JP7387990B2 - fin tube heat exchanger - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to a fin-tube heat exchanger.

Fin tube heat exchangers are commonly used as industrial heat exchangers. A fin-tube heat exchanger has a plurality of heat exchanger tubes arranged in a direction crossing the flow direction of heat exchange air, and a plurality of fins (heat exchanger plates) arranged in the tube axis direction of these heat exchanger tubes. A liquid medium is flowed inside the heat transfer tube, and a gas body (heat exchange air) is applied to the outer peripheral surface of the heat transfer tube and the fins to exchange heat. The plurality of fins contributes to increasing the amount of heat transfer by expanding the heat transfer area.

Conventionally, in such a fin tube heat exchanger, various proposals have been made to improve heat exchange efficiency while suppressing an increase in ventilation resistance (see, for example, Patent Document 1 and Patent Document 2). The fin-tube heat exchanger described in Patent Document 1 includes a slit-shaped louver that has a predetermined angle of attack with respect to the fin surface and has a receding angle at an end far from the center of the heat transfer tube. In this fin-tube heat exchanger, by providing the louvers with a swept back angle, it is possible to improve heat exchange efficiency while suppressing an increase in ventilation resistance due to an increase in the angle of attack.

Further, in the fin-tube heat exchanger described in Patent Document 2, a slit-like cut and raised portion is provided in the fins arranged around the heat exchanger tube (pipe), and the shape of the cut and raised portion is set in the vicinity of the heat exchanger tube. It is designed to be narrow, but widen as you move away from it. This fin-tube heat exchanger reduces ventilation resistance and improves heat exchange efficiency by changing the number of slits through which heat exchange air passes depending on the distance from the heat transfer tube.

Patent No. 4536583 Japanese Patent Application Publication No. 11-63874

In the fin-tube heat exchangers described in Patent Document 1 and Patent Document 2, the fins are provided with specially shaped louvers and cut-and-raised portions, thereby increasing the heat transfer coefficient and preventing an increase in ventilation resistance. It's suppressed. By the way, in a fin-tube heat exchanger having a cylindrical heat exchanger tube, separation of fluid (heat exchange air) from the heat exchanger tube becomes an obstacle to improving air resistance and heat transfer coefficient. It is thought that suppressing such fluid separation contributes to improving the heat exchange efficiency of the entire heat exchanger.

The present invention has been made in view of the above circumstances, and aims to provide a fin-tube heat exchanger that can reduce air resistance and improve heat exchange efficiency by suppressing separation of heat exchange air. Make it one of the objectives.

A fin-tube heat exchanger according to one aspect of the present invention includes a plurality of heat exchanger tubes arranged in a direction crossing the flow direction of heat exchange air, and a plurality of heat exchanger tubes arranged at regular intervals in the tube axis direction of the heat exchanger tubes. fins, and a fin collar portion that covers the heat transfer tube arranged between the plurality of fins, a flow path is provided in the heat transfer tube arranged between the plurality of fins, and the flow path is provided with a flow path. through which a part of the heat exchange air is discharged to the downstream side in the flow direction of the heat exchange air , and the flow path is formed in a plurality of through holes formed in the fin collar portion and in the heat transfer tube, A groove portion communicating with the plurality of through holes .

According to the present invention, it is possible to reduce air resistance and improve heat exchange efficiency by suppressing separation of heat exchange air.

FIG. 2 is a perspective view of a fin tube heat exchanger according to the present embodiment. It is an explanatory view of an example of the distribution state of heat exchange air around a heat exchanger tube in a fin tube heat exchanger. FIG. 2 is a perspective view of main parts of the fin tube heat exchanger according to the present embodiment. FIG. 3 is an explanatory diagram of the flow state of heat exchange air around the heat exchanger tubes in the fin-tube heat exchanger according to the present embodiment.

Hereinafter, a plurality of embodiments of the present invention will be described in detail with reference to the accompanying drawings. The fin tube heat exchanger according to the present invention is suitably used, for example, in a condenser installed in geothermal power generation equipment. However, the fin tube heat exchanger according to the present invention is not limited to this, and can be used for any heat exchange such as air-cooled heat exchangers in petrochemical plants and oil refineries, and air-cooled condensers in incinerators. Can be applied to vessels.

Fin-tube heat exchangers, which are generally used as industrial heat exchangers, consist of multiple heat exchanger tubes arranged in a direction that intersects with the flow direction of heat exchange air, and these heat exchanger tubes are arranged in the tube axis direction. It has a plurality of fins. In such a fin-tube heat exchanger, a liquid medium is caused to flow inside the heat exchanger tube, and a gas body is applied to the outer peripheral surface of the heat exchanger tube and the fins to exchange heat.

Conventionally, in such fin tube heat exchangers, various proposals have been made to improve heat exchange efficiency while suppressing an increase in ventilation resistance. For example, a fin-tube heat exchanger is known that includes a slit-like louver that has a predetermined angle of attack with respect to the fin surface and has a receding angle at the end far from the center of the heat exchanger tube. In this fin-tube heat exchanger, louvers having a special shape are provided on the fins to suppress an increase in ventilation resistance while increasing the heat transfer coefficient.

By the way, in a fin-tube heat exchanger having a cylindrical heat exchanger tube, separation of the heat exchange air from the heat exchanger tube causes a dead area to be formed in the downstream region of the heat exchange air in the heat exchanger tube. In the dead zone, there is no pressure recovery in the downstream region of the heat transfer tube, and a negative pressure region is formed, resulting in large air resistance. Furthermore, since no heat exchange action occurs in the dead zone, it does not contribute to improving the heat transfer coefficient. In this way, the heat exchange efficiency in the fin-tube heat exchanger cannot be sufficiently improved.

The present inventors have focused on the fact that such separation of heat exchange air from the heat exchanger tube is a cause of both an increase in ventilation resistance and a problem with heat transfer performance. Then, the present inventors discovered that suppressing the separation of heat exchange air from the heat exchanger tubes reduces the dead area formed in the downstream region of the heat exchanger tubes, and contributes to improving heat exchange efficiency, and thus arrived at the present invention.

That is, the gist of the present invention is that a plurality of heat exchanger tubes are arranged in a direction crossing the flow direction of heat exchange air, a plurality of fins are arranged at regular intervals in the tube axis direction of these heat exchanger tubes, A flow path is provided inside the contact surface of the heat exchange air between the plurality of fins, and a part of the heat exchange air is sent through the flow path to the downstream side in the flow direction of the heat exchange air in the heat transfer tube. It is to discharge. In the present invention, the contact surface refers to the surface of the heat exchanger tube with which heat exchange air comes into contact, or the fin collar portion protruding from the fins to the surface of the heat exchanger tube.

According to the present invention, the heat exchange air whose flow has slowed near the heat exchanger tube is sucked into the downstream side of the heat exchanger tube through the flow path provided on the contact surface of the heat exchange air between the plurality of fins, and , it is possible to draw heat exchange air (fast-flowing heat exchange air) flowing at a position slightly away from the vicinity of the heat exchanger tubes to the vicinity of the heat exchanger tubes. Thereby, it is possible to suppress a decrease in the velocity gradient on the surface of the heat exchanger tube, and it is possible to delay separation of the heat exchange air from the heat exchanger tube. As a result, it is possible to reduce the dead zone formed in the downstream region of the heat exchanger tubes, thereby improving heat exchange efficiency.

Hereinafter, the configuration of a fin tube heat exchanger according to an embodiment of the present invention will be described with reference to FIG. 1. In the following, for convenience of explanation, a case will be described in which the fin-tube exchanger according to the present invention is applied to a condenser installed in a geothermal power generation facility. However, as will be described in detail later, the fin-tube exchanger according to the present invention can be applied to heat recovery equipment installed in various factories by changing the liquid medium flowing through the heat transfer tubes that constitute the fin-tube heat exchanger. You can also do that.

FIG. 1 is a perspective view of a fin-tube heat exchanger (hereinafter referred to as "heat exchanger" as appropriate) 1 according to the present embodiment. In addition, in FIG. 1, for convenience of explanation, a part of the fin tube 10 is extracted and shown, and a cross section of the part of the fin tube 10 is shown. Below, the up-down direction, the front-back direction, and the left-right direction shown in FIG. 1 are demonstrated as the up-down direction, the front-back direction, and the left-right direction of the heat exchanger 1 based on this Embodiment.

A condenser to which the heat exchanger 1 according to the present embodiment is applied includes the heat exchanger 1 and a blower (not shown) disposed opposite to the heat exchanger 1. Here, it is assumed that the blower is disposed above the heat exchanger 1, but the present invention is not limited thereto. The blower sucks up air (heat exchange air) from the lower side of the heat exchanger 1 and sends it out to the upper external space. That is, the heat exchange air flows in the vertical direction of the heat exchanger 1. The sucked up heat exchange air is warmed by heat exchange in the heat exchanger 1, and is then discharged to the outside.

As shown in FIG. 1, the heat exchanger 1 includes a plurality of fin tubes 10. The fin tubes 10 are arranged in the direction of flow of heat exchange air (the vertical direction of the heat exchanger 1), and are also arranged in the direction intersecting the direction of flow of the heat exchange air (for example, the left-right direction of the heat exchanger 1). ing. The plurality of fin tubes 10 arranged in a direction intersecting the direction of flow of heat exchange air are generally arranged in a direction perpendicular to the direction of flow of heat exchange air.

As shown in FIG. 1, the fin tubes 10 are arranged at regular intervals in the left-right direction of the heat exchanger 1. The fin tube 10 arranged relatively upward is arranged at the center of a pair of adjacent fin tubes 10 arranged relatively downward (see the fin tube 10 in the uppermost position shown in FIG. 1). . Similarly, the fin tube 10 disposed relatively downward is disposed at the center of a pair of adjacent fin tubes 10 disposed relatively upward (the fin tube 10 at the lowest position shown in FIG. 10). In other words, the plurality of fin tubes 10 are arranged in a staggered manner when viewed from the front.

The fin tube 10 includes a heat exchanger tube 11 and a plurality of fins (heat exchanger plates) 12 arranged on the outer peripheral surface of the heat exchanger tube 11. The heat exchanger tube 11 has a generally circular tube shape and is configured to extend in the front-rear direction of the heat exchanger 1 . For example, the heat exchanger tube 11 is a circular tube having an outer diameter of 25 mm, but is not limited thereto. The inside of the heat exchanger tube 11 is configured to allow a liquid medium to flow therethrough. For example, hot water can be used as liquid medium. The surface temperature of the heat exchanger tube 11 changes depending on the temperature of the liquid medium flowing inside.

The plurality of fins 12 are joined to the outer peripheral surface of the heat exchanger tube 11. For example, the fins 12 are joined to the outer circumferential surface of the heat exchanger tube 11 by expanding a part or all of the outer diameter of the heat exchanger tube 11, but the present invention is not limited thereto. The fins 12 are arranged at regular intervals in the tube axis direction of the heat transfer tube 11 . For example, the fins 12 are arranged at intervals of 2 mm or 5 mm. All fins 12 have the same shape. The fins 12 generally have an annular shape when viewed from the front. A fin collar portion 121 is provided at the inner edge of each fin 12. A plurality of through holes 122 are formed at predetermined positions of the fin collar portion 121 . These through holes 122 constitute a part of a heat exchange air flow path 13, which will be described later.

Here, the flow state of heat exchange air around the heat exchanger tubes 11 in a general fin tube heat exchanger will be described with reference to FIG. 2. FIG. 2 is an explanatory diagram of an example of the flow state of heat exchange air around the heat exchanger tubes 11 in the fin-tube heat exchanger. 2A shows a front view of the fin tube 10, and FIG. 2B schematically shows the vicinity of the surface of the heat exchanger tube 11. In FIG. 2, for convenience of explanation, the same reference numerals as in this embodiment are given. Moreover, in FIG. 2A, the flow of heat exchange air is shown by broken line arrows. Note that, unlike the heat exchanger 1 according to the present embodiment, the fin tube heat exchanger shown in FIG. 2 is not provided with a flow path 13 for heat exchange air.

When heat exchange air is sucked up from the lower side of the fin-tube heat exchanger by the blower, the heat exchange air hits the lower side portion of the heat transfer tube 11 and flows upward along the outer peripheral surface thereof. Then, as shown in FIG. 2A, the heat exchange air separates from the heat exchange tubes 11 in the downstream region of the heat exchange air in the flow direction of the heat exchange tubes 11, and is separated from the heat exchange tubes 11 (outside in the left-right direction). It is distributed in the area of As a result, a dead area A is formed above the heat exchanger tube 11.

Here, the mechanism by which the heat exchange air is separated from the heat exchanger tubes 11 will be explained. Around the surface of the heat exchanger tube 11, the heat exchange air flows with a velocity boundary layer B shown by a broken line in FIG. 2B. The heat exchange air flowing inside the velocity boundary layer B has a velocity gradient (∂u/∂y) due to the influence of viscosity. Under the influence of friction with the surface of the heat exchanger tube 11, it flows while losing energy as it moves downstream. For example, in a flow with a reverse pressure gradient (a flow in which the pressure increases in the flow direction), The value of the velocity gradient (∂u/∂y) becomes smaller in the order of position A, position B, and position C shown in FIG. 2B. Then, it becomes 0 at position D.

On the downstream side of position D, the heat exchange air that has lost energy cannot flow against the pressure and separates from the surface of the heat exchanger tube 11. The position where the heat exchange air separates from the surface of the heat exchanger tube 11 (here, position D) is called a separation point. On the downstream side of the separation point, a region C in which heat exchange air does not flow is formed near the surface of the heat exchanger tube 11. In region C, a backflow occurs near the surface of the heat exchanger tube 11, and a vortex is generated as shown in FIG. 2B.

In order to suppress such separation of the heat exchange air, in the heat exchanger 1 according to the present embodiment, a flow path is provided inside the contact surface of the heat exchange air between the adjacent fins 12, and the flow path is A part of the heat exchange air is discharged to the back side of the heat exchange tube 11 (downstream side in the flow direction of the heat exchange air) through the passage. In this embodiment, the contact surface of the heat exchange air is constituted by the outer circumferential surface of the fin collar portion 121. FIG. 3 is a perspective view of the main parts of the heat exchanger 1 according to the present embodiment. 3A shows a state before the fins 12 are joined to the heat exchanger tube 11, and FIG. 3B shows a state where the fins 12 are joined to the heat exchanger tube 11.

As shown in FIG. 3, a plurality of grooves 111 are provided on the surface of the heat exchanger tube 11. The groove portion 111 is provided in a part of the outer peripheral surface of the heat exchanger tube 11 along the circumferential direction of the heat exchanger tube 11 . For example, the groove portion 111 is provided in a portion of the downstream side of the heat exchanger tube 11 in the flow direction of the heat exchange air, but the groove portion 111 is not limited thereto. The groove portions 111 are arranged at regular intervals in the tube axis direction of the heat transfer tube 11 . These grooves 111 are arranged at positions between adjacent fins 12 when the fins 12 are joined to the heat exchanger tubes 11. That is, these groove portions 111 are arranged so as to overlap the fin collar portion 121.

On the other hand, a plurality (three in this embodiment) of through holes 122 are formed in the fin collar portion 121 . The plurality of through holes 122 include a pair of through holes 122a and 122b arranged on a straight line along a direction perpendicular to the flow direction of heat exchange air (the left-right direction shown in FIG. 3A), It has a through hole 122c arranged corresponding to the most downstream position in the direction (vertical direction shown in FIG. 3A). These through holes 122a to 122c are arranged at 90 degree intervals. The through hole 122a and the through hole 122b are arranged at positions facing each other across the center of the heat exchanger tube 11 in the tube axis direction when viewed from the front. These through holes 122a and 122b can also be called heat exchange air inflow holes or suction holes. The through hole 122c can also be called a heat exchange air exhaust hole.

When a plurality of fins 12 are joined to the outer peripheral surface of the heat exchanger tube 11, the through holes 122a to 122c formed in the same fin collar portion 121 are arranged at positions corresponding to the same groove portion 111. These through holes 122a to 122c, the groove portion 111, and the inner peripheral surface of the fin collar portion 121 form a flow path 13 for heat exchange air (see FIG. 4). That is, the heat exchange air that has flowed into the flow path 13 from the through holes 122a and 122b passes through the groove portion 111 and is discharged from the through hole 122c. These channels play the role of sucking in a part of the heat exchange air flowing near the heat exchanger tubes 11 and causing it to flow to the back side of the heat exchanger tubes 11 (the upper side shown in FIG. 3).

Here, the flow state of heat exchange air around the heat exchanger tubes 11 in the heat exchanger 1 according to the present embodiment will be described with reference to FIG. 4. FIG. 4 is an explanatory diagram of the flow state of heat exchange air around the heat exchanger tubes 11 in the heat exchanger 1 according to the present embodiment. 4A schematically shows a cross section near the heat exchanger tube 11 passing through the flow path 13, and FIG. 4B shows a front view of the fin tube 10. In addition, in FIGS. 4A and 4B, the flow of some heat exchange air is indicated by broken line arrows.

As shown in FIG. 4A, the heat exchange air flowing near the surface of the heat exchanger tube 11 (fin collar portion 121) enters the flow path 13 via the through hole 122a. As a result, the heat exchange air whose flow has slowed in the vicinity of the heat exchanger tubes 11 is discharged to the downstream side of the heat exchanger tubes 11 via the flow path 13. More specifically, the heat exchange air whose flow has become slow in the vicinity of the heat exchanger tubes 11 at position C is discharged to the downstream side of the heat exchanger tubes 11 via the flow path 13. As a result, heat exchange air (fast-flowing heat exchange air) flowing at a position slightly away from the vicinity of the heat exchanger tubes 11 is drawn to the vicinity of the heat exchanger tubes 11 . As a result, a decrease in the velocity gradient on the surface of the heat exchanger tube 11 can be suppressed, and separation of the heat exchange air from the surface of the heat exchanger tube 11 can be delayed.

This will be specifically explained in comparison with FIG. 2B. As shown in FIG. 2B, in the fin-tube heat exchanger in which the flow path 13 was not provided, the separation point of the heat exchange air was at position D. In contrast, in the heat exchanger 1 according to the present embodiment, the separation point of the heat exchange air is delayed to the position E. Therefore, separation of the heat exchange air occurs downstream of position E.

By delaying the separation of the heat exchange air in this manner, as shown in FIG. 4B, the region of the dead zone A shown in FIG. 2A is reduced in the downstream region of the heat exchanger tube 11, as shown in FIG. 4B. As a result, it is possible to reduce the negative pressure area on the downstream side of the heat transfer tube, reduce air resistance, and expand the area where the fins 12 exert heat exchange action, improving heat exchange efficiency. I can do it.

As explained above, in the heat exchanger 1 according to the present embodiment, there are a plurality of heat exchanger tubes 11 arranged in a direction intersecting the flow direction of heat exchange air, and a tube axis direction of these heat exchanger tubes 11. a plurality of fins 12 arranged at regular intervals, a flow path 13 is provided inside the contact surface of the heat exchange air between the plurality of fins 12, and the heat exchange air is passed through the flow path 13. A part of the heat exchange air is discharged to the downstream side of the heat exchanger tube 11 in the flow direction of the heat exchange air. According to this configuration, the heat exchange air whose flow has become slow in the vicinity of the heat exchange tubes 11 is transferred to the downstream side of the heat exchange tubes 11 through the flow path 13 provided on the contact surface of the heat exchange air between the plurality of fins 12. At the same time, it is possible to draw heat exchange air (fast-flowing heat exchange air) flowing slightly away from the vicinity of the heat exchanger tubes to the vicinity of the heat exchanger tubes. Thereby, a decrease in the velocity gradient on the surface of the heat exchanger tube 11 can be suppressed, and separation of the heat exchange air from the surface of the heat exchanger tube 11 can be delayed. As a result, the dead zone can be reduced in the downstream region of the heat exchanger tubes 11, so the area through which heat exchange air flows within the fins 12 can be expanded, reducing air resistance and improving heat exchange efficiency. .

In particular, the heat exchanger 1 according to the present embodiment includes a fin collar portion 121 that covers the heat transfer tube 11 arranged between the plurality of fins 12. The flow path 13 includes a plurality of through holes 122 formed in the fin collar portion 121 and a groove portion 111 formed in the heat transfer tube 11 and communicating with the plurality of through holes 122. In this way, by configuring the flow path 13 by combining a portion of the heat transfer tube 11 (groove portion 111) and a portion of the fin collar portion 121 (through hole 122), it is possible to eliminate the need for complicated processing. The flow path 13 can be formed, and the cost and time required for manufacturing the fin tube 10 can be reduced.

Note that the present invention is not limited to the above embodiments, and can be implemented with various modifications. In the embodiments described above, the sizes and shapes of the members and holes shown in the accompanying drawings are not limited to these, and can be changed as appropriate within the scope of achieving the effects of the present invention. Other changes may be made as appropriate without departing from the scope of the invention.

For example, in the embodiment described above, a pair of through holes 122a and 122b are arranged at positions on a straight line along a direction perpendicular to the flow direction of heat exchange air (the left-right direction shown in FIG. 3A), and A case will be described in which the through hole 122c is arranged corresponding to the most downstream position in the flow direction (vertical direction shown in FIG. 3A). However, the arrangement of these through holes 122 is not limited to the above content and can be changed as appropriate. The pair of through holes 122a and 122b do not need to be arranged in a direction perpendicular to the flow direction of the heat exchange air, and can be arranged at any position provided that the holes are near the separation point of the heat exchange air. can. Further, the through hole 122c can be arranged at any position on the premise that the through hole 122c is located on the downstream side in the direction of flow of heat exchange air (vertical direction shown in FIG. 3A).

Further, in the above embodiment, a case is described in which the flow path 13 is formed by the groove portion 111 provided in the heat exchanger tube 11, the through holes 122a to 122c, and the inner circumferential surface of the fin collar portion 121. However, the configuration of the flow path 13 is not limited to this and can be changed as appropriate. For example, in an embodiment in which the fins 12 do not include the fin collar portions 121, a flow path may be formed inside the heat exchanger tubes 11. That is, the flow path may be configured by providing the heat exchanger tube 11 itself with inflow holes and exhaust holes for heat exchange air, and by providing a groove portion that connects these holes. In this case, the surface of the heat exchanger tube 11 constitutes the contact surface of the heat exchange air between the plurality of fins 12. Furthermore, the entire configuration of the flow path 13 may be provided inside the fin collar portion 121.

As explained above, the present invention has the effect of reducing air resistance and improving heat exchange efficiency by suppressing separation of heat exchange air. Useful for heat exchangers.

1: Heat exchanger 10: Fin tube 11: Heat exchanger tube 12: Fin 13: Channel 111: Groove portion 121: Fin collar portion 122, 122a to 122c: Through hole

Claims (1)

a plurality of heat exchanger tubes arranged in a direction crossing the flow direction of heat exchange air;
a plurality of fins arranged at regular intervals in the tube axis direction of the heat exchanger tube;
a fin collar portion that covers the heat exchanger tube disposed between the plurality of fins ;
A flow path is provided in the heat exchanger tube arranged between the plurality of fins, and a part of the heat exchange air is discharged to the downstream side in the flow direction of the heat exchange air through the flow path ,
The fin tube is characterized in that the flow path includes a plurality of through holes formed in the fin collar portion and a groove portion formed in the heat transfer tube and communicating with the plurality of through holes. Heat exchanger.

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