JP4994402B2 - Latent heat exchanger - Google Patents

Description

  The present invention relates to a latent heat exchanger that condenses water vapor contained in combustion exhaust gas on the surface of the heat absorption tube and recovers latent heat from the combustion exhaust gas, and more particularly to a latent heat heat exchanger incorporated in a water heater, a bath tub or the like. It is.

  As a conventional heat exchanger incorporated in a water heater, a bath tub, or the like, a sensible heat recovery type heat exchanger having a spiral heat absorption tube is known (for example, see Patent Document 1).

  FIG. 5 is a schematic configuration diagram of a gas water heater 7 provided with the conventional sensible heat exchanger 9. This gas water heater 7 is a downflow type gas water heater that exhausts from an open portion at the lower end of the outer case 70, and a mixed gas of gas and air is combusted in a cylindrical outer case 70 whose lower end is open. A burner 8 to be recovered and a sensible heat exchanger 9 for recovering sensible heat from the combustion exhaust gas of the mixed gas discharged from the burner are accommodated.

  The casing 90 of the sensible heat exchanger 9 is formed in a cylindrical shape whose lower end is opened, and an exhaust introduction cylinder 93 having an open upper end that covers the outer periphery of the burner 8 is provided in the casing 90. Further, the internal space S1 of the exhaust introduction tube 93 is connected to the internal space S2 of the casing 90 via the upper end opening portion 932, and the internal space S2 of the casing 90 is out of the exterior case 70 via the lower end opening portion 902. It is connected. A heat absorption pipe 91 for recovering sensible heat from the combustion exhaust is spirally disposed on the inner peripheral surfaces of the exhaust introduction cylinder 93 and the casing 90.

  Accordingly, the combustion exhaust gas of the mixed gas discharged from the burner 8 is guided to the upper end opening portion 932 through the inner space S1 of the exhaust introduction cylinder 93 and then further passed through the inner space S2 of the casing 90 to the lower end opening portion 902. From the outer casing 70, and at that time, sensible heat is recovered from the surfaces of the heat absorption pipes 91 provided on the inner peripheral surfaces of the exhaust introduction cylinder 93 and the casing 90.

  In this configuration, the heat absorption pipe 91 is disposed in a relatively wide range from the inner peripheral surface of the exhaust introduction cylinder 93 to the inner peripheral surface of the casing 90, so that the contact area between the surface of the heat absorption pipe 91 and the combustion exhaust is small. Wide and high sensible heat recovery capability.

JP 60-48442 A JP 59-63449 A

By the way, in general, in a latent heat recovery type heat exchanger that recovers latent heat from combustion exhaust, the lower the flow rate of the combustion exhaust that passes through the gap between the heat absorption tubes, the longer the contact time between the heat absorption tube and the combustion exhaust Accordingly, the amount of water vapor that can be condensed on the surface of the endothermic tube is increased, and the endothermic efficiency is improved.
However, in the conventional sensible heat exchanger 9, the heat absorption pipe 91 is provided in a spiral shape along the inner peripheral surfaces of the exhaust introduction cylinder 93 and the casing 90, and the combustion exhaust covers the surface of the heat absorption pipe 91. Since the structure passes smoothly, even if this structure is simply adopted in a latent heat recovery type heat exchanger, improvement in heat absorption efficiency cannot be expected.

  This invention is made in view of the point which concerns, and makes it a subject to provide a latent heat heat exchanger with high heat absorption efficiency.

The latent heat exchanger according to the present invention is
A casing having an exhaust inlet at the bottom, a vertically open exhaust introduction pipe for guiding the combustion exhaust gas sent to the exhaust inlet to the upper region in the casing, and a combustion exhaust sent into the casing through the exhaust introduction pipe An endothermic tube that collects latent heat,
The endothermic tube is characterized in that a plurality of spiral portions formed in a spiral shape centering on the exhaust introduction tube are arranged side by side in layers.

  According to the above configuration, the combustion exhaust led from the exhaust introduction cylinder into the casing becomes a turbulent flow around the spirals arranged in parallel in the upper and lower layers, and the spirals are reduced while reducing the flow velocity. Since it passes, the contact time between the surface of the heat absorption tube and the combustion exhaust becomes relatively long. Thereby, it is possible to condense a lot of water vapor on the surface of the endothermic tube and recover the latent heat.

In the latent heat exchanger, the outer periphery of the exhaust introduction cylinder is covered with a predetermined gap, and a lower end open cylinder cover is provided to guide the combustion exhaust sent to the upper area in the casing to the lower area of the casing,
It is desirable to dispose the heat absorption tube in a space sandwiched between the outer peripheral surface of the exhaust introduction cylinder and the inner peripheral surface of the cylinder cover.

  If a large amount of drainage is generated on the surface of the endothermic tube and remains as a water film, heat transfer to the tube may be hindered and the endothermic efficiency may be reduced. On the other hand, in the thing of the said structure, since the flow of the drain which adhered to the surface of the heat absorption pipe | tube is promoted by the combustion exhaust gas flowing from the upper region to the lower region in the casing, it is difficult to form a water film on the surface. Thereby, high heat absorption efficiency can be exhibited stably.

  In the latent heat exchanger, it is desirable that the spiral portions are in close contact with each other. According to this, since the drain adhering to the surface of the endothermic tube easily flows down along the surface of each of the spiral portions, it is difficult to form a water film on the surface. Thereby, high heat absorption efficiency can be exhibited more stably.

  In the latent heat exchanger, the peripheral wall of the exhaust introduction cylinder may have a double structure. According to this, since the water vapor in the combustion exhaust is difficult to condense on the inner peripheral surface of the exhaust introduction cylinder, the heat in the combustion exhaust is taken away until the combustion exhaust reaches the heat absorption pipe. Can be suppressed.

Since the present invention has the above configuration, the present invention has the following specific effects.
Because it is possible to condense a lot of water vapor on the surface of the endothermic tube by reducing the flow rate of the combustion exhaust passing through the gap between the endothermic tubes and increasing the contact time between the surface of the endothermic tube and the combustion exhaust, The endothermic efficiency is improved.

It is a schematic block diagram of the water heater provided with the latent heat exchanger which concerns on embodiment of this invention. It is a longitudinal section schematic diagram of a latent heat exchanger concerning an embodiment of the invention. It is a disassembled perspective view of the heat sink tube of the latent heat exchanger which concerns on embodiment of this invention. It is a disassembled perspective view of the latent heat exchanger which concerns on embodiment of this invention. It is a longitudinal cross-sectional schematic diagram of the bathtub provided with the conventional heat exchanger.

Next, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a water heater 1 provided with a latent heat exchanger 4 according to an embodiment of the present invention, which mainly includes a burner 2 for burning a mixed gas of gas and air, and a mixed gas released from the burner 2. A sensible heat exchanger 3 that recovers sensible heat from the combustion exhaust, a latent heat exchanger 4 that recovers latent heat from the combustion exhaust, and an air supply fan 5 that sends outside air to the burner 2 are configured.

  The burner 2 is housed in a rectangular box-like combustion case 10 whose upper end is open, and is a mixture of air sent from the supply fan 5 into the combustion case 10 and fuel gas sent from the gas pipe LG. Gas combustion exhaust is discharged into a can 30 described later.

  The sensible heat exchanger 3 has a rectangular tube-shaped can body 30 that opens up and down, and a heat absorption pipe 31 that collects sensible heat from the combustion exhaust. The combustion case is disposed at the lower end of the can body 30. The upper end of 10 is connected.

  One end of the heat absorption pipe 31 of the sensible heat exchanger 3 is connected to an outgoing pipe L2 connected to a hot water supply destination such as a currant or a shower, and the other end is the heat absorption of the latent heat exchanger 4 described later. It is connected to one end side of the tube 41.

  The latent heat exchanger 4 has a rectangular box-shaped casing 40 in which a heat absorption pipe 41 for recovering latent heat from the combustion exhaust is accommodated, and the upper end of the can 30 is connected to the bottom of the casing 40. .

  An exhaust inlet 401 for combustion exhaust gas that has passed through the can 30 is provided at the bottom of the casing 40, while an exhaust outlet 402 for combustion exhaust gas that has passed through the casing 40 is provided at the top of the casing 40. Yes.

  One end side of the heat absorption pipe 41 of the latent heat exchanger 4 is connected to one end of the heat absorption pipe 31 of the sensible heat exchanger 3, while the other end side is a return pipe L1 connected to a water supply pipe (not shown). Is connected.

  Therefore, the water sent from the water supply pipe (not shown) through the return pipe L1 to the heat absorption pipe 41 of the latent heat exchanger 4 is heated by the latent heat of the combustion exhaust gas, and then to the heat absorption pipe 31 of the sensible heat exchanger 3. Further, it is further heated by the sensible heat of the combustion exhaust, and sent out from the forward piping L2 to the hot water supply destination.

  The latent heat exchanger 4 will be described in detail. As shown in FIG. 2, a raised portion 420 having an inverted V-shaped cross section is formed at the center of the bottom plate 42 of the casing 40 and is raised upward in the casing 40. A cylindrical body (hereinafter referred to as “exhaust gas introducing cylinder”) 43 extending up to the upper area inside the casing 40 is provided upright on the top of the raised portion 420. In addition, a drainage hole (not shown) connected to a drain neutralizer provided in the water heater 1 is opened at the bottom of the upper surface of the bottom plate 42.

  The back surface of the bottom plate 42 is covered with a bottom cover 44 having a raised portion 440 having substantially the same shape as the raised portion 420 at the center, and an air layer is formed between the bottom plate 42 and the bottom cover 44. Has been.

  On the other hand, the inner peripheral surface of the exhaust introduction cylinder 43 is covered with an inner cylinder 45 that opens up and down, and an air layer is formed between the exhaust introduction cylinder 43 and the inner cylinder 45. The lower end opening portion 451 of the inner cylinder 45 passes through the top of the raised portion 440 of the bottom cover 44 and faces the casing 40, and the lower end opening portion 451 corresponds to the exhaust inlet 401 described above.

  In the casing 40, a lower end open box-shaped tube cover 46 is provided to cover from the upper end to the outer periphery of the exhaust introduction tube 43, and the heat absorption tube 41 includes an inner peripheral surface of the tube cover 46 and an outer periphery of the exhaust introduction tube 43. It is accommodated in a space (hereinafter referred to as “endothermic chamber”) S2 sandwiched between the surfaces.

  A concave portion 460 having an inverted V-shaped cross section is formed at the center of the inner upper surface of the tube cover 46, and an internal space (hereinafter referred to as “exhaust introduction path”) S <b> 1 of the inner tube 45 is a space below the concave portion 460. Is connected to the upper region of the endothermic chamber S2.

  The lower end opening 462 of the tube cover 46 is located above the inclined surface R2 of the raised portion 420, and the heat absorption chamber S2 is connected to the outer peripheral surface of the tube cover 46 and the casing 40 via the space above the raised portion 420. Is connected to a lower area of a space (hereinafter referred to as “exhaust lead-out path”) S3 surrounded by the inner peripheral surface.

  Further, an exhaust cylinder 48 for discharging the air in the casing 40 to the outside of the container is provided upright at the center upper portion of the top plate 47 of the casing 40. The lower end opening 481 of the exhaust cylinder 48 is located above the inclined surface R3 formed on the back surface side of the recess 460 (upper surface side of the tube cover 46), and the exhaust lead-out path S3 extends from the space on the back surface of the recess 460. The exhaust pipe 48 is connected to the outside through the internal space.

  Therefore, the combustion exhaust gas of the mixed gas discharged from the burner 2 into the can 30 is guided to the exhaust inlet 401 along the back surface of the raised portion 440 of the bottom cover 44 and ascends in the exhaust introduction path S1. Then, the combustion exhaust sent to the upper side of the inner cylinder 45 is guided to the upper region of the combustion chamber S2 along the inclined surface R1 of the recess 460 and descends in the combustion chamber S2 through the gap of the heat absorption pipe 41. At this time, water vapor in the combustion exhaust is condensed on the surface of the heat absorption pipe 41, and latent heat is recovered.

  Further, the combustion exhaust sent to the lower side of the tube cover 46 is guided to the lower region of the exhaust lead-out path S3 along the inclined surface R2 of the raised portion 420, and ascends the exhaust lead-out path S3. And it guide | induces into the exhaust pipe 48 along the inclined surface R3 of the back surface of the recessed part 460, and is discharged | emitted upwards outside the container.

  On the other hand, the strongly acidic drain condensed on the surface of the endothermic tube 41 is dropped onto the inclined surface R2 of the raised portion 420, and is collected to the drain neutralizer through the inclined surface R2 through a drain hole (not shown).

  As shown in FIG. 3, the endothermic tube 41 uses a single bellows tube and is wound from the outside to the inside on the same plane around the exhaust introduction tube 43 to form the first spiral portion 411. A plurality of (in this case, four) spiral tubes 410, which are wound from the inside to the outside on the same plane that has been raised one step to form the second spiral portion 412, are configured to overlap each other.

  Further, the spiral portions 411 and 412 of the spiral tube 410 have a predetermined interval (for example, 1 mm) in the lateral direction, and the spiral portions 411 and 412 are in close contact with each other. They are arranged side by side (see FIG. 2).

  Accordingly, the combustion exhaust gas introduced into the heat absorption chamber S2 becomes turbulent around the spiral portions 411 and 412, passes through the spiral portions 411 and 412 while reducing the flow velocity, and is sent to the exhaust lead-out path S3 side. .

  As shown in FIG. 4, a plurality of heat absorption pipe connection ports 40 a and 40 b are formed in the side wall 400 of the casing 40, and each water inlet side pipe end 41 a and water outlet side pipe end 41 b of the spiral tube 410 are The heat absorption pipe connection ports 40 a and 40 b are connected and fixed from the inner side surface of the side wall 400.

  Furthermore, a water inlet header 49A covering the water inlet side heat absorbing pipe connection port 40a and a water outlet header 49B covering the water outlet side heat absorbing pipe connection port 40b are connected to the outer surface of the side wall 400. The water inlet side pipe end 41a is connected to the return pipe L1 via the water inlet header 49A, and the water outlet side pipe end 41b is connected to the heat absorption pipe 31 of the sensible heat exchanger 3 via the water outlet header 49B.

  Accordingly, the water sent to the incoming water header 49A through the return pipe L1 is dispersed to each incoming water side pipe end 41a in the incoming water header 49A and flows into the spiral tube 410 in parallel. At that time, the water fed into the spiral tube 410 flows spirally from the lower outer side to the center, and further flows from the upper inner side to the outer side, and flows out from each outlet side pipe end 41b to the outlet header 49B. Sent out. And it collects in the outflow header 49B and reaches the heat absorption pipe 31 of the sensible heat exchanger 3.

  In this configuration, by arranging the spiral portions 411 and 412 of the spiral tube body 410 in layers in the endothermic chamber S2, the combustion exhaust introduced into the endothermic chamber S2 is converted into the respective spiral portions 411 and 412. Since it passes through the spiral portions 411 and 412 while reducing the flow velocity as a turbulent flow around, the contact time between the surface of the heat absorption tube 41 and the combustion exhaust gas becomes relatively long. As a result, a large amount of water vapor is condensed on the surface of the heat absorption tube 41, and latent heat is recovered. Thereby, endothermic efficiency improves.

  On the other hand, when a large amount of drainage is generated on the surface of the heat absorption tube 41 and remains as a water film, heat transfer to each of the spiral portions 411 and 412 may be hindered, which may reduce the heat absorption efficiency. In this case, since the endothermic tube 41 is provided in the endothermic chamber S2, the downward flow of the combustion exhaust promotes the flow of the drain adhering to the surface of the endothermic tube 41. Therefore, a water film is formed on the surfaces of the spiral portions 411 and 412. Is difficult to form. Thereby, high heat absorption efficiency can be exhibited stably.

  The endothermic tube 31 of the sensible heat exchanger 3 is made of a copper material, and the surface of the heat absorption pipe 31 may corrode if strongly acidic drain adheres. By providing the endothermic tube 41 in the endothermic chamber S2, the drain adhering to the surface of the endothermic tube 41 does not drop to the sensible heat exchanger 3 side. Thereby, corrosion of the heat absorption pipe | tube 31 of the sensible heat exchanger 3 by a drain can be prevented.

  Further, since the spiral tube bodies 410 are overlapped with each other in close contact with each other, the drain adhering to the surface of the endothermic tube 41 easily flows down along the surface of each of the spiral tube bodies 410, so that a water film is further formed on the surfaces. It is difficult to form. Thereby, high heat absorption efficiency can be exhibited more stably.

  Further, since the back surface of the bottom plate 42 and the inner peripheral surface of the exhaust introduction cylinder 43 have a double structure, water vapor in the combustion exhaust gas is unlikely to condense on the rear surface of the bottom cover 44 and the inner peripheral surface of the inner cylinder 45. It is possible to prevent the heat in the combustion exhaust from being taken away until the exhaust reaches the heat absorption pipe 41. Thereby, the endothermic efficiency is further improved.

  Furthermore, since the back surface of the bottom plate 42 and the inner peripheral surface of the exhaust introduction cylinder 43 have a double structure, it is difficult for the drain to adhere to the rear surface of the bottom cover 44 and the inner peripheral surface of the inner cylinder 45. It is difficult for the drain to drip to the heat exchanger 3 side. Thereby, corrosion of the heat absorption pipe | tube 31 of the sensible heat exchanger 3 by a drain can be prevented much more effectively.

  Further, since the endothermic pipe 41 is spirally arranged in the endothermic chamber S2, the overall size of the latent heat exchanger 4 can be made relatively compact, so that the latent heat recovery type water heater 1 can be downsized. It is possible.

  In addition, by forming a single heat absorption tube 41 by superimposing a plurality of spiral tubes 410, the latent heat heat that matches the performance of the water heater 1 can be obtained simply by increasing or decreasing the number of spiral tubes 410 incorporated in the casing 40. The exchanger 4 can be manufactured.

  In the above embodiment, the water sent from the return pipe L1 is configured to flow in parallel to the spiral tubes 410 and to the heat absorption pipe 31 of the sensible heat exchanger 3. Each spiral tube 410 is connected in series, and water sent from the return pipe L1 to one spiral tube 410 sequentially flows through the other spiral tube 410, and then the endothermic tube 31 of the sensible heat exchanger 3. You may comprise so that it may be sent out.

  In the above embodiment, the latent heat exchanger according to the present invention incorporated in the water heater 1 has been exemplarily described. However, the latent heat exchanger according to the present invention can be used in a gas water heater or a bathtub. Is also applicable.

DESCRIPTION OF SYMBOLS 1 ... Hot water heater 2 ... Burner 3 ... Sensible heat exchanger 4 ... Latent heat exchanger 40 ... Casing 401 ... Exhaust inlet 41 ... Heat absorption pipe 410 ... Spiral shape Tube bodies 411, 412 ... spiral portion 43 ... exhaust introduction cylinder

Claims (4)

A casing having an exhaust inlet at the bottom, a vertically open exhaust introduction pipe for guiding the combustion exhaust gas sent to the exhaust inlet to the upper region in the casing, and a combustion exhaust sent into the casing through the exhaust introduction pipe An endothermic tube that collects latent heat,
The heat absorption pipe has a configuration in which a plurality of spiral portions formed in a spiral shape with the exhaust introduction cylinder as a center are arranged in parallel in a vertical layer. The latent heat exchanger according to claim 1,
Covering the outer periphery of the exhaust introduction cylinder with a predetermined gap, and provided with a lower end open cylinder cover that guides the combustion exhaust sent to the upper area in the casing to the lower area of the casing,
A latent heat heat exchanger, wherein the heat absorption pipe is disposed in a space sandwiched between an outer peripheral surface of the exhaust introduction cylinder and an inner peripheral surface of the cylinder cover. The latent heat exchanger according to claim 1 or 2,
A latent heat exchanger, characterized in that the vortex portions are in close contact with each other vertically. The latent heat exchanger according to any one of claims 1 to 3,
A latent heat heat exchanger characterized in that the peripheral wall of the exhaust introduction cylinder has a double structure.

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