in which the heat exchanger tube is assembled.
[0002]
[Prior art]
[Patent Document 1]
JP 11-108578 A [Patent Document 2]
Japanese Patent Laid-Open No. 2001-227413
Conventionally, in an automobile engine or the like, an EGR system in which a part of exhaust gas is extracted from the exhaust gas system, returned to the engine intake system, and added to the mixture or intake air has been used for both gasoline engines and diesel engines. . EGR systems, especially cooled EGR systems with a high EGR rate for diesel engines, reduce NOx in exhaust gas, prevent fuel consumption deterioration and prevent deterioration of EGR valve function and durability due to excessive temperature rise. Therefore, a device for cooling high-temperature EGR gas with cooling water, cooling air, refrigerant, or other cooling medium is provided.
[0004]
As shown in FIG. 5, this EGR gas cooling device is provided with a plurality of small-diameter heat transfer tubes (1) through which EGR gas can flow, and outside the heat transfer tubes (1), cooling water and cooling By circulating a cooling medium such as wind or refrigerant, heat exchange between the EGR gas and the cooling medium is performed via the heat transfer tube (1).
[0005]
As such a heat transfer tube, an invention described in Patent Document 1 and an invention described in Patent Document 2 are known. Since these conventionally known heat transfer tubes have a smooth inner peripheral surface through which fluid flows, soot (2) contained in the flowing exhaust gas is likely to accumulate as shown in FIG. If the soot (2) adheres to and accumulates on the inner surface of the heat transfer tube (1), the soot (2) has an adiabatic effect and the exchange heat amount is reduced, which reduces the performance of the heat transfer tube (1). Absent. Therefore, conventionally, as a method of removing the tub (2) from the inner surface of the heat transfer tube (1), after the heat transfer tube (1) has been used for a certain period of time, it is scraped off with a brush or the heat transfer tube (1). The cooling operation is stopped and the heat transfer tube (1) is heated to a high temperature to incinerate and remove the soot (2).
[0006]
[Problems to be solved by the invention]
However, by scraping off the scissors (2) adhering to the inner surface of the heat transfer tube (1) with a brush, or stopping the cooling operation of the heat transfer tube (1) and raising the heat transfer tube (1) to a high temperature The method of incinerating the firewood (2) not only requires a lot of work, 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 addition, in order to prevent such defects and to prevent the fouling (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, the method of applying this low surface energy coating to the inner surface of the heat transfer tube is essentially a heat exchanger because the coating with low surface energy such as fluororesin has a low thermal conductivity and poor heat transfer compared to 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, without reducing the heat transfer efficiency, which is the original purpose of the heat transfer tube (1), and without stopping the cooling operation of the heat transfer tube. It is possible to automatically remove the soot (2) adhering to the inner surface of the heat transfer tube (1). In addition, the removal of the soot (2) is performed while the amount of soot (2) attached to the inner surface of the heat transfer tube (1) is small, so that 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]
In order to solve the above-described problems, the present invention provides a first pipe on the inner peripheral surface of a pipe having a fluid inlet at one end in the axial direction and a fluid outlet at the other end in the axial direction. A plurality of straight metal wires are arranged in an annular shape in parallel with the axial direction of the tube, and at least one end portion of the straight metal wires is fixed to the fluid inlet side of the raw pipe, and The strength of the metal wire is that it can swing with the introduction of fluid into the fluid inlet, and the wrinkles adhering to the inner peripheral surface of the base tube can be peeled off by swinging the straight metal wire. This relates to a heat transfer tube.
[0009]
Further, the second aspect of the invention provides a plurality of straight lines parallel to the axial direction of the raw pipe on the inner peripheral surface of the raw pipe provided with a fluid inlet at one end in the axial direction and a fluid outlet at the other end in the axial direction. The metal wire is arranged in an annular shape with a space, and at least one end of the straight metal wire is fixed to the fluid inlet side of the base tube, and the straight metal wire is fluidized to the fluid inlet. Assembling a heat transfer tube, which has a strength that can be swung with the introduction of the heat transfer tube, and that can be peeled off by swinging a straight metal wire. Related to the heat exchanger.
[0010]
In addition, the straight metal wire is arranged continuously over the entire length from the fluid inlet to the fluid outlet of the elementary pipe, with one end fixed to the fluid inlet and the other end fixed to the fluid outlet. It may be.
[0011]
In addition, the base tube is fixed to the inner ring from the fluid inlet side to the fluid outlet port side with a fixed ring, and one end of each straight metal wire is fixed to the fluid inlet side of the plurality of fixed rings. It may be formed.
[0012]
[Action]
In the above configuration, when a fluid such as EGR gas or combustion exhaust gas containing soot is introduced from the fluid inlet of the raw pipe, the soot is removed from the inner surface of the fluid in the process of flowing in the direction of the fluid outlet. At the same time, a linear metal wire is vibrated by the fluid flow energy, and is swung with random amplitude vertically and horizontally with respect to the axial direction. This oscillation is particularly likely to occur when the velocity of the fluid flowing in the heat transfer tube changes, or when vibration occurs in the EGR system. By this swinging, the straight metal wire comes into contact with the inner peripheral surface of the raw tube and rubs, and the wrinkles adhering to the inner peripheral surface are peeled off from the inner peripheral surface of the raw tube in the initial stage of attachment. Is possible. And the soot peeled from the inner peripheral surface of the blank pipe flows downstream together with the fluid.
[0013]
The linear metal wire does not produce a technical effect when formed to have a strength that does not cause oscillation by the fluid, and it swings with random amplitude as the fluid is introduced into the fluid inlet. Strength. As for this strength, if the straight metal wire is shortened, the swing is less likely to occur, and if it is longer, the swing is likely to occur. Further, if the diameter of the straight metal wire is increased, the strength is increased and it is difficult to cause the oscillation, and if the diameter is reduced, the oscillation is likely to occur.
[0014]
Further, the straight metal wire may be continuously arranged over the entire length from the fluid inlet to the fluid outlet of the elementary pipe. In this case, one end of the metal pipe is used as the fluid inlet and the other end. The part is fixed to the fluid outlet.
[0015]
In addition, as described above, a straight metal wire may be formed by continuously arranging a single metal tube over the entire length from the fluid inlet to the fluid outlet of the elementary tube, but in the axial direction of the elementary tube. A plurality of straight metal wires may be arranged. In this case, the stationary ring is fixed with an interval from the fluid introduction port side to the inner surface of the fluid outlet port side, and one end of each linear metal wire is fixed to the fluid introduction port side of the plurality of stationary rings. To form.
[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 inlet ( 4) and a fluid outlet (5) is formed at the other end in the axial direction. A plurality of linear metal wires (7) are annularly arranged on the inner peripheral surface (6) of the raw tube (3) in parallel with the axial direction of the raw tube (3) with a desired interval. At least one end (8) of the linear metal wire (7) is engaged and fixed to the opening edge (10) of the fluid introduction port (4) of the elementary pipe (3). In addition, in one embodiment, the straight metal wire (7) is the total length from the fluid inlet (4) to the fluid outlet (5) of the elementary pipe (3) as shown in FIGS. And the other end (11) is opened to the other end of the fluid outlet (5) while the other end (11) is bent and engaged with the opening edge (10) of the fluid inlet (4). It is bent and fixed to the edge (12).
[0017]
The linear metal wire (7) is made of a corrosion-resistant metal such as SUS or Inconel and has a diameter in the range of 50 to 250 μm. If the diameter of the straight metal wire (7) is made thinner than 50μ, the strength becomes weak and undesirably causes disconnection during use. Further, when the diameter of the straight metal wire (7) is thicker than 250 [mu], straight metal wire strength becomes large (7), causing the rocking by introduction into the fluid of the base pipe (3) Is less or does not occur, and the heel (2) attached to the inner surface of the base tube (3) cannot be effectively peeled off. As described above, the straight metal wire (7) has a strength capable of swinging with a random amplitude as the fluid is introduced into the fluid introduction port (4), and the inner peripheral surface (6) of the base tube (3). ) (2) adhering to) can be peeled off by swinging a linear metal wire (7).
[0018]
Moreover, in the said Example, one linear metal wire (7) is arrange | positioned over the full length from the fluid inlet port (4) of the elementary pipe (3) to the fluid outlet port (5), and one end part ( 8) is bent and engaged with the opening edge (10) of the fluid introduction port (4), and the other end portion (11) is bent and engaged with the other end opening edge (12) of the fluid outlet port (5). It is fixed. However, in another different second embodiment, a plurality of linear metal wires (7) may be arranged in the axial direction of the raw tube (3) as shown in FIG. In this case, the fixed ring (13) is fixed to the inner surface from the fluid inlet (4) side to the fluid outlet port (5) side at desired intervals in the axial direction. Further, the fixed ring (13) is provided with an insertion interval (14) of a linear metal wire (7) between the inner pipe (3) and the inner peripheral surface (6), and the insertion interval (14) is provided. One end (8) of the straight metal wire (7) is inserted and engaged with the fixed ring (13) by bending. The engagement and fixation of the linear metal wire (7) to the plurality of fixing rings (13) is fixed so that the engagement fixing position of the one end (8) is arranged on the fluid introduction port (4) side. To form.
[0019]
FIG. 5 shows a heat exchanger which is an EGR gas cooling device (15) using the heat transfer tube (1) as described above. In the EGR gas cooling device (15), which is a heat exchanger, a pair of tube sheets (17) are connected near both ends of a cylindrical body tube (16) so that the inside can be sealed. Between the pair of tube sheets (17), a plurality of the heat transfer tubes (1) of the present embodiment are connected through the tube sheet (17). A bonnet (21) provided with an EGR gas inlet (18) and outlet (20) is connected to both ends of the trunk pipe (16).
[0020]
Further, an outer inlet (22) and an outlet (23) for a cooling medium such as engine cooling water, cooling air, or a car air conditioner refrigerant are provided on the outer periphery of the trunk pipe (16), so that a pair of tube sheets (17 ) Is a cooling section (24) through which a cooling medium can flow. Preferably, a plurality of support plates (25) are joined and disposed in the cooling section (24), and the heat transfer tube (1) is inserted into the insertion hole (26) provided in the support plate (25). Thus, the heat transfer tube (1) is stably supported as a baffle plate, and the flow of the cooling medium flowing in the cooling section (24) is meandered.
[0021]
In the EGR gas cooling device (15) as described above, when high-temperature EGR gas is introduced into the trunk pipe (16) from the introduction port (18), a plurality of EGR gases are arranged in the trunk pipe (16). Into the heat transfer tube (1). In the cooling section (24) in which the heat transfer tube (1) is disposed, a cooling medium such as engine cooling water is circulated in advance to the outside of the heat transfer tube (1), so that both the inner and outer surfaces of the heat transfer tube (1) are passed through. Thus, heat exchange is performed between the EGR gas and the cooling medium.
[0022]
In the heat exchange described above, if the fluid flowing inside the heat transfer tube (1) contains soot (2) in the fluid, such as exhaust gas from a diesel engine, the inner circumference of the heat transfer tube (1) This soot (2) is deposited and deposited on the surface. However, in the embodiment of the present invention, when fluid such as combustion exhaust gas containing EGR gas and soot (2) is introduced from the fluid inlet (4) of the elementary pipe (3), the fluid is fluid outlet. (5) In the process of flowing in the direction, the spear (2) is attached to the inner surface of the heat transfer tube (1) and the fluid energy of the fluid vibrates the straight metal wire (7) as shown in FIG. Oscillate with random amplitude vertically and horizontally with respect to the axial direction. By this swinging, the straight metal wire (7) is attached to the inner peripheral surface (6) of the raw pipe (3) at the initial stage of attachment. Can be peeled off. And the spear (2) peeled from the inner peripheral surface (6) of the raw pipe (3) flows downstream together with the fluid.
[0023]
Therefore, after using the heat transfer tube (1) for a certain period of time as before, scraping it off with a brush or stopping the cooling operation of the heat transfer tube (1) to bring the heat transfer tube (1) to a high temperature. There is no need to take removal measures such as incineration and removal of firewood (2). In the present invention, the adhesion of the soot (2) to the inner surface of the heat transfer tube (1) is automatically removed, so that there is no need for trouble and the use of the heat transfer tube (1) for removing the soot (2). Will not be interrupted.
[0024]
【The invention's effect】
Since the present invention is configured as described above, the heat transfer efficiency, which is the original purpose of the heat transfer tube, is not lowered, and the heat transfer tube does not stop the cooling operation and is attached to the inner surface of the heat transfer tube. Can remove the candy automatically. Further, the removal of the soot can be performed while the amount of adhesion to the inner surface of the heat transfer tube is small, and the 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 straight metal wire and a raw tube.
FIG. 3 is an enlarged cross-sectional view showing a state of removal of soot by a straight 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 cross-sectional view showing an example of soot adhesion to a heat transfer tube according to a conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat transfer tube 2 ３ 3 Elementary tube 4 Fluid introduction port 5 Fluid outlet port 6 Inner peripheral surface 7 Linear metal wire 8 One end portion 11 The other end portion 13 Fixed ring 15 Gas cooling device

Claims (6)

A plurality of straight metal wires are spaced in parallel to the axial direction of the raw pipe on the inner peripheral surface of the raw pipe having a fluid inlet at one end in the axial direction and a fluid outlet at the other end in the axial direction. And at least one end of the straight metal wire is fixed to the fluid inlet side of the base tube, and the straight metal wire is swung as the fluid is introduced into the fluid inlet. A heat transfer tube characterized by having a strength to be obtained and capable of peeling off wrinkles adhering to the inner peripheral surface of the base tube by swinging a linear metal wire. A plurality of straight metal wires are spaced in parallel to the axial direction of the raw pipe on the inner peripheral surface of the raw pipe having a fluid inlet at one end in the axial direction and a fluid outlet at the other end in the axial direction. And at least one end of the straight metal wire is fixed to the fluid inlet side of the base tube, and the straight metal wire is swung as the fluid is introduced into the fluid inlet. A heat exchanger assembled with a heat transfer tube, which is assembled with a heat transfer tube which has a strength to obtain and which can be attached to the inner peripheral surface of the element tube by peeling off the wrinkles of a straight metal wire. The straight metal wire is continuously arranged over the entire length from the fluid inlet to the fluid outlet of the base tube, and one end is fixed to the fluid inlet and the other end is fixed to the fluid outlet. The heat transfer tube according to claim 1. The straight metal wire is continuously arranged over the entire length from the fluid inlet to the fluid outlet of the base tube, and one end is fixed to the fluid inlet and the other end is fixed to the fluid outlet. The heat exchanger which assembled | attached the heat exchanger tube of Claim 2. The element pipe is fixed to a fixed ring with an interval from the fluid inlet side to the inner surface of the fluid outlet side, and one end of each linear metal wire is fixed to the fluid inlet side of the plurality of fixed rings. The heat transfer tube according to claim 1, wherein the heat transfer tube is formed. The element pipe is fixed to a fixed ring with an interval from the fluid inlet side to the inner surface of the fluid outlet side, and one end of each linear metal wire is fixed to the fluid inlet side of the plurality of fixed rings. It formed, The heat exchanger which assembled | attached the heat exchanger tube of Claim 2.

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