JP2021165600A - Heat exchanger and water heating system with the same - Google Patents

Abstract

To provide a heat exchanger capable of cancelling a failure such as increasing of flow passage resistance of a meandering heat transfer pipe or generating of much residual stress in the heat transfer pipe, and appropriately attaining entire downsizing, and a water heating system with the same.SOLUTION: The present invention relates to a heat exchanger HE comprising a plurality of meandering heat transfer pipes 2, and first and second heat transfer pipes 2A and 2B which are adjacent to each other in a predetermined (y) direction and positionally displaced in a (z) direction in such a manner that a plurality of straight pipe parts 20 are in a non-overlapped state in a view in the (y) direction are included as the plurality of heat transfer pipes 2. In each bent pipe part 21 of at least the first heat transfer pipe 2A between the first and second heat transfer pipes 2A and 2B, a first recess 3A is provided for partially reducing a thickness in the (y) direction at a position overlapped with each bent pipe part 21 of the second heat transfer pipe 2B, and a portion of each bent pipe part 21 of the second heat transfer pipe 2B is fitted into the first recess 3A.SELECTED DRAWING: Figure 2

Description

The present invention relates to a heat exchanger of a type that is used as a component of a water heating device such as a hot water supply device and recovers heat from a heating medium such as combustion gas by using a heat transfer tube, and a hot water device including the heat exchanger.

As an example of the heat exchanger, there is one described in Patent Document 1.
In the heat exchanger described in the same document, a meandering heat transfer tube is used as a heat transfer tube for recovering heat from the combustion gas. The meandering heat transfer tube has a configuration in which a plurality of straight tube portions are connected via a plurality of curved tube portions. In the above document, a plurality of heat transfer tubes are used as such meandering heat transfer tubes, and these are laminated in the vertical height direction, for example. Further, the heat transfer tubes adjacent to each other are set in an array displaced in a substantially horizontal direction, for example, so that the combustion gas can easily act on each heat transfer tube.

On the other hand, of the heat transfer tubes, the curved tube portion is processed into a flat shape and has a thickness smaller than that of the straight tube portion. This makes it possible to bring heat transfer tubes adjacent to each other close to each other. As a result, it is possible to reduce the width of the entire plurality of heat transfer tubes in the stacking direction and reduce the size of the entire heat exchanger.

However, according to the prior art, there is still room for improvement, as described below.

First, since the entire curved tube portion of the meandering heat transfer tube is formed in a flat shape, there is a disadvantage that the resistance (flow path resistance) when the fluid to be heated flows through the inside of the heat transfer tube becomes large. be.
Secondly, since the amount of processing for forming the entire curved tube portion into a flat shape is large, the residual stress becomes large. This causes stress cracking in the heat transfer tube, which is not preferable. When using a heat exchanger, a large pressure may act on the heat transfer tube due to, for example, a water hammer phenomenon, so it is desirable to reduce the above-mentioned residual stress as much as possible.
Thirdly, as a means for flattening each curved tube portion of the meandering heat transfer tube, for example, as shown in FIG. 13, the bending direction of the curved tube portion 21 with respect to the curved tube portion 21 of the heat transfer tube 2e Is conceivable as a means of pressing in the intersecting direction. However, when such press working is performed, as shown by the arrow Na, a force is generated in which both ends of the curved tube portion 21 tend to be deformed in the opening direction. In Patent Document 1, since the amount of press working is large, the above-mentioned deformation is likely to occur, and the heat transfer tube 2e may differ from the original specifications.

Japanese Patent No. 4143431

The present invention has been conceived under the above-mentioned circumstances, and has problems such as an increase in the flow path resistance of the meandering heat transfer tube and a large amount of residual stress generated in the heat transfer tube. The challenge is to provide a heat exchanger that can be solved and that can appropriately reduce the overall size, and a water heater equipped with the heat exchanger.

In order to solve the above problems, the following technical measures are taken in the present invention.

In the heat exchanger provided by the first aspect of the present invention, a plurality of straight pipe portions extending in a predetermined x direction and arranged at intervals in the z direction intersecting the x direction are arranged in a plurality of curved pipes. A plurality of heat transfer tubes are provided in a serpentine shape connected in a series via a portion and are stacked and arranged in the y direction intersecting the x and z directions in the region where the heating medium is circulated. As these plurality of heat transfer tubes, the plurality of straight tube portions are adjacent to each other in the y direction, and the plurality of straight tube portions are in a non-overlapping state, and a part of the plurality of curved tube portions is in an overlapping state. A heat exchanger having first and second heat transfer tubes displaced in the z direction, and at least each of the first heat transfer tubes of the first and second heat transfer tubes. In the curved tube portion, the thickness of the portion of the second heat transfer tube that overlaps with each of the curved tube portions in the y direction is partially reduced as compared with the other portions of the curved tube portion. The recess is provided, and a part of each curved tube portion of the second heat transfer tube is fitted into the first recess.

According to such a configuration, of the meandering first and second heat transfer tubes adjacent to each other, a second recess is provided in at least a curved tube portion of the first heat transfer tube. Since a part of each curved tube portion of the heat transfer tube is fitted, the arrangement pitch of the first and second heat transfer tubes in the y direction can be reduced. As a result, it is possible to reduce the overall width of the plurality of heat transfer tubes in the y direction and reduce the size of the heat exchanger. Further, according to the present invention, in addition to such an effect, the following effects can be further obtained.
First, unlike Patent Document 1, the entire curved tube portion of the heat transfer tube is not formed in a flat shape, and only a first recess is partially provided in a part of the curved tube portion. , The resistance (flow path resistance) when the fluid to be heated flows through the inside of the heat transfer tube can be reduced.
Secondly, as compared with the means for forming the entire curved pipe portion of Patent Document 1 into a flat shape, the processing for partially providing the first concave portion in the curved pipe portion has a smaller amount of processing and residual stress. Can be made smaller. Therefore, it is possible to prevent stress cracking in the heat transfer tube, and it is possible to give the heat transfer tube sufficient durability against, for example, a water hammer phenomenon.
Thirdly, when the curved tube portion is pressed as a means for forming the first concave portion in the curved tube portion of the heat transfer tube, the press working amount can be reduced. Therefore, unlike the case described with reference to FIG. 13, it is avoided that the heat transfer tube is significantly deformed in the direction in which both ends of the curved tube portion are opened, and the heat transfer tube may be different from the original specifications. Can be properly resolved.

In the present invention, preferably, the first recesses are provided in pairs on both side surfaces of the first heat transfer tube facing each other in the y direction.

According to such a configuration, as compared with the case where the first recess is provided only on one side of the predetermined both side surfaces of each curved pipe portion, the depth of each first recess is reduced and the first and second recesses are provided. It is possible to reduce the arrangement pitch of the heat transfer tubes in the y direction. If the depth of the first recess is increased, the residual stress due to the processing of the first recess may be increased. However, according to the above configuration, the heat transfer tubes are arranged while avoiding such a risk. It is possible to reduce the pitch.

In the present invention, preferably, the first recess is provided only on one of the side surface portions of the first heat transfer tube facing each other in the y direction.

According to such a configuration, the structure of the heat transfer tube can be simplified as compared with the case where the first recesses are provided in pairs on both sides of the predetermined both side surface portions of each curved tube portion.

In the present invention, preferably, each of the curved tube portions of the second heat transfer tube has a second recess that partially reduces the thickness in the y direction as compared with other portions of the curved tube portion. It is provided, and the formed portions of the first and second recesses are fitted to each other.

According to such a configuration, it is possible to reduce the arrangement pitch of the plurality of heat transfer tubes in the y direction while reducing the depth of each of the first and second recesses. Therefore, it is more preferable in reducing the residual stress caused by forming the first and second recesses. Further, as compared with the configuration in which only the first recess is provided, it is possible to make the arrangement pitch of the plurality of heat transfer tubes in the y direction smaller and further promote the miniaturization of the heat exchanger.

In the present invention, preferably, the second heat transfer tube has a structure in which a heat transfer tube having the same shape and size as the first heat transfer tube is turned upside down.

According to such a configuration, the manufacturing cost of the heat exchanger can be reduced as compared with the case where the first and second heat transfer tubes having different shapes and sizes are used.

The water heating device provided by the second aspect of the present invention is characterized by comprising the heat exchanger provided by the first aspect of the present invention.

With such a configuration, the same effect as described for the heat exchanger provided by the first aspect of the present invention can be obtained.

Other features and advantages of the present invention will become more apparent from the following description of embodiments of the invention with reference to the accompanying drawings.

It is a schematic perspective view which shows an example of the heat exchanger which concerns on this invention. The schematic configuration of the water heating device using the heat exchanger of FIG. 1 is shown, and the heat exchanger shown by the solid line in the figure corresponds to the cross-sectional view II-II of FIG. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. It is a perspective view which shows the heat transfer tube (the 1st and 2nd heat transfer tubes) used in the heat exchanger shown in FIGS. 1 to 3. (A) is a front view of a main part of the heat transfer tube shown in FIG. 4, (b) is a cross-sectional view of Vb-Vb of (a), and (c) is a side surface of the arrow Vc of (a). It is a figure, (d) is a cross-sectional view of Vd-Vd of (a), and (e) is a cross-sectional view of Ve-Ve of (a). (A) is a front view of a main part in a state where the heat transfer tubes shown in FIG. 5 are stacked, (b) is a sectional view taken along line VIb-VIb of (a), and (c) is a sectional view of (a). It is a cross-sectional view of VIc-VIc. It is a perspective view which shows the other example of this invention. (A) is a front view of a main part of the heat transfer tube shown in FIG. 7, (b) is a cross-sectional view of VIIIb-VIIIb of (a), and (c) is a cross-sectional view of VIIIc-VIIIc of (a). Is. It is a perspective view which shows the other example of this invention. (A) is a front view of a main part of the heat transfer tube shown in FIG. 9, (b) is a cross-sectional view of Xb-Xb of (a), and (c) is a cross-sectional view of Xc-Xc of (a). Is. It is a perspective view which shows the other example of this invention. (A) is a front view of a main part of the heat transfer tube shown in FIG. 11, (b) is a cross-sectional view of XIIb-XIIb of (a), and (c) is a cross-sectional view of XIIc-XIIc of (a). Is. It is explanatory drawing which shows the operation in the prior art.

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

The heat exchanger HE shown in FIGS. 1 to 3 includes a case 1, a plurality of meandering heat transfer tubes 2, and a pair of header portions 7a and 7b for entering and discharging water.

The case 1 has a substantially rectangular cylindrical shape or a frame shape with an upper surface portion and a lower surface portion opened, and a heating medium is supplied to the inside of the case 1.
FIG. 2 shows a water heating device WH using the heat exchanger HE. In this water heating device WH, a burner 80 and another heat exchanger 81 are provided on the upper side of the case 1. The other heat exchanger 81 is a primary heat exchanger for recovering sensible heat, and the heat exchanger HE of the present embodiment is a secondary heat exchanger for recovering latent heat. In the water heating device WH, the combustion gas (heating medium) generated by the burner 80 travels downward and passes through the heat exchangers 81 and HE in sequence, so that sensible heat and latent heat are sequentially recovered from the combustion gas. Hot water heating is performed using this recovered heat. This hot water is supplied to, for example, a hot water tap in a kitchen, a hot water tap in a bathroom, or a bathtub.

The plurality of heat transfer tubes 2 are made of a metal such as stainless steel, are meandering heat transfer tubes, and are housed in the case 1.
More specifically, as shown in FIG. 3, each heat transfer tube 2 extends in the front-rear direction (an example of the x-direction in the present invention) of the case 1 and in the vertical-height direction (referred to in the present invention). A plurality of straight pipe portions 20 arranged at intervals in the z direction) are spirally connected in a series via a plurality of curved pipe portions 21 having a semi-arc shape in a side view.
Both ends of each heat transfer tube 2 penetrate the side wall portion 10 of the case 1 and are connected to header portions 7a and 7b provided on the outer surface side of the side wall portion 10. As a result, the hot water supplied from the outside to the header portion 7a passes through each heat transfer tube 2 and reaches the header portion 7b, where the hot water is discharged. In such a process, the hot water is heated by the combustion gas.

The plurality of heat transfer tubes 2 are divided into first and second heat transfer tubes 2A and 2B, and these are provided with first and second recesses 3A and 3B. This point will be described in more detail below.

The plurality of heat transfer tubes 2 are arranged in the width direction of the case 1 (the left-right direction in FIG. 2, which is an example of the y direction in the present invention), but the heat transfer tubes 2 adjacent to each other are in the vertical height direction. It is provided with a position shift by an appropriate size La. In the present embodiment, the low height side is the first heat transfer tube 2A (2), and the high height side is the second heat transfer tube 2B (2). The first and second heat transfer tubes 2A and 2B are misaligned so that the plurality of straight tube portions 20 do not overlap each other in the vertical height direction. However, a part of the plurality of curved pipe portions 21 overlap each other (the portion indicated by the reference numeral OV in FIG. 3 is the overlapping portion OV).

As shown in FIG. 4, the first recess 3A is provided in a portion of each curved tube portion 21 of the first heat transfer tube 2A, which corresponds to the overlap portion OV described above. As is well shown in FIG. 5, the first recess 3A is arranged offset from the center line CL of the curved pipe portion 21, and the left and right side surface portions of the curved pipe portion 21 (both side surface portions facing in the y direction). The left and right pairs are provided so as to face each other. As a result, the width Lb of the formed portion of the pair of first recesses 3A of the curved tube portion 21 is smaller than the width Lc of the other portion (corresponding to the outer diameter of the heat transfer tube 2). The first recess 3A can be formed by partially pressing the curved pipe portion 21.

The second recess 3B is provided in each of the curved tube portions 21 of the second heat transfer tube 2B at a portion corresponding to the overlap portion OV described above. Here, the second heat transfer tube 2B in the present embodiment corresponds to a configuration in which the first heat transfer tube 2A is turned upside down. Therefore, the second recess 3B is provided on the left and right side surface portions of each curved pipe portion 21 in pairs of left and right facing each other, similarly to the first recess 3A described above.
The plurality of first and second heat transfer tubes 2A and 2B are in a state in which the formed portion of the first recess 3A and the formed portion of the second recess 3B are fitted to each other, that is, the first recess 3A is second. The formed portion of the concave portion 3B of the above is fitted, and the formed portion of the first concave portion 3A is fitted into the second concave portion 3B) (see FIGS. 2 and 6).

Next, the operation of the heat exchanger HE described above will be described.

First, as described above, in the overlapping portion OV of the curved pipe portions 21 of the first and second heat transfer tubes 2A and 2B, the widths of the first and second recesses 3A and 3B are reduced. The formed parts are fitted together. Therefore, the straight pipe portions 20 of the first and second heat transfer tubes 2A and 2B are overlapped with each other in the lateral width direction of the case 1 by an appropriate dimension Ld as shown in a partially enlarged view of FIG. It is possible to arrange them in a different manner. Therefore, the overall width L1 of the plurality of heat transfer tubes 2 can be reduced, and the size of the heat exchanger HE can be reduced.

The first and second recesses 3A and 3B are only partially provided in each curved pipe portion 21. Therefore, due to the presence of the first and second recesses 3A and 3B, it is possible to prevent the flow path resistance when hot water flows inside the heat transfer tube 2 from becoming considerably large, and to allow water to flow to the heat transfer tube 2. It is possible to prevent the risk of suffering from the problem. Further, when the first and second recesses 3A and 3B are provided in each curved pipe portion 21 by press working, the first and second recesses 3A and 3B may have a relatively small size, so that the press working amount ( The amount of deformation) can be reduced. Therefore, it is possible to reduce the residual stress due to press working and to have excellent durability. Further, if the amount of press working on the curved tube portion 21 is large, the heat transfer tube 2 may be deformed so that both ends of the curved tube portion 21 are opened. However, in the present embodiment, such a risk is eliminated. Is possible.

7 to 12 show other embodiments of the present invention. In these figures, elements that are the same as or similar to those of the embodiment are designated by the same reference numerals as those of the embodiment.

In the embodiment shown in FIGS. 7 and 8, the first and second recesses 3A and 3B are provided only on one side of the left and right side surface portions of the curved pipe portions 21 of the first and second heat transfer tubes 2A and 2B, respectively. The first and second recesses 3A and 3B are not provided on the opposite side. The second heat transfer tube 2B corresponds to a configuration in which the first heat transfer tube 2A is turned upside down, as in the above embodiment.
As is clearly shown in FIG. 8 (c), on one side of the curved tube portion 21 of the first heat transfer tube 2A, the formed portion of the second recess 3B is fitted into the formed portion of the first recess 3A. There is. On the other hand, on one side of the curved tube portion 21 of the first heat transfer tube 2A opposite to the above, the positions where the first and second recesses 3A and 3B are not formed are in opposite contact or close to each other. It is said that.

In the present embodiment, as shown in FIG. 8B, the straight pipe portions 20 of the first and second heat transfer tubes 2A and 2B may be overlapped with each other by an appropriate size Le in the lateral width direction of the case 1. can. Therefore, similarly to the above-described embodiment, the overall width of the plurality of heat transfer tubes 2 (2A, 2B) can be reduced. Compared with the embodiment in which the first and second recesses 3A and 3B are provided on the left and right side surface portions of the curved tube portion 21, it is possible to simplify the configuration of each heat transfer tube 2.

In the embodiment shown in FIGS. 9 and 10, the first heat transfer tube 2A is provided with a pair of first recesses 3A on the left and right side surfaces of each curved tube portion 21, whereas the second heat transfer tube 2A is provided with a pair of first recesses 3A. The heat transfer tube 2B is not provided with a portion corresponding to the second recess 3B. As the second heat transfer tube 2B, an existing meandering tube can be used.
As is clearly shown in FIG. 10 (c), a part of the curved tube portion 21 of the second heat transfer tube 2B is fitted as it is into the pair of first recesses 3A of the first heat transfer tube 2A. ..

In the present embodiment, as shown in FIG. 10B, the straight pipe portions 20 of the first and second heat transfer tubes 2A and 2B may be overlapped with each other by an appropriate dimension Lf in the lateral width direction of the case 1. can. Therefore, similarly to the above-described embodiment, it is possible to reduce the overall width of the plurality of heat transfer tubes 2 (2A, 2B). As the second heat transfer tube 2B, an existing heat transfer tube having no second recess 3B can be used, so that the manufacturing cost can be reduced.

In the embodiment shown in FIGS. 11 and 12, the first heat transfer tube 2A is provided with the first recess 3A only on one side of the left and right side surface portions of each curved tube portion 21. The second heat transfer tube 2B is not provided with a portion corresponding to the second recess 3B.
As is clearly shown in FIG. 12 (c), a part of the curved tube portion 21 of the second heat transfer tube 2B is fitted in the first recess 3A of the first heat transfer tube 2A. On the other hand, the outer peripheral surface of the curved tube portion 21 of the second heat transfer tube 2B is in contact with or close to one side opposite to the first recess 3A.

In the present embodiment, as shown in FIG. 12B, the straight pipe portions 20 of the first and second heat transfer tubes 2A and 2B may be overlapped with each other by an appropriate dimension Lg in the lateral width direction of the case 1. can. Therefore, similarly to the above-described embodiment, it is possible to reduce the overall width of the plurality of heat transfer tubes 2 (2A, 2B). As the second heat transfer tube 2B, an existing heat transfer tube having no second recess 3B can be used, and the first heat transfer tube 2A is provided with the first recess 3A on only one side. Therefore, it is possible to reduce the manufacturing cost.

The present invention is not limited to the contents of the above-described embodiments. The specific configuration of each part of the heat exchanger and the water heating device according to the present invention can be variously redesigned within the scope intended by the present invention.

The specific shape, size, depth, etc. of the first and second recesses are not limited. The shapes and the like may be different depending on whether the heat transfer tube is provided on the left and right side surfaces of the curved tube portion or only on one side thereof.
In the above-described embodiment, of the plurality of heat transfer tubes displaced in the vertical height direction, one on the lower side is referred to as the first heat transfer tube and the other is referred to as the second heat transfer tube. The embodiment may be reversed from the above-described embodiment.
Further, in the above-described embodiment, the x and y directions referred to in the present invention are substantially horizontal directions, and the z direction corresponds to the vertical height direction, but the present invention is not limited to these, and these The direction can be selected as appropriate. For example, it is possible to have a configuration in which a plurality of heat transfer tubes lying in a substantially horizontal direction are stacked (arranged) in the vertical height direction, that is, a configuration in which the y direction is the vertical height direction. In this case, the width of the entire plurality of heat transfer tubes in the vertical height direction can be reduced to reduce the size of the heat exchanger.

The heat transfer tube has a meandering shape, but the specific size, number, material, etc. of the straight tube portion and the curved tube portion are not limited. The heat transfer tube can be formed by bending a single tube body member, but instead, the straight tube portion and the curved tube portion are formed by separate members, and these are integrally formed. It can also be configured to be connected.

The heating medium referred to in the present invention is not limited to the combustion gas generated by the burner, and may be high-temperature exhaust gas or the like.
The heat exchanger according to the present invention can be used for anything other than latent heat recovery.
The water heater referred to in the present invention is a concept including not only a water heater for general hot water supply and bath hot water supply, but also a water heater for hot water heating or snow melting.

HE heat exchanger WH water heater 1 case 2 heat transfer tubes 2A, 2B 1st and 2nd heat transfer tubes (heat transfer tubes)
3A, 3B 1st and 2nd recesses

Claims (6)

A plurality of straight pipe portions extending in a predetermined x direction and intersecting the x direction at intervals in the z direction are connected in a series via a plurality of curved pipe portions, and are for heating. A plurality of heat transfer tubes stacked in the y direction intersecting the x and z directions are provided in the area where the medium circulates.
As these plurality of heat transfer tubes, the plurality of straight pipe portions are adjacent to each other in the y direction, and the plurality of straight pipe portions are in a non-overlapping state, and a part of the plurality of curved pipe portions is in an overlapping state. A heat exchanger having first and second heat transfer tubes displaced in the z direction.
Of the first and second heat transfer tubes, at least each of the curved tube portions of the first heat transfer tube is provided with a thickness in the y direction of a portion that overlaps with each of the curved tube portions of the second heat transfer tube. , A first recess is provided which is partially smaller than the other parts of each curved pipe portion.
A heat exchanger characterized in that a part of each curved tube portion of the second heat transfer tube is fitted in the first recess. The heat exchanger according to claim 1.
A pair of heat exchangers are provided on both side surfaces of the first heat transfer tube, which face each other in the y direction, of the curved tube portions of the first heat transfer tube. The heat exchanger according to claim 1.
The first recess is a heat exchanger provided on only one of both side surface portions of the first heat transfer tube facing each other in the y direction of the curved tube portion. The heat exchanger according to any one of claims 1 to 3.
Each of the curved tube portions of the second heat transfer tube is provided with a second recess that partially reduces the thickness in the y direction as compared with other portions of the curved tube portion. A heat exchanger in which the formed portions of the first and second recesses are fitted to each other. The heat exchanger according to any one of claims 1 to 4.
The second heat transfer tube is a heat exchanger in which a heat transfer tube having the same shape and size as the first heat transfer tube is turned upside down. A water heating device comprising the heat exchanger according to any one of claims 1 to 5.

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