JP2019143874A - Fin tube heat exchanger - Google Patents

Abstract

To sufficiently improve a transmission rate without inviting enlargement of a heat exchanger itself.SOLUTION: A fin tube heat exchanger (1) comprises a plurality of heat transfer tubes (11) arranged in a direction crossing a flow direction of heat exchange air, and a plurality of fins (12) arranged at a fixed interval in a tube axis direction of the heat transfer tube, where the fin has plate parts (13, 14) provided substantially perpendicular to a fin surface. The plate part is arranged downstream of the heat transfer tube in the flow direction of the heat exchange air, in a region (A) inside an outer peripheral surface (11a) of the heat transfer tube, and along the flow direction of the heat exchange air.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a finned tube heat exchanger.

  In an industrial heat exchanger, a fin tube heat exchanger is generally used. In the finned tube heat exchanger, a plurality of heat transfer tubes arranged in a direction crossing the flow direction of the heat exchange air, and a plurality of fins (heat transfer plates) arranged in the tube axis direction of these heat transfer tubes, The liquid medium is flowed into the heat transfer tube, and heat is exchanged by applying a gas body (heat exchange air) to the outer peripheral surface of the heat transfer tube and the fin. The plurality of fins contribute to an increase in the amount of heat transfer by expanding the heat transfer area.

  Conventionally, in such a finned-tube heat exchanger, the annular fins fixed to the heat transfer tubes are projected on both sides of the annular fin with a predetermined length in a radial direction at predetermined angles. There has been proposed one in which the fins are bent radially at a predetermined pitch in the tube axis direction (see, for example, Patent Document 1). In this fin tube heat exchanger, the heat transfer rate is improved by disturbing the flow of heat exchange air flowing along the fin surface.

Japanese Patent No. 3854978

  However, in the fin tube heat exchanger described above, since the fin has a radially bent shape, the heat exchange air is partly (particularly, part on the downstream side in the flow direction of the heat exchange air) of the heat exchange air. There is a case where it leads to the outer edge side. For this reason, there is a problem that only a part of the fins can be utilized and a situation in which the heat transfer rate cannot be sufficiently improved may occur.

  Generally, when a fin tube heat exchanger is used for a large capacity air-cooled heat exchanger, the fin tube heat exchanger itself is increased in size. In recent years, due to factors such as the widespread use of cogeneration systems, it has been required to improve heat exchange performance without increasing the size of the fin tube heat exchanger.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a finned tube heat exchanger that can sufficiently improve the heat transfer rate without causing an increase in size of the heat exchanger itself. One of them.

  The finned tube heat exchanger according to one aspect of the present invention includes a plurality of heat transfer tubes arranged in a direction intersecting a flow direction of heat exchange air, and a plurality of sheets arranged at regular intervals in the tube axis direction of the heat transfer tubes. The fin has a plate portion provided substantially perpendicular to the fin surface, and the plate portion is downstream of the heat transfer tube in the flow direction of the heat exchange air, It arrange | positions along the distribution direction of the said heat exchange air in the area | region inside the outer peripheral surface of the said heat exchanger tube.

  According to the present invention, the heat transfer coefficient can be sufficiently improved without causing an increase in the size of the heat exchanger itself.

It is a perspective view of the finned-tube heat exchanger which concerns on this Embodiment. It is sectional drawing of the fin tube which the fin tube heat exchanger which concerns on this Embodiment has. It is a front view of the fin tube which the fin tube heat exchanger concerning this embodiment has.

  Hereinafter, the present embodiment will be described in detail with reference to the accompanying drawings. The finned tube heat exchanger according to the present invention is suitably used for, for example, a condenser installed in a geothermal power generation facility. However, the finned tube heat exchanger according to the present invention is not limited to this, and any heat exchange such as an air-cooled heat exchanger in a petrochemical factory or an essential oil factory, or an air-cooled condenser in an incinerator. Can be applied to the vessel.

  Generally, fin tube heat exchangers used as industrial heat exchangers are arranged in the direction of the tube axis of a plurality of heat transfer tubes arranged in a direction crossing the flow direction of heat exchange air. And a plurality of fins. In such a finned tube heat exchanger, a liquid medium is caused to flow in the heat transfer tube, and heat is exchanged by applying a gas body to the outer peripheral surface of the heat transfer tube and the fin.

  Conventionally, in such a fin tube heat exchanger, various proposals have been made to improve the heat transfer coefficient. For example, on both side surfaces of an annular fin fixed to the heat transfer tube, a projection is formed that has a circumferential shape and has a predetermined length in the radial direction at predetermined angles, and the fin is connected to the tube axis. Fin tube heat exchangers are known that are bent radially at predetermined pitches in the direction.

  However, in such a fin tube heat exchanger, since the fin has a radially bent shape, a part of the fin tube heat exchanger (particularly, a part on the downstream side in the flow direction of the heat exchange air) is used to transfer the heat exchange air to the fin. It leads to the outer edge side. As a result, the heat exchange air flows in the direction of separation (separation) from the vicinity of the heat transfer tube, and a dead water area is formed in a peripheral region of the heat transfer tube (more specifically, a downstream region of the heat exchange air). In dead water areas, heat exchange does not occur, so it does not contribute to the improvement of heat transfer coefficient. As a result, it is assumed that the heat transfer coefficient of the finned tube heat exchanger cannot be sufficiently improved.

  In the various fin tube heat exchangers that have been proposed in the past, the heat exchange air introduced into the fins flows in a direction away from the vicinity of the heat transfer tubes. We paid attention to the fact that it did not contribute to the improvement of heat transfer rate. Then, the inventors have found that expanding the region where the heat exchange air flows in the fins and increasing the portion where the heat exchange air hits the fin surface contributes to the improvement of the heat transfer coefficient.

  That is, the essence of the present invention is that a plurality of fins arranged in a heat transfer tube are provided with a plate portion provided substantially perpendicular to the fin surface, and this plate portion is provided on the heat transfer tube in the flow direction of heat exchange air. It is downstream and is arranged along the flow direction of heat exchange air in a region inside the outer peripheral surface of the heat transfer tube.

  According to the present invention, the plate portion provided substantially perpendicular to the fin surface is a downstream side of the heat transfer tube in the flow direction of the heat exchange air, and in the region inside the outer peripheral surface of the heat transfer tube, Since it arrange | positions along the distribution | circulation direction of exchange air, the heat exchange air which flowed to the downstream of the heat exchanger tube is drawn near to the plate part side by the Coanda effect. Thereby, since heat exchange air can be made to go around to the back side of a heat exchanger tube, while the area where heat exchange air flows in a fin can be expanded, the area where heat exchange air hits the fin surface can be increased. In addition, since the plate portion is disposed downstream of the heat transfer tube in the flow direction of the heat exchange air and inside the outer peripheral surface of the heat transfer tube, the outer peripheral size of the fin is greatly increased. There is no. As a result, the heat transfer rate can be sufficiently improved without increasing the size of the heat exchanger itself.

  Hereinafter, the structure of the finned-tube heat exchanger which concerns on one embodiment of this invention is demonstrated with reference to FIG. Below, the case where the fin tube exchanger which concerns on this invention is applied to the condenser installed in geothermal power generation equipment is demonstrated for convenience of explanation. However, as will be described in detail later, the fin tube exchanger according to the present invention is applied to a heat recovery device installed in various factories by changing the liquid medium flowing through the heat transfer tubes constituting the fin tube heat exchanger. You can also.

  FIG. 1 is a perspective view of a finned tube heat exchanger (hereinafter referred to as “heat exchanger” as appropriate) 1 according to the present embodiment. In FIG. 1, for convenience of explanation, a part of the fin tube 10 is extracted and shown, and a cross section of a part of the fin tube 10 is shown. Hereinafter, the vertical direction, the front-rear direction, and the left-right direction shown in FIG. 1 will be described as the vertical direction, the front-rear direction, and the left-right direction of the heat exchanger 1 according to the present embodiment.

  The condenser to which the heat exchanger 1 according to the present embodiment is applied includes the heat exchanger 1 and a blower (not shown) arranged to face the heat exchanger 1. Here, although a blower shall be arrange | positioned above the heat exchanger 1, it is not limited to this. The blower sucks air (heat exchange air) from the lower side of the heat exchanger 1 and sends it out to the external space on the upper side. That is, the heat exchange air flows in the vertical direction of the heat exchanger 1. The sucked heat exchange air is warmed by heat exchange in the heat exchanger 1 and 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 flow direction of the heat exchange air (up and down direction of the heat exchanger 1) and are arranged in a direction intersecting with the flow direction of the heat exchange air (for example, the left and right direction of the heat exchanger 1). ing. In general, the plurality of fin tubes 10 arranged in a direction crossing the flow direction of the heat exchange air are arranged in a direction orthogonal to the flow direction of the heat exchange air.

  As shown in FIG. 1, the fin tubes 10 are arranged with a certain interval in the left-right direction of the heat exchanger 1. The fin tube 10 disposed on the relatively upper side is disposed at the center of a pair of adjacent fin tubes 10 disposed on the relatively lower side (see the uppermost fin tube 10 shown in FIG. 1). . Similarly, the fin tube 10 disposed on the relatively lower side is disposed at the center of a pair of adjacent fin tubes 10 disposed on the relatively upper side (the fin tube at the lowest position shown in FIG. 1). 10). In other words, the plurality of fin tubes 10 are arranged in a staggered manner in a front view.

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

  The plurality of fins 12 are joined to the outer peripheral surface of the heat transfer tube 11. For example, although the fin 12 is joined to the outer peripheral surface of the heat transfer tube 11 by tube expansion processing that expands a part or all of the outer diameter of the heat transfer tube 11, it 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 2 mm intervals or 5 mm intervals. All the fins 12 have the same shape. The fin 12 has a generally annular shape when viewed from the front. Each fin 12 is provided with a pair of plate portions 13 and 14. These plate portions 13 and 14 are arranged to face each other with a certain interval. Between these plate parts 13 and 14, the gap | interval 15 provided continuously in the front-back direction of the heat exchanger 1 is arrange | positioned (refer FIG. 3).

  Hereinafter, the specific structure of the fin 12 which the heat exchanger 1 which concerns on this Embodiment has is demonstrated with reference to FIGS. 1-3. 2 and 3 are a cross-sectional view and a front view of the fin tube 10 included in the heat exchanger 1 according to the present embodiment, respectively. In addition, in FIG. 2, while showing the cross section which passes along the tube axis center of the heat exchanger tube 11, for convenience of explanation, a part of the fin tube 10 is extracted and shown. In the following, for convenience of explanation, the front surface of the fin 12 is referred to as a front surface, and the rear surface of the fin 12 is referred to as a back surface.

  As shown in FIGS. 1-3, the plate parts 13 and 14 are arrange | positioned in the position of the downstream of the heat exchanger tube 11 in the distribution direction of heat exchange air (above the heat exchanger tube 11 shown in FIGS. 1-3). ing. Moreover, the plate parts 13 and 14 are arrange | positioned in the area | region inside the outer peripheral surface 11a of the heat exchanger tube 11 on the basis of the distribution direction of heat exchange air. Specifically, it is disposed in a region A between a pair of broken lines L1 and L2 that are in contact with the outer peripheral surface 11a of the heat transfer tube 11 and parallel to the flow direction of heat exchange air (the vertical direction of the heat exchanger 1). (See FIG. 3).

  Moreover, the plate parts 13 and 14 are arrange | positioned in said area | region A along the distribution direction (up-down direction of the heat exchanger 1) of heat exchange air (refer FIG. 3). Here, it has shown about the case where the plate parts 13 and 14 are arrange | positioned so that it may extend in parallel with the up-down direction of the heat exchanger 1. FIG. However, the extending direction of the plate portions 13 and 14 is not limited to this, and can be changed as appropriate. The plate portions 13 and 14 may extend in any direction on condition that the heat exchange air is attracted by the Coanda effect described later.

  Further, the plate portions 13 and 14 are provided substantially perpendicular to the fin surface 121 of the fin 12. Here, “substantially perpendicular to the fin surface 121” means that it includes the perpendicular to the fin surface 121 and includes an angular error substantially generated in the process of manufacturing the plate portions 13 and 14. The plate portions 13 and 14 are provided to extend forward from the surface of the fin surface 121. In addition, the angle of the extending direction of the fin 12 with respect to the fin surface 121 is not limited to substantially vertical, and may have an angle slightly inclined with respect to the fin surface 121.

  The tip portions of the plate portions 13 and 14 are in contact with the fin surface 121 of the adjacent front fin 12 (see FIG. 2). More specifically, the front end portions (front end portions) of the plate portions 13 and 14 reach the back surface of the fin surface 121 of the adjacent front fin 12 and are in contact with each other. That is, the plate parts 13 and 14 constitute a wall surface part that connects a part of the surface of the fin surface 121 on the rear side and a part of the back surface of the fin surface 121 on the front side. The tip portions of the plate portions 13 and 14 may be at least in contact with the fin surfaces 121 of the adjacent front fins 12 and are not necessarily joined.

  For example, the plate portions 13 and 14 are formed by raising a part of the fin surface 121 of the fin 12 forward. By forming the plate portions 13 and 14 by cutting and raising in this way, it is possible to eliminate the need for joining other members to the fins 12 and the like, and the plate portions 13 and 14 can be easily formed.

  In addition, plate members corresponding to the plate portions 13 and 14 may be joined to the fin surfaces 121 of the respective fins 12. When joining plate members, slits are formed in advance at positions where the plate portions 13 and 14 of the fins 12 are formed, and plate members straddling a plurality of fins 12 are inserted and joined. May be.

  Here, a case is shown in which a pair of plate portions 13 and 14 are provided on the fin 12 on the downstream side of the heat transfer tube 11 and in the vicinity of the uppermost portion of the heat transfer tube 11. However, the configuration and arrangement of the plate portion are not limited to this and can be changed as appropriate. For example, a single plate portion may be provided, or three or more plate portions may be provided. Further, the plate portions 13 and 14 may be disposed at a position other than the vicinity of the uppermost portion of the heat transfer tube 11 on condition that the plate portions 13 and 14 are disposed in the region A.

  Here, the flow mode of the heat exchange air in the heat exchanger 1 according to the present embodiment will be described with reference to FIGS. 2 and 3. In FIG.2 and FIG.3, the part of the direction where heat exchange air flows is shown with the broken-line arrow. As described above, the heat exchange air is sucked up by a blower (not shown) and circulates from the lower side to the upper side of the heat exchanger 1. When the sucked heat exchange air reaches the fin tube 10, it is introduced between the plurality of fins 12 (fin surfaces 121) (see FIG. 2).

  The heat exchange air introduced between the fins 12 travels upward and hits the outer peripheral surface 11 a of the heat transfer tube 11. And it flows further upward along the peripheral surface of the outer peripheral surface 11a (refer FIG. 3). In the region downstream of the heat transfer tube 11 in the heat exchange air flow direction (the region above the center of the heat transfer tube 11), part of the heat exchange air is away from the outer peripheral surface 11 a of the heat transfer tube 11. Flowing.

  The heat exchange air that has advanced to the downstream side of the heat transfer tube 11 flows so as to be attracted to the plate portions 13 and 14. This depends on the Coanda effect attracted by the arrangement and configuration of the plate portions 13 and 14. That is, the plate portions 13 and 14 are provided substantially perpendicular to the fin surface 121 as described above, and are along the flow direction of the heat exchange air (more specifically, parallel to the flow direction of the heat exchange air. Is arranged). The heat exchange air that has advanced to the downstream side of the heat transfer tube 11 entrains the surrounding fluid due to the effect of viscosity, but the flow of the fluid is inhibited from the side where the plates 13 and 14 are arranged. Drawn to the side. Therefore, the heat exchange air flows upward while being guided to the center of the heat transfer tube 11. The heat exchange air induced to the upper side further flows upward in the space between the fin surfaces 121 and flows out of the fins 12.

  In the heat exchanger 1 according to the present embodiment, the plate portions 13 and 14 provided substantially perpendicular to the fin surface 121 are on the downstream side of the heat transfer tube 11 in the heat exchange air flow direction, and Since the heat exchange air is arranged in the region A on the inner side of the outer peripheral surface 11a of the heat tube 11 along the flow direction of the heat exchange air, the heat exchange air that has flowed downstream of the heat transfer tube 11 is caused by the Coanda effect. Drawn to the side. Thereby, since heat exchange air can be made to go around to the upper side of heat exchanger tube 11, while the area where heat exchange air flows in fin 12 can be expanded, the area where heat exchange air hits the fin surface can be increased. In addition, since the plate portions 13 and 14 are disposed in the region A on the downstream side of the heat transfer tube 11 in the heat exchange air flow direction and inside the outer peripheral surface 11a of the heat transfer tube 11, The outer circumference does not increase significantly. As a result, the heat transfer rate can be sufficiently improved without increasing the size of the heat exchanger itself.

  Further, heat exchange air that flows in a direction away from the outer peripheral surface 11 a of the heat transfer tube 11 in a front view is guided by the Coanda effect so as to wrap around the heat transfer tube 11. Thereby, the one part area | region of the fin 12 which conventionally comprised the dead water area can be reduced. As a result, the area where the heat exchange air touches the surface of the fin 12 can be enlarged, so that the heat transfer coefficient can be improved.

  Further, the plate portions 13 and 14 have their front end portions (front end portions) in contact with the back surface of the fin surface 121 of the adjacent front fin 12 (see FIG. 2). Thereby, since the Coanda effect can be exhibited by utilizing the entire region between the fins 12 arranged in the front-rear direction, the heat exchange air that has flowed to the downstream side of the heat transfer tube 11 is effectively drawn toward the plate portions 13 and 14 side. Can do.

  In the above-described embodiment, the case where the fins 12 have an annular shape in front view is described. However, the shape of the fin 12 is not limited to this, and can be changed as appropriate. Any shape can be adopted for the fin 12 on the premise that the manufacturing process of the fin tube 10 is simplified. For example, you may employ | adopt the rectangular shape or polygonal fin 12 by front view.

  Further, in the above embodiment, the case where a plurality of fins 12 are joined to the heat transfer tube 11 has been described. However, the configuration of the fins 12 is not limited to this and can be changed as appropriate. For example, a configuration in which a long metal thin plate is prepared and this is joined to the outer peripheral surface 11 a of the heat transfer tube 11 in a spiral shape may be employed. Also in this case, the same effects as in the present embodiment can be obtained by providing the plate portions 13 and 14 in a predetermined region around the heat transfer tube 11.

  Furthermore, in the said embodiment, the case where the front-end | tip part (front-end part) of the plate parts 13 and 14 contacts the back surface of the fin surface 121 of the fin 12 of the adjacent front side is demonstrated. However, the tip portions of the plate portions 13 and 14 do not necessarily need to be in contact with the back surface of the fin surface 121 of the adjacent front fin 12. That is, a gap may be formed between the front end portions of the plate portions 13 and 14 and the back surface of the fin surface 121 of the front fin 12. Also in this case, the Coanda effect beyond a certain level can be expected by the plate portions 13 and 14 projecting forward from the surface of the fin surface 121.

  Furthermore, in the said embodiment, the case where the clearance gap 15 provided in the fin 12 adjacent in the front-back direction is arrange | positioned in the same position by a front view is demonstrated (refer FIG. 3). However, the positions of the gaps 15 are not limited to this, and can be changed as appropriate. For example, in the fins 12 adjacent in the front-rear direction, the gaps 15 may be arranged at different positions in the circumferential direction of the fins 12.

  In addition, this invention is not limited to the said embodiment, It can implement variously. In the above-described embodiment, the size and shape of members and holes shown in the attached drawings are not limited to this, and can be appropriately changed within a range in which the effects of the present invention are exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  As described above, the present invention has an effect that the transfer rate can be sufficiently improved without causing an increase in the size of the heat exchanger itself, and in particular, industrial heat installed in a power plant or the like. Useful for exchangers.

1: heat exchanger 10: fin tube 11: heat transfer tube 11a: outer peripheral surface 12: fin 121: fin surface 13, 14: plate portion 15: gap

Claims (2)

A plurality of heat transfer tubes arranged in a direction crossing the flow direction of the heat exchange air;
A plurality of fins arranged at regular intervals in the tube axis direction of the heat transfer tube,
The fin has a plate portion provided substantially perpendicular to the fin surface,
The plate portion is disposed on the downstream side of the heat transfer tube in the flow direction of the heat exchange air and in the region inside the outer peripheral surface of the heat transfer tube along the flow direction of the heat exchange air. A finned tube heat exchanger.   The fin tube heat exchanger according to claim 1, wherein a tip portion of the plate portion is in contact with a fin surface of the adjacent fin.

Images