JP2010276319A - Heat exchanger - Google Patents

Abstract

An object of the present invention is to provide a heat exchanger that has a good pressure resistance and realizes high heat exchange performance by realizing well-balanced heat transfer promotion of two fluids to be heat exchanged.
A straight tubular inner tube is inserted and arranged in a straight tubular outer tube, and the wall of the tube is disposed in the gap between the outer tube and the inner tube. A twisted tube-shaped inner tube 16 is formed by coaxially arranging fins 18 that are alternately bent and protruded, and are formed on the inner and outer surfaces of the tube 18 in a spiral manner in the tube axis direction. The tip 22 is closely fitted to the inner surface of the outer tube 12 to form the outer flow path 26, while the fin tip 24 on the inner surface side of the fin 18 is closely fitted to the outer surface of the inner tube 14 to be connected to the inner flow path 28. And the heat exchanger 10 was configured.
[Selection] Figure 1

Description

  The present invention relates to a heat exchanger that performs heat exchange between a fluid flowing inside a pipe and a fluid flowing outside the pipe, and more particularly to a liquid-liquid heat exchanger used for a hot water heater.

  Conventionally, as a heat exchanger used for a hot water heater, a small-diameter heat transfer tube is arranged inside a large-diameter outer tube, and the first fluid is circulated in a gap between the inner tube and the outer tube, A double-pipe heat exchanger configured to exchange heat between the first fluid and the second fluid by circulating the second fluid in the inner tube, or a plurality of heat transfer 2. Description of the Related Art A plate heat exchanger or the like configured such that plates are overlapped to form a flow path between adjacent heat transfer plates and a heat exchange medium flows alternately therethrough is known.

  As such a double tube heat exchanger, for example, in Japanese Patent Laid-Open No. 2001-201275 (Patent Document 1), the inner flow path of the outer tube is partitioned in a spiral manner between the inner tube and the outer tube. By increasing the flow path length of the flow path formed between the inner pipe and the outer pipe and increasing the flow velocity and turbulence of the fluid flowing through the flow path by interposing a heat transfer promoting body A double-tube heat exchanger has been clarified in which heat transfer from a fluid flowing in the inner tube to a fluid flowing between the inner tube and the outer tube is promoted. Further, in Japanese Patent Application Laid-Open No. 2007-85595 (Patent Document 2), a liquid for a hot water heater constituted by an inner tube having a spiral pleated hollow fin and an outer tube disposed outside the inner tube is provided. A liquid heat exchanger has been disclosed.

  However, these double tube heat exchangers have been devised to add a heat transfer promoting effect to the circulating fluid, but the effect is not sufficient. The difference in heat transfer promotion effect with respect to the two fluids performing the process was large and unbalanced. For example, in the double-pipe heat exchanger disclosed in Patent Document 1, a gap between the inner pipe and the outer pipe is provided by interposing a heat transfer promoter between the inner pipe and the outer pipe. However, the heat transfer promoting effect on the fluid side flowing through the inner pipe is not sufficient. For this reason, it has also been clarified that a heat transfer promoting body for an inner tube made of a twisted tape or the like is inserted into the inner tube, but that alone does not exhibit a sufficient heat transfer promoting effect. In addition, if a twisted tape is inserted into the inner tube or a spiral heat transfer promoting body is interposed between the inner tube and the outer tube, the pressure loss of the circulating fluid increases. It is not preferable.

  Further, in the heat exchanger disclosed in Patent Document 2, a heat transfer tube having a spiral pleated hollow fin formed by buckling a wall surface by a torsional force is used as an inner tube, and flows in the inner tube. The heat transfer area of the fluid and the fluid flowing between the inner and outer pipes is increased together, and the turbulent effect is applied to both fluids to improve heat exchange efficiency. It is difficult for the fluid to enter the hollow fin of the inner tube having such a shape, and therefore the heat transfer promoting effect in the inner tube cannot be expected.

  On the other hand, the plate heat exchanger disclosed in Japanese Patent Laid-Open No. 2-89991 (Patent Document 3) is a heat exchanger having a good heat transfer promoting effect, but its structure has a pressure resistance. There was a drawback that it was easy to cause a lack of strength. Moreover, the plate type heat exchanger used in the heat pump type hot water supply apparatus disclosed in Japanese Patent Application Laid-Open No. 2007-322051 (Patent Document 4), that is, the cross-sectional shape in FIG. In the plate-type heat exchanger as described, the balance of the channel cross-sectional shape is poor, and in particular, the heat transfer promoting effect of the inner channel cannot be expected.

JP 2001-201275 A JP 2007-85595 A JP-A-2-89991 JP 2007-322051 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that it has a good pressure resistance and a good balance of heat transfer enhancement of two fluids to be heat exchanged. An object of the present invention is to provide a heat exchanger that exhibits high heat exchange performance.

  In the present invention, in order to solve such problems, a straight tubular inner tube is inserted and arranged in the straight tubular outer tube, and a gap between the outer tube and the inner tube is provided. A heat exchanger in which a middle pipe is coaxially disposed inside, and as the middle pipe, a pipe wall is bent and protruded alternately outward and inward of the pipe and spiraled in the pipe axis direction. A torsion tube in which fins extending in the shape of the tube are formed on the inner and outer surfaces of the tube, the tip of the fin on the outer surface side of the torsion tube is closely fitted to the inner surface of the outer tube, and the outer tube and the torsion tube Is formed between the torsion tube and the inner tube, and the tip of the fin on the inner surface side of the torsion tube is closely fitted to the outer surface of the inner tube. A spiral inner flow path is formed, and separate fluids are passed through the outer flow path and the inner flow path, and heat exchange is performed between the fluids. A heat exchanger which is characterized by being configured to be performed, is to its gist.

  According to one of the desirable embodiments of the heat exchanger according to the present invention, at least one set of an additional torsion tube having a structure similar to the torsion tube and a straight tubular extrapolation tube is provided on the radially outer side of the outer tube. These are alternately arranged in sequence, and each additional torsion tube is formed by forming additional spiral channels on both sides thereof.

  Therefore, according to such a heat exchanger configured according to the present invention, the inner tube, which is a torsion tube disposed coaxially in the gap between the outer tube and the inner tube, is replaced with the outer tube and the inner tube. Partitioning the gap between them and forming two substantially equivalent spiral channels, the heat transfer promoting effect of the two fluids flowing through each channel is almost equal, This makes it possible to realize a balanced heat exchanger. In addition, since the two flow paths are balanced in this way, the force applied to the torsion pipe forming the partition wall between the two flow paths is also canceled out. As a result, the heat exchanger has excellent pressure resistance. It can be.

  And since the fluid which flows through the two flow paths formed by the middle pipe which is such a torsion pipe turns into a swirl flow, the heat transfer promoting effect is advantageously exhibited in each flow path, A large heat transfer effect can be realized.

  Furthermore, in such a heat exchanger, an intermediate tube composed of a torsion tube, which is a relatively simple form, and a straight tubular outer tube and an inner tube are used. Since the heat exchanger can be configured, the heat exchanger can be manufactured relatively easily and the production cost can be advantageously reduced.

It is front explanatory drawing which shows an example of the heat exchanger according to this invention in the cross section which notched the part. It is longitudinal cross-sectional explanatory drawing which shows the cross section parallel to the axial direction of the heat exchanger shown by FIG. It is a longitudinal cross-sectional explanatory drawing which shows another example of the heat exchanger according to this invention with the form of a cross section parallel to an axial direction. It is explanatory drawing which shows the double tube | pipe type heat exchanger of the conventional structure, Comprising: (a) is the longitudinal cross-sectional form, (b) has each shown the AA cross section in (a).

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 shows an embodiment of a heat exchanger according to the present invention in the form of a front view showing a cross-section partly cut away. In this figure, the heat exchanger 10 includes a straight tubular inner tube 14 inserted into a straight tubular outer tube 12, which are arranged coaxially, and the inner peripheral surface of the outer tube 12 and the inner tube 14. In the gap formed between the inner tube 16 and the outer peripheral surface of the inner tube 16 is a coaxially disposed intermediate tube 16 in which fins 18 of a predetermined height are formed on the outer peripheral surface of the tube so as to continuously extend in a spiral shape in the tube axis direction. Has been configured.

More specifically, the outer tube 12 and the inner tube 14 are straight tubular tubes having a substantially circular cross section formed using a metal material such as aluminum, copper, or an alloy thereof. The size is appropriately determined according to the required size of the heat exchanger 10, the heat exchange performance, and the like. In general, the outer tube 12 is about 12.7 to 25.4 mm. and having a tube outer diameter of (D _1), the inner tube 14 is smaller in diameter than according outer tube 12, inserted into the outer tube 12 may be positioned, extravascular about 9.52~22.2mm It has a diameter (D ₃ ). In addition, the outer tube 12 and the inner tube 16 having a tube outer diameter of such a size generally have a tube thickness of about 0.25 to 1.3 mm.

  On the other hand, the intermediate tube 16 is a torsion tube formed using a metal material made of aluminum, copper, or an alloy thereof, and has the same thickness as or thinner than the outer tube 12 and the inner tube 14 described above. The tube wall having a thickness of 5 mm is bent and protruded alternately outward and inward of the tube so that the fin 18 has a predetermined height (H) and continuously extends in a spiral shape in the tube axis direction. It is formed on the inner and outer surfaces of the tube. The fins 18 are formed with a predetermined lead angle and a predetermined interval in the tube axis direction. Generally, the lead angle (spiral angle) is about 45 to 85 °, and the interval (pitch): P is 2 to 2. It is about 6 mm.

  The intermediate tube 16 having such a shape is disposed in a gap formed between the outer tube 12 and the inner tube 14, that is, the intermediate tube 16 and the intermediate tube in the outer tube 12. In the state where the inner tube 16 and the inner tube 14 are sequentially inserted into the outer tube 12 like the inner tube 14 and are arranged coaxially, the fins 18 of the inner tube 16 are connected to the fins on the outer surface side. The tip 22 is closely fitted with the inner peripheral surface of the outer tube 12, while the fin tip 24 on the inner surface side is closely fitted with the outer peripheral surface of the inner tube 14 so that they are integrated into heat. The exchanger 10 is formed.

  In addition, in this way, the fin tips 22 and 24 on the inner and outer surfaces of the fin 18 of the intermediate tube 16 disposed in the gap formed between the outer tube 12 and the inner tube 14 are respectively connected to the outer tube 12. 2 and the outer peripheral surface of the inner tube 14 are closely fitted to each other, so that two independent spiral outer flow paths 26 and inner flow paths 28 are continuously formed in the tube axis direction. ing. That is, as shown in an enlarged view in FIG. 2, the outer flow path 26 is formed in a space between the groove formed between the adjacent fins 18, 18 on the outer surface side of the intermediate tube 16 and the inner peripheral surface of the outer tube 12. On the other hand, an inner flow path 28 is formed in the space between the groove formed between the adjacent fins 18 and 18 on the inner surface side of the intermediate tube 16 and the outer peripheral surface of the inner tube 14. In other words, in other words, the gap formed between the outer pipe 12 and the inner pipe 14 is divided into two independent outer flow paths 26 and inner flow by the pipe wall of the middle pipe 16 disposed in the gap. The road 28 is divided.

  In such a heat exchanger 10, separate fluids are circulated through the two flow paths, the outer flow path 26 and the inner flow path 28, thus formed. Heat exchange is performed between them.

  Thus, according to the heat exchanger 10 having the structure according to the present invention, the gap between the outer tube 12 and the inner tube 14 divided by the inner tube 16 is divided into two substantially equivalent spiral outer flow paths 26. Therefore, the heat transfer promotion effect of the two fluids flowing through the respective flow paths 26 and 28 can be made substantially uniform. Since the two flow paths 26 and 28 are substantially equivalent and have a balanced structure, the force applied to the intermediate tube 16 serving as the partition wall between the two flow paths is also offset. As a result, the pressure strength of the heat exchanger 10 can be advantageously improved.

  Further, each of the flow paths 26 and 28 is a flow path extending in a spiral shape. Therefore, since the fluids circulated in the flow paths are both swirl flows, each flow path is effectively The heat transfer promoting effect is exhibited, and thus a large heat transfer effect can be realized.

  In addition, in such a heat exchanger 10, the target heat can be obtained only by assembling the simple straight tubular outer tube 12 and inner tube 14 and the torsion tube inner tube 16 having a relatively simple form. Since it is possible to configure the exchanger 10, it is possible to advantageously improve the manufacturability of the heat exchanger 10, and to exhibit the effect that the production cost can be advantageously reduced. Become.

  As described above, one of the representative embodiments of the present invention has been described in detail. However, this is merely an example, and the present invention is not limited by the specific description according to such an embodiment. It should be understood that this is not to be construed as limiting.

  For example, in the above-described embodiment, the heat exchanger in which the inner tube 16 is disposed in the gap between the outer tube 12 and the inner tube 14 and the two spiral flow paths 26 and 28 are formed. 10, as shown in FIG. 3, a torsion tube 32 having a structure similar to that of the intermediate tube 14 on the radially outer side of the outer tube 12, and a straight tube on the radially outer side of the torsion tube 32. The outer tube 34 is arranged so that the tip ends of the inner and outer surfaces of the torsion tube 32 are closely fitted to the outer peripheral surface of the outer tube 12 and the inner peripheral surface of the outer tube 34, respectively. Further, the heat exchanger 30 in which two spiral flow paths 36 and 38 are formed may be used. According to such a heat exchanger 30, a heat exchanger in which four flow paths are formed can be configured in a compact manner, and heat can be exchanged between fluids at three or more temperature levels. The effect can be realized advantageously.

  In addition to the one set of the torsion pipe 32 and the straight tubular extrapolation pipe 34 illustrated in FIG. 3 arranged on the outer side in the radial direction of the outer pipe 12, two sets, three sets, or more A number of sets of torsion tubes and extrapolation tubes are alternately arranged on the outer side in the radial direction of the outer tube 12 so that an additional spiral channel is formed for each additional torsion tube and extrapolation tube. Of course, it is also possible to provide a heat exchanger that can exchange heat between more fluids.

  In addition, although not listed one by one, the present invention is implemented in a mode to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art. It goes without saying that any one of them falls within the scope of the present invention without departing from the spirit of the invention.

  In the following, typical examples of the present invention will be shown to clarify the features of the present invention more specifically. However, the present invention is not restricted by the description of such examples. It goes without saying that it is not a thing.

  First, as shown in FIG. 1, in order to manufacture a heat exchanger having a structure according to the present invention, a tube used as an outer tube (12) has an outer diameter of 21.0 mm and a wall thickness of 0.7 mm. A large-diameter smooth tube having a simple cross section and made of phosphorous deoxidized copper (JIS H 3300 C1220) was prepared. In addition, as a tubular body to be used as the inner pipe (14), a smooth small pipe having a small cross section with a simple outer cross section having an outer diameter of 12 mm and a wall thickness of 0.6 mm made of the same phosphorous deoxidized copper as the outer pipe is prepared. did. Furthermore, as a torsion pipe used as the middle pipe (16), outer diameter: 19.1 mm, inner diameter: 12.5 mm, wall thickness: 0.7 mm, peak pitch: 3.0 mm, peak height: 2.6 mm The twisted tube made of phosphorous deoxidized copper similar to the outer tube and the inner tube was prepared. The torsion tube used as such an intermediate tube was manufactured using a conventionally known method. That is, as described in Japanese Patent Application Laid-Open No. 2-242091, both ends of the smooth tube are gripped by a gripping device, and the diameter-reducing regulating member is inserted into the smooth tube, and the axial direction of the smooth tube It was manufactured by rotating the both ends of the smooth tube around the axis in opposite directions while applying a compressive force.

Then, combining the three types of phosphorous deoxidized copper tubes prepared in this way, inserting the inner tube into the inner tube, and further inserting the inner tube into the outer tube, then by an operation such as a known combined drawing process, The outer tube is reduced in diameter to an outer diameter (D ₁ ): 20 mm, and the tip ends of the fins on the inner and outer surfaces of the inner tube are mechanically pressure-bonded to the inner peripheral surface of the outer tube and the outer peripheral surface of the inner tube, respectively. As shown in FIG. 1, a heat exchanger (10) according to the present invention was produced, and this was designated as Example 1. The dimensions of each tubular body after the diameter reduction of the outer tube are as follows: the outer tube (12) has an outer diameter (D ₁ ): 20 mm, an inner diameter (D ₂ ): 18.6 mm, a wall thickness = 0.7 mm, (14), outer diameter (D ₃ ): 12 mm, inner diameter (D ₂ ): 10.8 mm, wall thickness = 0.6 mm, middle tube (16), outer diameter: 18.6 mm, inner diameter: 12 mm, meat Thickness = 0.7 mm, peak pitch (P): 3.0 mm, peak height (H): 2.6 mm.

On the other hand, for comparison, as shown in FIG. 4, a simple double-tube heat exchanger having a configuration constructed by inserting and arranging a small-diameter inner tube 44 in a large-diameter outer tube 42. 40 was produced, and this was designated as Comparative Example 1. In addition, as a tubular body used as the outer tube 42 of the heat exchanger 40, an outer diameter (D ₅ ): 20 mm, an inner diameter (D ₆ ): 18.6 mm, a wall thickness: 0.7 mm, phosphorous deoxidized copper ( A circular large-diameter smooth tube having a simple cross section made of JIS H 3300 C1220) and a tubular body used as the inner tube 44 have an outer diameter (D _{7) made} of the same phosphorous deoxidized copper as the outer tube. ): 16 mm, inner diameter (D ₈ ): 14.6 mm, wall thickness: 0.7 mm, a circular small diameter smooth tube with a simple cross section was used.

  In the heat exchangers of Example 1 and Comparative Example 1 prepared as described above, high-temperature water at 80 ° C. is circulated in one flow path, while 25 ° C. is circulated in the other flow path. Low temperature water was circulated, heat exchange was performed between these high temperature water and low temperature water, and the heat exchange performance of each heat exchanger was measured. Here, in the heat exchanger of Example 1, the inner flow path (28) formed from the fin tip (24) on the inner surface side of the inner tube (16) and the outer peripheral surface of the inner tube (14) is used. The high-temperature water is circulated at a flow rate of 4 L / min, and the outer channel (26) formed from the fin tip (22) on the outer surface side of the inner tube (16) and the inner peripheral surface of the outer tube (12), Low temperature water was circulated at a flow rate of 8 L / min. On the other hand, in the heat exchanger of Comparative Example 1, high-temperature water is circulated at a flow rate of 4 L / min in the flow path 48 inside the inner tube 44, and the inner peripheral surface of the outer tube 42 and the outer peripheral surface of the inner tube 44. Low temperature water was circulated at a flow rate of 8 L / min in the flow path 46 formed in the gap between the two. In addition, it distribute | circulated so that the distribution | circulation direction of those water might be the direction from which each distribution direction becomes an opposite direction, ie, a counterflow.

  As a result of the above heat exchange performance evaluation test, the heat exchanger of Example 1 configured according to the present invention has a comparison with the simple double-pipe heat exchanger having the conventional configuration of Comparative Example 1. It was confirmed that the heat exchange performance was improved by 25%.

  As another example, as shown in FIG. 3, a heat exchanger in a form in which four spiral channels are formed by adding a pair of torsion tubes and an extrapolation tube was manufactured. That is, first, a tube similar to the outer tube (12), the inner tube (14), and the middle tube (16) prepared for configuring the heat exchanger of the first embodiment described above is prepared, An additional torsion pipe (32) having a large diameter and a round smooth pipe having a simple cross section used as an extrapolation pipe (34) were prepared. In addition, those pipe materials were phosphorus deoxidized copper like the outer pipe (12).

  Then, the inner pipe (14) was inserted into the middle pipe (16) in the same manner as when the heat exchanger of Example 1 was configured by combining the five types of phosphorous deoxidized copper pipes thus prepared. After that, they are inserted into the outer tube (12), and further inserted into the torsion tube (32) and the outer intubation tube (34) in sequence, and thereafter, by an operation such as a known combined drawing process, The diameter of the outer insertion tube is reduced, and the inner peripheral surface of the outer insertion tube (34) and the outer peripheral surface of the outer tube (12) are closely fitted to the fin tips of the inner and outer surfaces of the torsion tube (32). 38), and the inner peripheral surface of the outer tube (12) and the outer peripheral surface of the inner tube (14) are closely fitted to the fin tip portions of the inner and outer surfaces of the inner tube (16) to thereby form the flow paths (26, 28). ) To form a heat exchanger (30) as shown in FIG.

  The dimensions of each tube after the diameter of the outer tube (34) is reduced are as follows: the outer tube (34) has an outer diameter of 28.6 mm, an inner diameter: 26.6 mm, and the outer tube (12) has an outer diameter. The diameter: 20 mm, the inner diameter: 18.6 mm, and the inner tube (14) had an outer diameter: 12 mm and an inner diameter: 10.8 mm. Further, the outer diameter and inner diameter of the torsion pipe (32) are such that the outer diameter side fin tips are closely fitted to the inner peripheral surface of the outer insertion pipe (34), so that the outer insertion pipe (34) The inner diameter side is 26.6 mm, and the inner diameter side has a fin tip on the inner surface side that is in close contact with the outer peripheral surface of the outer tube (12), so it has the same diameter as the outer diameter of the outer tube (12). It is 20 mm. Further, for the same reason, the outer diameter of the intermediate pipe (16) is 18.6 mm which is the same as the inner diameter of the outer pipe (12), and the inner diameter is 12 mm which is the same diameter as the outer diameter of the inner pipe (14). Yes. Further, the peak pitch (fin pitch) of the torsion pipe (32) and the middle pipe (16) is both 3 mm, and the fin height is both 2.6 mm.

  And it was confirmed that high-temperature water and low-temperature water were circulated through each flow path of the heat exchanger (30) thus produced, and that heat exchange was performed between them. That is, of the two flow paths (26, 28) formed between the outer pipe (12) and the inner pipe (14), one of the flow paths (28) circulates high-temperature water at 80 ° C. In the other channel (26), low-temperature water at 25 ° C. is circulated, and two channels (36, 38) formed between the outer tube (12) and the outer tube (34). Among them, one channel (38) circulates high-temperature water at 80 ° C., while the other channel (36) circulates low-temperature water at 25 ° C. between the four fluids (water). It was confirmed that heat exchange was possible.

DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Outer pipe 14 Inner pipe 16 Middle pipe 18 Fin 22, 24 Fin front-end | tip part 26 Outer flow path 28 Inner flow path

Claims (2)

A heat exchanger having a configuration in which a straight tubular inner tube is inserted and disposed in a straight tubular outer tube, and a middle tube is coaxially disposed in a gap between the outer tube and the inner tube. And
As the intermediate tube, a twisted tube is used in which a tube wall is alternately bent and protruded outward and inward, and a fin extending spirally in the tube axis direction is formed on the inner and outer surfaces of the tube. The tip of the fin on the outer surface side of the tube is closely fitted to the inner surface of the outer tube, and a spiral outer flow path is formed between the outer tube and the torsion tube, while the inner surface of the torsion tube The fins on the side are closely fitted to the outer surface of the inner tube, and a spiral inner channel is formed between the torsion tube and the inner tube. A heat exchanger characterized in that separate fluids are circulated in each of the two and heat exchange is performed between the fluids. At least one set of additional torsion pipes and straight tubular extrapolation pipes having the same structure as the torsion pipes are alternately arranged on the outer side in the radial direction of the outer pipe, and each additional torsion pipe is provided on both sides thereof. The heat exchanger according to claim 1, wherein the additional spiral flow path is formed.

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