JP2020169758A - Water heater - Google Patents

Abstract

To maintain excellent heat efficiency even in a case where a fin tube type primary heat exchanger and a plate type secondary heat exchanger are combined.SOLUTION: A water heater comprises a fin tube type primary heat exchanger 5 and a plate type secondary heat exchanger 6, wherein a middle casing 20 of the primary heat exchanger 5 and a lower casing 35 of the secondary heat exchanger 6 are connected in a vertical direction, and combustion exhaust from a burner 4 is passed through the middle casing 20 and the lower casing 35 in this order, so that sensible heat and latent heat of the combustion exhaust can be recovered. The water heater is provided with a guide member 50 that guides the combustion exhaust having been subjected to heat exchange by the primary heat exchanger 5 toward a formation region of an internal flow passage of each pair plate 36 in the secondary heat exchanger 6.SELECTED DRAWING: Figure 4

Description

The present invention relates to a latent heat recovery type water heater.

In the latent heat recovery type water heater, a primary heat exchanger that recovers sensible heat and a secondary heat exchanger that recovers latent heat are installed side by side. As a primary heat exchanger, a plurality of heat transfer tubes are passed through a plurality of fins arranged side by side at predetermined intervals in the thickness direction, and a high-temperature gas such as a burner combustion exhaust is passed between the fins. A fin tube type that can recover sensible heat between a gas and a fluid flowing in a heat transfer tube is known.
On the other hand, as the secondary heat exchanger, as disclosed in Patent Document 1, a pair plate in which a pair of heat transfer plates having convex portions formed therein are joined to form an internal flow path between the convex portions is used. A plate type is known in which a plurality of layers are stacked in the thickness direction to form an exhaust passage between each pair plate, and both ends of the internal flow path of each pair plate are communicated with each other so that one is an inflow path and the other is an outflow path. There is. In this secondary heat exchanger, latent heat can be recovered from the combustion exhaust gas passing through the exhaust passage by passing the water flowing in from the inflow passage through each internal passage and letting it flow out from the outflow passage.

JP-A-2018-54155

However, in such a latent heat recovery type water heater, the combustion exhaust gas that has passed through the primary heat exchanger may flow to a region outside the inflow path and the outflow path in the secondary heat exchanger. For this reason, the thermal efficiency is deteriorated, and the combustion exhaust gas that is not heat exchanged may come into contact with the casing of the secondary heat exchanger, which may cause the temperature of the casing to rise. Patent Document 1 discloses a structure in which a rectifying plate that closes the space between the outer ends of the heat transfer plates is provided in the casing, but the rectifying plate extends beyond the inflow path and the outflow path to the internal flow path. Since the regions overlap, there may be a portion where the combustion exhaust does not flow in the exhaust passage, and the latent heat may not be sufficiently recovered.

Therefore, an object of the present invention is to provide a water heater capable of maintaining good thermal efficiency even when a fin tube type primary heat exchanger and a plate type secondary heat exchanger are combined. is there.

In order to achieve the above object, the invention according to claim 1 has a plurality of fins arranged side by side at predetermined intervals in the thickness direction and a plurality of heat transfer tubes penetrating each fin in a first casing. Fin tube type primary heat exchanger housed in
A pair of plates in which two heat transfer plates having a predetermined convex portion are combined with each other to form an internal flow path between the two heat transfer plates are arranged side by side in the second casing in the thickness direction, and each pair plate. It is provided with a plate-type secondary heat exchanger in which an exhaust flow path is formed between them and both ends of each internal flow path are communicated with each other to form an inflow path at one end and an outflow path at the other end. ,
A water heater that connects the first casing and the second casing in the vertical direction and allows the combustion exhaust of the burner to pass through the first casing and the second casing in this order so that the sensible heat and latent heat of the combustion exhaust can be recovered. ,
It is characterized in that a guide member is provided to guide the combustion exhaust heat exchanged by the primary heat exchanger toward the formation region of the internal flow path of each pair plate in the secondary heat exchanger.
According to the second aspect of the present invention, in the configuration of the first aspect, the guide member is attached to the inner surface of the first casing, is located on the downstream side of the fin in the passage direction of the combustion exhaust, and is formed as it goes downstream. It approaches the center side of the region and overlaps the inclined plate portion whose protruding end is located upstream of both ends of the internal flow path and the inclined plate portion extending downstream from the protruding end of the inclined plate portion in the passing direction with both ends of the internal flow path. It is characterized by including a flat plate portion.
According to a third aspect of the present invention, in the configuration of the second aspect, the guide member includes an insertion piece that abuts on the inner surface of the first casing outside the fins and fits between the heat transfer tubes from the downstream side. It is characterized by that.

According to the first aspect of the present invention, by adopting the guide member, the combustion exhaust can be surely guided to the exhaust passage and the latent heat can be recovered without loss. Therefore, good thermal efficiency can be maintained even when the fin tube type primary heat exchanger and the plate type secondary heat exchanger are combined.
Further, since the guide member prevents the combustion exhaust gas that is not heat-exchanged by the pair plate from coming into contact with the inner surface of the second casing, it also leads to the suppression of the temperature rise of the second casing.
According to the invention of claim 2, in addition to the effect of claim 1, the guide member is attached to the inner surface of the first casing and is located downstream of the fin in the passage direction of the combustion exhaust gas. As it goes toward, it approaches the center side of the forming region of the internal flow path, and the protruding ends of the internal flow path extend from the protruding ends of the inclined plate portion to the downstream side and the inclined plate portion located on the upstream side of both ends of the internal flow path. By including both ends and a flat plate portion that overlaps in the passing direction, it is possible to smoothly guide the combustion exhaust gas when flowing from the first casing to the second casing toward the formation region side of the internal flow path.
According to the third aspect of the invention, in addition to the effect of the second aspect, the guide member abuts on the inner surface of the first casing on the outside of the fin and is fitted between the heat transfer tubes from the downstream side. By providing the insertion piece, the guide member can be positioned in an appropriate posture, and leakage of combustion exhaust from the heat transfer tube can be prevented.

It is a front view of the water heater with the front cover removed. It is a front view of the water heater which omitted the resin sheet, the controller, and the display operation panel. FIG. 2 is a cross-sectional view taken along the line AA of only the inner body of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG. It is a perspective view from the lower side of the secondary heat exchanger. It is a perspective view of a guide member. In the explanatory view of the guide member, (A) shows the front surface, (B) shows the side surface, and (C) shows the plane surface. It is explanatory drawing of the guide action which shows the guide member part of FIG. 4 enlarged.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing an example of a water heater, and is shown with the front cover removed. FIG. 2 shows a state in which the resin sheet, the controller, and the display operation panel are excluded in FIG.
The water heater 1 accommodates an inner body 3 in which a burner 4, a primary heat exchanger 5, and a secondary heat exchanger 6 are provided in order from the top in a square box-shaped housing 2 having an open front surface. It is a reverse combustion type. Further, in the housing 2, an exhaust portion 7 is provided so as to wrap around from the lower part of the inner body 3 to the rear and upward, a fan unit 8 connected to a burner 4 on the right side of the inner body 3, and a fan unit 8. A gas supply unit 10 which is connected to the fan unit 8 on the lower side and supplies fuel gas from the gas introduction pipe 11 via the gas governor 9 is provided. A controller 12 accommodating an electrical board is installed sideways on the lower right side of the inner body 3, and a display operation panel 13 exposed from the front cover is provided in the lower center thereof.

The burner 4 is an all-primary air type in which a mixture of fuel gas and all combustion air necessary for combustion is burned, and has a horizontally long rectangular shape in a plan view having a predetermined depth in the vertical direction by opening the upper and lower surfaces. It has a casing 14, and the upper surface of the upper casing 14 projects upward and is closed by a chamber 15 to which the fan unit 8 is connected. As shown in FIGS. 3 and 4, the lower surface of the upper casing 14 is provided with a flame hole plate 16 in which a plurality of flame holes are formed and bulges downward in an arc shape, and the surface (lower surface) of the flame hole plate 16 is provided. ) Allows the air-fuel mixture to burn.
The fan unit 8 houses a fan (not shown) in a fan case 17 having a circular shape in a plan view, and a fan motor 18 for rotationally driving the fan is provided in the center of the upper side of the fan case 17.

As shown in FIG. 5, the primary heat exchanger 5 has a plurality of fins 21 and 21 ... (only a part of which is shown in each figure) in the lower part of the square tubular inner casing 20 to which the burner 4 is attached. It is made of stainless steel in which heat transfer tubes 22 penetrating each fin 21 in the left-right direction are arranged while being arranged side by side at predetermined intervals in the left-right direction which is the thickness direction.
The heat transfer tube 22 here has an elliptical cross section arranged at a predetermined interval in the front-rear direction at the lowermost stage, and eight linear large-diameter tubes 23, 23 with the long axis in the vertical direction. And, above that, three small diameter tubes 24, 24, etc. having a circular cross section are arranged above and below the middle casing 20 at predetermined intervals in the vertical direction. Of these, the large-diameter pipe 23 is connected to one as a whole by alternately connecting two ends adjacent to each other on the left and right by lower headers 25 provided on the left and right side surfaces of the middle casing 20. It has a meandering shape. However, the connecting pipe 26 with the secondary heat exchanger 6 is connected to the right end of the rearmost large diameter pipe 23, and the right end of the frontmost large diameter pipe 23 is provided by the front header 27 extending vertically. It is connected to the right end of the three small diameter pipes 24 on the front side. On the left side surface of the middle casing 20, a left side header 28 for connecting the left end portions of the three front and rear small diameter pipes 24 is provided. A right header 29 for connecting the right ends of the three rear small diameter pipes 24 is provided on the right side surface of the middle casing 20, and the hot water discharge pipe 30 is connected to the right header 29.

Therefore, in the heat transfer tube 22 of the primary heat exchanger 5, the hot water flowing from the connecting pipe 26 into the rearmost large-diameter pipe 23 meanders forward while alternately passing through the lowermost large-diameter pipes 23, 23, and so on. After moving in this shape, it flows from the frontmost large-diameter pipe 23 through the front three small-diameter pipes 24 and the rear three small-diameter pipes 24 in order to the hot water discharge pipe 30.
A strip-shaped resin sheet 31 in which the conductive pattern is covered in a meandering shape is wound around the upper outer circumference of the inner casing 20 so that leakage of combustion exhaust gas from the inner casing 20 can be detected. A turbulent plate 32 for agitating the passing hot water is inserted in each large-diameter pipe 23.

On the other hand, in the secondary heat exchanger 6, a pair of heat transfer plates 37, 37 are joined to face each other in a square tubular lower casing 35 communicating with the middle casing 20 in the thickness direction. A plurality of layers are laminated at predetermined intervals in the front-rear direction. Each heat transfer plate 37 has a horizontally long rectangular shape when viewed from the front, and a plurality of inclined ridges 38, 38, ... Are projected in parallel in the central portion, and the ridges 38 are formed on both the left and right sides. The convex portions in the vertical direction that communicate with each other are projected. Therefore, each pair plate 36 is formed with an internal flow path 39 that flows in a zigzag manner in the ridges 38, 38, and the inside, and the inflow portion 40 is formed at the left end portion and the outflow portion is formed at the right end portion due to the facing of the convex portions. 41 are formed respectively. Further, between the pair plates 36 and 36, an exhaust passage 42 in which the combustion exhaust flows in an inclined manner is formed between the ridges 38 and 38.

Further, in the pair plates 36, 36 ..., The lower ends of the inflow portions 40 form an inflow path 43 that communicates in the stacking direction, and the inflow path 43 is an inlet 44 provided at the lower front side of the lower casing 35. Is connected to. Further, in the pair plates 36, 36 ..., An outflow path 45 is formed in which the upper ends of the outflow portions 41 communicate with each other in the stacking direction, and the outflow path 45 is an outlet 46 provided on the upper front side of the lower casing 35. Is connected to. A water supply pipe 47 is connected to the inlet 44, and a connecting pipe 26 is connected to the outlet 46.
Therefore, in this secondary heat exchanger 6, the water that has flowed from the water supply pipe 47 through the inlet 44 into the inflow path 43 flows into the internal flow path 39 via the inflow portion 40 of each pair plate 36, and flows into the internal flow path 39. It flows into the outflow path 45 via 41, and flows from the outlet 46 to the connecting pipe 26.

A pair of guide members 50, 50 are provided on both the left and right sides of the inner casing 20 under the fins 21 and the large diameter pipe 23.
The guide member 50 is a plate-like body that fits in the front and rear inner parts of the inner casing 20, and as shown in FIGS. 6 and 7, the upper plate portion 51 extending upward and the upper plate portion 51 going downward from the lower end. It is composed of an inclined plate portion 52 extending laterally and a lower plate portion 53 extending downward from the protruding end of the inclined plate portion 52. At the upper end of the upper plate portion 51, seven mountain-shaped insertion pieces 54, 54 ... Fitted from below are extended upward between the large diameter pipes 23, 23. Further, attachment pieces 55 and 55 to the front and rear inner surfaces of the middle casing 20 are bent upward at both front and rear ends of the inclined plate portion 52.

As shown in FIGS. 4 and 8, the guide member 50 has an upper plate portion 51 positioned on the outer side of the left and right outermost fins 21 in a direction in which the inclined plate portions 52 and 52 face each other, and each insertion piece. The 54 is inserted and fitted between the large diameter pipes 23 in a state of being in contact with the inner surface of the inner casing 20. In that position, the front and rear mounting pieces 55 and 55 are fixed to the inner casing 20 by fixing them to the inner casing 20 with screws or rivets. In this state, the inclined plate portions 52 of the left and right guide members 50 extend downward toward the center side in the left-right direction below the fins 21, and the lower plate portions 53 are the pair plates 36 of the secondary heat exchanger 6. At both the left and right ends, they are located above the inflow portion 40 and the outflow portion 41 and extend in the front-rear direction. Therefore, the combustion exhaust that flows downward on the left and right inner surfaces of the middle casing 20 is guided from the inside of the upper plate portion 51 to the center side along the inclined plate portion 52 after passing between the fins 21 and 21, and is guided to the center side along the inclined plate portion 52. Will flow to. Further, the lower plate portion 53 regulates the flow of the inflow portion 40 and the outflow portion 41 to the left and right outside.

The exhaust unit 7 includes a drain receiver 60 attached to the lower surface of the lower casing 35 of the secondary heat exchanger 6 and an exhaust duct 61 erected at the rear portion of the drain receiver 60. The bottom of the drain receiver 60 is connected to the neutralizer 63 via the drain discharge pipe 62.
The exhaust duct 61 has a horizontally long square cylinder made of synthetic resin, and an upper cover 64 having a cylindrical exhaust cylinder portion 65 protruding from the upper surface of the housing 2 is joined to the opening at the upper end of the exhaust duct 61. ..

In the water heater 1 configured as described above, when water is passed through the water heater, the controller 12 drives the fan motor 18 to rotate the fan at a rotation speed corresponding to the amount of combustion required by the remote controller or the like. Then, in the fan unit 8, air proportional to the rotation speed of the fan is sucked. At the same time, fuel gas is supplied from the gas introduction pipe 11 and mixed with air in the gas supply unit 10 via a venturi provided on the suction side of the fan unit 8 to generate an air-fuel mixture. The generated air-fuel mixture is discharged from the discharge port of the fan case 17 into the chamber 15 of the burner 4, supplied into the upper casing 14, ejected from each flame hole of the flame hole plate 16, and ignited by an ignition electrode (not shown). Be burned.

The combustion exhaust from the burner 4 passes between the fins 21 and 21 in the inner casing 20 of the primary heat exchanger 5 to exchange heat with the hot water flowing in the heat transfer tube 22, and the sensible heat is recovered. Of the heat transfer tubes 22, hot water is agitated by the turbulent plate 32 in each of the large diameter tubes 23, so that retention and temperature unevenness are less likely to occur.
The combustion exhaust gas that has passed between the fins 21 and 21 reaches from the middle casing 20 to the inside of the lower casing 35 of the secondary heat exchanger 6.
At this time, on both the left and right sides of the middle casing 20, as shown in FIG. 8, the combustion exhaust G shown by the dotted line is formed of the internal flow path 39 in the lower casing 35 by the inclined plate portions 52 of the left and right guide members 50 and 50. It is guided to the region side (exhaust passage 42 side). Therefore, most of the combustion exhaust gas passes through the exhaust passage 42 between the left and right inflow portions 40 and the outflow portion 41, and exchanges heat with the water flowing through the internal flow path 39 to recover the latent heat.
Further, since the combustion exhaust G is guided toward the center by the guide member 50 and does not flow to the outside of the inflow portion 40 and the outflow portion 41, the combustion exhaust is prevented from coming into contact with the left and right inner surfaces of the lower casing 35, and the lower casing is prevented. The temperature of 35 is less likely to rise.

Then, the combustion exhaust that has passed through the lower casing 35 enters the drain receiver 60 of the exhaust portion 7, moves to the rear portion of the drain receiver 60, rises in the exhaust duct 61, and is discharged to the outside from the exhaust stack portion 65. Ru. The drain generated in the secondary heat exchanger 6 falls into the drain receiver 60 and is discharged to the outside of the appliance via the drain discharge pipe 62 and the neutralizer 63.

As described above, according to the water heater 1 of the above-described embodiment, the guide member guides the combustion exhaust heat exchanged by the primary heat exchanger 5 toward the formation region of each internal flow path 39 in the secondary heat exchanger 6. Since the 50 is provided, the combustion exhaust can be reliably guided to the exhaust passage 42 and the latent heat can be recovered without loss. Therefore, good thermal efficiency can be maintained even when the fin tube type primary heat exchanger and the plate type secondary heat exchanger are combined.
Further, since the guide member 50 prevents the combustion exhaust gas that is not heat-exchanged by the pair plate 36 from coming into contact with the inner surface of the lower casing 35, it also leads to the suppression of the temperature rise of the lower casing 35.

In particular, here, the guide member 50 is attached to the inner surface of the inner casing 20 (first casing), is located on the downstream side of the fin 21 in the passage direction of the combustion exhaust, and forms the internal flow path 39 as it goes downstream. The inclined plate portion 52 approaching the central side of the region and having protruding ends located on the upstream side of the inflow portion 40 and the outflow portion 41 at both ends of the internal flow path 39, and the inclined plate portion 52 extending downstream from the protruding end of the inclined plate portion 52. By including the inflow portion 40 and the outflow portion 41 and the lower plate portion 53 (flat plate portion) that overlaps in the passing direction, the internal flow path 39 is formed for the combustion exhaust when flowing from the middle casing 20 to the lower casing 35. It can be smoothly guided to the area side.
Further, the guide member 50 is provided with an insertion piece 54 that comes into contact with the inner surface of the inner casing 20 outside the fin 21 and fits between the large diameter tubes 23 of the heat transfer tube 22 from the downstream side. The 50 can be positioned in an appropriate posture, and leakage of combustion exhaust from the large diameter pipe 23 can be prevented.

The shape of the guide member is not limited to the above form, and the inclined plate portion can be formed long, the inclined plate portion can be changed, the guide member can be made horizontal without being inclined, or the upper plate portion can be attached to the middle casing without the attachment piece. Etc. can be changed as appropriate. Further, depending on the orientation of the pair plate, it may be attached to the front and rear inner surfaces of the inner casing. The lower plate portion can also be extended downward for a long time until it protrudes into the lower casing, or can be inclined inward, or the lower plate portion can be omitted.
Further, in the above embodiment, the guide member is provided in the inner casing, but it may be provided at the opening in the lower casing to guide the combustion exhaust, or it may be attached so as to straddle the inner casing and the lower casing. May be good.

In addition, each form of the burner, the primary heat exchanger, the secondary heat exchanger, the arrangement of the fan unit, the arrangement of the controller, etc. can be changed as appropriate. The present invention does not have to be a reverse combustion type, and the present invention can be applied to a water heater having a secondary heat exchanger on the upper side of the primary heat exchanger. As for the pair plate of the secondary heat exchanger, the shape of the ridge and the shapes of the inflow portion and the outflow portion may be appropriately changed.
Further, in the primary heat exchanger, the number of large-diameter pipes can be increased or decreased as appropriate, and there is no problem even if the heat transfer tube does not have a small-diameter pipe. The cross-sectional shape may be circular instead of elliptical. The orientation of the fins and the heat transfer tube may be opposite to that of the above embodiment, and the fins and the heat transfer tube may be provided in a plurality of stages instead of one stage.
Furthermore, the fan unit is a premix type that supplies a mixture of fuel gas and combustion air to the chamber, but it is not limited to this, and only the combustion air is supplied from the fan and downstream of the fan. The present invention is also applicable to a water heater that introduces fuel gas and combustion air into the chamber on the side.

1 ... Water heater, 2 ... Housing, 3 ... Inner body, 4 ... Burner, 5 ... Primary heat exchanger, 6 ... Secondary heat exchanger, 7 ... Exhaust section, 8 ... Fan Unit, 10 ... Gas supply unit, 12 ... Controller, 14 ... Upper casing, 20 ... Medium casing, 21 ... Fins, 22 ... Heat transfer tube, 23 ... Large diameter tube, 24 ... Small diameter tube, 26 ... Connection pipe, 30 ... Hot water supply pipe, 35 ... Lower casing, 36 ... Pair plate, 37 ... Heat transfer plate, 38 ... Ridge, 39 ... Internal flow path, 40 ... Inflow part, 41 ... Outflow part, 42 ... Exhaust passage, 43 ... Inflow route, 45 ... Outflow route, 47 ... Water supply pipe, 50 ... Guide member, 51 ... Upper plate part, 52 ... Inclined plate part, 53 ... Lower plate, 54 ... Insert piece, 60 ... Drain receiver, 61 ... Exhaust duct.

Claims (3)

A fin tube type primary heat exchanger in which a plurality of fins arranged side by side at predetermined intervals in the thickness direction and a plurality of heat transfer tubes penetrating each of the fins are housed in a first casing.
A plurality of pairs of plates in which two heat transfer plates having a predetermined convex portion are combined with each other to form an internal flow path between the heat transfer plates are arranged side by side in the second casing in the thickness direction. A plate-type secondary heat exchanger in which an exhaust flow path is formed between the pair plates and both ends of each of the internal flow paths are communicated with each other to form an inflow path at one end and an outflow path at the other end. With,
Hot water supply capable of recovering the sensible heat and latent heat of the combustion exhaust by connecting the first casing and the second casing in the vertical direction and passing the combustion exhaust of the burner in the order of the first casing and the second casing. It ’s a vessel,
A guide member is provided to guide the combustion exhaust heat exchanged by the primary heat exchanger toward the formation region of the internal flow path of each of the pair plates in the secondary heat exchanger. Water heater. The guide member is attached to the inner surface of the first casing, is located on the downstream side of the fin in the passage direction of the combustion exhaust, and approaches the central side of the forming region as it goes downstream, and the protruding end is inside the inside. It includes an inclined plate portion located on the upstream side of both ends of the flow path, and a flat plate portion extending downstream from the protruding end of the inclined plate portion and overlapping both ends of the internal flow path in the passing direction. The water heater according to claim 1. The hot water supply according to claim 2, wherein the guide member abuts on the inner surface of the first casing on the outside of the fins, and includes an insertion piece fitted between the heat transfer tubes from the downstream side. vessel.

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