JP6756972B2 - Heat exchanger and hot water supply device equipped with this - Google Patents

Description

The present invention relates to a heat exchanger for recovering heat from a heating gas such as a combustion gas generated by a burner, and a hot water supply device provided with the heat exchanger.

A specific example of a heat exchanger for a hot water supply device is described in Patent Document 1.
In the heat exchanger described in the same document, headers for entering and discharging water are attached to both ends of a plurality of heat transfer tubes for recovering heat from the combustion gas generated by the burner. Of the plurality of heat transfer tubes, the portion near the header for entering water is formed as a bent portion bent downward.
According to such a configuration, when draining water from each heat transfer tube to the outside for the purpose of preventing freezing in each heat transfer tube in winter, the water in each heat transfer tube is used for entering water. It is possible to flow smoothly into the header. If each heat transfer tube has a small diameter in order to improve the heat exchange efficiency of the heat exchanger, a water film will be generated at the end opening of each heat transfer tube due to surface tension when draining water. This may make it difficult to drain water. On the other hand, according to the above-described configuration, it is possible to prevent the water film from being generated by utilizing the head pressure of water existing in the bent portion of the heat transfer tube, and to appropriately perform the water draining operation.

However, according to the above-mentioned prior art, the following problems may occur.
That is, it is necessary to form a bent portion in each heat transfer tube to generate the above-mentioned head pressure, but due to space restrictions or other restrictions such as specification conditions, the bent portion is formed in each heat transfer tube. May not be able to form. In such a case, it may not be possible to appropriately eliminate the formation of a water film at the end opening of each heat transfer tube during the water draining operation, and it may be difficult to drain the water.

JP-A-2007-333343

The present invention has been conceived under the above-mentioned circumstances, and the water film generated at the end opening of the heat transfer tube makes it difficult to drain water from the heat transfer tube. It is an object of the present invention to provide a heat exchanger that can be appropriately eliminated by simple means, and a hot water supply device equipped with the heat exchanger.

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

The heat exchanger provided by the first aspect of the present invention forms inside a plurality of heat transfer tubes for recovering heat from the heating gas and a chamber communicating with the end opening of each of these heat transfer tubes. A heat exchanger, the drainage member arranged in the chamber of the header, comprising a header that is provided and has an opening for entering or exiting water from the outside to the chamber. Further provided, the drainage member is provided in connection with a first portion located outside the end opening of each of the heat transfer tubes and the first portion, and is present in the end opening. It is characterized in that it includes a second portion in which at least a part of the water can be transmitted to the first portion and has entered the end opening.

According to such a configuration, the following effects can be obtained.
That is, when draining water from each heat transfer tube, the water existing in the end opening of each heat transfer tube is transmitted from the second part to the first part of the drainage member, and the water transfer tube is used. It can be leaked to the outside. For this reason, it is possible to prevent a water film from being formed at the end opening of each heat transfer tube and to appropriately drain water from each heat transfer tube, and the water remaining in each heat transfer tube freezes in winter. The problem can be solved.
Unlike Patent Document 1, it is not necessary to provide a bent portion at the end of the heat transfer tube to generate a large head pressure. Further, since the drainage member is housed in the header, there is no problem that the heat exchanger becomes large.

In the present invention, preferably, the second portion is in the form of a plate piece having a thickness smaller than the length and width, and the first portion is connected at an angle intersecting the base of the second portion. Has a surface.

According to such a configuration, the following effects can be obtained.
That is, if the second portion is in the shape of the plate piece described above, the surface area of the second portion can be increased while decreasing the volume. If the volume of the second portion is small, the opening area of the end opening of the heat transfer tube can be prevented from being too narrowed by the second portion. Further, if the surface area of the second portion is increased, the water in the end opening of the heat transfer tube can be easily transferred to the second portion. On the other hand, if the first portion has a surface connected at an angle intersecting the base portion of the second portion, water can be easily transmitted from the base portion of the second portion to the first portion. Therefore, it is possible to improve the drainage property at the time of draining work.

In the present invention, preferably, the header forms the chamber between the header main body portion joined to the end portion of each heat transfer tube and the header main body portion joined to the header main body portion. The header lid member is provided, and the drainage member is fixed to the header by sandwiching the first portion between the header main body and the header lid member. ..

According to such a configuration, the positioning and fixing of the drainage member in the header can be rationally performed by a simple configuration. It is possible to eliminate the need for special parts for fixing the drainage member.

In the present invention, preferably, the drainage member has a base plate portion arranged in contact with or close to the end portion of each heat transfer tube, and projects from the base plate portion toward the end opening of each heat transfer tube. It has a plurality of convex portions, the base plate portion is the first portion, and each convex portion is the second portion.

According to such a configuration, it is possible to appropriately obtain the action intended by the present invention while simplifying the configuration of the drainage member.

In the present invention, preferably, the base plate portion is provided with a through hole facing the end opening of each of the heat transfer tubes.

According to such a configuration, even when the base plate portion of the drainage member is brought into contact with or considerably close to the end portion of the heat transfer tube, the end opening portion is unreasonably closed by the base plate portion. It is possible to prevent the heat transfer tube from being in a state or a state close to this, and to appropriately secure the water permeability of the end opening of the heat transfer tube.

In the present invention, preferably, each of the convex portions is a cut-up shape integrally formed with the base plate portion so as to bend and stand up from the peripheral edge portion of the through hole.

According to such a configuration, the production of the drainage member can be facilitated, and the production cost thereof can be reduced.

The hot water supply device provided according to the second aspect of the present invention is a hot water supply device provided with a heat exchanger for heating hot water by recovering heat from the heating gas, as the heat exchanger. , The heat exchanger provided by the first aspect of the present invention is used.

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 perspective view which shows an example of the heat exchanger which concerns on this invention. It is an exploded perspective view of the main part of the heat exchanger shown in FIG. FIG. 3 is a sectional view taken along line III-III of FIG. FIG. 6 is a sectional view taken along line IV-IV of FIG. (A) is a cross-sectional view of Va-Va of FIG. 1, (b) is a cross-sectional view of Vb-Vb of (a), and (c) is a cross-sectional view of Vc-Vc of (a). It is an enlarged exploded perspective view of the main part of FIG. It is sectional drawing of FIG. (A) is a front view of arrow view VIIIa of the drainage member shown in FIG. 6, (b) is a rear view of arrow view VIIIb, and (c) is VIIIc-VIIIc of (b). It is a sectional view. It is a perspective view which shows an example of the hot water supply apparatus provided with the heat exchanger shown in FIG. It is sectional drawing of the main part which shows the other example of this invention. (A) to (c) are cross-sectional views of a main part showing another example of the present invention.

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

The heat exchanger HE shown in FIGS. 1 and 2 includes a case 1, a plurality of heat transfer tubes 2 housed in the case 1, and a pair of headers H and Ha for entering and discharging water. Inside the header H for entering water, a drainage member 3 is incorporated to prevent a water film from being formed at the end opening 20 of the heat transfer tube 2 when water is drained from the heat transfer tube 2.

As shown in FIGS. 3 and 4, the case 1 has a substantially rectangular parallelepiped shape as a whole, and an air supply port 11 for allowing a combustion gas as a heating gas to flow into the case 1 is provided on the rear wall portion 10a. ing. Further, an exhaust port 12 for discharging the combustion gas (exhaust gas) after heat recovery by the heat transfer tube 2 to the outside of the case 1 is provided on the front wall portion 10b. Each heat transfer tube 2 has, for example, a meandering shape in a plan view, and a plurality of straight tube body portions 22 extending in the lateral width direction of the case 1 and a plurality of substantially semicircular arc-shaped body portions 22 connecting the plurality of straight tube body portions 22. It has a curved tube body portion 23. The plurality of heat transfer tubes 2 are laminated in the vertical height direction so that adjacent ones in the vertical height direction are displaced by an appropriate dimension in the front-rear direction of the case 1.

Both ends 2a of each heat transfer tube 2 penetrate the side wall portion 10c of the case 1, and headers H and Ha for entering and discharging water are attached. Each heat transfer tube 2 is set to be inclined forward and downward. This inclination is useful for allowing the hot water in each heat transfer tube 2 to flow into the header H for water entry by gravity when draining water from each heat transfer tube 2 for freeze prevention or the like. In the heat exchanger HE of the present embodiment, water is drained from each heat transfer tube 2 from the header H side for entering water at a low position.

In FIG. 2, each of the headers H and Ha for entering and discharging water includes a header main body 4 and a header lid member 5. Since the drainage member 3 is for appropriately draining water from each heat transfer tube 2, as described above, it is incorporated in the header H for entering water, but the header Ha for discharging hot water Not built into. The header body 4 and the header lid member 5 of the header Ha for hot water have the same basic configuration as those of the header H for entering water.

As well shown in FIGS. 6 and 7, the header main body 4 includes a back plate portion 40 provided with a plurality of holes 42 through which the end portions 2a of the plurality of heat transfer tubes 2 are inserted, and a back plate portion 40 thereof. It has a substantially cup shape having a substantially oval or substantially rectangular peripheral wall portion 41 projecting from the outer peripheral edge of the back plate portion 40. The header lid member 5 has a back plate portion 50 to which a joint pipe 53 for connecting an external pipe is joined and an opening 52 for entering water, and a substantially length projecting from the outer peripheral edge of the back plate portion 50. It has a circular or substantially rectangular peripheral wall portion 51. The header body 4 and the header lid member 5 are fitted to each other and joined by means such as brazing, and a chamber 48 communicating with the end opening 20 of each heat transfer tube 2 is connected between them. Is formed (see FIG. 5). The header body 4 and the end 2a of each heat transfer tube 2 are also joined to each other by means such as brazing.

The drainage member 3 is formed by pressing a thin metal plate made of stainless steel or the like, and forms on the base plate portion 31, a plurality of convex portions 32 protruding from the base plate portion 31 to one side, and the base plate portion 31. It includes a plurality of through holes 30 provided, and a plurality of positioning pieces 33 projecting from the outer peripheral edge of the base plate portion 31. The plurality of convex portions 32 and the plurality of positioning pieces 33 are integrally formed on the base plate portion 31. The base plate portion 31 corresponds to an example of the "first portion" in the present invention, and each convex portion 32 corresponds to an example of the "second portion" in the present invention.

As shown in FIG. 5, the base plate portion 31 is a plate-shaped portion having a shape and size that can be fitted inside the peripheral wall portion 41 of the header main body portion 4, and in the present embodiment, the end portion 2a of the heat transfer tube 2 (Strictly speaking, it is arranged so as to be in contact with the end face 2a'). The plurality of convex portions 32 and the through holes 30 are provided in an arrangement corresponding to the end portions 2a of the plurality of heat transfer tubes 2, and each convex portion 32 enters the end opening 20 of each heat transfer tube 2. However, each through hole 30 is set so as to face the end opening 20 of each heat transfer tube 2. Each convex portion 32 is bent and stands up from the peripheral edge portion of each through hole 30, and is formed by subjecting the base plate portion 31 to a so-called cut-up process (see also FIG. 8).

Preferably, as shown in FIGS. 5A and 5C, each convex portion 32 has a plate piece shape having a thickness t smaller than its length L and width W, and each convex portion 32. It is configured so that the surface area (contact area with water) is slightly larger while reducing the volume of. Both the front and back surfaces of the base plate portion 31 are surfaces that intersect and are connected to the base portion of each convex portion 32. As will be described later, such a surface has an effect of facilitating the transfer of water in the end opening 20 of the heat transfer tube 2 from the base of each convex portion 32 to the base plate portion 31 when draining water in the heat transfer tube 2. Can bring.

The positioning and fixing of the drainage member 3 is achieved by sandwiching the plurality of positioning pieces 33 by the peripheral wall portions 41 and 51 of the header main body portion 4 and the header lid member 5, respectively. More specifically, as shown in FIGS. 5A and 5C, a step portion for locking a bent tip portion of each positioning piece 33 is provided on the inner peripheral surface of the peripheral wall portion 41 of the header main body portion 4. 43 is formed, and the bent tip portion of each positioning piece 33 is clamped by both the step portion 43 and the tip portion of the peripheral wall portion 51 of the header lid member 5.

Preferably, as shown in FIGS. 6 and 7, the tip of the peripheral wall portion 51 of the header lid member 5 is provided with a plurality of small-sized convex portions 54 for facing contact with the plurality of positioning pieces 33. There is. By providing such a plurality of convex portions 54, it is possible to reliably and firmly press each of the plurality of positioning pieces 33 by the header lid member 5. In FIGS. 5A and 5C, the outer surface side of the base portion of the plurality of positioning pieces 33 is formed so as to abut on the inner peripheral surface of the peripheral wall portion 41 of the header main body portion 4. As a result, the drainage member 3 is also positioned in the direction intersecting the axial length direction of the heat transfer tube 2 (directions of arrows N1 and N2). The drainage member 3 is preferably formed in a point-symmetrical shape. This is useful for eliminating the possibility that the drainage member 3 is incorporated in the header H by mistake in the vertical direction when the drainage member 3 is incorporated.

FIG. 9 shows an example of the hot water supply device WH provided with the heat exchanger HE described above.
This hot water supply device WH is mounted on a burner 60 for generating combustion gas, a fan 61 for supplying air for combustion, and a burner case 62, and is a primary heat exchanger for recovering sensible heat from the combustion gas. The heat exchanger HE is used as a secondary heat exchanger for recovering latent heat. The combustion gas after the actual heat recovery is supplied to the air supply port 11 of the heat exchanger HE via the auxiliary can body 79. The hot water to be heated is supplied to the water inlet header H of the heat exchanger HE, passes through the plurality of heat transfer tubes 2 and is heated, and then from the hot water discharge header Ha to the heat transfer tube 71 of the primary heat exchanger 7. It is supplied to the hot water supply destination and further heated, and then supplied to a predetermined hot water supply destination.

The primary heat exchanger 7 has a configuration in which a heat transfer tube 71 is housed in a can body 70. The heat transfer tube 71 is a tube with fins that is joined through a plurality of fins 72, and the heat is exposed. Since it is for recovery, a heat transfer tube 71 having a relatively large diameter is used. Therefore, with respect to the primary heat exchanger 7, there is no possibility that a water film will be formed when draining water from the heat transfer tube 71, and draining water will not be difficult. Therefore, the member corresponding to the drainage member 3 is not provided in the primary heat exchanger 7.

Next, the operation of the heat exchanger HE and the hot water supply device WH provided with the heat exchanger HE will be described.

First, when the hot water supply device WH is shut down for a long period of time in winter, water is drained from each heat transfer tube 2 in order to prevent freezing in the heat exchanger HE (transfer of the primary heat exchanger 7). The hot tube 71 is drained at the same time, but the description thereof will be omitted). The drainage of each heat transfer tube 2 is performed by allowing the water in each heat transfer tube 2 to flow into the header H for water entry in a state where the water supply to the header H for water entry is stopped.

When the heat transfer tube 2 is drained, even if the water existing in the end opening 20 of the heat transfer tube 2 tries to become a water film due to its surface tension, this water flows from the convex portion 32 of the drainage member 3 to the base plate. It is transmitted to the part 31 and flows out to the outside of the heat transfer tube 2. In the present embodiment, since the base plate portion 31 is in contact with the end surface 2a'of the heat transfer tube 2, the water that has reached the base plate portion 31 from the base portion of the convex portion 32 finally passes through the through hole 30. Is discharged to the outside of the heat transfer tube 2.

In the state where the convex portion 32 is in contact with water, the surface tension of the convex portion 32 (the interfacial tension acting at the interface between the convex portion 32 and the air) is such that the water is applied to the surface of the convex portion 32. It works as a force in the direction of moving along. Therefore, even if a water film is to be generated in the end opening 20, if the above-mentioned force is larger than a certain level, it is possible to obtain an action of preventing the water film from being generated by using this force. (The larger the surface area of the convex portion 32 and the higher the hydrophilicity of the convex portion 32, the greater the above-mentioned force can be increased). Further, if the water in the end opening 20 is continuously flowing through the drainage member 3 and the drainage member 3 is wet with a volume of water equal to or larger than the water film (water droplet size), The surface tension of the water also causes the water in the end opening 20 to be drawn toward the drainage member 3, and such an action also causes a water film preventing action.

According to the present embodiment, it is possible to prevent a water film from being formed at the end opening 20 by the above-mentioned action, and to appropriately prevent or suppress the generation of residual water in the heat transfer tube 2. As a result, it is possible to solve the problem that the residual water freezes and the heat transfer tube 2 is damaged. As described above, the heat transfer tube 2 is set to be inclined forward in consideration of draining water, but the inclination angle is relatively small, and the end of the heat transfer tube 2 is set at the time of draining water. The head pressure acting in the portion 2a is low. Therefore, when the diameter of the heat transfer tube 2 is reduced, a water film is inherently likely to be formed, but according to the present embodiment, such a problem can be appropriately eliminated.

As described above, since the convex portion 32 is in the shape of a plate piece having a thickness t smaller than the length L and the width W, its volume is small, and there is a problem that the end opening 20 of the heat transfer tube 2 is largely closed. Properly avoided. On the other hand, since the surface area of the convex portion 32 can be made large, it is possible to increase the amount of water that tends to flow to the base plate portion 31 side along the convex portion 32. This enhances the water film prevention effect. Further, the base plate portion 31 has a surface (both front and back surfaces) connected to the base portion of the convex portion 32 at an angle intersecting the base portion. According to such a configuration, water reaching the base portion of the convex portion 32 is the surface. Easy to progress to. Therefore, it is possible to improve the drainage property.

In the present embodiment, the drainage member 3 is incorporated in the header H as a means for appropriately performing the drainage work, but the drainage member 3 is relatively formed by pressing a metal plate. It can be manufactured at low cost. Further, since the positioning and fixing of the drainage member 3 in the header H is performed by sandwiching the positioning piece 33 of the drainage member 3 between the header main body 4 and the header lid member 5, the configuration is simple. And the assembly work is easy. Therefore, it is possible to appropriately avoid problems such as a significant increase in the manufacturing cost of the heat exchanger HE.

10 and 11 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, and duplicate description will be omitted.

In the embodiment shown in FIG. 10, the base plate portion 31 of the drainage member 3 is provided in a state of being separated from the end portion 2a of the heat transfer tube 2. The separation dimension La is preferably such that, when it is assumed that a water film is generated in the end opening 20, the water film is formed from the end 2a to the outside so that the base plate portion 31 comes into contact with the water film. It is less than or equal to the bulging size. However, since the water in the end opening 20 is attracted to the base plate portion 31 side by the surface tension of the convex portion 32 (the interfacial tension acting at the interface between the convex portion 32 and the air), the size is La or more. It is also possible to do.

FIG. 11 shows an example of the positional relationship between the heat transfer tube 2 and the convex portion 32. In FIGS. (A) and (b), the convex portion 32 is biased into the lower position or the upper position in the end opening 20 of the heat transfer tube 2. In FIG. 3C, the upper and lower ends of the convex portion 32 are in contact with the inner peripheral surface of the end opening 20. As can be seen from these examples, the convex portion 32 can enter the end opening 20 in various ways. It does not matter whether the heat transfer tube 2 is in contact or non-contact.
Although the illustration will be omitted, in the present invention, a plurality of convex portions 32 or similar portions may be inserted into the end opening 20 of one heat transfer tube 2.

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 hot water supply device according to the present invention can be variously redesigned within the scope intended by the present invention.

The drainage member does not necessarily have to be formed in a plate shape or a shape close to the whole, for example, a plurality of comb-shaped convex portions (second portion) on one side of the strip-shaped member (first portion). It can also be in the form of a protruding part). When the end openings of a plurality of heat transfer tubes are arranged in two rows, for example, by using two drainage members, these two drainage members are individually corresponded to the two rows of end openings. It is also possible to set it up. The second portion of the drainage member in the present invention preferably has a plate piece shape, but is not limited to this. It is also possible to adopt a means such as applying a hydrophilic treatment to the drainage member.

The header is not limited to the one that is configured separately from the case. For example, it can be configured by using the side wall portion of the case. To give a specific example, the header is formed by penetrating the side wall of the case through the end of the heat transfer tube to make this part the header body and joining the header lid member to the header body. Is possible.

The heat transfer tube is not limited to a meandering shape, and other heat transfer tubes such as a spiral shape and a straight tubular shape can be used.
The present invention is not limited to the heat exchanger for latent heat recovery, and can be applied regardless of the type of sensible heat recovery and latent heat recovery. Further, the case is not limited to the one in which the heat transfer tubes constituting one system of water channels are housed in one case (one can and one water channel type), and the plurality of heat transfer tubes constituting one system of water channels are housed in one case. It can also be configured as a single can (one can, two waterways, or the like).
The heating gas is not limited to the combustion gas generated by the burner, and can be, for example, high-temperature exhaust gas discharged from a cogeneration system or the like.

HE heat exchanger WH hot water supply device H header 1 case 2 heat transfer tube 2a end (of heat transfer tube)
20 End opening (of heat transfer tube)
3 Drainage member 30 Through hole 31 Base plate part (first part)
32 Convex part (second part)
33 Positioning piece 4 Header body 48 Chamber 5 Header lid member

Claims (7)

Multiple heat transfer tubes for recovering heat from the heating gas,
A header having a chamber internally formed to communicate with the end opening of each of these heat transfer tubes and having an opening for entering or discharging water from the outside to this chamber.
Is a heat exchanger equipped with
A drainage member arranged in the chamber of the header is further provided.
The drainage member is provided with a first portion located outside the end opening of each heat transfer tube, and water connected to the first portion and existing in the end opening. A heat exchanger comprising a second portion that is capable of transmitting to one portion and at least a portion of which has entered the end opening. The heat exchanger according to claim 1.
The second portion is in the form of a plate piece having a thickness smaller than the length and width, and the first portion has a surface connected at an angle intersecting the base of the second portion. ,Heat exchanger. The heat exchanger according to claim 1 or 2.
The header includes a header main body portion joined to the end portion of each heat transfer tube, and a header lid member that forms the chamber between the header main body portion and the header main body portion by being joined to the header main body portion. Header
The drainage member is a heat exchanger in which the first portion is fixed to the header by being sandwiched between both the header main body portion and the header lid member. The heat exchanger according to any one of claims 1 to 3.
The drainage member includes a base plate portion arranged in contact with or close to the end portion of each heat transfer tube, and a plurality of convex portions projecting from the base plate portion toward the end opening of each heat transfer tube. Have and
A heat exchanger in which the base plate portion is the first portion and each convex portion is the second portion. The heat exchanger according to claim 4.
A heat exchanger in which the base plate portion is provided with a through hole facing the end opening of each heat transfer tube. The heat exchanger according to claim 5.
A heat exchanger in which each of the convex portions is integrally formed with the base plate portion so as to bend and stand up from the peripheral edge of the through hole. A hot water supply device equipped with a heat exchanger for heating hot water by recovering heat from the heating gas.
A hot water supply device, wherein the heat exchanger according to any one of claims 1 to 6 is used as the heat exchanger.

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