JP4178944B2 - Heat exchanger - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a heat exchanger suitable for being applied to a heat exchanger for a hot water heater that is built in a hot water heater or the like, exchanges heat with a high-temperature gas containing water vapor, and heats hot water.
[0002]
[Prior art]
As a conventional heat exchanger for a hot water heater, for example, in the invention described in Patent Document 1, a thin fin is provided on the outer wall surface of a tube through which hot water is circulated to promote heat exchange between hot water and combustion gas. Yes.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-146305
[Problems to be solved by the invention]
In recent years, there is a strong demand for improving the performance of heat exchangers, and one possible measure is to deal with fin densification.
[0005]
However, the combustion gas exchanges heat with hot water and lowers the temperature. However, when the temperature of the combustion gas falls below the dew point temperature, the water vapor in the combustion gas condenses to produce condensed water. At this time, as shown in FIG. 15, the condensed water adheres (collects) by forming a thick liquid film over a wide area of the fin 3. Or depending on the above-mentioned densification of the fins 3, as shown in FIG. 16, the condensed water stretches completely between the fins 3 and stagnates. And it becomes the thermal resistance which inhibits a heat | fever moving to the fin 3 from combustion gas. Furthermore, when the flow path of the combustion gas is blocked by condensed water, the ventilation resistance increases. As a result, the heat exchange efficiency is deteriorated.
[0006]
The present invention has been made based on the above points, and prevents adhesion and stagnation of condensed water generated during heat exchange to the fins, and prevents deterioration of the heat exchange efficiency of the heat exchanger. Objective.
[0007]
[Means for Solving the Problems]
The present invention employs the following technical means to achieve the above object.
[0008]
In addition, the code | symbol in the parenthesis of each means shown below is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.
[0009]
In invention of Claim 1, it has a plurality of flat tubes (2) arranged in a stack,
Between the adjacent tubes (2), the first wall surface (3A) joined to the outer wall surface (4c) of the tube (2) and the second wall surface intersecting with the first wall surface (3A) (3B) and fins (3) for improving heat transfer performance are provided,
A high-temperature gas containing water vapor flows from the upper side to the lower side through the gas passage (11) formed between the adjacent tubes (2), and the temperature is lower than the high-temperature gas in the fluid passage (2A) in the tube (2). A heat exchanger for circulating a fluid and recovering not only sensible heat but also latent heat of condensation from a high-temperature gas to heat a low-temperature fluid,
On the first wall (3A)
Cut out from the first wall (3A) leaving one side of the triangle and protruding into the gas passage (11),
One side with respect to the hot gas flow direction is arranged to be inclined, Ri is Na large amount of projection of the own as a hot gas stream downstream,
A plurality of gaps (δ) are provided so that the direction of inclination of one side is alternately different from the high-temperature gas flow direction,
Condensed water condensed from the high-temperature gas by the recovery of the latent heat of condensation once gathers by surface tension, and a cut-and-raised piece (10) for dropping the collected condensed water downward by its own weight and the wind pressure of the high-temperature gas. It is characterized by being provided.
[0010]
Condensed water condensed from the high-temperature gas in the gas passage (11) is first generated as fine droplets and then drops down by its own weight. In the present invention, the condensed water can be once cut and raised and actively collected in the piece (10). That is, since the flow velocity of the high-temperature gas decreases in the vicinity of the surface of the cut and raised piece (10), the fine droplets that hang down can be cut and raised and gathered on the piece (10) by its surface tension.
[0011]
In this case, hot gas is allowed to pass through a small area of the protruding amount on the upstream side of the cut-and-raised piece (10), it is not the heat exchange between the hot gas and cold fluid stagnates, cut In the region on the upstream side and the downstream side (upper and lower side) with respect to the raising piece (10), the generation of condensed water is continued.
[0012]
Then, when the downward force due to the weight of the condensed water collected on the cut and raised piece (10) and the wind pressure of the high-temperature gas exceeds the surface tension of the condensed water on the cut and raised piece (10), the condensed water is discharged all at once. Can be dropped down.
[0013]
By repeating the cycle of collecting and condensing condensed water on the cut and raised pieces (10) and sequentially dropping the collected condensed water, the condensed water is collected in a wide area of the gas passage (11) as in the past. It is possible to prevent adhesion and stagnation. Therefore, it is possible to prevent an increase in heat resistance and ventilation resistance due to condensed water, and it is possible to prevent deterioration in heat exchange efficiency of the heat exchanger (1).
[0014]
Moreover, since the quantity of the condensed water adhering to a gas channel | path (11) surface can be reduced incidentally, it suppresses that a gas channel | path (11) and a cut-and-raised piece (10) corrode early. Can do.
[0015]
The cut and raised pieces (10) are discretely provided with gaps (δ) in the flow direction of the high-temperature gas, so that the gas passage (11) is balanced over the entire high-temperature gas flow direction. The effect described in claim 1 can be obtained well.
[0019]
Further, by providing a plurality of cut and raised pieces (10) so that the directions of inclination of one side are alternately different , the protruding amount of the cut and raised pieces (10) is small with respect to the direction intersecting the flow of high-temperature gas. It can be arranged so that the positions on the sides are different. The high-temperature gas mainly passes through the side with a small amount of protrusion, and can form a regular meandering flow. Therefore, high-temperature gas can be made to flow evenly with respect to the gas passage (11), and the heat exchange efficiency is not lowered.
[0022]
Cut-and-raised piece (10), since so as to be formed by cut and raised from the surface of the fin (3), can be easily processed projections (10).
[0024]
In the present heat exchanger (1), condensed water tends to be generated on the outer wall surface (4c) of the tube (2) where the temperature difference between the high temperature gas and the low temperature fluid is maximized. Therefore, by forming the first wall (3A) to be bonded cut-and-raised piece (10) on the outer wall surface (4c), easily lead to piece cut and raised condensed water (10). The opening (10c) on the surface of the fin (3) formed when the cut and raised piece (10) is cut up can be closed by the outer wall surface (4c) of the tube (2), and the flow of high-temperature gas can be prevented. There is no disturbance.
[0025]
Moreover, cut-and-raised piece (10), since so as to be formed in a triangular, can be easily formed on the cut-and-raised piece (10).
Further, as in the invention described in claim 2, the plurality of cut and raised pieces (10) may overlap each other when viewed from the high-temperature gas flow direction.
Further, as in the invention described in claim 3 , if the apex of the cut and raised piece (10) formed in a triangle is formed in an obtuse angle or a smooth curved shape, it is cut and raised (press molding). Is even easier.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
[0027]
3 is a front view of the heat exchanger 1, FIG. 4 is a plan view of the heat exchanger 1, and FIG. 5 is a side view of the heat exchanger 1.
[0028]
The heat exchanger 1 of the present embodiment is used in a hot water heater and performs heat exchange between hot water (a low-temperature fluid of the present invention) and combustion gas containing water vapor (a high-temperature gas of the present invention). However, the temperature of the hot water is lower than that of the combustion gas, and the hot water is heated by the combustion gas), and a plurality of flat tubes 2 are laminated together with the outer fins 3 as shown in FIGS. The heat exchanger 1 is a so-called drone cup type configured as described above, and is manufactured by integral brazing after the whole is assembled.
[0029]
The tube 2 is formed by combining two heat transfer plates 4 (4A, 4B) shown in FIGS. 6 and 7, and a flat tube portion that forms a U-shaped flowing water passage (fluid passage of the present invention) therein. 2A (see FIG. 4) and a set of tank portions 2B (see FIG. 4) communicating with both ends of the running water passage are provided, and a communication port 2b is opened in the tank portion 2B.
[0030]
The two heat transfer plates 4 have substantially the same shape except that the winding portion 4a is provided at the peripheral edge portion of the first heat transfer plate 4A (see FIG. 6). As shown in FIG. 1 (b), the two heat transfer plates 4 are formed by folding the winding portion 4a of the first heat transfer plate 4A from the inner surface side to the outer surface side of the second heat transfer plate 4B. The end of the second heat transfer plate 4B is assembled by being wound so as to be sandwiched from both sides, and the contact surfaces 4b of both are brazed.
[0031]
The tank portion 2B is provided with a larger thickness than the flat tube portion 2A, and a flat surface 2c (see FIG. 5) that is a brazed surface around the communication port 2b is formed on the outer wall surface of the heat transfer plate 4 forming the tank portion 2B. 8 and FIG. 10) are provided in an annular shape. In addition, the cross-sectional shape (BB cross section, CC cross section, DD cross section) of the heat transfer plate forming the tank portion 2B and the cross-sectional shape of the heat transfer plate 4 forming the flat tube portion 2A. (EE cross section) is shown in FIGS.
[0032]
As shown in FIGS. 4 and 5, the plurality of tubes 2 are stacked with the tank portions 2 </ b> B connected to each other, and the flat portions 2 c provided around the communication port 2 b are joined to each other. Thereby, the flowing water passage of each tube 2 is mutually connected through the communication port 2b opened to the tank part 2B. Note that an inner fin 5 may be inserted inside the tube 2 in order to increase the heat transfer area as shown in FIG.
[0033]
As shown in FIG. 5, a hot water supply port 6 and a hot water outlet 7 of the hot water supply are joined to the tank portion 2 </ b> B in the tube 2 disposed on one end side in the stacking direction. Reinforcing plates 8 are joined to both ends of the tube 2 in the stacking direction.
[0034]
In the flat tube portion 2A having a thickness smaller than that of the tank portion 2B, a flat space having a substantially constant width is formed between the adjacent flat tube portions 2A. This space is a combustion gas passage 11 (gas passage of the present invention) through which combustion gas passes, and an outer fin (fin of the present invention) 3 is disposed in the combustion gas passage 11.
[0035]
As shown in FIG. 2A, the outer fin 3 is formed by bending a thin plate material made of a metal (for example, stainless steel, aluminum, etc.) having excellent heat conductivity into an uneven shape, and the combustion gas flows downward from above into the uneven space. And is brazed to the outer wall surface 4c of the heat transfer plate 4 forming the flat tube portion 2A (tube 2). The combustion gas passage 11 is partitioned into a plurality of narrow flow passages 11a by the outer fins 3 bent in such an uneven shape.
[0036]
Of the wall surfaces of the outer fin 3 that are bent into the concavo-convex shape, the wall surface that is arranged substantially parallel to the outer wall surface 4c of the tube 2 and is brazed to the outer wall surface 4c is the first wall surface 3A. Of the wall surfaces of the outer fin 3 that are bent into an uneven shape, the side wall surface intersecting with the first wall surface 3A is the second wall surface 3B.
[0037]
As shown in FIGS. 1A and 2A, the first wall surface 3A of the outer fin 3 has a plurality of discretely spaced gaps δ over almost the entire area of the outer fin 3 disposed in the combustion gas passage 11. There are provided cut and raised pieces (hereinafter referred to as wings) 10.
[0038]
Here, the wing 10 is cut and raised from the first wall surface 3 </ b> A of the outer fin 3, leaving one side of the triangle, and is a protruding portion that protrudes into the combustion gas passage 11. The wing 10 is arranged in such a direction that the height (projection amount) from the first wall surface 3A becomes higher as it becomes downstream of the combustion gas flow.
[0039]
The wing 10 is provided to be inclined at a predetermined angle with respect to the flow direction of the combustion gas, and the two wings 10a and 10b continuous in the vertical direction of the outer fin 3 are as shown in FIG. The inclination direction with respect to the flow direction of the combustion gas is cut and raised. That is, the upper wing 10a (first projecting portion of the present invention) shown in FIG. 2B is cut and raised from the fin surface leaving one side of the right side of the triangle, whereas the lower wing 10b ( The second protrusion of the present invention is cut and raised from the fin surface leaving one side of the left side of the triangle. Therefore, the wing 10 has a staggered arrangement in which the inclination angles are alternately different with respect to the flow direction of the combustion gas. Note that the height and width of the wing 10 are such that the combustion gas passages are not blocked.
[0040]
Next, the operation and effect of this embodiment will be described.
[0041]
Hot water flows from the hot water supply port 6 of the heat exchanger 1 into one tank portion 2B of each tube 2, and flows from the one tank portion 2B through a flowing water passage formed in the flat tube portion 2A to the other tank portion. It flows into 2B and flows out from the other tank part 2B through the hot water outlet 7. On the other hand, as shown in FIG. 3, the combustion gas flows from the upper side to the lower side of the heat exchanger 1 and exchanges heat with hot water when passing through the heat exchanger 1 to heat the hot water. To do. At this time, the temperature of the combustion gas decreases to at least the dew point temperature (for example, 30 to 50 ° C.) at least on the outlet side of the heat exchanger 1, and the water vapor contained therein condenses. That is, the heat exchanger 1 can absorb not only the sensible heat of the combustion gas but also the condensation latent heat released when the combustion gas condenses to heat the hot water.
[0042]
In this invention, the characteristic part is given to the place which drains the condensed water produced | generated as mentioned above effectively.
[0043]
First, the condensed water condensed from the combustion gas is generated as fine droplets on the first wall surface 3A of the outer fin 3 as shown in FIG. And this condensed water is once collected by the wing 10 positively. That is, since the flow velocity of the combustion gas decreases near the surface of the wing 10, fine droplets that hang down can be collected on the wing 10 by its surface tension. Note that condensed water generated near the lower surface of the wing 10 is also collected by surface tension (white arrow in FIG. 11A).
[0044]
At this time, the combustion gas can pass through a region with a small amount of protrusion on the upstream side of the wing 10 (a in FIG. 11), and heat exchange between the combustion gas and hot water is not delayed, and the wing In the region upstream and downstream (upper and lower) with respect to 10, the generation of condensed water is continued.
[0045]
Then, as shown in FIG. 11B, when the downward force due to the weight of the condensed water collected in the wing 10 and the wind pressure of the combustion gas exceeds the surface tension of the condensed water in the wing 10, the condensed water is It is dropped downward at a stretch (hatching arrow in FIG. 11B). In addition, in the wing (not shown) located on the further downstream side (lower side) of the wing 10 shown in FIG. 11, the condensed water falling as described above is further collected and dropped again. Further, the process is repeated toward the downstream side (lower side).
[0046]
In this way, by repeating the cycle of collecting condensed water in the wing 10 and sequentially dropping the collected condensed water, the condensed water adheres or stagnates in a wide area of the gas passage 11 as in the past. Can be prevented. Therefore, it is possible to prevent an increase in heat resistance and ventilation resistance due to condensed water, and to prevent deterioration in heat exchange efficiency of the heat exchanger 1.
[0047]
Here, since a plurality of wings 10 are discretely provided with gaps δ in the flow direction of the combustion gas, it is possible to prevent adhesion and stagnation of condensed water in a well-balanced manner throughout the flow direction of the combustion gas.
[0048]
Further, since the plurality of wings 10 are arranged in a staggered manner so that the inclination angles thereof are alternately different in the flow direction of the combustion gas, the position on the side where the protrusion amount of the wing 10 is small with respect to the direction intersecting the flow of the combustion gas. Can be arranged differently. And combustion gas can mainly pass the side with small protrusion amount, and can form a regular meandering flow. Therefore, combustion gas can be made to flow evenly with respect to the gas passage 11, and heat exchange efficiency is not reduced.
[0049]
Moreover, since the wing 10 is formed by cutting and raising the first wall surface 3A of the outer fin 3, the wing 10 can be easily processed. And it becomes easy to guide the condensed water produced | generated on the outer wall surface 4c of the tube 2 in which the temperature difference of combustion gas and hot water supply becomes the maximum to the wing 10. Note that the opening 10c on the fin surface formed when the wing 10 is cut and raised can be closed by the outer wall surface 4c of the tube 2, and the flow of combustion gas is not disturbed.
[0050]
Further, since the wing 10 has a triangular shape, it is possible to easily form a protruding portion whose protruding amount increases toward the downstream side of the combustion gas.
[0051]
Further, in the present embodiment, the outer fin 3 is a fin formed by bending a thin plate member into a concavo-convex shape, so that it is easier to manufacture fins with a finer pitch than an offset fin, and the heat dissipation area of the fin is easily expanded. can do.
[0052]
Further, since the amount of condensed water adhering to the surface of the combustion gas passage 11 can be reduced, it is possible to prevent the tube 2 and the wing 10 (outer fin 3) from corroding early.
[0053]
As a first modification of the first embodiment, as shown in FIG. 12, when the plurality of wings 10 are provided so as to overlap each other when viewed from the flow direction of the combustion gas, the combustion gas flow is uniform. Can be further enhanced.
[0054]
Further, as a second modification of the first embodiment, as shown in FIG. 13, the apex of the wing 10 formed in a triangular shape is formed into a polygonal shape so as to be an obtuse angle, or formed with a smooth curve. In this way, the cut and raise molding (press molding) can be further facilitated.
[0055]
(Second Embodiment)
A second embodiment of the present invention is shown in FIG. In the second embodiment, the protruding portion is formed in the tube 2 with respect to the first embodiment. Here, the projecting portion 4d is formed as a protruding portion on the outer wall surface 4c of the heat transfer plates 4A and 4B constituting the tube 2 as a protruding portion.
[0056]
Thereby, the effect similar to the said 1st Embodiment can be acquired. Further, as compared with the case where the outer fin 3 is cut and raised to form the wing 10 (protrusion) as in the first embodiment, the heat transfer plates 4A and 4B of the tube 2 are simultaneously stamped at the time of press molding. The portion 4d can be formed, and an inexpensive response is possible.
[0057]
(Other embodiments)
In the first embodiment, the example in which the wing 10 is formed by cutting and raising the outer fin 3 has been described. For example, the wing 10 is formed as a separate part and brazed to the outer fin 3 bent into an uneven shape. You may join by the means of. Furthermore, although the embodiment in which the wing 10 is formed on the first wall surface 3A has been described, the wing 10 may be formed on the second wall surface 3B.
[0058]
In the above embodiment, the heat exchanger 1 of the present invention has been described as applied to a hot water heater. However, the present invention is not limited to this, and other applications such as an evaporator disposed in a refrigeration cycle are also applicable. May be.
[Brief description of the drawings]
1A is a cross-sectional view showing an AA portion in FIG. 3, and FIG. 1B is an enlarged cross-sectional view showing an F portion (tube tightening portion) of FIG.
2A is a perspective view showing an outer appearance of an outer fin, and FIG. 2B is a front view of a brazing surface showing a shape of a wing.
FIG. 3 is a front view showing a heat exchanger for a water heater.
FIG. 4 is a plan view showing a heat exchanger for a water heater.
FIG. 5 is a side view showing a heat exchanger for a water heater.
FIG. 6 is a three-side view showing a first heat transfer plate.
FIG. 7 is a three-sided view showing a second heat transfer plate.
8 is a cross-sectional view showing a BB part in FIG. 6. FIG.
9 is a cross-sectional view showing an EE portion in FIG. 6. FIG.
10A is a cross-sectional view showing a CC section, and FIG. 10B is a cross-sectional view showing a DD section.
FIGS. 11A and 11B are enlarged views of the main part of the wing, in which FIG. 11A is a model diagram showing the behavior of condensed water gathering in the wing, and FIG. 11B is a model diagram showing the behavior of gathered condensed water falling;
12A is an external perspective view of an outer fin, and FIG. 12B is an arrow view from the G direction of FIG.
13A is a plan view of a wing variation 2 and FIG. 13B is a plan view of a wing variation 2 showing a second modification of the first embodiment;
14A is a front view showing a protrusion in the second embodiment, and FIG. 14B is an arrow view from the H direction of FIG. 14A.
FIG. 15 is a model diagram showing the behavior of condensed water in the prior art.
FIG. 16 is a model diagram showing the behavior of condensed water when fins are densified in the prior art.
[Explanation of symbols]
1 Heat exchanger for water heater 2 Tube 2A Flat tube (fluid passage)
3 Outer fin (fin)
3A 1st wall surface 3B 2nd wall surface 4c outer wall surface 4d Launching part 10 Cut-and-raised piece (wing, projecting part)
10a Upper wing (first protrusion)
10b Lower wing (second protrusion)
11 Combustion gas passage (gas passage)

Claims (3)

It has a plurality of flat tubes (2) arranged in a stack,
Between the adjacent tubes (2), a first wall surface (3A) joined to the outer wall surface (4c) of the tube (2) and a second wall that intersects the first wall surface (3A). And a fin (3) for improving the heat transfer performance is provided.
A high-temperature gas containing water vapor flows from the upper side to the lower side through the gas passage (11) formed between the adjacent tubes (2), and the high-temperature gas flows into the fluid passage (2A) in the tube (2). A heat exchanger that circulates a lower temperature fluid and recovers not only sensible heat but also latent heat of condensation from the high temperature gas to heat the low temperature fluid,
In the first wall surface (3A),
Is cut and raised from the first wall surface (3A) leaving one side of the triangle, and protrudes into the gas passage (11),
Wherein it is arranged such that the one side against the hot gas flow direction is inclined, Ri is Na large amount of projection of the own as a gas flow downstream of said high temperature,
A plurality of gaps (δ) are provided so that the direction of inclination of the one side is alternately different from the high-temperature gas flow direction,
Condensed water condensed from the high-temperature gas due to the recovery of the latent heat of condensation is once collected by surface tension, and the collected condensed water is dropped downwards at once by its own weight and the wind pressure of the high-temperature gas ( 10) is provided, and the heat exchanger. The heat exchanger according to claim 1 , wherein the plurality of cut and raised pieces (10) are provided so as to overlap each other when viewed from the high-temperature gas flow direction. Apex of the cut-and-raised piece that is formed on the triangle (10) A heat exchanger according to claim 1 or claim 2, characterized in that it is formed at an obtuse angle or a smooth curve.

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