CN102301197A - Heat exchanger - Google Patents

Abstract

The present invention provides a heat exchanger, which is equipped with a heat transfer tube group, in which a plurality of first heat transfer tubes (3) for making a first fluid flow and a plurality of first heat transfer tubes (3) for making the first fluid flow A plurality of second heat transfer tubes (4) through which the second fluid flows for heat exchange are alternately arranged in a state of mutual contact. The heat transfer tube group is wound in a helical shape in the X direction perpendicular to the Y direction in which the first heat transfer tubes (3) and the second heat transfer tubes (4) are arranged. On both sides of the outer peripheral surface (31) of each first heat transfer tube (3) in the X direction, a plurality of recesses (3a) are provided along the extension direction of the first heat transfer tube (3), and the plurality of recesses (3a) A convex portion is formed on the inner peripheral surface of the first heat transfer tube (3).

Description

heat exchanger

technical field

The present invention relates to a heat exchanger for exchanging heat between a first fluid and a second fluid, and more particularly to a heat exchanger suitable for a heat pump water heater.

Background technique

Conventional heat pump water heaters, air conditioners, underfloor heating devices, and the like use heat exchangers for exchanging heat between two fluids (for example, water and refrigerant, air and refrigerant).

For example, Patent Document 1 discloses a heat exchanger 10 shown in FIGS. 10A and 10B . In this heat exchanger 10, one round pipe 11 for water used for water supply flow and two round pipes 12 for refrigerant used for flowing refrigerant are closely connected on the entire length, and the above-mentioned round pipes 11, 12 form Wind the shape for the runway. The outer diameter of the circular tube 12 for refrigerant is set to about half of the outer diameter of the circular tube 11 for water, and the two circular tubes 12 for refrigerant are arranged at an angle from the center of the circular tube 11 for water to the horizontal line across a horizontal line. 45 degree position. In addition, FIG. 4 of Patent Document 1 describes a heat exchanger unit in which heat exchangers 10 formed in a racetrack coil shape are laminated with heat insulating sheets interposed therebetween.

Patent Document 1: Japanese Patent Laid-Open No. 2006-162204

If the heat exchanger 10 disclosed in Patent Document 1 has a structure in which the round tube 11 for water and the round tube 12 for refrigerant are wound in a state of being in contact, their contact length can be reduced with a small occupied area. Make sure it's bigger. Therefore, it can be downsized compared with heat exchangers of other structures having the same level of performance. However, further miniaturization is required for this type of heat exchanger.

Contents of the invention

Therefore, an object of the present invention is to provide a heat exchanger that can be further downsized.

That is, the present invention provides a heat exchanger including a heat transfer tube group in which a plurality of first heat transfer tubes for flowing a first fluid and a plurality of first heat transfer tubes for supplying and communicating with the first fluid are provided. A plurality of second heat transfer tubes through which the second fluid of heat exchange flows is arranged alternately in a state of contact with each other, and the heat transfer tube group is aligned in the direction parallel to the first heat transfer tubes and the second heat transfer tubes. wound in the orthogonal direction to form a helical shape, and a plurality of The recesses, the plurality of recesses form protrusions on the inner peripheral surface of the first heat transfer tube.

Invention effect

According to the above structure, since the first heat transfer tubes and the second heat transfer tubes constituting the spiral heat transfer tube group are provided in plural, small-sized tubes can be used as the above-mentioned heat transfer tubes. Therefore, the minimum bending radius of the heat transfer tube group can be reduced. Furthermore, since the first heat transfer tubes and the second heat transfer tubes are arranged in a direction perpendicular to the direction in which the heat transfer tube group is wound, the width of the row can also be kept small. Furthermore, since the first heat transfer tubes and the second heat transfer tubes are alternately arranged in contact with each other, one heat transfer tube is sandwiched by the other heat transfer tube except for the heat transfer tubes located at both ends. Therefore, a large contact area between the first heat transfer tube and the second heat transfer tube can be ensured, and the total lengths of the first heat transfer tube and the second heat transfer tube can be shortened accordingly. With the above configuration, in the heat exchanger according to the present embodiment, it is possible to achieve further downsizing compared with a conventional heat exchanger having the same level of performance.

Furthermore, in the present invention, on both sides of the outer peripheral surfaces of the first heat transfer tubes in the direction perpendicular to the arrangement direction, recesses are provided along the extending direction of the first heat transfer tubes, and the recesses are formed on the first heat transfer tubes. A convex portion is formed on the inner peripheral surface of the heat pipe. Therefore, the first fluid flows while colliding with the protrusions inside the first heat transfer tube, and the flow of the first fluid is disturbed. Thereby, the in-plane temperature uniformity of the first fluid can be improved, and the heat exchange efficiency between the first fluid and the second fluid can be improved. Thereby, further miniaturization is possible.

Description of drawings

FIG. 1 is a plan view showing a heat exchanger according to one embodiment of the present invention.

FIG. 2 is an enlarged view of main parts of FIG. 1 .

Fig. 3 is an enlarged cross-sectional view of main parts corresponding to line III-III in Fig. 1 .

Fig. 4 is an enlarged side view of main parts of the heat exchanger of Fig. 1 .

5A is a sectional view taken along line VA-VA in FIG. 4 , and FIG. 5B is a sectional view taken along line VB-VB in FIG. 4 .

6A is a graph showing the relationship between the maximum depth of the concave portion of the second heat transfer tube and the flow velocity of the refrigerant near the inner peripheral surface, and FIG. 6B is a graph showing the relationship between the maximum depth of the concave portion of the second heat transfer tube and the pressure loss. Graph.

Fig. 7 is an enlarged side view of main parts of a heat exchanger according to a modified example.

Fig. 8 is an enlarged side view of main parts of a heat exchanger according to another modification.

Fig. 9 is a block diagram of a heat pump water heater including the heat exchanger shown in Fig. 1 .

FIG. 10A is a plan view showing a conventional heat exchanger, and FIG. 10B is a cross-sectional view taken along line XB-XB in FIG. 10A .

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, a heat exchanger for exchanging heat between a refrigerant such as carbon dioxide or alternative freon and water used in a heat pump water heater or the like will be described as an example. However, the present invention is not limited thereto. For example, it can also be applied to a heat exchanger for heat exchange between water and water (hot water), or for heat exchange between a high-temperature refrigerant and a low-temperature refrigerant in a heat pump cycle. internal heat exchanger etc.

As shown in FIGS. 1 to 3 , a heat exchanger 1 according to an embodiment of the present invention includes a spiral heat transfer tube group 2 formed in a flat rectangular plate shape. In the heat transfer tube group 2, a plurality of (four in the illustration) first heat transfer tubes 3 and a plurality of (three in the illustration) second heat transfer tubes 4 are bonded in contact with each other substantially over the entire length. integrated and constituted. And, by making relatively low-temperature water (first fluid) flow in the first heat transfer tube 3 and making relatively high-temperature refrigerant (second fluid) flow in the second heat transfer tube 4, the water and refrigerant The water is heated by the refrigerant through the heat exchange between them.

The first heat transfer tube 3 and the second heat transfer tube 4 may be made of a metal having good thermal conductivity such as copper, copper alloy, or SUS. As the first heat transfer tube 3 and the second heat transfer tube 4, circular tubes are suitably used.

As shown in FIG. 3 , the first heat transfer tube 3 and the second heat transfer tube 4 are in contact with each other in a direction perpendicular to the extension direction (central axis direction) of the first heat transfer tube 3 and the second heat transfer tube 4 . direction (up and down in Figure 3) alternately arranged in a row. In the present embodiment, the first heat transfer tubes 3 and the second heat transfer tubes 4 are arranged so that their centers are aligned on the same straight line. Furthermore, adjacent first heat transfer tubes 3 and second heat transfer tubes 4 are joined to each other.

The joining of the first heat transfer tube 3 and the second heat transfer tube 4 can be performed by brazing, soldering, or a thermally conductive adhesive. When such bonding using a bonding agent is performed, the bonding area between the first heat transfer tube 3 and the second heat transfer tube 4 becomes large, and a large effective heat transfer area can be ensured. It should be noted that the first heat transfer tube 3 and the second heat transfer tube 4 may also be bonded together by bundling the first heat transfer tube 3 and the second heat transfer tube 4 with, for example, heat shrinkable tubes.

Here, it is preferable that the outer diameter D ₁ of the first heat transfer tube 3 is greater than or equal to the outer diameter D ₂ of the second heat transfer tube 4 (D ₂ ≤ _{D 1} ). The outer diameter and wall thickness of the first heat transfer tube 3 in this embodiment are larger than the outer diameter and wall thickness of the second heat transfer tube 4 . For example, in the case of using carbon dioxide (CO ₂ ) as the refrigerant, the outer diameter D ₂ of the second heat transfer tube 4 is 5.0 mm, and the outer diameter D ₁ of the first heat transfer tube 3 is 6.0 mm.

The heat transfer tube group 2 is arranged in parallel with the first heat transfer tubes 3 and the second heat transfer tubes 4 in an arrangement direction (hereinafter referred to as "Y direction") and perpendicular to an orthogonal direction (hereinafter referred to as "X direction"). Winding up. Specifically, as shown in FIG. 1 , the heat transfer tube group 2 is formed in a substantially rectangular helical shape obtained by alternately and repeatedly winding a straight portion 2 a and four semicircular curved portions 2 b smoothly bent by approximately 90°.

Preferably, a gap S is formed between the adjacent outer winding part and the inner winding part in the heat transfer tube group 2, that is, between the part of the nth (n is a natural number) cycle calculated from the outside and the part of the n+1th cycle (Refer to Figure 2 and Figure 3). If the gap S is formed, it is possible to prevent direct heat transfer between adjacent winding portions in the heat transfer tube group 2 . It should be noted that spacers such as copper tubes or resin sheets can be arranged at appropriate positions between the adjacent outer winding parts and inner winding parts in the heat transfer tube group 2 to ensure the gap S. Alternatively, insulating material may be interposed between adjacent wraps. Also in this way, the same effect as in the case of forming the gap S can be obtained.

In addition, as shown in FIG. 2 , it is preferable that the bending radius R of the bent portion 2 b in the heat transfer tube group 2 is constant throughout. In this way, the types of jigs used in the bending process can be reduced, and workability can be improved.

In this embodiment, water flows from the spiral outer peripheral side of the heat transfer tube group 2 toward the center side in the first heat transfer tube 3 , and the refrigerant flows from the spiral shape of the heat transfer tube group 2 in the second heat transfer tube 4 . The center side of the shape flows toward the outer peripheral side. In this way, water and the refrigerant form convective flow, and heat exchange is performed efficiently.

Specifically, the first outlet member 6 and the second inlet member 7 are arranged on the spiral center side of the heat transfer tube group 2 , and the first inlet member 5 is arranged on the spiral outer peripheral side of the heat transfer tube group 2 . and the second outlet member 8 . Each member 5 to 8 has a rectangular parallelepiped shape extending in the Y direction, and has internal spaces 51 , 61 , 71 , and 81 opened on one end surface in the longitudinal direction (one end surface drawn in FIG. 1 ). In addition, one end of all the first heat transfer tubes 3 is connected to one side of the first outflow member 6 , and the other end of all the first heat transfer tubes 3 is connected to one side of the first inflow member 5 . In addition, one end of all the second heat transfer tubes 4 is formed on one side of the second inlet member 7 , and the other ends of all the second heat transfer tubes 4 are connected to one side of the second outflow member 8 . That is, the first inlet member 5 forms a water inlet for guiding water into each first heat transfer tube 3 , and the first outlet member 6 forms a water outlet for collectively discharging water flowing in each first heat transfer tube 3 . outlet. In addition, the second inlet member 7 forms a refrigerant inlet for guiding the refrigerant into each second heat transfer tube 4 , and the second outlet member 8 forms a refrigerant inlet for flowing in each second heat transfer tube 4 . An outflow port for collectively discharged refrigerant.

In addition, in this embodiment, the predetermined region E1 in the long side straight portion 2a of the heat transfer tube group 2 shown in FIG. 1 and the predetermined region E2 in the short side straight portion 2a are formed with the A plurality of recesses 3a, 4a as shown in Figs. 5A and 5B. Thus, when the bending radius R of the bending part 2b is small, it is preferable to provide the recessed part 3a, 4a in the area|region other than the bending part 2b. In this way, damage during bending can be prevented. Here, the predetermined regions E1 and E2 may be equal to or shorter than the length of the linear portion 2a. Alternatively, the lengths of the predetermined regions E1 and E2 may be shortened toward the inner side of the spiral shape. In addition, the recessed parts 3a and 4a do not need to be provided in both the long-side straight part 2a and the short-side straight part 2a, and may be provided only in either one.

Specifically, in the predetermined regions E1 and E2, a plurality of recesses 3a are provided at predetermined intervals along the extending direction of the first heat transfer tubes 3 on both sides of the outer peripheral surface 31 of each first heat transfer tube 3 in the X direction. , and on both sides of the outer peripheral surface 41 of each second heat transfer tube 4 in the X direction along the extending direction of the second heat transfer tube 4, a plurality of recesses 4a are provided at predetermined intervals. As shown in FIG. 5A , the concave portion 3 a provided on the first heat transfer tube 3 forms a convex portion 3 b on the inner peripheral surface 32 of the first heat transfer tube 3 , and as shown in FIG. 5B , it is provided on the second heat transfer tube 3 On the inner peripheral surface 42 of the second heat transfer tube 4, the concave portion 4a forms a convex portion 4b. It should be noted that the recesses 3 a , 4 a may be provided on both sides in the X direction of the outer peripheral surfaces 31 , 41 of the heat transfer tubes 3 , 4 , and do not have to be located directly beside the centers of the heat transfer tubes 3 , 4 . For example, the recesses 3a, 4a may be provided at positions shifted from the position right next to the center of the heat transfer tubes 3, 4 toward the upper side or the lower side in FIG. 4 .

In this embodiment, the recess 3 a provided on one side in the X direction of the outer peripheral surface 31 of the first heat transfer tube 3 and the recess 3 a provided on the other side in the X direction are aligned along the extending direction of the first heat transfer tube 3 . alternate configuration. Similarly, the recesses 4 a provided on one side in the X direction of the outer peripheral surface 41 of the second heat transfer tube 4 and the recesses 4 a provided on the other side in the X direction are alternately arranged along the extending direction of the second heat transfer tube 4 . In addition, in the present embodiment, the concave portion 3 a provided in the first heat transfer tube 3 and the concave portion 4 a provided in the second heat transfer tube 4 are aligned with the extending direction of the first heat transfer tube 3 or the second heat transfer tube 4 . Linear dimples extending in parallel directions.

For example, when using carbon dioxide as the refrigerant, the pitch of the recesses 4a of the second heat transfer tube 4 is 10 mm on both sides of the X direction, and the length is 5.0 mm, and the pitch of the recesses 3 a of the first heat transfer tube 3 is 10 mm in the X direction. Both sides are 10mm and the length is 5.0mm. In addition, the so-called pitch means the center-to-center distance of adjacent concave portions on one side in the X direction. In addition, it is preferable that the maximum depth of the recesses 3a, 4a (the depth of the lowest point at the deepest position) is 5% or more and 20% or less of the outer diameter of the heat transfer tubes 3, 4, respectively.

In order to form the heat transfer tube group 2 constituted in this way, for example, linear first heat transfer tubes 3 and second heat transfer tubes 4 are alternately stacked, and after the stacked bodies are joined by the above-mentioned method, the heat transfer tubes are formed by pressing. Recesses 3 a, 4 a are formed on both left and right surfaces of the tube group 2 . After that, it is sufficient to bend the heat transfer tube group 2 on the same plane so that the heat transfer tube group 2 has a substantially rectangular spiral shape. Alternatively, the first heat transfer tube 3 and the second heat transfer tube, in which the recesses 3a, 4a are previously formed by pressing or the like, may be bent on the same plane so that they have a substantially rectangular spiral shape, and the They cascade.

As described above, in the heat exchanger 1 of the present embodiment, since a plurality of first heat transfer tubes 3 and second heat transfer tubes 4 constituting the spiral heat transfer tube group 2 are provided, it is possible to use Small-sized tubes serve as the above-mentioned heat transfer tubes. Therefore, the minimum bending radius of the heat transfer tube group 2 can be reduced. Furthermore, since the first heat transfer tubes 3 and the second heat transfer tubes 4 are arranged in a direction perpendicular to the direction in which the heat transfer tube group 2 is wound, the width of the row can also be kept small. Furthermore, since the first heat transfer tubes 3 and the second heat transfer tubes 4 are alternately arranged in contact with each other, one heat transfer tube is sandwiched by the other heat transfer tube except for the heat transfer tubes located at both ends. Therefore, the contact area of the 1st heat transfer tube 3 and the 2nd heat transfer tube 4 can be ensured large, and the total length of the 1st heat transfer tube 3 and the 2nd heat transfer tube 4 can be shortened accordingly. With the above configuration, in the heat exchanger 1 according to the present embodiment, it is possible to further reduce the size of the heat exchanger 1 as compared with a conventional heat exchanger having the same level of performance.

In addition, in the heat exchanger 1 of the present embodiment, recesses 3 a are provided on both sides of the outer peripheral surface 31 of each first heat transfer tube 3 in the X direction along the extending direction of the first heat transfer tube 3 . The inner peripheral surface 32 of the first heat transfer tube 3 forms a convex portion 3b. Therefore, the water flows while colliding with the convex portion 3 b in the first heat transfer tube 3 , and the flow of the water is disturbed. Thereby, the temperature uniformity of water in a plane can be improved, and the heat exchange efficiency of water and a refrigerant|coolant can be improved. Thereby, further miniaturization is possible. In addition, since the concave portion 3a is not provided in the Y direction where the first heat transfer tube 3 and the second heat transfer tube 4 are in contact, but is provided in the X direction, the above-mentioned effect can be obtained without increasing the above-mentioned contact heat resistance. .

Here, in the present embodiment, recesses 4 a are provided on both sides in the X direction of the outer peripheral surface 41 of the second heat transfer tube 4 through which the refrigerant flows along the extending direction of the second heat transfer tube 4 . 4a forms a convex portion 4b on the inner peripheral surface 42 of the second heat transfer tube 4, and the refrigerant flows while colliding with the convex portion 4b in the second heat transfer tube 4. That is, since the flow of the refrigerant is also disturbed, it is possible to further increase the heat exchange efficiency between the water and the refrigerant. However, as the second heat transfer tube 4 for the refrigerant, instead of the circular tube having the concave portion 4 a on the outer peripheral surface 41 , a grooved tube having a plurality of grooves provided on the inner peripheral surface may be used. However, since such a grooved pipe is relatively expensive, the cost can be suppressed by using a circular pipe provided with the concave portion 4 a on the outer peripheral surface 41 as in the present embodiment.

10A and 10B have a runway winding shape, in other words, including a pair of linear parts arranged in parallel to face each other and the ends of the above-mentioned linear parts are bent to connect each other. In the heat exchanger 10 including a pair of semicircular portions at 180°, a large dead zone in the shape of a substantially right triangle is formed outside the semicircular portions, which is a factor of increasing the dedicated area. On the other hand, in the heat exchanger 1 of the present embodiment, the heat transfer tube group 2 is formed in a substantially rectangular spiral shape, and the bending radius R of the bending portion 2b at the corner is constant, so it is located at a lower position than the racetrack winding shape. The bending radius of the outermost curved portion 2b is extremely small. Therefore, the dead space formed outside the heat exchanger 1 can be kept small. Looking at the structure from another aspect, in the structure of the present embodiment, unlike the winding shape of the track, the bending radius of the curved portion 2b does not decrease even from the spiral outer peripheral side toward the center side. Therefore, the heat transfer tube group 2 can be arranged near the center of the spiral shape, thereby reducing the dead space near the center. Moreover, since the bending radius R of the bending part 2b is constant, workability is also favorable.

In addition, as described above, small-sized tubes can be used as the first heat transfer tube 3 and the second heat transfer tube 4, so the bending radius R of the curved portion 2b of the heat transfer tube group 2 formed in a spiral shape can be suppressed to a minimum. Smaller, the substantially right-angled triangle-shaped dead space formed on the outside of the heat exchanger 1 by the bent portion 2b can be suppressed even smaller.

In addition, in this embodiment, the first inlet member 5 and the second outlet member 8 are arranged on the spiral outer peripheral side of the heat transfer tube group 2 , and the first outlet member is arranged on the spiral center side of the heat transfer tube group 2 . Component 6 and the second inlet component 7 . In other words, relatively low-temperature water flows in the first heat transfer tube 3 from the other end located on the outer peripheral side of the spiral shape to one end located on the spiral-shaped central side, and relatively high-temperature refrigerant flows in the second heat transfer tube 4 from the end located on the spiral-shaped central side. One end on the helical central side flows toward the other end on the helical outer peripheral side. That is, when the heat exchanger 1 is viewed as a whole, both the water and the refrigerant flow so as to increase in temperature from the periphery of the heat exchanger 1 toward the center, so that a high-temperature portion that radiates a large amount of heat to the outside can be arranged in a small area. , can more effectively suppress heat loss. Furthermore, since the viscosity of water decreases as the temperature becomes higher, it is also preferable to have a structure in which water flows so that the temperature increases toward the center of the helical shape from the viewpoint of pressure loss.

In addition, the protrusion 4b protruding inward of the second heat transfer tube 4 through which the refrigerant flows also has the following effects. Refrigerants are usually mixed with oil such as PAG (polyalkylene glycol) for lubricating compressors and the like. Therefore, the flow in the second heat transfer tube 4 becomes a double-layer flow, and an oil film is formed on the inner peripheral surface 42 of the second heat transfer tube 4 . In order to maintain high heat exchange efficiency, it is preferable that the thickness of the oil film is extremely thin. The convex portion 4b also contributes to reducing the thickness of the oil film. That is, when the convex portion 4b exists, the flow velocity of the refrigerant near the inner peripheral surface 42 increases, thereby increasing the speed difference between the oil film flowing on the inner peripheral surface 42 and the refrigerant. Then, a lot of oil is taken away from the surface of the oil film by the refrigerant, and the thickness of the oil film becomes thinner. On the other hand, when the height of the convex part 4b is too high, the pressure loss will increase and the performance of the heat exchanger 1 will fall. Therefore, it is preferable to set the maximum depth of the recessed part 4a appropriately and keep the height of the convex part 4b within a preferable range.

For example, FIGS. 6A and 6B show the results of analyzing the flow state of the refrigerant when the maximum depth of the concave portion 4 a of the second heat transfer tube 4 is changed when carbon dioxide is used as the refrigerant. The software "FULENT6.3" was used for the analysis. As conditions, the mass flow rate of the refrigerant was 650 kg/m ² s, the temperature was 60° C., the pressure was 10 MPa, and the oil concentration in the refrigerant was 1.0 mass %. In addition, in the second heat transfer tube 4 having an outer diameter of 5.0 mm and an inner diameter of 4.1 mm, recesses 4 a with a length of 5.0 mm are arranged at a pitch of 10 mm on both sides in the X direction in the form shown in FIG. 4 . In addition, calculations were performed for the cases where the maximum depth of the concave portion 4 a was 0, 0.4, 0.5, and 0.6 mm. The maximum depth of the recessed portion 4a is 0 mm in the case of a round pipe not provided with the recessed portion 4a.

As shown in FIG. 6A , the flow velocity of the refrigerant in the vicinity of the inner peripheral surface 42 is saturated in the range where the maximum depth of the concave portion 4 a is 0.4 to 0.5 mm. This means that even if the maximum depth of the concave portion 4a is further deepened, the thickness of the oil film is less likely to decrease. On the other hand, as shown in FIG. 6B , the pressure loss increases sharply in the range where the maximum depth of the concave portion 4 a is 0.4 to 0.5 mm. Therefore, it is preferable that the maximum depth of the recessed part 4a is 0.3-0.6 mm which slightly widens toward both sides from the said range.

The heat exchanger 1 as described above is suitably used for the heat pump water heater 200 . FIG. 9 shows a heat pump water heater 200 including the heat exchanger 1 according to this embodiment. This heat pump water heater 200 has a heat pump unit 201 and a tank unit 203 . The tank unit 203 has a hot water storage tank 202 made of a heat pump unit 201 for storing hot water, and the hot water stored in the hot water storage tank 202 is supplied to a hot water supply faucet 204 . The heat pump unit 201 includes a compressor 205 that compresses refrigerant, a radiator 207 that radiates heat from the refrigerant, an expansion valve 209 that expands the refrigerant, an evaporator 211 that evaporates the refrigerant, and refrigerant pipes that connect the above devices in this order. 213. Furthermore, the heat exchanger 1 of this embodiment is used as the radiator 207 . It should be noted that, in the heat pump unit 201 , instead of the expansion valve 209 , a volumetric expander capable of recovering the expansion energy of the refrigerant may be used.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the number and outer diameter of the first heat transfer tube 3 and the second heat transfer tube 4 may be appropriately selected according to the required performance of the heat exchanger 1 or the types of the first fluid and the second fluid. In addition, the number of turns and the size of the helical shape of the heat transfer tube group 2 can also be appropriately determined.

Furthermore, the heat transfer tube group 2 does not need to be formed in a substantially rectangular spiral shape, but may be formed in a circular spiral shape, or may be formed in a racetrack winding shape as shown in FIG. 10A . However, from the viewpoint of the dead space as described above, it is preferable that the heat transfer tube group 2 is formed in a substantially rectangular spiral shape.

In addition, in the above-mentioned embodiment, the first heat transfer tube 3 and the second heat transfer tube 4 are arranged so that their centers are aligned on the same straight line, but for example, when the outer diameter _D1 of the first heat transfer tube 3 and the second heat transfer tube In the case where the outer diameters _D2 of the two heat transfer tubes 4 are different, the first heat transfer tube 3 and the second heat transfer tube 4 are juxtaposed on the same straight line at the outermost points on one side of the direction perpendicular to the arrangement direction. can also be arranged in the same way. In this case, the centers of the first heat transfer tubes 3 and the second heat transfer tubes 4 are arranged in a zigzag shape.

In the above-described embodiment, the recess 3 a provided on one side in the X direction of the outer peripheral surface 31 of the first heat transfer tube 3 and the recess 3 a provided on the other side in the X direction are along the extension of the first heat transfer tube 3 . The directions are arranged alternately, but they may also be arranged at opposing positions in the X direction. However, in the case where the concave portion 3a is parallel to the extending direction of the first heat transfer tube 3, such an arrangement makes the narrow portion inside the first heat transfer tube 3 longer, so the arrangement as in the above-mentioned embodiment is preferable. . This point also applies to the recessed portion 4 a provided in the second heat transfer tube 4 .

And, as shown in FIG. 7, the recesses 3a provided on both sides in the X direction of the outer peripheral surface 31 of each first heat transfer tube 3 may extend in a direction inclined relative to the extending direction of the first heat transfer tube 3. The linear recesses, the recesses 4a provided on both sides of the outer peripheral surface 41 of each second heat transfer tube 4 in the X direction may extend in a direction inclined relative to the extending direction of the second heat transfer tube 4 Linear pits. Such recesses 3a, 4a allow water and refrigerant to flow while efficiently stirring them. Especially when the heat exchanger 1 is used in the heat pump water heater 200 shown in FIG. The extension direction of 4 is inclined. Oil for lubricating the compressor 205 may be mixed into the refrigerant, and the oil may remain relatively large at the bottom of the second heat transfer tube 4 to lower the heat exchange efficiency. Therefore, if the concave portion 4a is inclined, the refrigerant can be agitated and stagnation of oil can be suppressed. It should be noted that when the heat transfer tubes 3, 4 are provided with inclined recesses 3a, 4a, the recesses 3a, 4a on one side of the X direction and the recesses 3a, 4a on the other side can be arranged in the X direction as shown in Fig. 7 . Positions facing each other in the direction may be alternately arranged along the extending direction of the heat transfer tubes 3 and 4 as shown in FIG. 8 .

In addition, it is also possible to appropriately choose to provide a concave portion 3a parallel to the extending direction on the first heat transfer tube 3 and to provide a concave portion 4a inclined relative to the extending direction on the second heat transfer tube 4, or to provide a concave portion 4a on the first heat transfer tube 3. A combination of the above-mentioned shapes and positions such that the recesses 3 a provided on both sides are alternately arranged and the recesses 4 a provided on both sides of the second heat transfer tube 4 are arranged at opposing positions.

In addition, the recesses of the present invention do not need to be linear dimples, and it is only necessary to form protrusions on the inner peripheral surface of the first heat transfer tube or the second heat transfer tube. For example, the first heat transfer tube 3 and the second heat transfer tube 4 may be formed in a wave shape that meanders along the X direction, and the troughs thereof may be used as recesses. That is, the convex portion of the present invention does not need to narrow the cross-sectional area of the space surrounded by the inner peripheral surface of the first heat transfer tube or the second heat transfer tube, and may protrude inward while maintaining the cross-sectional area. part. However, from the standpoint of workability, it is preferable that the concave portion of the present invention is a dimple forming a convex portion 3b as in the above-mentioned embodiment, and it is particularly preferably a linear dimple extending in a predetermined direction, wherein the convex portion 3b is formed by the first The cross-sectional area of the space surrounded by the inner peripheral surfaces 32 and 42 of the first heat transfer tube 3 or the second heat transfer tube 4 becomes narrower.

Industrial Applicability

The heat exchanger of the present invention is useful as a heat exchanger for a heat pump, especially as a heat exchanger for a heat pump water heater. In addition, the present invention can also be applied to a heat exchanger for exchanging heat between liquids or between gases.

Claims (16)

1. A heat exchanger, which is provided with a heat transfer tube group, and in the heat transfer tube group, a plurality of first heat transfer tubes for flowing a first fluid and a plurality of first heat transfer tubes for exchanging heat with the first fluid A plurality of second heat transfer tubes through which the second fluid flows are alternately arranged in contact with each other. winding in the cross direction to form a helical shape, A plurality of recesses are provided on both sides of the respective outer peripheral surfaces of the first heat transfer tube in the orthogonal direction along the extending direction of the first heat transfer tube, and the plurality of recesses are located on the first heat transfer tube. The inner peripheral surface forms a convex portion. 2. The heat exchanger according to claim 1, wherein, The recess provided on one side of the orthogonal direction in the outer peripheral surface of the first heat transfer tube and the recess provided on the other side of the orthogonal direction are along the extending direction of the first heat transfer tube alternate configuration. 3. The heat exchanger according to claim 1, wherein, The concave portion provided on one side of the orthogonal direction and the concave portion provided on the other side of the orthogonal direction in the outer peripheral surface of the first heat transfer tube are arranged on opposite sides of the orthogonal direction. Location. 4. The heat exchanger according to any one of claims 1 to 3, wherein: Recesses are provided on both sides of the outer peripheral surfaces of the second heat transfer tubes in the orthogonal direction along the extending direction of the second heat transfer tubes, and the concave parts are formed on the inner peripheral surfaces of the second heat transfer tubes Convex. 5. The heat exchanger according to claim 4, wherein, The recess provided on one side of the orthogonal direction in the outer peripheral surface of the second heat transfer tube and the recess provided on the other side of the orthogonal direction are along the extending direction of the second heat transfer tube alternate configuration. 6. The heat exchanger according to claim 4, wherein, The concave portion provided on one side of the orthogonal direction and the concave portion provided on the other side of the orthogonal direction in the outer peripheral surface of the second heat transfer tube are arranged on opposite sides of the orthogonal direction. Location. 7. The heat exchanger according to any one of claims 1 to 6, wherein: The recesses are linear dimples extending in a predetermined direction. 8. The heat exchanger according to claim 7, wherein, The predetermined direction is a direction parallel to an extending direction of the first heat transfer tube or the second heat transfer tube. 9. The heat exchanger according to claim 7, wherein, The predetermined direction is a direction inclined with respect to the extending direction of the first heat transfer tube or the second heat transfer tube. 10. The heat exchanger according to any one of claims 1 to 9, wherein: The heat transfer tube group is formed in a substantially rectangular helical shape obtained by alternately and repeatedly winding a straight portion and a bent portion bent at approximately 90° at a constant bending radius. 11. The heat exchanger according to any one of claims 1 to 10, wherein: A gap is formed between the adjacent outer winding parts and inner winding parts in the heat transfer tube group. 12. The heat exchanger according to any one of claims 1 to 10, wherein: A heat insulating material is inserted between adjacent outer winding parts and inner winding parts in the heat transfer tube group. 13. The heat exchanger according to any one of claims 1 to 12, wherein: The first fluid is heated by the second fluid. 14. The heat exchanger of claim 13, wherein: The first fluid is water and the second fluid is refrigerant. 15. The heat exchanger according to any one of claims 1 to 14, wherein: Both the first heat transfer tube and the second heat transfer tube are circular tubes, and the outer diameter of the first heat transfer tube is larger than the outer diameter of the second heat transfer tube. 16. The heat exchanger according to any one of claims 1 to 15, wherein: The first fluid flows from the helical outer peripheral side toward the central side in the first heat transfer tube, and the second fluid flows from the helical central side toward the outer peripheral side in the second heat transfer tube. flow.

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