JP2023146903A - Heat exchanger - Google Patents

Abstract

To provide a heat exchanger which may inhibit pressure fluctuation in a passage when used in a situation where fluctuation of a fluid pressure easily occurs.SOLUTION: A heat exchanger 100 includes: a first pipe 10; a second pipe 20 into which the first pipe 10 is inserted; and a third pipe 30 into which the first pipe 10 and the second pipe 20 are inserted. A first passage 41 is formed between the first pipe 10 and the second pipe 20 to allow a first fluid 1 to circulate therebetween, and a second passage 42 for allowing a second fluid 2 which conducts heat exchange with the first fluid 1 to circulate is formed between the second pipe 20 and the third pipe 30. The first pipe 10 includes: a passage 11 which communicates with the second pipe 20 at both ends; and a pressure fluctuation suppression part 12 which limits circulation of the first fluid 1 in the passage 11 and releases a pressure fluctuated in the first passage 41 from an end of the passage 11.SELECTED DRAWING: Figure 1

Description

The present invention relates to a heat exchanger, and particularly to a multi-tube heat exchanger.

Conventionally, multi-tube heat exchangers are known (for example, see Patent Document 1).

Patent Document 1 includes an outer tube, an inner tube, and a masking tube provided in the inner tube, and a first flow path is formed between the outer tube and the inner tube, and a connection between the inner tube and the masking tube is provided. A double tube heat exchanger with a second flow path formed therebetween is disclosed. Both ends of the masking tube are closed, and the inside of the masking tube is filled with a heat insulating material. One end of the second flow path and one end of the first flow path are connected to the catalyst section. Raw material gas is supplied into the second flow path from a supply section connected to the other end of the second flow path. Raw material gas is supplied to the catalyst section from the second flow path. The raw material gas is reformed by the catalytic reaction, and the reformed gas is supplied from the catalyst section to the first flow path. The reformed gas is discharged from the discharge section connected to the other end of the first channel. Heat exchange is performed between the raw material gas flowing through the second flow path and the reformed gas flowing through the first flow path.

JP2003-302177A

The double-tube heat exchanger of Patent Document 1 is used as a heat exchanger for reforming gas, but when such a heat exchanger is used in applications where fluid pressure fluctuations are likely to occur, Heat exchange performance becomes unstable due to pressure fluctuations occurring within the flow path, and repeated stress due to pressure fluctuations occurs, which adversely affects the durability (long-term reliability) of the heat exchanger. Therefore, when used in applications where fluid pressure fluctuations are likely to occur, it is desirable to suppress pressure fluctuations within the flow path.

This invention was made to solve the above-mentioned problems, and one purpose of the invention is to suppress pressure fluctuations in a flow path even when used in applications where fluid pressure fluctuations are likely to occur. The purpose of the present invention is to provide a heat exchanger capable of

In order to achieve the above object, a heat exchanger according to the present invention includes a first tube, a second tube into which the first tube is inserted, and a third tube into which the first tube and the second tube are inserted. A first flow path is formed between the first pipe and the second pipe to allow the first fluid to flow therethrough, and a second fluid that exchanges heat with the first fluid is passed between the second pipe and the third pipe. A second flow path is formed, and the first pipe has a passage that communicates with the second pipe at both ends, and restricts the flow of the first fluid in the passage, and also controls the pressure that fluctuates within the first flow path. and a pressure fluctuation suppressor that releases pressure from the end of the passage.

Note that in the present invention, "restricting the flow of the first fluid in the passage" refers not only to restricting the flow of the first fluid in a state where no pressure fluctuation occurs; This is a broad concept that includes restricting the flow in the passage (increasing the flow resistance) so that the first fluid flows at a flow rate that is sufficiently small compared to the flow rate of the first fluid.

In the heat exchanger according to the present invention, the first tube includes a passage whose both ends communicate with the inside of the second tube. will be provided in parallel. Here, since the first pipe includes a pressure fluctuation suppressing part that restricts the flow of the first fluid in the passage, even if the passage is provided in the first pipe, the first fluid is located closer to the first flow path than the passage. By actively circulating the fluid, it is possible to exchange heat between the first fluid flowing through the first flow path and the second fluid flowing through the second flow path. The pressure fluctuation suppressor releases the pressure that fluctuates within the first flow path from the end of the passage, so when pressure fluctuation occurs within the first flow path due to heat exchange, the pressure fluctuation suppressor releases the pressure that fluctuates within the first pipe. It becomes a bypass path for releasing pressure, and can reduce the pressure difference between one end side and the other end side of the second pipe. As a result, even when used in applications where fluid pressure fluctuations are likely to occur, pressure fluctuations within the flow path can be suppressed.

In the heat exchanger according to the above invention, preferably, the first fluid is a liquid that is vaporized by heat exchange with the second fluid, and the pressure fluctuation suppressing section restricts the flow of the first fluid to allow the first fluid to flow into the passage. It is configured to retain one fluid of vaporized gas and to circulate the vaporized gas in response to pressure fluctuations within the first flow path. With this configuration, the liquid first fluid boils and evaporates within the first flow path, so the pressure within the first flow path changes depending on the boiling situation. Even in such a case, the pressure fluctuation suppressing section restricts the flow of the first fluid to retain the vaporized gas of the first fluid in the passage, and allows the vaporized gas to flow according to the pressure fluctuation in the first flow path. Therefore, by passing the vaporized gas in the passage in accordance with the change in pressure on the first flow passage side, pressure fluctuations can be suppressed. As a result, even in an unstable boiling state, it is possible to prevent the heat exchange performance from becoming unstable, and it is also possible to effectively suppress the occurrence of repetitive stress (pulsation) due to pressure fluctuations.

In the heat exchanger according to the above invention, preferably the pressure fluctuation suppressing section includes a throttle member provided in the passage. With this configuration, the flow resistance of the passage can be made sufficiently higher than the flow resistance of the first flow passage by narrowing the inner diameter of the passage using the throttle member. As a result, the first fluid hardly flows into the passage (substantially it flows only to the first flow path side), and when a pressure difference occurs between both ends, the first fluid flows only by the amount to eliminate the pressure difference. A pressure fluctuation suppressor that allows one fluid to flow in and out can be realized with a simple structure.

In the heat exchanger according to the above invention, preferably, one end of the passage is open into the second pipe, and the pressure fluctuation suppressor is provided so as to cover the other end of the passage. With this configuration, the pressure fluctuation suppressor can be easily provided, unlike a configuration in which the pressure fluctuation suppressor is arranged inside the first pipe, for example.

In the configuration in which the first fluid is a liquid that is vaporized by heat exchange with the second fluid, preferably, the first pipe, the second pipe, and the third pipe are provided to extend in the vertical direction, and the second pipe A first fluid inlet is provided at the lower end of the tube, a vaporized gas outlet is provided at the upper end of the second tube, and a pressure fluctuation suppressor is provided at the upper end of the first tube. With this configuration, the first fluid introduced from the inlet at the lower end is vaporized in the process of flowing upward, and the vaporized gas of the first fluid flows out from the outlet at the upper end. Therefore, the difference in specific gravity can be used to move the vaporized gas of the first fluid upward, so that the vaporized gas can be smoothly circulated. The lower end of the passage in the first pipe will be in contact with the liquid of the first fluid, and the upper end of the passage will be in contact with the vaporized gas of the first fluid.If a pressure fluctuation occurs, the first fluid will be in contact with the liquid in the passage. By temporarily flowing in liquid or vaporized gas, pressure fluctuations between the inlet and outlet can be suppressed.

The heat exchanger according to the above invention preferably further includes fins provided in the first flow path so as to contact the outer circumferential surface of the first tube and the inner circumferential surface of the second tube, respectively, and the fins include: At the contact portion with the first tube and the contact portion with the second tube, there is a portion where the materials of each of the first tube and the second tube and the fin are integrated. With this configuration, heat from the second fluid supplied from the outer circumferential side of the first channel can be efficiently transmitted to the inner circumferential side of the first channel (outer circumferential surface of the first pipe) by the fins. I can do it. Since this fin has a portion in which the materials of each of the first tube and the second tube and the fin are integrated at the abutting portion with the first tube and the abutting portion with the second tube, the fin Compared to the case where the surface of the fin and the surface of the first tube (second tube) contact without being integrated, it is possible to increase the contact area between the fin and the first tube (second tube) at the contact part. can. As the contact area increases, thermal resistance decreases, making it easier to conduct heat and improving heat exchange performance. Therefore, the temperature difference between the outer circumferential surface of the first tube and the inner circumferential surface of the second tube can be reduced, and variations in heat exchange performance in the radial direction of the first flow path can be reduced.

According to the present invention, as described above, it is possible to provide a heat exchanger that can suppress pressure fluctuations within a flow path even when used in applications where fluid pressure fluctuations are likely to occur.

FIG. 2 is a schematic vertical cross-sectional view showing the entire heat exchanger. FIG. 3 is a schematic horizontal sectional view of a heat exchanger. FIG. 3 is a schematic enlarged sectional view showing a pressure fluctuation suppressing section. FIG. 3 is a schematic diagram for explaining the structure of an offset fin. It is a schematic diagram for explaining the flow of the 1st fluid with respect to an offset fin. FIG. 2 is an enlarged horizontal cross-sectional view of the contact portion between the first tube and the second tube and the fin. FIG. 3 is a schematic diagram for explaining the operation of a heat exchanger. It is a schematic diagram for demonstrating the manufacturing method of a heat exchanger tube. It is a schematic diagram which showed the pressure fluctuation suppression part by a modification. FIG. 7 is a schematic diagram showing a modification in which a pressure fluctuation suppressing section is provided at the lower end of the first pipe.

Embodiments of the present invention will be described below based on the drawings.

First, a heat exchanger 100 according to an embodiment will be described with reference to FIGS. 1 to 6.

(Overall configuration of heat exchanger)
As shown in FIG. 1, the heat exchanger 100 is a multi-tube heat exchanger. The heat exchanger 100 of this embodiment circulates the first fluid 1 and the second fluid 2 to exchange heat between the first fluid 1 and the second fluid 2. As an example, the first fluid 1 is a fluid having a lower temperature than the second fluid 2. The second fluid 2 is a fluid with a higher temperature than the first fluid 1. The first fluid 1 receives heat from the second fluid 2 through heat exchange. The second fluid 2 gives heat to the first fluid 1 through heat exchange.

Specifically, the heat exchanger 100 of this embodiment is configured as a vaporizer for the first fluid 1. The first fluid 1 is a liquid that is vaporized by heat exchange with the second fluid 2. In this embodiment, the first fluid 1 is a cryogenic liquefied gas. Specifically, the first fluid 1 is liquefied nitrogen, but may also be liquefied hydrogen, LNG (liquefied natural gas), or the like. The second fluid 2 is not particularly limited. As an example, the second fluid 2 is water or antifreeze.

The heat exchanger 100 has an inlet section 3a and an outlet section 3b for the first fluid 1, and an inlet section 4a and an outlet section 4b for the second fluid 2. The first fluid 1 is introduced into the inlet portion 3a in a liquid state. The first fluid 1 is vaporized in the process of passing through the heat exchanger 100, and is led out from the outlet section 3b in a gaseous state (referred to as vaporized gas). The second fluid 2 is introduced into the inlet portion 4a, releases heat while passing through the heat exchanger 100, and is led out from the outlet portion 4b in a liquid state at a temperature lower than the inlet temperature.

The heat exchanger 100 has a cylindrical shape that extends linearly as a whole. The heat exchanger 100 includes a first tube 10, a second tube 20, and a third tube 30. The first tube 10 is inserted into the second tube 20. The first tube 10 and the second tube 20 are inserted into the third tube 30 . The diameter increases in the order of the first tube 10, the second tube 20, and the third tube 30. The first tube 10, the second tube 20, and the third tube 30 all have a cylindrical shape. The heat exchanger 100 (that is, the first tube 10, the second tube 20, and the third tube 30) is provided to extend in the vertical direction.

(1st pipe and 2nd pipe)
A first flow path 41 through which the first fluid 1 flows is formed between the first pipe 10 and the second pipe 20. Fins 50 are provided in the first flow path 41 . A second flow path 42 is formed between the second pipe 20 and the third pipe 30, through which the second fluid 2 that exchanges heat with the first fluid 1 flows. The first flow path 41 and the second flow path 42 are partitioned so as not to communicate with each other. The second pipe 20 serves as a partition wall that partitions the first flow path 41 and the second flow path 42 . The heat exchanger 100 has a structure in which an assembly including a first pipe 10, a second pipe 20, and a fin 50, through which the first fluid 1 flows, is arranged inside a third pipe 30 through which the second fluid 2 flows. It has become. Hereinafter, the assembly of the first tube 10, the second tube 20, and the fin 50 will be referred to as a "heat transfer tube HT."

The first pipe 10 extends from near the inlet section 3a to near the outlet section 3b. The lower end portion 10b of the first tube 10 faces the inlet portion 3a. The upper end portion 10a of the first tube 10 faces the outlet portion 3b. The first pipe 10 is a single pipe member that extends continuously from an upper end 10a to a lower end 10b.

In this embodiment, the first tube 10 includes a passage 11 . The passage 11 is an internal space of the first tube 10 defined by the inner circumferential surface 10d of the first tube 10. The passage 11 extends continuously from the upper end 10a to the lower end 10b. Therefore, both ends of the passage 11 communicate with the inside of the second pipe 20.

The second tube 20 extends vertically while accommodating the first tube 10 inside. The second pipe 20 is a single pipe member that extends continuously from the upper end 20a to the lower end 20b. An inlet portion 3a for the first fluid 1 is provided at the lower end 20b of the second pipe 20, and an outlet portion 3b for vaporized gas is provided at the upper end 20a of the second pipe 20. The inlet portion 3a is a through hole formed in the lower end portion 20b. The outlet portion 3b is a through hole formed in the upper end portion 20a.

The first tube 10 and the second tube 20 are provided so that their central axes coincide with each other. As shown in FIG. 2, the space between the outer circumferential surface 10c of the first tube 10 and the inner circumferential surface 20d of the second tube 20 is the first flow path 41. As shown in FIG. 1, the first flow path 41 is a cylindrical space extending vertically with a flow path height corresponding to the difference between the outer diameter D1 of the first pipe 10 and the inner diameter D2 of the second pipe 20. be.

The first flow path 41 passing through the outer periphery of the first tube 10 and the passage 11 passing through the inside of the first tube 10 are provided in parallel between the inlet section 3a and the outlet section 3b in the heat transfer tube HT. There is. However, compared to the flow rate of the first fluid 1 flowing through the first flow path 41, the flow rate of the first fluid 1 passing through the passage 11 is very small, so that almost no first fluid 1 flows through the passage 11. It has become.

(Pressure fluctuation suppressor)
Specifically, as shown in FIG. 3, the first pipe 10 includes a pressure fluctuation suppressor 12. The pressure fluctuation suppressor 12 is configured to restrict the flow of the first fluid 1 within the passage 11 and to release the pressure that fluctuates within the first passage 41 from the end of the passage 11.

The pressure fluctuation suppressing section 12 is configured to restrict the flow of the first fluid 1 and to cause the vaporized gas of the first fluid 1 to stay in the passage 11 . The passage 11 has one end (lower end) open into the second pipe 20 (see FIG. 1), and the pressure fluctuation suppressor 12 covers the other end (upper end) of the passage 11. It is set in. That is, the pressure fluctuation suppressor 12 is provided at the upper end portion 10a of the first pipe 10. Therefore, the upper end of the passage 11 of the first pipe 10 is connected to the outlet section 3b via the pressure fluctuation suppressing section 12, and the lower end is an opening open to the inlet section 3a. The pressure fluctuation suppressor 12 limits the flow of the first fluid 1 within the passage 11 by covering the upper end of the passage 11 .

More specifically, the pressure fluctuation suppressor 12 includes a throttle member 12a provided in the passage 11. In this embodiment, the aperture member 12a is a lid that closes the upper end 10a of the first tube 10. The aperture member 12a has a disk shape, and its peripheral edge is joined to the upper end 10a of the first tube 10. A throttle hole 12b is formed in the throttle member 12a, passing through the throttle member 12a in the thickness direction.

The throttle hole 12b has an opening area (see FIG. 2) that is sufficiently smaller than the cross-sectional area of the first flow path 41. Note that the channel cross-sectional area and the opening area are areas in a plane perpendicular to the direction in which the first channel 41 extends (vertical direction). Further, the inner diameter of the throttle hole 12b is smaller than the inner diameter of the first pipe 10 (the inner diameter of the passage 11). The inner diameter of the throttle hole 12b is, for example, 1/20 or less of the inner diameter of the first pipe 10.

As a result, the passage 11 has a passage resistance that is sufficiently larger than that of the first passage 41 because the passage cross-sectional area is reduced at the throttle hole 12b. Therefore, the flow of the first fluid 1 within the passage 11 is restricted by the throttle hole 12b. The inside of the passage 11 is mostly filled with vaporized gas of the first fluid 1, and the inside of the passage 11 is not filled with the first fluid 1 which is a liquid. Even when the liquid first fluid 1 flows into the passage 11, the liquid first fluid 1 flows only to a partial range near the lower end of the passage 11. The liquid of the first fluid 1 existing near the lower end of the passage 11 is vaporized at a slower pace than in the first flow passage 41, and flows out little by little to the outlet part 3b side through the throttle hole 12b. . As a result, the pressure fluctuation suppressor 12 limits the flow rate of the first fluid 1 in the passage 11 to such an extent that it can be considered that it does not substantially flow (ignorable) compared to the flow rate in the first flow path 41 .

On the other hand, the pressure fluctuation suppressing section 12 is configured to allow vaporized gas to flow according to pressure fluctuations within the first flow path 41 . That is, at the upper end of the first tube 10, the inside of the passage 11 below the throttle member 12a and the space near the outlet portion 3b above the throttle member 12a communicate with each other via the small throttle hole 12b. Therefore, when a pressure difference occurs between the upper side and the lower side of the throttle member 12a, the vaporized gas of the first fluid 1 flows through the throttle hole 12b so as to reduce this pressure difference. As a result, pressure fluctuations caused by the unstable phenomenon of boiling of the first fluid 1 within the first flow path 41 are suppressed by the pressure fluctuation suppressor 12.

(fin)
As shown in FIG. 1, the fins 50 are provided in a predetermined range within the first flow path 41. As shown in FIG. One end (upper end portion 50a) of the fin 50 is arranged at a position between the outlet portion 3b of the first fluid 1 and the outlet portion 4b of the second fluid 2 in the vertical direction. The other end (lower end portion 50b) of the fin 50 is arranged at a position between the inlet portion 3a of the first fluid 1 and the inlet portion 4a of the second fluid 2 in the vertical direction.

As shown in FIG. 2, the fins 50 are formed of corrugated corrugated fins. The fin 50 includes a plurality of vertical plate parts 51 extending in the radial direction between the first pipe 10 and the second pipe 20, and a horizontal plate part 51 connecting the ends of the vertical plate parts 51 adjacent to each other along the circumferential direction. A plate portion 52 is included. The fins 50 are provided in the first flow path 41 so as to abut on the outer circumferential surface 10c of the first tube 10 and the inner circumferential surface 20d of the second tube 20, respectively. The fins 50 connect the first tube 10 and the second tube 20 to transfer heat between the first tube 10 and the second tube 20 by thermal conduction. The fin 50 has a function of increasing the heat transfer area (surface area) within the first flow path 41 by using a plurality of vertical plate portions 51 that extend to partition the inside of the first flow path 41 .

As shown in FIG. 4, the fin 50 is arranged so that the position of the vertical plate portion 51 is aligned with the first flow path 41 every predetermined length L in the direction along the first flow path 41 (vertical direction, direction A in FIG. 4). These are offset fins formed to be offset in the circumferential direction (direction B in FIG. 4). Note that FIG. 4 is a perspective view showing a state in which the corrugated fin of FIG. 2 is simplified and developed on a plane. As shown in FIG. 5, in the offset fin, another vertical plate portion 51 appears at a location that was a gap between the vertical plate portions 51 every predetermined length L in the A direction along the flow path. Therefore, the first fluid 1 collides with the vertical plate portion 51 of the fin 50 and turbulence is likely to occur.

Furthermore, in the present embodiment, the fin 50 is connected to each of the first tube 10 and the second tube 20 at the contact portion CP with the first tube 10 and the contact portion CP with the second tube 20. It has a part where the materials are integrated. As shown in FIG. 6, in the fin 50, a portion of the horizontal plate portion 52 on the inner peripheral side is in contact with the outer peripheral surface 10c of the first pipe 10, and a contact portion between the horizontal plate portion 52 and the outer peripheral surface 10c is in contact with the outer peripheral surface 10c. It is part CP. Similarly, in the fin 50, a portion of the horizontal plate portion 52 on the outer peripheral side contacts the inner peripheral surface 20d of the second pipe 20, and a contact portion between the horizontal plate portion 52 and the inner peripheral surface 20d is a contact portion CP. be.

Here, the heat transfer tube HT is produced by heat-treating the fins 50 in a state in which the fins 50 are crimped between the outer circumferential surface 10c of the first tube 10 and the inner circumferential surface 20d of the second tube 20. As a result of the heat treatment, atomic diffusion occurs in at least a portion of each contact portion CP, and the materials become integrated as shown in FIG. In FIG. 2, the boundaries between the first tube 10, the second tube 20, and the fins 50 are clearly illustrated for convenience. Note that the first tube 10, the second tube 20, and the fins 50 are made of the same material. Specifically, the first tube 10, the second tube 20, and the fin 50 are all made of stainless steel.

(3rd pipe)
Returning to FIG. 1, the third tube 30 has an inner diameter larger than the outer diameters of the first tube 10 and the second tube 20. The inner diameter D3 of the third tube 30 is approximately twice the outer diameter of the second tube 20 in the example of FIG. 1, for example. The third pipe 30 has an upper end 30a and a lower end 30b closed. The third pipe 30 includes an inlet pipe 31 connected from the side near the lower end 30b of the third pipe 30, and an outlet pipe 32 connected from the side near the upper end 30a of the third pipe 30. , is provided. The introduction pipe 31 has an inlet portion 4 a for the second fluid 2 . The outlet pipe 32 has an outlet section 4b for the second fluid 2.

The introduction pipe 31 is connected to the third pipe 30 so as to face the outer peripheral surface of the heat transfer tube HT near the inlet portion 3a. Thereby, the introduction pipe 31 causes the second fluid 2 having the highest temperature immediately after flowing into the third pipe 30 from the introduction pipe 31 to collide with the portion near the inlet portion 3a of the heat transfer tube HT where the temperature is likely to be the lowest. As a result, compared to other parts of the heat transfer tube HT, the heat transfer coefficient near the inlet portion 3a of the heat transfer tube HT becomes locally higher, and the surface temperature of the second tube 20 becomes locally higher, so that the inlet portion Freezing of the second fluid 2 near 3a is suppressed.

The outlet pipe 32 is configured to discharge the second fluid 2 that has passed through the second flow path 42 between the third pipe 30 and the second pipe 20 and released heat from the outlet portion 4b.

A heat transfer tube HT is provided so as to pass through the upper end 30a and the lower end 30b of the third tube 30, and the outer peripheral surface of the heat transfer tube HT is fixed to the upper end 30a and the lower end 30b. The third tube 30 and the heat transfer tube HT (the first tube 10 and the second tube 20) are provided so that their central axes coincide with each other. The space between the outer circumferential surface 20c of the second tube 20 and the inner circumferential surface 30d of the third tube 30 is the second flow path 42. The second flow path 42 is a cylindrical space extending vertically with a flow path height corresponding to the difference between the outer diameter of the second pipe 20 and the inner diameter D3 of the third pipe 30. In this embodiment, unlike the first flow path 41, the second flow path 42 is not provided with fins.

(Operation of heat exchanger)
Next, the operation of the heat exchanger 100 of this embodiment will be explained.

First, as shown in FIG. 7, a first fluid 1 and a second fluid 2 are introduced into the heat exchanger 100, respectively. In FIG. 7, the first fluid 1 that is a liquid and the first fluid 1 that is a vaporized gas are shown with different hatching.

In this embodiment, the first fluid 1 is supplied from a storage section such as a liquid nitrogen tank, for example. The first fluid 1 flows into the inlet portion 3a through a pipe (not shown) connected to the inlet portion 3a of the heat transfer tube HT. The first fluid 1 flows upward inside the heat transfer tube HT from the inlet portion 3a at the lower end of the heat transfer tube HT to the outlet portion 3b at the upper end. The temperature of the first fluid 1 (inlet temperature) at the inlet portion 3a is, for example, -180°C.

The second fluid 2 flows from the hot water supply equipment into the inlet portion 4a via a pipe (not shown) connected to the inlet portion 4a (introduction pipe 31) of the third pipe 30. The temperature of the second fluid 2 at the inlet portion 4a (inlet temperature) is, for example, 30° C. or more and 80° C. or less. The heat exchanger 100 is configured to form turbulence in the flow of the second fluid 2 by causing the second fluid 2 to collide with the outer circumferential surface 20c of the second pipe 20 from the inlet portion 4a. For this purpose, the second fluid 2 is supplied from the inlet portion 4a at a flow rate that can form a turbulent flow. Due to the formation of turbulence, the heat transfer coefficient near the inlet section 3a locally increases, and the surface temperature of the second pipe 20 near the inlet section 3a can be increased. Freezing can be suppressed.

The second fluid 2 flows from the outlet of the introduction pipe 31 toward the heat transfer tube HT in the third pipe 30 , flows upward through the second flow path 42 in the third pipe 30 , and flows upward into the third pipe 30 . It flows into the outlet pipe 32 near the upper end 30a and flows out from the outlet 4b.

The first fluid 1 that has flowed into the second pipe 20 from the inlet portion 3a flows through the first flow path 41 between the first pipe 10 and the second pipe 20. As described above, the passage 11 inside the first pipe 10 has a sufficiently higher flow resistance than the first flow passage 41 due to the pressure fluctuation suppressor 12 (throttle hole 12b), so the first fluid 1 Almost no water flows into the passage 11.

The first fluid 1 flowing through the first flow path 41 exchanges heat with the second fluid 2 flowing through the second flow path 42 . The first fluid 1 in the first flow path 41 receives heat from the second fluid 2 in the second flow path 42 surrounding the outer periphery of the first flow path 41 . Therefore, heat transfer generally decreases as the distance from the inner circumferential surface 20d of the second tube 20 increases inward in the radial direction. In this embodiment, by arranging the first tube 10 within the second tube 20 and making the first flow path 41 a cylindrical space, the vicinity of the central axis away from the inner circumferential surface 20d of the second tube 20 ( The first flow path 41 is not formed at the position where the first pipe 10 is formed. Therefore, the height of the first flow path 41 becomes sufficiently small, so that the temperature distribution in the first flow path 41 (inside the second pipe 20) is made more uniform compared to the case where the first pipe 10 is not provided. Ru.

The first fluid 1 flowing through the first flow path 41 receives heat from the second fluid 2 using the inner circumferential surface 20d of the second pipe 20 and the surface of the fin 50 as heat transfer surfaces. In this embodiment, since the temperature difference between the first fluid 1 and the second fluid 2 is large (the heat transfer surface becomes high temperature compared to the boiling point of the first fluid 1), the first fluid 1 has a continuous heat transfer surface. A phenomenon called film boiling, in which the material is covered with a vapor film, can occur.

Normally, in a film boiling state, the liquid first fluid 1 and the heat transfer surface cannot come into direct contact due to the presence of a vapor film. Further, in a situation where the first fluid 1 flows in a laminar flow, the liquid first fluid 1 flows as if sliding on the surface of the vapor film. Therefore, the heat transfer coefficient is lower than when the liquid and the heat transfer surface are in direct contact.

In contrast, in this embodiment, since the fins 50 in the first flow path 41 are offset fins (see FIGS. 4 and 5), the first fluid 1 collides with the end surface of the vertical plate portion 51. The flow is disturbed. As a result, the vapor film is disturbed, and even in the film boiling state, the liquid first fluid 1 and the heat transfer surface tend to come into direct contact. Therefore, even when the temperature difference between the first fluid 1 and the second fluid 2 is large, the influence of film boiling can be suppressed and a high heat transfer coefficient can be obtained.

The vaporized gas of the first fluid 1 in the first flow path 41 moves upward and flows out from the upper end of the first flow path 41, and flows out from the heat exchanger 100 via the outlet portion 3b of the second pipe 20. do. In this way, the first fluid 1 is vaporized and sent to the vaporized gas supply destination from a pipe (not shown) connected to the outlet portion 3b.

<Effect of pressure fluctuation suppressor>
Since the inside of the first flow path 41 is in an unstable boiling state, pressure fluctuations (pulsations) are likely to occur easily. Pressure fluctuations occurring within the first flow path 41 are suppressed by the pressure fluctuation suppressor 12. That is, when a pressure difference occurs between the upper side and the lower side of the throttle hole 12b, this pressure difference is reduced by the vaporized gas moving through the throttle hole 12b.

For example, when the pressure P2 on the outlet part 3b side becomes lower than the pressure P1 in the passage 11, the vaporized gas of the first fluid 1 in the passage 11 flows out to the outlet part 3b side through the throttle hole 12b. This reduces the pressure difference. The liquid-phase first fluid 1 corresponding to the amount flowing out from the throttle hole 12b temporarily flows into the passage 11 from the lower end of the passage 11. When the pressure P2 on the outlet part 3b side becomes higher than the pressure P1 in the passage 11, the vaporized gas of the first fluid 1 on the outlet part 3b side flows into the passage 11 through the throttle hole 12b. , the pressure difference is reduced.

If the pressure fluctuation suppressor 12 is not provided and the pressure fluctuation is not suppressed, for example, if the pressure is temporarily lowered, the boiling point of the first fluid 1 is lowered. When the amount of evaporation of the first fluid 1 temporarily increases due to a decrease in the boiling point, the pressure within the first flow path 41 increases. The flow rate of the first fluid 1 also changes according to changes in pressure. These fluctuation factors cause the state inside the first flow path 41 to become unstable, resulting in unstable heat exchange performance and generation of repeated stress due to pulsation.

In the present embodiment, the pressure fluctuation suppressor 12 suppresses pressure fluctuations that cause instability of heat exchange performance and generation of repeated stress due to pulsation.

(Method for manufacturing heat exchanger)
Next, a method for manufacturing the heat exchanger 100 of this embodiment will be explained.

First, the heat transfer tube HT is produced. As shown in FIG. 8, the production of the heat transfer tube HT includes the following steps S1 to S4.
(Step S1) Fins 50 are arranged on the outer peripheral surface 10c of the first tube 10.
(Step S2) A first assembly of the first tube 10 and the fins 50 is placed inside the second tube 20.
(Step S3) The second assembly in which the first tube 10 and the fins 50 are arranged inside the second tube 20 is subjected to a drawing process to reduce the diameter of the second tube 20 and the outer periphery of the first tube 10. The fins 50 are crimped and fixed between the surface 10c and the inner peripheral surface 20d of the second tube 20.
(Step S4) By performing heat treatment on the second assembly after the drawing process, the contact portion CP between the fin 50 and the first tube 10 (see FIG. 6) and the contact portion CP between the fin 50 and the second tube 20 are A portion in which the materials of each of the first tube 10 and the second tube 20 and the fin 50 are integrated is formed in the contact portion CP.

Step S1 is performed by winding the corrugated fin sheet FS on which the fins 50 are formed around the outer circumferential surface 10c of the first tube 10.

In step S2, a second tube 20 having an inner diameter larger than the maximum outer diameter of the first assembly of the first tube 10 and the fins 50 is prepared, and the first assembly is inserted into the second tube 20. That is, the inner diameter D2a of the second tube 20 in step S2 (see step S3 in FIG. 8) is larger than the inner diameter D2 of the second tube 20 shown in FIG.

In step S3, as a result of cold drawing, the second pipe 20 is reduced from the inner diameter D2a to the inner diameter D2. Due to the reduction in diameter, the inner circumferential surface 20d of the second tube 20 comes into contact with the outer circumferential side plate portion 52 of the fin 50 disposed on the outer circumferential surface 10c of the first tube 10. By tightly sandwiching the fins 50 between the first tube 10 and the second tube 20, the first tube 10, the fins 50, and the second tube 20 are fixed to each other by pressure.

In step S4, the second assembly after drawing is heated in the heating furnace 90 at a predetermined holding temperature and for a predetermined holding time. In this embodiment, where the first tube 10, the second tube 20, and the fins 50 are made of stainless steel, the holding temperature of the heat treatment is a predetermined temperature of about 900° C. or more and about 1200° C. or less. The holding time of the heat treatment is, for example, a predetermined time of 1 hour or more and 10 hours or less.

The heat treatment causes atomic diffusion at the interface between the fin 50 and each contact portion CP (see FIG. 6) of the first tube 10 and the second tube 20. As a result, at least a portion of the contact portion CP between the inner circumferential side plate portion 52 of the fin 50 and the outer circumferential surface 10c of the first tube 10 is integrated. Similarly, at least a portion of the contact portion CP between the outer circumferential side plate portion 52 of the fin 50 and the inner circumferential surface 20d of the second pipe 20 is integrated. Note that the fin 50, the first tube 10, and the second tube 20 may be integrated in their entirety at the contact portion CP, but may be integrated only in part in consideration of uneven heating.

As a result of steps S1 to S4, heat transfer tubes HT are manufactured. The heat transfer tube HT is inserted into the third tube 30 and fixed to the third tube 30. Note that a description of the manufacturing process of the third tube 30 will be omitted. In this way, the heat exchanger 100 is manufactured.

(Effects of this embodiment)
In this embodiment, the following effects can be obtained.

In this embodiment, as described above, the first pipe 10 includes the passage 11 that communicates with the second pipe 20 at both ends, so that between one end and the other end of the second pipe 20, the first passage 41 and the passage 11 in the first tube 10 are provided in parallel. Here, since the first pipe 10 includes the pressure fluctuation suppressor 12 that restricts the flow of the first fluid 1 in the passage 11, even if the passage 11 is provided in the first pipe 10, the The first fluid 1 is actively circulated toward the first flow path 41 to exchange heat between the first fluid 1 flowing through the first flow path 41 and the second fluid 2 flowing through the second flow path 42. can be done. Then, since the pressure fluctuation suppressing section 12 releases the pressure fluctuated within the first passage 41 from the end of the passage 11, when a pressure fluctuation occurs within the first passage 41 due to heat exchange, the first The passage 11 within the pipe 10 serves as a bypass path for releasing pressure, and the pressure difference between one end and the other end of the second pipe 20 can be reduced. As a result, even when used in applications where fluid pressure fluctuations are likely to occur, pressure fluctuations within the flow path can be suppressed.

Further, in this embodiment, as described above, the first fluid 1 is a liquid that is vaporized by heat exchange with the second fluid 2, so the first fluid 1 is boiled in the first flow path 41. Since the boiling water vaporizes and vaporizes, the pressure inside the first flow path 41 fluctuates depending on the boiling situation. Even in such a case, in the present embodiment, the pressure fluctuation suppressing unit 12 restricts the flow of the first fluid 1 and causes the vaporized gas of the first fluid 1 to stay in the passage 11, thereby reducing the flow of the first fluid 1 in the first passage 41. Since the structure is configured to flow the vaporized gas according to pressure fluctuations, pressure fluctuations can be suppressed by passing the vaporized gas in the passage 11 in accordance with changes in the pressure on the first flow path 41 side. can. As a result, even in an unstable boiling state, it is possible to prevent the heat exchange performance from becoming unstable, and it is also possible to effectively suppress the occurrence of repetitive stress (pulsation) due to pressure fluctuations.

In particular, the influence of pressure fluctuations occurring in a boiling state becomes greater as the supply pressure of the first fluid 1 is lower. Therefore, the configuration of this embodiment in which pressure fluctuations can be suppressed by the pressure fluctuation suppressor 12 is particularly effective when the first fluid 1 is supplied to the heat transfer tube HT at a relatively low pressure (for example, less than 1 MPa).

Furthermore, in this embodiment, as described above, the pressure fluctuation suppressing section 12 includes the throttle member 12a provided in the passage 11, so that the flow path of the passage 11 is reduced by narrowing the inner diameter of the passage 11 with the throttle member 12a. The resistance can be made sufficiently higher than the flow path resistance of the first flow path 41. As a result, when the first fluid 1 hardly flows into the passage 11 (substantially only flows to the first flow passage 41 side), and when a pressure difference occurs between both ends, the pressure difference is eliminated. The pressure fluctuation suppressing section 12 that allows the first fluid 1 to flow in and out by the amount required can be realized with a simple structure.

Furthermore, in the present embodiment, as described above, one end of the passage 11 is open into the second pipe 20, and the pressure fluctuation suppressor 12 is arranged so as to cover the other end of the passage 11. Therefore, unlike a configuration in which the pressure fluctuation suppressing section 12 is arranged inside the first pipe 10, the pressure fluctuation suppressing section 12 can be easily provided.

Further, in this embodiment, as described above, the first pipe 10, the second pipe 20, and the third pipe 30 are provided so as to extend in the vertical direction, and the first fluid 1 is provided at the lower end 20b of the second pipe 20. An inlet portion 3a is provided at the upper end portion 20a of the second pipe 20, an outlet portion 3b for vaporized gas is provided at the upper end portion 20a of the second pipe 20, and the pressure fluctuation suppressing portion 12 is provided at the upper end portion 10a of the first pipe 10. The first fluid 1 introduced from the inlet portion 3a is vaporized in the process of flowing upward, and the vaporized gas of the first fluid 1 flows out from the outlet portion 3b at the upper end. Therefore, the difference in specific gravity can be used to move the vaporized gas of the first fluid 1 upward, so that the vaporized gas can be smoothly circulated. The lower end of the passage 11 in the first pipe 10 will be in contact with the liquid of the first fluid 1, and the upper end of the passage 11 will be in contact with the vaporized gas of the first fluid 1. When a pressure fluctuation occurs, the passage When the liquid of the first fluid 1 temporarily flows into the first fluid 11 or the vaporized gas flows into the first fluid 11, pressure fluctuations between the inlet portion 3a and the outlet portion 3b can be suppressed.

Furthermore, in the present embodiment, as described above, the fins 50 are provided in the first flow path 41 so as to contact the outer circumferential surface 10c of the first tube 10 and the inner circumferential surface 20d of the second tube 20, respectively. The fin 50 further includes a material of each of the first tube 10 and the second tube 20 and the fin 50 at the contact portion CP with the first tube 10 and the contact portion CP with the second tube 20. Since it has an integrated part, the heat from the second fluid 2 supplied from the outer circumferential side of the first flow path 41 is transferred by the fins 50 to the inner circumferential side of the first flow path 41 (the outer circumferential surface 10c of the first pipe 10). ) can be communicated efficiently. The materials of each of the first tube 10 and the second tube 20 and the fin 50 are integral with each other at the contact portion CP with the first tube 10 and the contact portion CP with the second tube 20. Since the surface of the fin 50 and the surface of the first pipe 10 (second pipe 20) contact each other without being integrated, the fin 50 and the first pipe 10 at the contact portion CP are (the second pipe 20) can be increased in contact area. As the contact area increases, thermal resistance decreases, making it easier to conduct heat and improving heat exchange performance. Therefore, the temperature difference between the outer circumferential surface 10c of the first tube 10 and the inner circumferential surface 20d of the second tube 20 can be reduced, and variations in heat exchange performance in the radial direction of the first flow path 41 can be reduced.

[Modified example]
Note that the embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is indicated by the claims rather than the description of the embodiments described above, and further includes all changes (modifications) within the meaning and range equivalent to the claims.

For example, in the above embodiment, an example was shown in which the heat exchanger 100 was configured as a vaporizer for the first fluid 1, but the present invention is not limited to this. In the present invention, the heat exchanger 100 may be a heat exchanger that performs other than vaporization of fluid. In other words, there is no need for a phase change of the fluid to occur within the flow path. The first fluid 1 may be on the high temperature side and the second fluid 2 may be on the low temperature side.

Further, in the above embodiment, an example has been shown in which the pressure fluctuation suppressing section 12 is the throttle member 12a in which the throttle hole 12b is formed and closes the end of the first pipe 10, but the present invention is not limited to this. For example, in the example of FIG. 9, the pressure fluctuation suppressing section 12 includes a throttle member 112 in which a throttle hole 12b is formed, and a lid body 113 in which a mounting hole 113a for the throttle member 112 is formed. The lid body 113 is joined to the end of the first tube 10 so as to close the end opening of the first tube 10. The mounting hole 113a is a screw hole (female thread) that penetrates the lid 113 in the thickness direction. A threaded portion (external thread) that engages with the threaded portion of the mounting hole 113a is formed on the outer peripheral surface of the aperture member 112. The aperture member 112 is removably attached within the mounting hole 113a. In this configuration, by preparing a plurality of types of throttle members 112 having different diameters of the throttle hole 12b, the diameter of the throttle hole 12b can be changed (adjusted) to an appropriate size by replacing the throttle member 112.

Further, in the above embodiment, an example was shown in which the aperture member 12a is joined to the end of the first pipe 10 by welding or the like, but the present invention is not limited to this. A throttle member 12a having a thread groove (female thread) formed on the inner peripheral surface 10d of the end of the first pipe 10 and a thread groove (male thread) formed on the outer peripheral surface is screwed to the inner peripheral surface 10d of the first pipe 10. It's okay.

Further, in the embodiment described above, an example has been shown in which the pressure fluctuation suppressing section 12 is the aperture member 12a joined to the end of the first pipe 10, but the present invention is not limited to this. In the present invention, the pressure fluctuation suppressor 12 may be integrally formed with the first pipe 10. For example, by tapering the end of the first tube 10 and reducing the inner diameter of the passage 11 at the end of the first tube 10 to a size corresponding to the diameter of the throttle hole 12b, the first tube 10 is A pressure fluctuation suppressor 12 may also be formed.

Further, in the above embodiment, an example was shown in which the pressure fluctuation suppressing section 12 is the throttle member 12a having the throttle hole 12b, but the present invention is not limited to this. In the present invention, the pressure fluctuation suppressing section 12 does not need to have the throttle hole 12b. The pressure fluctuation suppressing section 12 includes a filter member made of, for example, a porous material or fibers and provided so as to close the passage 11, and the filter member restricts the pressure of the first fluid 1 in the first pipe 10 while suppressing the fluctuating pressure. may be configured to allow the

Further, in the embodiment described above, an example was shown in which the pressure fluctuation suppressing section 12 was provided at the upper end portion 10a of the first pipe 10, but the present invention is not limited to this. As shown in FIG. 10, the pressure fluctuation suppressor 12 may be provided at the lower end 10b of the first pipe 10. In addition, the pressure fluctuation suppressor 12 is provided not at the end of the first pipe 10 but at an intermediate position within the first pipe 10 between one end (upper end 10a) and the other end (lower end 10b). Good too. The pressure fluctuation suppressor 12 may be provided at a plurality of locations among one end, the other end, and an intermediate position of the first pipe 10.

Further, in the above embodiment, an example was shown in which the fins 50 were provided in the first flow path 41, but in the present invention, the fins 50 may not be provided in the first flow path 41. Further, in the above embodiment, an example was shown in which no fins were provided in the second flow path 42, but in the present invention, fins may be provided in the second flow path 42.

Further, in the embodiment described above, the fin 50 is connected to each of the first pipe 10 and the second pipe 20 at the contact part CP with the first pipe 10 and the contact part CP with the second pipe 20. Although an example is shown in which there is a part where the materials are integrated, the present invention is not limited to this. In the contact portion CP, a portion where the materials of each of the first tube 10 and the second tube 20 and the fin 50 are integrated may not be formed. In other words, it is not necessary to perform heat treatment in the manufacturing process of the heat transfer tube HT.

Further, in the above embodiment, the heat transfer tubes HT are Although an example of manufacturing has been shown, the present invention is not limited to this. In the present invention, it is not necessary to perform the drawing process (step S3). In this case, in step S4 of performing heat treatment, the inside of the first tube 10 is pressurized to expand, or the second tube 20 is heated with an expanding substance sealed inside the first tube 10. The process of crimping the horizontal plate part 52 on the outer circumferential side of the fin 50 to the inner circumferential surface 20d of the fin 50 and the process of integrating the materials in the contact part CP by heating may be performed in a single process.

Further, in the above embodiment, an example was shown in which the first pipe 10, the second pipe 20, and the third pipe 30 are provided so as to extend in the vertical direction, but the present invention is not limited to this. The first pipe 10, the second pipe 20, and the third pipe 30 may be provided so as to extend horizontally or diagonally up and down. When each pipe is provided in the horizontal direction, different temperature distributions and gas-liquid distributions are formed above and below the first flow path 41, so the heat exchanger 100 is configured as a vaporizer for the first fluid 1. In this case, it is preferable that each tube extends in the vertical direction.

1 First fluid 2 Second fluid 3a Inlet part 3b Outlet part 4a Inlet part 4b Outlet part 10 First pipe 10a Upper end part 10b Lower end part 10c Outer peripheral surface 10d Inner peripheral surface 11 Passage 12 Pressure fluctuation suppressor 12a, 112 Throttle member 20 Second pipe 20a Upper end 20b Lower end 20d Inner peripheral surface 30 Third pipe 30d Inner peripheral surface 41 First flow path 42 Second flow path 50 Fin 100 Heat exchanger CP Contact portion HT Heat transfer tube

Claims (6)

comprising a first tube, a second tube into which the first tube is inserted, and a third tube into which the first tube and the second tube are inserted;
A first flow path through which a first fluid flows is formed between the first pipe and the second pipe, and a first flow path through which a first fluid flows is formed between the second pipe and the third pipe. A second flow path is formed that allows the two fluids to flow,
The first pipe has a passage whose both ends communicate with the inside of the second pipe, and restricts the flow of the first fluid in the passage, and discharges the pressure fluctuated within the first passage from the end of the passage. A heat exchanger including a relief pressure fluctuation suppressor. The first fluid is a liquid that is vaporized by heat exchange with the second fluid,
The pressure fluctuation suppressing section restricts the flow of the first fluid to retain the vaporized gas of the first fluid in the passage, and causes the vaporized gas to flow according to pressure fluctuations in the first flow path. The heat exchanger according to claim 1, configured as follows. The heat exchanger according to claim 1 or 2, wherein the pressure fluctuation suppressor includes a throttle member provided in the passage. The passage has one end open into the second pipe,
The heat exchanger according to claim 1, wherein the pressure fluctuation suppressor is provided to cover the other end of the passage. The first pipe, the second pipe, and the third pipe are provided to extend in the vertical direction,
An inlet for the first fluid is provided at a lower end of the second pipe, and an outlet for the vaporized gas is provided at an upper end of the second pipe.
The heat exchanger according to claim 2, wherein the pressure fluctuation suppressor is provided at an upper end of the first pipe. Further comprising fins provided in the first flow path so as to contact the outer circumferential surface of the first tube and the inner circumferential surface of the second tube, respectively,
The fin has a portion in which the materials of each of the first tube and the second tube and the fin are integrated at a contact portion with the first tube and a contact portion with the second tube. , the heat exchanger according to any one of claims 1 to 5.

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