JP5158404B2 - Heat exchanger and water heater - Google Patents

Description

  The present invention relates to a heat exchanger including a heater for preventing freezing and a hot water device.

  Conventionally, as this type of heat exchanger, there is one described in Patent Document 1. The heat exchanger described in this document has a freezing prevention heater attached to the outer surface of a case (can) to which combustion gas is supplied. In this heat exchanger, when water remaining in the heat transfer tube is likely to freeze, the heater is driven to heat the case, thereby preventing the heat transfer tube from freezing. In this document, a flat portion is formed in the case so that the heat of the heater is efficiently transmitted to the case, and the heater is brought into surface contact with the flat portion.

  However, in the said prior art, as a means for heating a heat exchanger tube, the heater is only attached to the case. For this reason, if the heat exchanger is of a type in which the heat transfer tube is wound around the can body, the heat transfer tube can be heated relatively efficiently, but in a heat exchanger having a different structure from this May be difficult to heat the heat transfer tube. That is, in the type of heat exchanger in which the heat transfer tubes are housed in the case, if only a heater is provided on the outer surface of the case, most of the heat generated from the heater is released to the atmosphere through the case. Therefore, it is difficult to efficiently heat the heat transfer tube. Therefore, the trouble that the electric power consumption by a heater becomes large is caused. It is possible to arrange a heater in the case and heat the heat transfer tube directly with the heater. However, since a high-temperature heat medium such as combustion gas is supplied into the case, If the heater is arranged, the heater and its electric wiring are easily damaged, which is not preferable.

JP-A-6-50606

The present invention has been conceived under such circumstances, and a heat exchanger capable of effectively and appropriately preventing freezing in a heat transfer tube with a simple configuration, and this It is an object to provide a hot water device provided with

  In order to solve the above problems, the present invention takes the following technical means.

The heat exchanger provided by the first aspect of the present invention has a heat transfer tube through which hot water flows, a case surrounding the heat transfer tube, and a heating gas supplied to the inside. A freezing prevention heater provided on an outer surface portion of the wall portion of the case, wherein a portion of the wall portion of the case is in contact with a portion heated by the heater. The heat transfer tube has a pair of upright pieces attached to the wall portion of the case so as to be provided in the case and projecting inward from the inner surface side of the case wall portion. The heat transfer tube is supported by being partly disposed between the pair of upright pieces, and is in contact with the support, and the heat of the heater in the heat transfer tube through the wall portion and the support of the case It is characterized in that there is a reach possible configurations.

According to such a configuration, when the heater is driven to generate heat, a part of the wall portion of the case is heated, and the heat in this portion reaches the heat transfer tube through the support body which is a heat conducting member. Therefore, it is possible to increase the amount of heat transfer to the heat transfer tube, increase the heating efficiency of the heat transfer tube, and appropriately prevent freezing in the heat transfer tube with less power consumption. The present invention has been made under a novel idea of transferring heat of a heater provided outside a case to a heat transfer tube inside the case using a support that is a heat conducting member. The value is tremendous.
Moreover, the support body for supporting a heat exchanger tube in a case is utilized as a heat conductive member, and the structure is rational.

  In a preferred embodiment of the present invention, the heater is provided in the opposite region of the support or in the vicinity of the opposite region across the wall portion of the case.

  According to such a configuration, it is possible to increase the heat conduction amount from the heater to the support by bringing the heater and the support close to each other, and it is more preferable to increase the heating efficiency of the heat transfer tube.

In a preferred embodiment of the present invention, the support has a bottom that is wider than the pair of upstanding pieces, and the bottom is in surface contact with the wall of the case.

  According to such a configuration, an effect of increasing the amount of heat conduction from the wall portion of the case to the support and increasing the amount of heat transmitted to the heat transfer tube can be obtained.

  In a preferred embodiment of the present invention, the heat transfer tube includes a spiral tube portion in which a plurality of loop portions connected in series are stacked in a vertical direction of the case, and the heater includes the case The support is attached to the upper surface of the bottom wall and is in contact with the lower portion of the helical tube.

  The helical tube portion of the heat transfer tube is connected in a series of a plurality of loop portions in the vertical direction, but when water is present inside the helical tube portion having such a configuration, There is a tendency that the lower part is more likely to freeze than the upper part. On the other hand, according to the said structure, since the heater and the support body are provided in the bottom wall part of the case, it is easy to transmit the heat of a heater to the lower part of a helical tube part, and a helical tube part Can be efficiently prevented from freezing.

In a preferred embodiment of the present invention, the pair of upright pieces of the support is shaped so that the lower part is wider than the upper part.

  According to such a configuration, it is possible to efficiently heat this portion by bringing the wide portion of the lower portion of the support into contact with the lower portion where the spiral tubular body portion is likely to freeze.

In a preferred embodiment of the present invention, the heat transfer tube includes a plurality of heat transfer tubes, and further includes a tube spacer for defining the arrangement of the plurality of heat transfer tubes. The spacer is disposed between or in the vicinity of the pair of upright pieces of the support and is in contact with each of the plurality of heat transfer tubes, and the heat of the heater Can be transmitted to the plurality of heat transfer tubes.

  According to such a configuration, the heat of the heater can be transmitted to each of the plurality of heat transfer tubes by using the tube spacer for defining the arrangement of the plurality of heat transfer tubes, and a more preferable anti-freezing effect can be obtained. can get.

  In a preferred embodiment of the present invention, each of the plurality of loop portions of the spiral tubular body portion is partially provided with a flattened portion, and the flattened portions contact each other, thereby A gap for allowing the heating gas to pass through is formed in the other portion between the loop portions.

  According to such a configuration, it is possible to form gaps for allowing the heating gas to pass between the plurality of loop portions of the spiral tubular body portion without using a spacer, reducing the number of parts, It is suitable for reducing the manufacturing cost of the exchanger.

  The hot water apparatus provided by the second aspect of the present invention supplies the heat exchanger provided by the first aspect of the present invention and the combustion gas as the heating gas into the case of the heat exchanger. And a combustor.

  According to 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 present invention with reference to the accompanying drawings.

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

  FIGS. 1-12 has shown the example of the structure related to the heat exchanger to which this invention was applied, the hot water apparatus as a hot-water supply apparatus provided with the same, and this. As clearly shown in FIG. 1, the hot water apparatus A of this embodiment includes a combustor 3, a primary heat exchanger 1, and a secondary heat exchanger B. The secondary heat exchanger B corresponds to an example of a heat exchanger to which the present invention is applied.

  The combustor 3 is, for example, a gas combustor, and is disposed in a can 30 to which combustion air is supplied from a blower fan 31, and can burn fuel gas supplied from the outside via a gas pipe 32. It is. The primary heat exchanger 1 is for recovering sensible heat from the combustion gas generated by the combustor 3 and has a structure in which a heat transfer tube 11 having a plurality of fins 12 is arranged in the can body 10. doing.

  The secondary heat exchanger B is for recovering latent heat from the combustion gas from which the sensible heat has been recovered by the primary heat exchanger 1. The secondary heat exchanger B is disposed above the primary heat exchanger 1 and can body 30. Are connected via an auxiliary can 19. The secondary heat exchanger B includes a case 7, a plurality of heat transfer tubes P, two heaters H for preventing freezing, a plurality of supports 6 for supporting the heat transfer tubes P, and a plurality of tube spacers S. I have. The plurality of heat transfer tubes P have a plurality of helical tube portions 5 accommodated in the case 7.

  As clearly shown in FIG. 3, the rear wall portion 70 a and the front wall portion 70 b of the case 7 are provided with an intake port 71 and an exhaust port 72 for combustion gas, and the primary heat exchanger 1. The combustion gas that has passed through passes through the auxiliary can 19 and enters the case 7 through the air supply port 71, and passes through the gaps 59 between the plurality of spiral tubular body parts 5. As will be described later, each gap 59 is formed by using a plurality of tubular body spacers S, and heat recovery is performed when combustion gas passes through each gap 59. The combustion gas from which heat has been recovered is discharged from the exhaust port 72 to the outside of the case 7. The exhaust port 72 has a substantially rectangular shape as shown in FIG. 2, for example, and the air supply port 71 is the same as this. When latent heat is recovered from the combustion gas by the spiral tubular body portion 5, a drain (condensed water) is generated on the surface and drops onto the bottom wall portion 70 d of the case 7. The bottom wall portion 70d is inclined in a front-down manner, and is provided with a drain outlet 73 at a position closer to the front portion. As a result, the drain dripped onto the bottom wall portion 70 d from the spiral tubular body portion 5 flows into the discharge port 73 and is discharged to the outside of the case 7.

  As shown in FIGS. 4 and 5, each helical tube portion 5 has a plurality of loop portions 50 connected in a series of substantially oval shapes in plan view with a plurality of gaps 59. The structure is laminated in the direction. The sizes of the loop portions 50 of the plurality of spiral tubular body portions 5 are different from each other, and these are arranged in a substantially concentric overlapping winding shape. The extended tubular body parts 51 and 52 connected to the lower and upper ends of the plurality of spiral tubular body parts 5 pass through one side wall 70e of the case 7 and are drawn out of the case, and are used for entering and discharging water. The headers 55A and 55B are connected. As shown in FIG. 1, in this hot water apparatus A, when water enters the water inlet 550 of the header 55 </ b> A, the water flows through the spiral tubular body 5 of each heat transfer pipe P. It is heated and then flows into the heat transfer tube 11 from the hot water outlet 551 of the header 55B via the connection pipe 18 and is reheated. Thereafter, the heated hot water is discharged from the hot water outlet 14 and supplied to a desired hot water supply destination through an appropriate pipe (not shown).

A plurality of supports 6, members der for mounting by fixing a plurality of heat transfer tubes P in the casing 7 is, equivalent to the heat conducting member. As shown in FIG. 4, the plurality of support bodies 6 are, for example, a total of four locations in a region where a plurality of linear tube portions 50 a extending in the width direction of the case 7 are arranged among the plurality of spiral tube portions 5. It is provided to support. In each spiral tube portion 5, the straight tube portion 50a is substantially horizontal, and the semicircular arc-shaped tube portions located at both ends of each spiral tube portion 5 are in the horizontal plane. Is inclined.

  Each support body 6 is made of, for example, stainless steel, and includes a main body portion 60 and an auxiliary portion 61 formed separately from each other as shown in FIG. The main body portion 60 has a form in which a pair of upright pieces 60b rises upward from both ends of the base portion 60a. The base portion 60a has a substantially flat bottom portion 60a 'and a pair of receiving plate portions 60d connected to both side edges of the bottom portion 60a'. The width W1 of the bottom portion 60a ' It is made larger than the width W2 of the lower part. The standing piece 60b has a lower width W2 larger than an upper width W3. The auxiliary portion 61 has a pair of projecting pieces 61b that project downward from both longitudinal ends of the substantially horizontal belt-like portion 61a. A hole 60c and a convex portion 61c are provided as engaging means that can be engaged with each other at the upper end of each standing piece 60b and the lower end tip of each protruding piece 61b. In combination with the auxiliary portion 61, the support 6 can be formed and held in a substantially rectangular frame shape.

  As shown in FIGS. 3 and 6, the bottom 60 a ′ of the support 6 is attached to the bottom wall 70 d of the case 7 so as to be in surface contact with the upper surface of the bottom wall 70 d by, for example, welding. . The plurality of linear tube portions 50a are arranged between the pair of upright pieces 60b, thereby preventing the case 7 from being displaced in the front-rear direction (left-right direction in FIG. 3). Since the bottom wall portion 70d of the case 7 has a front-lowering shape as described above, the base portion 60a has a shape in which the thickness dimension increases correspondingly to the front portion. However, the pair of receiving plate portions 60d are substantially horizontal, and the linear tube portion 50a positioned at the lowermost end is placed on the upper surface thereof. The auxiliary portion 61 of the support 6 is assembled to the upper portion of the base portion 60a, and prevents the plurality of tube portions 50a from floating upward.

  As the two heaters H for preventing freezing, ceramic heaters and other various heaters can be used. The heater H is provided outside the case 7 so as to be in surface contact with a portion of the lower surface of the bottom wall portion 70d of the case 7 that is directly under or near the bottom 60a 'of the support 6. As a means for attaching the heater H, various means such as a means using an appropriate bracket (not shown) and a screwing means can be adopted. In the present embodiment, as shown in FIG. 4, the support 6 is provided at a total of four locations, whereas the heater H is provided only at portions corresponding to two of them. The support 6 and the heater H may be provided in a one-to-one ratio, or the ratio of the number of heaters H to the number of supports 6 may be further reduced than in this embodiment.

  The tube spacer S is for forming a combustion gas passage gap 59 between the loop portions 50 of the plurality of heat transfer tubes P. In the present embodiment, as will be described later, the heater H It also plays a role of transferring the heat of each to the plurality of heat transfer tubes P. As shown in FIGS. 9 and 10, the tube spacer S is formed by bending a circular metal wire 2 having a diameter of about several millimeters, for example, in the vertical Z direction. Are provided with a plurality of (five in the drawing) projecting function portions 20 arranged at intervals, and a plurality of base end bending portions 21 connecting them. Each protrusion function part 20 is a part for inserting between the loop parts 50 of the heat transfer tube P. As shown well in FIG. 10A, each of the projection function units 20 is substantially U-shaped in plan view (viewed in the Z direction), spaced apart in the horizontal Y direction, and with respect to the horizontal Y direction. And a pair of extending portions 201 extending in the horizontal X direction intersecting with each other and a semicircular arc-shaped tip bending portion 202 connecting the tip portions of the pair of extending portions 201. Each base end bending portion 21 has a semicircular arc shape that connects the base end portions of the extending portions 201 of the two protruding functional portions 20 adjacent in the vertical Z direction. As shown in FIG. 10C, the plurality of proximal end bent portions 21 are provided in a staggered manner, and as a result, the plurality of projection function portions 20 are partially in the horizontal X direction. In addition, they overlap each other without greatly protruding in the Y direction, and are arranged in a line in the vertical Z direction. Of the two protruding functional portions 20 (20a, 20b) positioned at the upper end and the lower end, the base end portion of the extending portion 201 on the side where the base end bending portion 21 is not formed is bent or curved in a substantially L shape. Bending portions 22a and 22b are provided.

  As shown in FIG. 11, the tube spacer S described above is formed from one side of the plurality of tubes 80 in a state where the tube portions 50 a of the heat transfer tubes P are arranged in the vertical Z direction and the horizontal X direction. The protruding function portions 20 of the tube spacer S are inserted between the tubes 80 and used. If it does in this way, the some pipe 80 will be supported so that the clearance gap same as the diameter of the wire 2 may be produced in a Z direction. When each protrusion function part 20 is inserted deeply between the tube bodies 80, the inner peripheral surface of each base end bending portion 21 comes into close contact with the outer peripheral surface of the tube body 80. Therefore, it is possible to prevent the proximal bent portions 21 from protruding greatly to the side of the tubular body 80 and to suppress the bulk of the tubular spacer S. As shown in FIG. 12, between the tubular body portions 50a, a pair of extending portions 201 are arranged at intervals in the horizontal Y direction, and each tubular body 80 and one protruding function portion 20 are two points. It becomes a contact state. Such two-point contact is preferable for increasing the amount of heat transfer to the tube portion 50a.

  When the heat exchanger tube P is to be attached when the secondary heat exchanger B is manufactured, the bottom wall portion 70d of the case 7 is first opened in a state where the upper surface portion of the case 7 is opened, for example, as shown in FIG. The main body 60 of the support 6 is fixed and attached on the top. Next, the plurality of spiral tubular body parts 5 to which the tubular body spacers S are mounted in advance are accommodated in the case 7. At that time, the linear tube portion 50 a is disposed between the pair of standing pieces 60 b of the main body portion 60. After that, by engaging the auxiliary portion 61 with the pair of upright pieces 60b and assembling, the entire support body 6 can surround the plurality of tube portions 50a. The upper surface opening of the case 7 is then closed.

  However, the tube spacer S is set so that, for example, the base end bent portions 21 are arranged on both sides of the upright piece 60b as shown in FIG. In this way, when the tube spacer S receives the force of moving in the left-right direction in the figure, the proximal end bending portion 21 comes into contact with the upright piece 60b, and the tube in the above direction The positional deviation of the spacer S for use is prevented. The two upper and lower bent portions 22a and 22b of the tube spacer S are arranged inside the upright piece 60b and face the inner surface of the upright piece 60b. According to such a configuration, when the tubular body spacer S tries to retreat in the direction opposite to the insertion direction with respect to the tubular body portion 50a, the bent portions 22a and 22b come into contact with the standing piece 60b, and the retreat Is blocked. Accordingly, it is possible to appropriately prevent the tubular spacer S from being detached from the spiral tubular body portion 5.

  Next, the operation of the hot water apparatus A will be described.

  First, when generating warm water, the combustor 3 is driven while water is passed through each heat transfer pipe P of the secondary heat exchanger B and the water pipe 11 of the primary heat exchanger 1. From the combustion gas generated by the combustor 3, sensible heat and latent heat are efficiently recovered by the water pipe 11 and the plurality of heat transfer pipes P, and hot water is appropriately generated.

  Next, for example, when the operation of the combustor 3 is stopped in winter, the heater H is turned on if there is a risk of freezing in the heat transfer pipe P due to the outside air temperature dropping to a predetermined temperature. The heat of the heater H is transmitted to the plurality of heat transfer tubes P via a part of the bottom wall portion 70 d of the case 7 and the support body 6. For this reason, the freezing in the some heat exchanger tube P is prevented appropriately. Further, the tube spacers S are in contact with the plurality of spiral tube bodies 5 individually. Therefore, this tubular body spacer S plays a role of transferring heat from one spiral tubular body portion 5 to another spiral tubular body portion 5, and the non-heated spiral tubular body portion 5 Occurrence is also suppressed. As a result, the freeze prevention effect is further enhanced.

  The helical tube portion 5 of the heat transfer tube P has a form in which a plurality of loop portions 50 are connected in series and stacked vertically, and when the outside air temperature decreases, the lower portion of the helical tube portion 5 Tend to freeze most. On the other hand, in the present embodiment, the heater H is attached to the bottom wall portion 70d of the case 7, and the distance between the heater H and the lower portion of the spiral tubular body portion 5 is shortened. It becomes a preferable thing for heating the lower part of the cylindrical tube part 5 efficiently. In addition, since the bottom portion 60a ′ of the support 6 has a large width dimension W1, its area is relatively large and is in surface contact with the bottom wall portion 70d of the case 7, the amount of heat received from the heater H can be increased. it can. Further, since the pair of upright pieces 60b of the support 6 has a lower width W2 wider than an upper width W3, the amount of heat transfer from the lower portion of the width W2 to the lower portion of the spiral tubular body portion 5 is achieved. Can be expected to increase the effect. Since the pair of receiving plate portions 60d are also in contact with the lowermost tube portion 50a of the spiral tube portion 5, the effect of heating the lower freezing region of the spiral tube portion 5 is also this. Is increased. In the present embodiment, since the support 6 for supporting the heat transfer tube P plays a role of transferring the heat of the heater H to the heat transfer tube P, it is not necessary to use a dedicated heat conduction member, and the number of parts is small. This is also preferable in terms of achieving the above.

  The present invention is not limited to the embodiment described above. The specific configuration of each part of the heat exchanger and the hot water apparatus according to the present invention can be varied in design in various ways.

  As means for forming the gap 59 for passing the combustion gas between the loop parts 50 of the spiral tubular body part 5, for example, as shown in FIG. Various means can also be adopted. In this means, a plurality of flattened portions 58 are formed in each loop portion 50 of the spiral tubular body portion 5. The flat processed portion 58 is a portion narrower than the other portions of the loop portion 50 in a plan view, and a part of the spiral tubular body portion 5 is formed by a set of pressing members (not shown) from both sides thereof. This is the part that is sandwiched and press-deformed. As shown in FIG. 4B, each flattened portion 48 has a large width in the vertical height direction, and a part of the flattened portions 48 adjacent in the vertical height direction is in contact with each other. As a result, a portion of the loop portion 40 a other than the contact portion of the flattened portion 48 is a gap 59. According to such a means, it is not necessary to use a tube spacer, which is suitable for reducing the manufacturing cost by reducing the number of parts.

The antifreezing heater is not limited to the bottom wall portion of the case, and may be configured to be provided on another wall portion of the case such as an upper wall portion or a side wall portion. Further, when the heater is attached to the wall portion of the case, if the recess is formed in the case and the heater is brought into contact with the inner wall surface of the recess, the contact area between the heater and the wall portion of the case is increased, and It is suitable for increasing the amount of heat transfer to the case. As the heat transfer tube, for example, a straight tube other than the spiral tube can be used.

  In the embodiment described above, the present invention is not applied to the primary heat exchanger for sensible heat recovery, but the heat exchanger according to the present invention may be of any type for sensible heat recovery and latent heat recovery. . The heat exchanger according to the present invention can also be used for sensible heat recovery. The hot water device as used in the present invention means a device having a function of generating hot water, and is used for various types of hot water supply devices for general hot water supply, bath hot water supply, heating, snow melting, and the like, and hot water supply. It is a concept that includes a wide range of equipment for producing hot water.

It is a schematic front sectional view showing an example of a hot water device to which the present invention is applied. It is a principal part front view of the hot water apparatus shown in FIG. It is a principal part longitudinal cross-sectional view of the hot water apparatus shown in FIG. It is a plane sectional view of the secondary heat exchanger of the hot water device shown in FIG. It is front sectional drawing of the secondary heat exchanger shown in FIG. FIG. 6 is a cross-sectional view of the main part VI-VI in FIG. 4. It is a disassembled perspective view of the support body used for the secondary heat exchanger shown in FIG. It is a disassembled sectional view of the secondary heat exchanger shown in FIG. It is a perspective view which shows an example of the spacer for pipes integrated in the secondary heat exchanger shown in FIG. (A) is a top view of the spacer for tube bodies shown in FIG. 9, (b) is the front view, (c) is the right view. It is sectional drawing which shows one usage example of the spacer for pipe bodies shown in FIG. 9 and FIG. It is principal part left side sectional drawing of FIG. (A) is a top view which shows the other example of the means which forms the clearance gap for heating gas passage in a heat exchanger tube, (b) is XIII-XIII sectional drawing of (a).

Explanation of symbols

A Hot water device B Secondary heat exchanger (heat exchanger)
P Heat transfer tube S Tube spacer H Antifreeze heater 3 Combustor 5 Spiral tube (heat transfer tube)
6 Support (heat conduction member)
7 Case 50 Loop part 58 Flat part 60a 'Bottom part (of support)
60b Standing piece (for support)
70d Bottom wall (case wall)

Claims (8)

A heat transfer pipe through which hot water circulates,
A case having a wall portion surrounding the heat transfer tube, and a heating gas supplied therein;
A freezing prevention heater provided on the outer surface of the wall of the case;
A heat exchanger comprising:
A part of the wall of the case is attached to the wall of the case so that a part of the wall is heated by the heater and provided in the case, and the inner surface of the wall of the case A support for a heat transfer tube having a pair of upstanding pieces projecting inward of the case ;
The heat transfer tube is supported by being partly disposed between the pair of upright pieces, and is in contact with the support,
The heat of the heater is characterized in that there is a configurable transferred to the heat transfer tube through the wall portion and the support of the case, the heat exchanger. 2. The heat exchanger according to claim 1, wherein the heater is provided in a region opposite to the support or in the vicinity of the opposite region across the wall portion of the case . The heat exchanger according to claim 1 or 2, wherein the support has a bottom that is wider than the pair of upstanding pieces, and the bottom is in surface contact with a wall of the case. The heat transfer tube includes a spiral tube body portion in which a plurality of loop portions connected in series are stacked in the vertical height direction of the case,
The heater is provided on a lower surface portion of the bottom wall portion of the case, and the support body is attached to an upper surface portion of the bottom wall portion and is in contact with a lower portion of the helical tube portion . The heat exchanger according to any one of claims 1 to 3 . 5. The heat exchanger according to claim 4, wherein the pair of upright pieces of the support body has a shape in which the lower part is wider than the upper part. The heat transfer tube includes a plurality of heat transfer tubes, and further includes a tube spacer for defining the arrangement of the plurality of heat transfer tubes,
The tube spacer is disposed between or near the pair of upright pieces of the support, and is in contact with each of the plurality of heat transfer tubes.
The heat exchanger according to any one of claims 1 to 5, wherein heat of the heater can be transmitted to the plurality of heat transfer tubes also by the tube spacer. Each of the plurality of loop portions of the spiral tubular body portion is partially provided with a flattened portion. When the flattened portions are in contact with each other, the other portions between the plurality of loop portions are heated. The heat exchanger according to claim 4 or 5 , wherein a gap for allowing the working gas to pass therethrough is formed . Hot water comprising: the heat exchanger according to any one of claims 1 to 7; and a combustor that supplies combustion gas as a heating gas into the case of the heat exchanger. apparatus.

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