JP2011099630A - Heat exchanger, and refrigerator and air conditioner using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent, even if heat transfer tubes are flattened, the flattened heat transfer tubes from being deformed by tube internal pressure, provide excellent heat transfer performance, reduce draft resistance and increase heat exchange capacity. <P>SOLUTION: A heat exchanger includes the flattened heat transfer tubes 3A each having first and second refrigerant flow passages 31a, 31b defined by an internal partition wall 32, and a plurality of heat resistant fins 2 having heat transfer characteristics and provided side by side on the outer peripheries of the flattened heat transfer tubes to form air flow passages. The flattened heat transfer tubes are applied with low-temperature brazing material on the outer surfaces and are inserted in mounting holes 21 provided in the heat resistant fins so that the longitudinal direction of their flat shape is parallel to the inflow direction A of air. The flattened heat transfer tubes and the heat resistant fins are joined by blazing in a furnace of 150 to 350 degrees and are fixed integrally. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a heat exchanger suitable as a heat exchanger for a refrigerator or a heat exchanger for an air conditioner, for example.

  Conventional heat exchangers constituting refrigerators and air conditioners include what are called heat-resistant finned tube heat exchangers. This heat-resistant finned tube heat exchanger is composed of plate-like fins that are arranged at regular intervals and through which gas (air) flows, and heat transfer tubes that are inserted perpendicularly to the plate-like fins and into which refrigerant flows. It is configured.

  Factors affecting the heat transfer performance of the finned tube heat exchanger include the refrigerant side heat transfer coefficient between the refrigerant and the heat transfer tube, the contact heat transfer coefficient between the heat transfer tube and the fin, and the air and fin The air side heat transfer coefficient between is known.

  In order to improve the refrigerant-side heat transfer coefficient between the refrigerant and the heat transfer tube, the inner surface grooved heat transfer tube is provided that can expand the heat transfer area and obtain the refrigerant stirring effect. Thereby, it is supposed that the in-pipe performance can be promoted.

  Moreover, as a method of promoting the air side heat transfer coefficient between air and a fin, a slit group by cutting and raising a plate-like fin is provided between adjacent heat transfer tubes. This slit group is provided so that the cut-and-raised portion of the slit is opposed to the wind direction. . As a result, heat transfer is promoted and heat exchange capacity is increased.

  The contact heat transfer coefficient between the heat transfer tube and the fin is affected by the contact state between the heat transfer tube and the fin. For example, when the heat transfer tube is expanded and fixed to the fin, a gap due to the undulation of the heat transfer tube outer surface and a gap due to fin collar deformation are generated between the outer surface of the heat transfer tube and the fin. It is considered that the contact heat transfer rate decrease due to these gaps is about 5% of the heat transfer performance of the entire heat exchanger (see, for example, Non-Patent Document 1).

  By the way, the gap as described above is formed by interposing a paste in which heat conductive fine powder such as metal powder is mixed with oil on the inner surface of the fin collar that becomes the joint between the fin and the heat transfer tube. There is one that can minimize and improve the contact heat transfer coefficient (see, for example, Patent Document 1).

  In addition, there is a heat transfer tube that can improve heat exchange efficiency by using a flat tube having an uneven shape on the inner surface (see, for example, Patent Document 2).

A plate made of a heat-resistant copper alloy precipitated and hardened by one or more of Fe ₂ P, CO ₂ P, Mg ₃ P ₂ , Cu ₃ Zr, Cr, Co, Fe, NiB, Ni ₂ Si, TiFe ₂ Laminating tubes and corrugated fins, and brazing them with low-temperature phosphorus-containing brazing material having a melting point of 450 ° C. to 650 ° C., thereby improving characteristics excellent in thermal conductivity, mechanical strength, heat resistance, and corrosion resistance (For example, see Patent Document 3).

Japanese Patent Laid-Open No. 58-158493 (FIGS. 2 and 3) JP-A-11-94481 (FIGS. 1 and 2) JP 2000-135558 (FIG. 1)

Nakata, “Optimum Design and Economics in Air-Conditioning Heat Exchangers”, Research on Machines, 1989, Vol. 41, No. 9, pp. 1005-1101

  However, in the case where a paste in which heat conductive fine powder such as metal powder is mixed with oil is interposed on the inner surface of the fin collar that becomes the joint between the fin and the heat transfer tube, the metal on the inner surface of the fin collar It is difficult to apply the powder without gaps, and the manufacturing cost increases.

  Further, in the case of using a flat tube as the heat transfer tube, the flat tube is easily deformed by the pressure in the tube during the operation of the refrigeration system, and in this case, the adhesion between the flat tube and the plate fin is deteriorated.

  Moreover, in the case of laminating plate tubes and corrugated fins made of a heat-resistant copper alloy and brazing them with a low-temperature phosphorus brazing material having a melting point of 450 ° C. to 650 ° C., a high-temperature heating step is performed. This increases the manufacturing cost. Furthermore, when corrugated fins are used, the condensate tends to always be present on the fin surface, and there is a possibility that the problem of jumping out and corrosion may occur.

  By the way, it is conceivable to reduce the diameter of the heat transfer tube for the purpose of improving the performance of the heat exchanger. However, in this case, pressure loss also increases as the heat transfer coefficient in the tube increases by reducing the diameter of the heat transfer tube, so it is necessary to optimize them. In addition, the small-diameter heat transfer tube is advantageous in terms of heat transfer performance, but has a drawback that the manufacturing cost of the heat transfer tube increases.

  The technical problem of the present invention is that even if the heat transfer tube is flattened, the flat heat transfer tube is not deformed by the pressure in the tube, and the heat transfer performance is excellent, the ventilation resistance is reduced, and the heat exchange capacity is increased. There is to be able to do it.

  The heat exchanger according to the present invention has the following configuration. That is, a flat heat transfer tube having first and second refrigerant flow paths defined by a septum wall and a plurality of heat transfer characteristics arranged in parallel on the outer periphery of the flat heat transfer pipe to form an air flow path The flat heat transfer tube is inserted into a mounting hole provided in the heat-resistant fin so that the low-temperature brazing material is applied to the outer surface of the flat heat-transfer tube and the flat shape has a longitudinal direction parallel to the air inflow direction. These flat heat transfer tubes and heat-resistant fins are joined and fixed integrally by brazing in a furnace at 150 to 350 degrees.

According to the heat exchanger of the present invention, since the flat heat transfer tube and the heat-resistant fin are integrally fixed by brazing, the contact heat resistance between the flat heat transfer tube and the heat-resistant fin can be made substantially zero.
Further, since the flat heat transfer tube is provided with the first and second refrigerant channels defined by the septum wall, the refrigerant channel is reduced in diameter and the heat transfer performance is improved.
Furthermore, since the flat heat transfer tube is inserted into the mounting hole provided in the heat-resistant fin so that the longitudinal direction of the flat shape is parallel to the air inflow direction, the ventilation resistance is reduced, and the heat exchange capability Therefore, highly efficient operation of a refrigerator and an air conditioner using this heat exchanger can be realized.

It is a front view which shows the heat exchanger which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the flat heat exchanger tube which is the principal part of the heat exchanger which concerns on Embodiment 1 of this invention. It is sectional drawing which expands and shows the junction part of the flat heat exchanger tube and heat resistant fin of the heat exchanger which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the flat heat exchanger tube which is the principal part of the heat exchanger which concerns on Embodiment 2 of this invention. It is a graph which shows the relationship between the height of the protrusion after the expansion of the flat heat exchanger tube of the heat exchanger which concerns on Embodiment 2 of this invention, and a heat exchange rate. It is a front view which shows the heat exchanger which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the flat heat exchanger tube which is the principal part of the heat exchanger which concerns on Embodiment 3 of this invention. It is sectional drawing which shows the flat heat exchanger tube which is the principal part of the heat exchanger which concerns on Embodiment 4 of this invention.

Embodiment 1 FIG.
The present invention will be described below with reference to illustrated embodiments.
FIG. 1 is a front view showing a heat exchanger according to Embodiment 1 of the present invention, FIG. 2 is a cross-sectional view showing a flat heat transfer tube as the main part, and FIG. 3 is an enlarged view of a joint between the flat heat transfer tube and heat-resistant fins. It is sectional drawing shown.

  The heat exchanger, that is, the fin tube type heat exchanger 1 according to the present embodiment is configured by a metal plate such as a copper alloy or an aluminum alloy in which fins have heat resistance and heat transfer characteristics as shown in FIGS. (The same applies to other embodiments described later). A plurality of the heat-resistant fins 2 are arranged in parallel at a predetermined interval in the direction perpendicular to the paper surface as viewed in FIG. A plurality of flat heat transfer tubes 3 </ b> A penetrating perpendicularly to the heat-resistant fins 2 are provided in the vertical direction of the heat-resistant fins 2. In addition, it is desirable to form the thickness of the heat-resistant fin 2 to 20 to 40 μm. Thereby, the ventilation resistance of the heat-resistant fin 2 can be reduced.

  The flat heat transfer tube 3A is made of a metal material such as copper or a copper alloy, or aluminum or an aluminum alloy (the same applies to other embodiments described later). Further, the flat heat transfer tube 3A has a cross-sectional contour shape that is elongated along the air inflow direction A as shown in FIGS. 1 and 2 and whose upper and lower sides are straight (the upper and lower surfaces of the flat heat transfer tube 3A are flat. ). Then, first and second refrigerant flow paths 31a and 31b having a semicircular cross section are provided on the left and right sides of the horizontally long contour as viewed in FIG. 2, and extend in parallel to the axial direction. A septum wall 32 is formed between the first and second refrigerant flow paths 31 a and 31 b, and the upper and lower flat surfaces are connected by the septum wall 32. Therefore, the septum wall 32 acts as a reinforcing rib on the upper and lower flat surfaces against the internal pressure of the flat heat transfer tube 3A, and has a function of preventing the flat heat transfer tube 3A from being deformed by the internal pressure.

The first and second refrigerant flow paths 31a and 31b are expanded in diameter, for example, by applying a hydraulic pressure (high pressure) inside the flow path so that the radius r is 1 to 3 mm. The reason why the radius r is set to 1 to 3 mm is as follows.
That is, when the radius r is less than 1 mm, the amount of increase in pressure loss is larger than the amount of increase in heat transfer coefficient, resulting in a decrease in heat exchange performance.
On the other hand, when the radius r exceeds 3 mm, not only the flow rate of refrigerant in the tube is slowed and the heat exchange performance is lowered, but also the width of the flat heat transfer tube 3A is increased and the pressure loss of the air flow is increased.
Therefore, the radius r after diameter expansion of the first and second refrigerant flow paths 31a and 31b in the present embodiment is 1 to 3 mm (the radius r of the refrigerant flow path in other embodiments described later). Is the same).

  Next, an example of joining of the flat heat transfer tube 3A having the first and second refrigerant flow paths 31a and 31b as described above and the mounting hole 21 of the heat-resistant fin 2 will be described. The flat heat transfer tube 3A is coated with a low-temperature brazing material 4 on its outer surface, and is inserted into a mounting hole 21 provided in the heat-resistant fin 2 as shown in FIG. The flat heat transfer tubes 3A, to which the heat-resistant fins 2 and the low-temperature brazing material 4 have been applied in advance, are completely joined together by brazing with the low-temperature brazing material 4 in a furnace at a low temperature of 150 to 350 degrees. It is fixed.

  In this case, the thickness t2 of the thinnest wall portion of the septum wall 32 of the first and second refrigerant flow paths 31a and 31b is set to the wall of the other part of the first and second refrigerant flow paths 31a and 31b. The wall thickness is desirably 1.5 times the wall thickness t1. Thereby, the rib function of the septum wall 32 can be strengthened, and the pressure resistance of the flat heat transfer tube 3A can be increased. For this reason, even if the outer shape of the heat transfer tube is flattened, the deformation of the flat heat transfer tube 3A due to the pressure in the tube does not occur, and the heat exchange efficiency is improved without deteriorating the adhesion between the flat heat transfer tube 3A and the heat-resistant fin 2. Therefore, it is possible to obtain a highly efficient heat exchanger that can perform high-efficiency operation of a refrigerator and an air conditioner using the heat exchanger.

Embodiment 2. FIG.
FIG. 4 is a cross-sectional view showing a flat heat transfer tube that is a main part of the heat exchanger according to Embodiment 2 of the present invention, and FIG. 5 shows the relationship between the height of the ridge after the flat heat transfer tube expansion and the heat exchange rate. In FIG. 4, the same reference numerals are given to the portions corresponding to those in the first embodiment described above. In the description, reference is made to FIG. 1 and FIG. 3 described above.

  In the heat exchanger of the present embodiment, that is, the finned tube heat exchanger 1, the flat heat transfer tube 3B is made of a metal material such as copper or copper alloy, or aluminum or aluminum alloy. Further, the pipe shaft is arranged at predetermined intervals in the circumferential direction on the inner wall surfaces of the first and second refrigerant flow paths 31a and 31b having a semicircular cross section provided on the left and right in the horizontally long outline of the flat heat transfer tube 3B. A protrusion (or groove) 33 having a substantially square cross section extending in a spiral shape in the direction is provided. Other configurations are the same as those in the first embodiment.

  In the finned-tube heat exchanger of the present embodiment, the flat heat transfer tube 3B is inserted into the mounting hole 21 of the heat-resistant fin 2 in the manner described above (with the first and second refrigerant flow paths 31a and 31b). The heat-resistant fins 2 and the flat heat transfer tubes 3B are completely joined together with a low-temperature brazing material in the same low-temperature furnace as described above and fixed integrally.

  In the flat heat transfer tube 3B of the present embodiment, basically, the higher the height h (projection length) of the ridge 33 after tube expansion, the higher the heat transfer coefficient. This is because the contact area with the refrigerant increases due to the presence of the protrusions 33. In addition, even if it replaces the protrusion 33 with a groove | channel, the contact area with a refrigerant | coolant similarly increases.

  However, if the height h of the ridge 33 after tube expansion exceeds 0.3 mm as shown in FIG. 5, the amount of increase in pressure loss is greater than the amount of increase in heat transfer coefficient, resulting in a heat exchange rate. Decreases. On the other hand, when the height h of the ridge 33 after the pipe expansion is less than 0.1 mm, the heat transfer coefficient is not improved.

  Therefore, the height h (projection length) of the protrusion 33 after the expansion of the first and second refrigerant flow paths 31a and 31b of the flat heat transfer tube 3B in the present embodiment is set to 0.1 to 0.3 mm. Is. As a result, it is possible to obtain a highly efficient heat exchanger that can further improve the heat transfer performance without increasing the pressure in the flow path. As a result, a refrigerator and an air conditioner using this heat exchanger Highly efficient operation can be realized.

  Note that the cross-sectional shape of the protrusion 33 is not limited to a square shape, and may be appropriately selected from, for example, a triangular shape, a trapezoidal shape, and a semicircular shape, and any cross-sectional shape can be employed. Furthermore, as described above, even if the groove is formed instead of the protrusion 33, the same operation and effect can be obtained.

Embodiment 3 FIG.
FIG. 6 is a front view showing a heat exchanger according to Embodiment 3 of the present invention, and FIG. 7 is a cross-sectional view showing a flat heat transfer tube which is a main part of the heat exchanger. The parts corresponding to are given the same reference numerals. In the description, reference is made to FIG.

  In the heat exchanger, that is, the fin tube type heat exchanger 1 according to the present embodiment, the heat-resistant fins 2 are made of a heat-resistant metal plate such as a copper alloy or an aluminum alloy. Further, a plurality of heat-resistant fins 2 are arranged in parallel with the air inflow direction A at a predetermined interval in the direction perpendicular to the paper surface as viewed in FIG. A plurality of flat heat transfer tubes 3 </ b> C penetrating perpendicularly to the heat-resistant fins 2 are provided in the vertical direction of the heat-resistant fins 2.

  The flat heat transfer tube 3C is made of a metal material such as copper or a copper alloy, or aluminum or an aluminum alloy. Further, the flat heat transfer tube 3C has a cross-sectional contour shape that is elongated along the air inflow direction A as shown in FIGS. Then, first and second refrigerant flow paths 31c and 31d having a circular cross section are provided on the left and right sides of the horizontally long outline as viewed in FIG. 7, and extend parallel to the axial direction. A septum wall 32 is formed between the first and second refrigerant flow paths 31 c and 31 d, and the upper and lower concave surfaces are connected by the septum wall 32. Therefore, the septum wall 32 acts as a reinforcing rib having upper and lower concave surfaces against the internal pressure of the flat heat transfer tube 3C, and has a function of preventing the flat heat transfer tube 3C from being deformed by the internal pressure.

  Next, an example of joining of the flat heat transfer tube 3C having the first and second refrigerant flow paths 31c and 31d as described above and the mounting hole 21 (FIG. 3) of the heat-resistant fin 2 will be described. The flat heat transfer tube 3C is coated with a low-temperature brazing material 4 on the outer surface thereof, and is inserted into a mounting hole 21 provided in the heat-resistant fin 2 as shown in FIG. The heat-resistant fins 2 and the flat heat transfer tubes 3C are completely joined and fixed integrally by brazing with a low-temperature brazing material 4 in a furnace having a low temperature of 150 to 350 degrees.

  In this case, the thickness t2 of the thinnest wall portion 32 of the septum wall 32 of the first and second refrigerant flow paths 31c and 31d is set to the wall of the other part of the first and second refrigerant flow paths 31c and 31d. The wall thickness is desirably 1.5 times the wall thickness t1. Thereby, the rib function of the septum wall 32 can be strengthened, and the pressure resistance of the flat heat transfer tube 3C can be increased. For this reason, even if the outer shape of the heat transfer tube is flattened, the deformation of the flat heat transfer tube 3C due to the pressure in the tube does not occur, and the heat exchange efficiency is improved without deteriorating the adhesion between the flat heat transfer tube 3C and the heat-resistant fin 2. Therefore, it is possible to obtain a highly efficient heat exchanger that can perform high-efficiency operation of a refrigerator and an air conditioner using the heat exchanger.

Embodiment 4 FIG.
FIG. 8 is a cross-sectional view showing a flat heat transfer tube, which is a main part of a heat exchanger according to Embodiment 4 of the present invention, in which the same parts as those in Embodiments 2 and 3 are the same The code | symbol is attached | subjected. In the description, reference is made to FIG. 3 and FIG.

  In the heat exchanger, that is, the finned tube heat exchanger 1 according to the present embodiment, the flat heat transfer tube 3D is made of a metal material such as copper or a copper alloy, or aluminum or an aluminum alloy. Further, the flat heat transfer tube 3D has a cross-sectional contour shape that is elongated along the air inflow direction A as shown in FIGS. Then, first and second refrigerant flow paths 31c and 31d having a circular cross section are provided on the left and right sides of the horizontally long outline as viewed in FIG. 8, and extend in parallel to the axial direction. A septum wall 32 is formed between the first and second refrigerant flow paths 31 c and 31 d, and the upper and lower concave surfaces are connected by the septum wall 32. The first and second refrigerant flow paths 31c and 31d are provided with protrusions 33 having a substantially rectangular cross section that are arranged at predetermined intervals in the circumferential direction and extend in a spiral shape in the axial direction on the inner wall surfaces. . All other configurations are the same as those of the third embodiment.

  Next, an example of joining of the flat heat transfer tube 3D having the first and second refrigerant flow paths 31c and 31d as described above and the attachment hole 21 (FIG. 3) of the heat-resistant fin 2 will be described. The flat heat transfer tube 3D is coated with a low-temperature brazing material 4 on the outer surface thereof, and is inserted into a mounting hole 21 provided in the heat-resistant fin 2 as shown in FIG. The heat-resistant fins 2 and the flat heat transfer tubes 3D are completely joined and fixed integrally by brazing with a low-temperature brazing material 4 in a furnace having a low temperature of 150 to 350 degrees.

  Also in the flat heat transfer tube 3D of the present embodiment, basically, the higher the height h (projection length) of the ridge 33 after tube expansion, the higher the heat transfer coefficient. However, as described above, when the height h of the protruding ridge 33 after the tube expansion exceeds 0.3 mm, the amount of increase in pressure loss is larger than the amount of increase in heat transfer coefficient. As a result, the heat exchange rate is increased. Decreases. On the other hand, when the height h of the ridge 33 after the pipe expansion is less than 0.1 mm, the heat transfer coefficient is not improved.

  Therefore, the height h (projection length) of the protrusion 33 after the expansion of the first and second refrigerant flow paths 31c and 31d of the flat heat transfer tube 3D is also set to 0.1 to 0.3 mm. As a result, it is possible to obtain a highly efficient heat exchanger that can further improve the heat transfer performance without increasing the pressure in the flow path. As a result, a refrigerator and an air conditioner using this heat exchanger Highly efficient operation can be realized.

  Here, the cross-sectional shape of the ridge 33 is not limited to a quadrangular shape, and may be selected as appropriate, for example, a triangular shape, a trapezoidal shape, a semicircular shape, and any cross-sectional shape can be adopted. Needless to say. Further, even if a groove is formed instead of the protrusion 33, the same operation and effect can be obtained.

  The fin tube type heat exchanger 1 described above includes an HC single refrigerant or a mixed refrigerant containing HC, R32, R410A, R407C, tetrafluoropropene, and an HFC refrigerant having a boiling point lower than that of tetrafluoropropene. As a heat exchanger using any one of non-azeotropic refrigerants or carbon dioxide, it is used for an evaporator or a condenser of a refrigerator or an air conditioner.

  DESCRIPTION OF SYMBOLS 1 Fin tube type heat exchanger (heat exchanger), 2 Heat resistant fin, 3A-3D flat heat exchanger tube, 21 Mounting hole, 31a, 31c 1st refrigerant | coolant flow path, 31b, 31d 2nd refrigerant | coolant flow path, 32 Separation wall, 33 ridges.

Claims (8)

A flat heat transfer tube having first and second refrigerant channels defined by a septum wall;
A plurality of heat-resistant fins having heat transfer characteristics and arranged in parallel on the outer periphery of the flat heat transfer tube to form an air flow path;
The flat heat transfer tube is coated with a low-temperature brazing material on the outer surface thereof, and is inserted into a mounting hole provided in the heat-resistant fin so that the longitudinal direction of the flat shape is parallel to the air inflow direction. A heat exchanger characterized in that a heat tube and a heat-resistant fin are brazed to be joined and fixed integrally.   2. The heat exchange according to claim 1, wherein ridges or grooves extending spirally in the tube axis direction are formed on the inner surfaces of the first and second refrigerant flow paths of the flat heat transfer tube. vessel.   The flat heat transfer tube is characterized in that the outer peripheral surfaces on both sides sandwiching the long axis of the flat shape are flat, or the outer peripheral surfaces on both sides sandwiching the septal wall are formed in a symmetric uneven shape. Item 3. The heat exchanger according to item 1 or 2.   The heat exchanger according to any one of claims 1 to 3, wherein the first and second refrigerant channels are expanded so that the radius r is 1 to 3 mm.   The heat exchanger according to any one of claims 1 to 4, wherein the heat-resistant fin has a thickness of 20 to 40 µm.   A refrigerator using the heat exchanger according to any one of claims 1 to 5.   An air conditioner using the heat exchanger according to any one of claims 1 to 5.   As a refrigerant, HC single refrigerant, a mixed refrigerant containing HC, R32, R410A, R407C, a non-azeotropic mixed refrigerant containing tetrafluoropropene and an HFC refrigerant having a boiling point lower than that of tetrafluoropropene, or carbon dioxide Any one of them is used, The air conditioner of Claim 7 characterized by the above-mentioned.

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