JPH07159071A - Heat exchanger - Google Patents

Abstract

PURPOSE:To properly perform soldering, while a lowering of durability due to condensed water is avoided. CONSTITUTION:Heating tubes 1, through which fluid to be heated passes, are arranged in a combustion gas passage F, in which combustion gas from burners flows, and bosses 4 of a heating plate 3, which is disposed in the direction of flow of the combustion gas, are fitted onto the tubes 1 so as to be soldered thereto, in such a manner that the boss 4 is formed so that a heat transfer limiting part R thereof for limiting heat transfer may not contact the outer peripheral surface of the tube 1. And a solder material guiding part P extending apart from the outer periphery of the tube 1 is provided at the end, in the circumferential direction, of a contact part 44 of the boss 4 in contact with the tube 1, or a holder for the soldering material 5 is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat transfer tube in which a fluid to be heated flows, which is arranged in a combustion gas passage through which a combustion gas from a burner flows, and the heat transfer tube is provided in a flow direction of the combustion gas. The present invention relates to a heat exchanger in which bosses of heat transfer plates arranged alongside are brazed in an externally fitted state.

[0002]

2. Description of the Related Art Such a heat exchanger is used, for example, as a heat exchanger for supplying hot water, and it is desired to improve the thermal efficiency. However, if the thermal efficiency is simply improved, when the heat load becomes small, that is, when the burner combustion amount is reduced and a large amount of heated fluid (water in the case of hot water supply) is made to flow, combustion The gas may be supercooled to a temperature below the dew point, dew condensation water may be generated on the heat transfer plate or the heat transfer tube, and the dew condensation water may cause deterioration in durability. In addition, the generated condensed water reacts with the sulfur content and the nitrogen content in the combustion gas to become a highly corrosive corrosive liquid containing a sulfuric acid component and a nitric acid component. Since the heat exchanger is generally made of a copper material, the copper melted by the corrosive liquid becomes copper sulfate or copper nitrate, and the scale expands to block between the adjacent heat transfer plates. As a result, the flow of combustion gas is hindered. As a result, the heat exchange rate is lowered and the burner burns poorly, and the durability is lowered.

Incidentally, the heat exchanger has a plurality of heat transfer tubes 1 in a zigzag shape, as shown in FIGS. 10 and 11, for example.
In addition, since the dew condensation water tends to be generated in the peripheral portion of the heat transfer tube 1 on the lower side in the combustion gas flow direction because the heat exchanger tubes are arranged in a plurality of rows in the flow direction of the combustion gas. Among the parts, it tends to occur in a half-circumferential part corresponding to the lower side in the combustion gas flow direction. This is because the combustion gas is pre-cooled by the heat transfer tube 1 on the upstream side in the flow direction of the combustion gas, or the combustion gas itself is obstructed to form a so-called non-ventilation region S in which the ventilation of the combustion gas is small. It becomes the main factor. Even if a portion of the half-circumferential portion located within the non-ventilated area S is blocked by the scale, it is possible to avoid a large decrease in durability, but it is possible to avoid the non-ventilated area S of the half-circular portion. If the broken portion is blocked by the scale, the durability will be greatly reduced.

Therefore, for example, as shown in FIGS. 10 and 11, one of the bosses 4 fitted on the heat transfer tubes 1 on the lower side in the combustion gas flow direction of the heat transfer plate 3 on the lower side in the combustion gas flow direction. Is cut out in a state including the heat transfer plate main body portion adjacent thereto to form a cutout portion 47, and the cutout portion 47 is formed.
It is conceivable that the boss 4 is configured with a heat transfer suppressing portion R that suppresses heat transfer by not contacting the outer peripheral surface of the heat transfer tube 1. Then, it is conceivable to form the hole 34 as the holding portion of the brazing material 5 in the upper portion of the heat transfer suppressing portion R. By the way, as the brazing material 5, a paste-like material may be used in some cases, but a bar-like material is often used, and the bar-shaped brazing material 5 is formed on each of the plurality of heat transfer plates 1. It will be inserted into the hole 34. Also, heat transfer plate 1
With respect to the boss 4 that is fitted onto the heat transfer tube 1 on the upstream side in the combustion gas flow direction, a hole 31 as a holding portion for the brazing material 5 is generally formed near the upper part of the boss 4. is there.

For the sake of caution, the manufacturing procedure of the heat exchanger will be briefly described. A heat transfer plate is externally fitted to the heat transfer tube, and the heat transfer tube is expanded in this state, and the heat transfer tube and the outer peripheral surface are heat-transferred. The inner peripheral surface of the boss of the plate is brought into close contact with the inner peripheral surface of the boss in a state suitable for the brazing material to invade between them by capillarity. After that, by heating in a heating furnace, the molten brazing material is infiltrated between the outer peripheral surface of the heat transfer tube and the inner peripheral surface of the boss of the heat transfer plate by the capillary phenomenon as described above, and brazing is performed. Become.

[0006]

When the heat transfer suppressing portion is formed on a part of the boss of the heat transfer plate as described above, if the brazing material is simply held above the heat transfer suppressing portion, the heat gradually increases with heating. Even if the molten brazing material does not easily flow down toward the end in the circumferential direction of the contact part that contacts the heat transfer tube of the boss in the heat transfer plate, or if it flows down to the end in the circumferential direction of the contact part. Due to the above-mentioned capillary phenomenon, the brazing may not be performed properly due to the fact that it flows down further before entering between the outer peripheral surface of the heat transfer tube and the inner peripheral surface of the boss. The present invention has been made in view of the above circumstances, and an object thereof is to form a heat transfer suppressing portion in a part of a boss of a heat transfer plate to avoid a decrease in durability due to dew condensation water. However, the point is that brazing can be performed properly.

[0007]

In the heat exchanger according to the present invention, a heat transfer tube through which a fluid to be heated flows is arranged in a combustion gas passage through which combustion gas from a burner flows, and the heat transfer tube has a heat transfer tube. A boss of a heat transfer plate arranged along the flow direction of the combustion gas is brazed in an externally fitted state, and the first characteristic configuration is that the boss suppresses heat transfer of the boss. The heat suppressing portion is configured so as not to come into contact with the outer peripheral surface of the heat transfer tube, and the end portion in the circumferential direction of the contact portion of the boss that comes into contact with the heat transfer tube extends toward the side away from the outer peripheral surface of the heat transfer tube. The point is that the material guides are connected. A second characteristic configuration is configured such that the boss does not bring a heat transfer suppressing portion of the boss that suppresses heat transfer into contact with an outer peripheral surface of the heat transfer tube, and a contact portion of the boss that contacts the heat transfer tube. This is in that a brazing material holding portion is formed at an end portion in the circumferential direction. The third characteristic configuration and the fourth characteristic configuration specify a specific configuration when the first or second characteristic configuration is carried out. In the third characteristic configuration, the heat transfer suppressing portion is the boss. It is formed by a part of the notch.
A fourth characteristic configuration is that the heat transfer suppressing portion is formed by arranging a part of the boss at a distance from the outer peripheral surface of the heat transfer tube.

[0008]

According to the first characteristic construction of the present invention, by providing the heat transfer suppressing portion on the boss of the heat transfer plate, it is possible to suppress the generation of dew condensation water and avoid the deterioration of the durability due to the dew condensation water. it can. In addition, the brazing material guide portion, which is connected to the end of the boss in contact with the heat transfer tube in the circumferential direction, exerts the function of properly receiving the molten brazing material flowing down from above and the function of holding the received brazing material. Then, the held brazing material can be appropriately infiltrated and brazed between the outer peripheral surface of the heat transfer tube and the inner peripheral surface of the boss by the capillary phenomenon.

According to the second characteristic constitution of the present invention, similarly to the first characteristic constitution, it is possible to avoid the deterioration of the durability due to the dew condensation water, and moreover, in the circumferential direction of the contact portion of the boss which contacts the heat transfer tube. By holding the brazing material at the end of the brazing material, the brazing material is gradually melted by heating, and the brazing material is appropriately inserted between the outer peripheral surface of the heat transfer tube and the inner peripheral surface of the boss due to the capillary phenomenon for brazing. be able to.

According to the third characteristic construction of the present invention, the heat transfer suppressing portion provided on the boss of the heat transfer plate is achieved by a notch in a part of the boss, and in the heat transfer plate main body portion. It is easy to adjust the heat transfer suppression ability, such as notches including the part close to the boss.

According to the fourth characteristic configuration of the present invention, the heat transfer suppressing portion provided on the boss of the heat transfer plate is achieved by locating a part of the boss at a distance from the outer peripheral surface of the heat transfer tube. The boss corresponding to the heat transfer suppressing portion exerts an effect of preventing the combustion gas from flowing toward the outer peripheral surface of the heat transfer tube, and suppresses the occurrence of dew condensation on the outer peripheral surface of the heat transfer tube. Be advantageous to.

[0012]

According to the first and second characteristic configurations described above, the brazing between the heat transfer tube and the boss of the heat transfer plate is properly performed while avoiding a decrease in durability caused by the generation of dew condensation water. Therefore, the heat transfer between the heat transfer tube and the heat transfer plate can be satisfactorily performed. Therefore, it is possible to provide a heat exchanger capable of appropriately maintaining heat efficiency while improving durability.

According to the third characteristic constitution, in addition to the effects of the first characteristic constitution and the second characteristic constitution, it becomes easy to manufacture in a state where the heat transfer suppressing ability according to various uses is exhibited.

According to the fourth characteristic structure, in addition to the effects of the first characteristic structure and the second characteristic structure, the generation of dew condensation water on the outer peripheral surface of the heat transfer tube is also appropriately suppressed, and the durability is further improved. It is easy to improve the property.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a heat exchanger in a water heater will be described below with reference to the drawings. First, the overall configuration of the water heater will be described with reference to FIG. A burner B is arranged on the lower end side of the barrel A, and the barrel A
A combustion gas flow path F through which the combustion gas flows from the lower side to the upper side is formed inside. A heat exchanger C is arranged on the upper end side of the barrel A and in the combustion gas flow passage F. In the figure, D is a water supply pipe for the heat exchanger C, E is a hot water outlet pipe from the heat exchanger C, G is a fan for supplying combustion air, and H is an outer casing.

Next, the heat exchanger C will be described with reference to FIGS. 2 to 5. A plurality of heat transfer tubes 1 through which water as a fluid to be heated flows are staggered in the combustion gas flow passage F in a direction orthogonal to the combustion gas flow direction and in the combustion gas flow direction 2 They are arranged side by side in a row. A plurality of heat transfer tubes 1 are provided outside the barrel A so that the heat transfer tubes 1 in the same row form a series of meandering flow paths, and two meandering flow paths are connected to form a series of flow paths. It is connected by the connecting pipe 2. In the following description, the row of the heat transfer tubes 1 on the upstream side in the combustion gas flow direction is abbreviated as the lower row, and the row of the heat transfer tubes 1 on the lower side in the combustion gas flow direction is abbreviated as the upper row.

A large number of heat transfer plates 3 are attached to the outer peripheral portion of the heat transfer tube 1 in a state of being along the flow direction of the combustion gas. still,
Bosses 4 are formed on the heat transfer plate 3 in accordance with the arrangement of the plurality of heat transfer tubes 1, and the heat transfer plate 3 is mounted by externally fitting each of the plurality of bosses 4 to the corresponding heat transfer tube 1. It is attached to the outer peripheral portion of the heat transfer tube 1. Also, the boss 4 of the adjacent heat transfer plate 3
The two bosses are brought into contact with each other, whereby the boss 4
Thus, the peripheral portion of the heat transfer tube 1 is entirely covered.

As shown in FIGS. 3 to 5, of the bosses 4 fitted on the heat transfer tubes 1 in the upper row of the heat transfer plate 3, a half peripheral portion 41 corresponding to the lower side in the combustion gas flow direction is connected to the heat transfer tubes. 1
Is formed so as to be spaced from the outer peripheral surface thereof, and a portion corresponding to the half peripheral portion 41 is a heat transfer suppressing portion R for suppressing heat transfer with the heat transfer tube 1. In addition, S in the figure is a non-ventilated region where the ventilation of the combustion gas is small.

A projecting portion 42 projecting in a semicircular shape in the combustion gas flow direction is formed at a portion of the boss 4 located at the uppermost portion of the half peripheral portion 41. Further, a hole 31 is formed near the uppermost portion of the boss 4 which is fitted on the heat transfer tubes 1 in the lower row of the heat transfer plate 3. As will be described later, the protrusion 42 and the hole 31 are used for inserting a rod-shaped brazing material when manufacturing the heat exchanger.

Next, the manufacturing procedure of the heat exchanger will be described. A plurality of heat transfer plates 3 are externally fitted to the heat transfer tube 1, and the heat transfer tube 1 is expanded in that state, and the outer peripheral surface of the heat transfer tube 1 and the inner peripheral surface of the boss of the heat transfer plate 3 are placed between them. The brazing material is brought into close contact with a suitable state (for example, an interval of about 0 to 0.05 mm) so that the brazing material can invade due to the capillary phenomenon, and subsequently, as shown in FIGS. The rod-shaped brazing material 5 is inserted into each of them. Then, in the assembled state as described above, the brazing material 5 is melted by heating in a heating furnace, and the molten brazing material is melted inside the outer peripheral surface of the heat transfer tube 1 and the boss 4 of the heat transfer plate 3 by a capillary phenomenon. Insert it between the peripheral surface and braze it.

In the boss 4 which is fitted onto the upper row heat transfer tubes 1 of the heat transfer plate 3, a half peripheral portion 41 corresponding to the lower side of the combustion gas flow direction and a half peripheral portion 44 (heat transfer tube corresponding to the upper side of the combustion gas flow direction). 1 corresponds to a contact portion that contacts the outer peripheral surface of 1) and is formed in a state of extending to the side away from the outer peripheral surface of the heat transfer tube 1. Then, at the connecting portion 43, the action of receiving the molten brazing material (the molten brazing material 5 inserted into the protruding portion 42) that flows down from above and the action of holding the received brazing material are exerted, The held brazing material is infiltrated by brazing between the outer peripheral surface of the heat transfer tube 1 and the inner peripheral surface of the boss 4 of the heat transfer plate 3 for brazing. Therefore, the connecting portion 43 is configured to function as the brazing material guide portion P.

As shown in FIG. 1, the water supply pipe D is connected to the heat transfer pipes 1 in the lower row. Further, the water supply pipe D is attached to the outer peripheral portion of the cylindrical body A in the middle of the spiral winding from the upper side to the lower side in the combustion gas flow direction, whereby the water flowing in the water supply pipe D is attached. Is preheated, and the cylinder body A is cooled and protected by the water. The tap pipe E is connected to the heat transfer pipes 1 in the upper row.

Another Embodiment Next, another embodiment will be described. Another embodiment will be described with reference to FIGS. 6 to 8. A notch 32 is formed by cutting out a half-circumferential portion of the boss 4 of the heat transfer plate 3 fitted on the upper row of the heat transfer tubes 1 on the lower side in the combustion gas flow direction so as to include the heat transfer plate body portion adjacent thereto.
Is formed, and the cutout portion 32 serves as a heat transfer suppressing portion R that suppresses heat transfer by not contacting the outer peripheral surface of the heat transfer tube 1.

Ends 45 on both sides in the circumferential direction of the semi-peripheral portion 44 (corresponding to a contact portion which contacts the outer peripheral surface of the heat transfer tube 1) of the boss 4 on the upstream side in the flow direction of the combustion gas are the heat transfer tubes 1. Is formed to extend to the side away from the outer peripheral surface of
The end portion 45 is configured to function as the brazing material guide portion P.

Further, a bow-shaped recess 33 is formed in a portion of the notch 32 which is close to the end 45 of the boss 4, and the rod-shaped brazing material 5 is inserted into the recess 33 when the heat exchanger is manufactured. And hold it. Then, as the brazing material that is gradually melted by heating is melted, the brazing material is caused to flow to the end portion 45 as the brazing material guiding portion P and held by the end portion 45, and the held brazing material is heated by the capillary phenomenon. 1 and the inner surface of the boss 4 of the heat transfer plate 3 are penetrated and brazed.
Therefore, the concave portion 33 is configured to function as the holding portion Q.

In FIGS. 6 to 8, the half circumference portion 44
Is formed so that only one end in the circumferential direction of the heat transfer tube 1 extends to the side away from the outer peripheral surface of the heat transfer tube 1, and the one end is made to function as the brazing material guide P, and the notch is formed. Three
It is also possible to form a bow-shaped concave portion in a portion of 2 close to the one end portion and to make the concave portion function as the holding portion Q.

As shown in FIG. 9, of the bosses 4 that are fitted onto the heat transfer tubes 1 in the upper row of the heat transfer plate 3, the lower half side in the combustion gas flow direction of the boss 4 and the heat transfer plate main body portion adjacent thereto are In this state, the notch 35 is formed in the state of including the notch, and the notch 35 serves as a heat transfer suppressing portion R that suppresses heat transfer by not contacting the outer peripheral surface of the heat transfer tube 1.

Ends 46 on both sides in the circumferential direction of the semi-peripheral portion 44 (corresponding to a contact portion contacting the outer peripheral surface of the heat transfer tube 1) of the boss 4 corresponding to the upstream side of the flow direction of the heat transfer tube 1 are formed. Is formed to extend to the side away from the outer peripheral surface of
At the time of manufacturing the heat exchanger, the rod-shaped brazing material 5 is placed and held on the end portion 46.

Then, as the brazing material that gradually melts by heating is melted, it is held at the end portion 46, and the held brazing material is capillarized by the outer peripheral surface of the heat transfer tube 1 and the boss of the heat transfer plate 3. It is inserted between the inner surface of 4 and the inner surface and brazed. Therefore, the end portion 46 is configured to function as the brazing material guide portion P and the holding portion Q.

In FIG. 9, only one end portion in the circumferential direction of the semi-peripheral portion 44 is formed to extend to the side away from the outer peripheral surface of the heat transfer tube 1, and the one end portion is connected to the brazing material guide portion P and the holding portion. It may be configured to function as the section Q.

By fitting the boss 4 of the heat transfer plate 3 onto the heat transfer tube 1 in a state where a gap is formed between the tip of the boss 4 and the adjacent heat transfer plate 3, a plurality of heat transfer plates 3 are attached. It may be attached to the outer peripheral portion of the heat transfer tube 1.

The fluid to be heated is not limited to water.

The heat exchanger according to the present invention is applicable not only to the hot water supply device but also to, for example, an air conditioning combustor.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a water heater equipped with a heat exchanger according to the present invention

FIG. 2 is a partially cutaway perspective view of the water heater.

FIG. 3 is a vertical cross-sectional view of a heat exchanger

FIG. 4 is a view on arrow I-I in FIG.

FIG. 5 is a perspective view of a heat transfer plate.

FIG. 6 is a vertical cross-sectional view of a heat exchanger showing a first alternative embodiment.

FIG. 7 is a view on arrow II-II in FIG.

FIG. 8 is a perspective view of a heat transfer plate showing a first alternative embodiment.

FIG. 9 is a longitudinal sectional view of a heat exchanger showing a second alternative embodiment.

FIG. 10 is a vertical sectional view of a conventional heat exchanger.

11 is a view on arrow III-III in FIG.

[Explanation of symbols]

 1 Heat Transfer Tube 3 Heat Transfer Plate 4 Boss 5 Brazing Material 44 Contact Area B Burner F Combustion Gas Flow Path P Brazing Material Guide Part Q Holding Part R Heat Transfer Suppression Part

Claims (4)

[Claims] 1. A heat transfer tube (1) through which a fluid to be heated flows is arranged in a combustion gas passage (F) through which combustion gas from a burner (B) flows, and the heat transfer tube (1) has A heat exchanger in which a boss (4) of a heat transfer plate (3) arranged along a flow direction of combustion gas is brazed in an externally fitted state, wherein the boss (4) is a heat transfer member of the heat transfer plate. The heat transfer suppressing portion (R) for suppressing heat is configured so as not to contact the outer peripheral surface of the heat transfer tube (1), and the contact portion (44) of the boss (4) that contacts the heat transfer tube (1). A heat exchanger in which a brazing material guide portion (P) extending toward the side away from the outer peripheral surface of the heat transfer tube (1) is continuously provided at an end portion in the circumferential direction. 2. A heat transfer tube (1) through which a fluid to be heated flows is arranged in a combustion gas flow path (F) through which combustion gas from a burner (B) flows, and the heat transfer tube (1) has A heat exchanger in which a boss (4) of a heat transfer plate (3) arranged along a flow direction of combustion gas is brazed in an externally fitted state, wherein the boss (4) is a heat transfer member of the heat transfer plate. The heat transfer suppressing portion (R) for suppressing heat is configured so as not to contact the outer peripheral surface of the heat transfer tube (1), and the contact portion (44) of the boss (4) that contacts the heat transfer tube (1). A heat exchanger in which a holding portion (Q) for a brazing material (5) is formed at an end portion in the circumferential direction. 3. The heat exchanger according to claim 1, wherein the heat transfer suppressing portion (R) is formed by cutting out a part of the boss (4). 4. The heat transfer suppressing portion (R) is formed by locating a part of the boss (4) at a distance from an outer peripheral surface of the heat transfer tube (1). Or the heat exchanger according to 2.