JP2020079668A - Heat exchanger and combined water heater - Google Patents

Abstract

To reduce cost related to a partition member and labor and time for attachment without inhibiting heat exchange in each exhaust passage.SOLUTION: In a secondary heat exchanger 6, a partition plate 40 shorter than a front-back distance in a casing 20 in a combustion gas flowing direction is installed at a position close to the rear side in the casing 20. An opening 46 communicating two exhaust passages 41, 42 with each other is formed between a front side inner surface of the casing 20 and a front end 40a of the partition plate 40 on the combustion gas flowing downstream side in the casing 20.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a latent heat recovery type heat exchanger used in a bath water heater and the like, and a combined water heater such as a bath water heater provided with the heat exchanger.

  A combined water heater such as a bath water heater is equipped with a heat exchanger for sensible heat recovery, which mainly recovers sensible heat, and a heat exchanger for latent heat recovery, which mainly recovers latent heat, in order to improve thermal efficiency. What you have done is known. As a heat exchanger for recovering latent heat, for example, in Patent Document 1, two exhaust passages (here, for hot water supply and for heating) are formed by a partition member in a box-shaped casing having a rectangular plan view. A plurality of endothermic tubes are arranged in each exhaust passage in a meandering shape or a spiral shape. Therefore, the combustion gas of the burner in which the sensible heat is recovered by passing through the sensible heat recovery heat exchanger flows through the casing independently for each exhaust passage by the partition member, and the latent heat recovery heat exchanger is used. When it passes through the inside, it comes into contact with the heat absorbing tube and exchanges heat with water or the like flowing through the heat absorbing tube to recover latent heat.

Japanese Patent No. 4246749

  In the above-mentioned conventional latent heat recovery type heat exchanger, a partition member for partitioning and forming the two exhaust passages is prepared in a size corresponding to the cross-sectional area of the casing so that combustion gas does not leak between the two exhaust passages. Since it is necessary to assemble it in the casing, the cost and the labor of the assembly are increased.

  Therefore, an object of the present invention is to provide a heat exchanger and a composite water heater that can reduce the cost of the partition member and the labor of assembly without hindering heat exchange in each exhaust passage.

To achieve the above object, the invention according to claim 1 provides a partition member inside a casing to form two left and right exhaust passages, and at least one of the exhaust passages is provided with a heat exchanger for recovering sensible heat. A heat exchanger that accommodates an endothermic tube for recovering latent heat from the combustion gas that has passed through, and a partition member that is shorter than the front-rear distance in the casing in the front-rear direction in which the combustion gas flows is provided to the rear of the casing. It is characterized in that it is provided with an opening formed between the front inner surface of the casing and the front end of the partition member on the downstream side of the flow of the combustion gas in the casing so that the two exhaust passages communicate with each other.
According to a second aspect of the invention, in the configuration of the first aspect, the front-rear distance of the partition member has a ratio of 75% or more with respect to the front-rear distance when the entire inside of the casing is partitioned.
In order to achieve the above object, the invention according to claim 3 is a composite water heater, comprising: a burner; and a heat exchanger for recovering sensible heat, which is arranged upstream of the flow of combustion gas in the burner, The heat exchanger according to claim 1 or 2 arranged downstream of the flow.

ADVANTAGE OF THE INVENTION According to this invention, the partition member can be short, the cost concerning the partition member and the labor of assembly can be reduced without hindering the heat exchange in each exhaust passage.
In particular, according to the invention described in claim 2, in addition to the above effects, high heat exchange efficiency can be ensured even if an opening is provided by setting the front-rear distance of the partition member.

It is sectional drawing of a bath water heater. It is a front view of a secondary heat exchanger. It is a side view of a secondary heat exchanger. It is the sectional view on the AA line of FIG. It is the BB sectional view taken on the line of FIG. It is a table which shows the relationship between the distance of a partition plate and heat exchange efficiency. 7 is a graph showing changes in heat exchange efficiency according to the table of FIG. 6.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a sectional view showing a bath water heater which is an example of a combined water heater. The bath water heater 1 includes a combustion device 2 in a housing (not shown), and the combustion device 2 includes a burner unit 4 and a sensible heat recovery unit for recovering mainly sensible heat from below in a can body 3 communicating with the inside. A primary heat exchanger 5 for heat recovery, and a secondary heat exchanger 6 mainly as a heat exchanger for recovering latent heat are provided in this order.
First, in the burner unit 4, the first burner group 7 and the second burner group 8 are arranged side by side in the left-right direction. Each of the burner groups 7 and 8 is formed by arranging a plurality of flat burners 9 having a flame hole at the upper end surface side by side in the left-right direction, and supplies gas to the rear end of the mixing pipe 10 provided at the bottom of each burner 9. The primary air for combustion is supplied together with the fuel gas by facing a nozzle (not shown) connected to the pipe. Here, the first burner group 7 is the hot water supply side burner and the second burner group 8 is the bath side burner, and the number of burners 9 of the first burner group 7 having a large capacity is set to be larger than that of the second burner group 8. There is.

Next, in the primary heat exchanger 5, the hot water supply side primary heat exchanger 11 located above the first burner group 7 and the bath side primary heat exchanger 12 located above the second burner group 8 are arranged in the left-right direction. Will be installed side by side. Each heat exchanger 11 and 12 is composed of a plurality of fins 13, 13... Stacked at predetermined intervals in the front-rear direction, and a heat transfer tube 14 penetrating each fin 13 in a meandering manner.
Further, in the secondary heat exchanger 6, there is a hot water supply side secondary heat exchanger 15 which is located above the hot water supply side primary heat exchanger 11 and is composed of a plurality of spirally wound endothermic tubes 16, 16... A bath-side secondary heat exchanger 17, which is located above the bath-side primary heat exchanger 12 and is composed of a plurality of meandering heat-absorbing tubes 18, 18, is arranged side by side.

The hot water supply side secondary heat exchanger 15 and the bath side secondary heat exchanger 17 are housed in a box-shaped casing 20, as shown in FIGS. An inlet 21 for the combustion gas that has passed through the primary heat exchanger 5 is formed on the rear surface of the casing 20, and an exhaust port 22 for the combustion gas that has passed through the inside of the casing 20 is formed on the front surface in the left-right direction. An inclined plate 23 is provided at the lower edge of the exhaust port 22 so as to project obliquely forward and upward, and the front end abuts the inner surface of the housing.
Further, on the left side surface of the casing 20, an inlet side header 24 and an outlet side header 25, which communicate with the end portions of the heat absorption tubes 16, 16 of the hot water supply side secondary heat exchanger 15, are provided respectively above and below. There is. An inlet 26 is provided in the inlet header 24, and a water supply pipe 27 is connected to the inlet 26. An outlet 28 is provided in the outlet header 25, and a connecting pipe 29 is connected to the inlet of the heat transfer pipe 14 of the hot water supply side primary heat exchanger 11. A hot water outlet pipe 30 is connected to the outlet of the heat transfer pipe 14 of the hot water supply side primary heat exchanger 11.

  Further, on the right side surface of the casing 20, an inlet side header 31 and an outlet side header 32, which communicate with the end portions of the heat absorbing tubes 18, 18 of the bath side secondary heat exchanger 17, are provided at the front and rear, respectively. There is. An inlet 33 is provided in the inlet header 31 and a return pipe 34 from the bathtub is connected to the inlet 33. An outlet 35 is provided in the outlet header 32, and a connection pipe (not shown) to the inlet of the heat transfer pipe 14 of the bath-side primary heat exchanger 12 is connected to the outlet header 32. An outlet pipe 36 to the bathtub is connected to the outlet of the heat transfer pipe 14 of the bath-side primary heat exchanger 12.

  Then, as shown in FIGS. 4 and 5, inside the casing 20, a partition plate 40 as a partition member for partitioning between the hot water supply side secondary heat exchanger 15 and the bath side secondary heat exchanger 17 is provided. It is provided in the direction. The partition plate 40 allows the combustion gas flowing from the inflow port 21 into the casing 20 to pass through the heat absorption pipes 16, 16 of the hot water supply side secondary heat exchanger 15 and to be discharged from the exhaust port 22. A passage 41 and a bath-side exhaust passage 42 through which the combustion gas flowing from the inflow port 21 passes between the heat absorbing tubes 18, 18 of the bath-side secondary heat exchanger 17 and is discharged from the exhaust port 22 are formed. There is.

Further, above the exhaust port 22 in the front of the casing 20, it hangs down from a rear position with a predetermined distance from the front face of the casing 20 in parallel with the front face, to a position slightly lower than the vertical center in the casing 20. A straightening plate 43 having an L-shape in a side view is provided, which includes a hanging portion 44 and a left-right guide portion 45 that extends obliquely upward and forward from the lower end of the hanging portion 44 and is connected to the upper end of the exhaust port 22. There is.
Therefore, when the combustion gas moving forward through the hot water supply side exhaust passage 41 and the bath side exhaust passage 42 from the inflow port 21 comes into contact with the drooping portion 44 of the current plate 43, as shown by the dotted line in FIG. After being lowered along with, it goes around below the hanging portion 44, moves forward along the guide portion 45, and is discharged from the exhaust port 22.

The partition plate 40 here has a dimension in the front-rear direction shorter than the distance in the front-rear direction in the casing 20, is arranged rearward in the casing 20, the upper end is the upper surface in the casing 20, and the lower end is the casing. The rear end is fixed to the bottom surface of the casing 20 and the rear surface of the casing 20 respectively defines the left and right hot water supply side exhaust passages 41 and the bath side exhaust passage 42.
Therefore, the front end 40a of the partition plate 40 does not contact the hanging portion 44 of the straightening plate 43 and the front inner surface of the casing 20, but is formed up to the front of the hanging portion 44, and the inner front surface of the casing 20 including the straightening plate 43. An opening 46 is formed vertically between the hot water supply side exhaust passage 41 and the bath side exhaust passage 42 to communicate with each other.

  On the other hand, in the can body 3, between the lower partition member 50 located between the first burner group 7 and the second burner group 8, the hot water supply side primary heat exchanger 11 and the bath side primary heat exchanger 12. The partition member 51 located is provided. By the lower partition member 50, the middle partition member 51, and the partition plate 40, the first burner group 7, the hot water supply side primary heat exchanger 11 and the hot water supply side secondary heat exchanger 15 are arranged in the can body 3. It is partitioned into a hot water supply side combustion chamber 52, a second burner group 8, a bath side primary heat exchanger 12, and a bath side combustion chamber 53 in which a bath side secondary heat exchanger 17 is arranged. The lower partition member 50 is provided with a thermistor 54 for detecting the temperature of the combustion gas and monitoring the blockage of the fins 13. An air supply fan (not shown) is connected to the lower portion of the can body 3 so that the air sent from the air supply fan can be supplied to the combustion chambers 52 and 53.

  In the bath water heater 1 configured as described above, when the hot water tap provided on the downstream side of the hot water outlet pipe 30 is opened to allow water to flow through the equipment, the water from the hot water pipe 27 becomes the secondary hot water supply side. After passing through the heat absorption pipes 16 of the heat exchanger 15, the water passes through the heat transfer pipes 14 of the hot water supply side primary heat exchanger 11. On the other hand, a controller (not shown) provided outside the appliance ignites the first burner group 7 and rotates the air supply fan to supply combustion air to the first burner group 7. The combustion gas of the first burner group 7 passes through the hot water supply side primary heat exchanger 11 and the hot water supply side secondary heat exchanger 15 in this order in the hot water supply side combustion chamber 52, so that the hot water supply side primary heat exchanger 11 mainly Sensible heat is recovered, latent heat is mainly recovered in the hot water supply side secondary heat exchanger 15, and hot water of a predetermined temperature is discharged from the hot water discharge pipe 30.

  On the other hand, when the additional cooking switch provided in the controller is turned on, the controller drives the pump provided in the circulation path to the bathtub to ignite the second burner group 8 and rotate the air supply fan. Combustion air is supplied to the second burner group 8. The hot water from the bathtub passes through the heat absorbing pipe 18 of the bath side secondary heat exchanger 17, and then passes through the heat transfer pipe 14 of the bath side primary heat exchanger 12, and the combustion gas of the second burner group 8 becomes the bath side. In the combustion chamber 53, the bath-side primary heat exchanger 12 and the bath-side secondary heat exchanger 17 pass in that order. Therefore, the sensible heat is mainly recovered in the bath-side primary heat exchanger 12, and the latent heat is mainly recovered in the bath-side secondary heat exchanger 17, and the hot water in the bathtub is circulated and reheated.

At this time, in the secondary heat exchanger 6, the combustion gas flowing in from the inflow port 21 via the primary heat exchanger 5 passes through the hot water supply side exhaust passage 41 or the bath side exhaust passage 42, respectively, and goes below the straightening plate 43. And is discharged to the outside of the device through the exhaust port 22.
Here, even if the opening 46 is formed between the partition plate 40 and the straightening plate 43 and the inner surface of the front side of the casing 20, both exhaust passages 41 and 42 are partitioned by the partition plate 40 on the rear side, so that the hot water supply is performed. The combustion gas is smoothly guided to the exhaust port 22 by the partition plate 40 even when only one of the side and the bath is operated.
The drain generated in the hot water supply side exhaust passage 41 and the bath side exhaust passage 42 is received by a recess 55 that is recessed in front of the bottom surface of the casing 20 that inclines forward and slopes downward to the right, and the deepest portion on the right side of the recess 55. It is discharged to a neutralizer (not shown) from the drain discharge pipe 56 provided in the.

  As described above, according to the secondary heat exchanger 6 and the bath water heater 1 of the above-described embodiment, the partition plate 40, which is shorter than the front-rear distance in the casing 20 in the direction in which the combustion gas flows, is installed in the rear portion of the casing 20. Then, an opening 46 is formed between the front inner surface of the casing 20 and the front end 40a of the partition plate 40 on the downstream side of the flow of the combustion gas in the casing 20 so that the two exhaust passages 41, 42 communicate with each other. Therefore, the partition plate 40 can be short, and the cost and the labor of assembly of the partition plate 40 can be reduced without hindering the heat exchange in the exhaust passages 41 and 42.

FIGS. 6 and 7 show changes in heat exchange efficiency when a plurality of partition plates 40 whose lengths in the front-rear direction in the casing 20 are gradually reduced are prepared and only the water heater side is operated at each length. It is the verified table and graph.
Here, when the partition plate 40 partitions all of the casing 20 in the front-rear direction (100%), the heat exchange efficiency becomes 95%, and the length of the partition plate 40 (ratio to the length when partitioning all) is calculated from there. 95%, 90%, 85%, 80% ··································································· As the rear side shortens, the heat exchange efficiency gradually decreases to 95%, 94.761%, 94.741%, 94.541%, Has become.
From this table and graph, it can be seen that a heat exchange efficiency of 90% or more can be obtained even when the length of the partition plate 40 is 55%. However, in consideration of securing a high heat exchange efficiency of 94% or more in the latent heat recovery type, it is desirable that the length of the partition plate 40 be 75% or more.

The structure of the partition member is not limited to the one partition plate as in the above embodiment, and a plurality of plate materials or parts may be combined or one plate material may be bent. The shape of the opening can also be changed as appropriate by changing the shape of the front end of the partition member.
Further, in the above-described embodiment, the combined water heater has two heating units, one for the hot water supply side and the other for the bath side, but the bath side may be another heating unit for heating equipment.
Further, the heat exchangers for recovering latent heat are not limited to those having heat absorbing tubes provided in both exhaust passages to form a secondary heat exchanger, and heat absorbing tubes are provided only in one of the exhaust passages (for example, hot water supply side). The present invention can be applied even to a combined water heater that forms a secondary heat exchanger as a result.

  1...Bath water heater, 2...Combustion device, 3...Can body, 4... Burner unit, 5...Primary heat exchanger, 6...Secondary heat exchanger, 7...First burner group, 8・・Second burner group, 9・・Burner, 11・・Hot water supply side primary heat exchanger, 12・・Bath side primary heat exchanger, 13・・Fin, 14・・Heat transfer tube, 15・・Hot water supply side Secondary heat exchanger, 16, 18... Heat absorption pipe, 17... Bath secondary heat exchanger, 20... Casing, 21... Inflow port, 22... Exhaust port, 27... Water supply pipe, 30... Hot water supply pipe, 40... Partition plate, 40a... Front end, 41... Hot water supply side exhaust passage, 42... Bath side exhaust passage, 43... Current plate, 46... Opening, 52... Hot water supply side combustion chamber, 53 ..Bath side combustion chamber

Claims (3)

A partition member is provided inside the casing to form two left and right exhaust passages, and at least one of the exhaust passages accommodates an endothermic tube for recovering latent heat from the combustion gas that has passed through the sensible heat recovery heat exchanger. A heat exchanger consisting of
The partition member, which is shorter than the front-rear distance in the casing in the front-rear direction in which the combustion gas flows, is installed near the rear in the casing, and the casing is provided on the downstream side of the flow of the combustion gas in the casing. A heat exchanger, characterized in that an opening is formed between a front inner surface and a front end of the partition member so that the two exhaust passages communicate with each other.   The heat exchanger according to claim 1, wherein a front-rear distance of the partition member has a ratio of 75% or more to a front-rear distance when the inside of the casing is completely partitioned.   A burner, a heat exchanger for sensible heat recovery arranged upstream of the combustion gas flow of the burner, and a heat exchanger according to claim 1 or 2 arranged downstream of the flow. A complex water heater.

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