JP2013100964A - Serpentine heat exchanger for air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serpentine heat exchanger for an air conditioner, configured to effectively prevent reduction in heat exchange performance due to condensation, and to sufficiently respond to reduction in size of the air conditioner.SOLUTION: The serpentine heat exchanger 10 for an air conditioner is configured by: arranging a large number of fins 12 parallel to each other at intervals of 0.6-5.0 mm in a direction (y direction) orthogonal to a direction (x direction) in which air flows as a heat exchange fluid, to form a fin group 14; arranging the fin groups 14 in line in a direction (z direction) orthogonal to the x and y directions at a distance of 2.0 mm or less, to form multiple stages of fin groups 14; and arranging a heat transfer pipe 16 in a serpentine configuration so as to sequentially pass through the fin group 14 at each stage.

Description

  The present invention relates to a serpentine heat exchanger in which heat is exchanged between a heat exchange fluid such as air and a refrigerant, and more particularly to a serpentine heat exchanger suitably used as a heat exchanger for an air conditioner. is there.

  Conventionally, as a heat exchanger for an air conditioner, a cross fin tube type heat exchanger has been mainly used. This cross fin tube heat exchanger is formed by joining a plurality of heat transfer tubes bent in a hairpin to a plurality of fins in the vertical direction and expanding the heat transfer tubes to join the fins and the heat transfer tubes. It is structured. And in such a heat exchanger, while circulating a predetermined | prescribed refrigerant | coolant in a heat exchanger tube, while allowing air to flow along a fin in the orthogonal | vertical direction with respect to a heat exchanger tube, a refrigerant | coolant and air are made to flow. Heat exchange takes place between them.

  However, in order to manufacture the cross fin tube type heat exchanger having such a structure, a large capital investment is required. That is, a large press device for forming aluminum plate fins and a press die thereof, a tube expansion device for expanding and fixing the aluminum plate fin and the heat transfer tube, and a tube expansion burette used therefor are required. It becomes. In particular, the indoor heat exchanger and the outdoor heat exchanger have different fin shapes (such as slits and louvers) and heat transfer tube diameters. Factors that obstruct drastic model changes that would change the shape of the heat exchangers, because it is necessary to prepare press dies, expanded burettes, etc. It has become.

  On the other hand, a heat exchanger used in a refrigerator or the like is composed of a large number of plate fins arranged in parallel and refrigerant pipes that penetrate these fins, and the refrigerant pipes are staggered with respect to the air flow direction. There are many independent fin type fin-and-tube heat exchangers (serpentine heat exchangers) that are arranged in a row and divided into rows and stages with respect to the refrigerant pipe. (See Patent Documents 1 and 2). According to such a serpentine heat exchanger, it is possible to improve productivity because the heat exchanger is configured by bending the refrigerant pipe to which independent fin groups are attached in a staggered manner. In addition, the heat exchange performance can be improved by the leading edge effect obtained by using the independent fins.

  For this reason, the application of such a serpentine heat exchanger is also being studied in heat exchangers for air conditioners, but most of the actual heat exchangers for air conditioners are used. The cross fin tube type heat exchanger as described above has been used, and a serpentine heat exchanger has not been adopted so far. This is because the heat exchanger for the air conditioner is a heat exchanger (2 to 3 stages) having a relatively thin structure in the air flow direction as compared with the heat exchanger for the refrigerator. This is because the effect obtained by using the fin is considered to be small.

  In addition, since the heat exchangers described in Patent Documents 1 and 2 are designed as heat exchangers for cooling systems such as refrigerators, heat transfer tubes are used to suppress blockage between fins due to frost formation. The pitch and the fin interval (fin pitch) are increased, and the heat transfer area on the air side is decreased. On the other hand, in a heat exchanger for an air conditioner, it is necessary to suppress clogging between fins due to condensation. Because of such circumstances, it has been difficult to apply conventional serpentine heat exchangers such as those described in Patent Documents 1 and 2 as heat exchangers for air conditioners as they are. is there.

  By the way, in the fin-and-tube heat exchanger (serpentine heat exchanger), which has a structure in which the fins and the heat transfer tubes are joined, the material of the fins and the material of the heat transfer tubes are different. In many cases, heat exchangers are configured. In such a case, there is a risk that electrolytic corrosion will occur between the fins and the heat transfer tubes due to condensed water and the fins or heat transfer tubes will corrode. It was something to do. Therefore, the applicant of the present application disclosed in Patent Document 3 (Japanese Patent Application Laid-Open No. 2011-185589) a serpentine heat for an air conditioner having improved fin corrosion resistance by forming a single-layer or multi-layer coating film on the fin. Although the heat exchanger disclosed in this patent document has a good corrosion resistance, the heat exchanger tube is likely to be corroded. There is also a problem that the production cost of the heat exchanger increases due to the coating cost for forming the coating film on the fin.

Japanese Utility Model Publication No. 5-8265 JP 2002-243382 A JP 2011-185589 A

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that a decrease in heat exchange performance due to condensation is effectively suppressed, and an air conditioner An object of the present invention is to provide a serpentine heat exchanger for an air conditioner that can sufficiently cope with downsizing.

  In the present invention, in order to solve such problems, the heat exchange fluids are arranged in parallel to each other at a predetermined interval in the direction (y direction) perpendicular to the flow direction (x direction) of the heat exchange fluid. A plurality of fin groups composed of a large number of fins are arranged in a line at a predetermined distance from each other in a direction perpendicular to the x direction and the y direction (z direction) to form a multi-stage fin group In addition, in the form in which one or two metal heat transfer tubes are penetrated by one fin, the metal heat transfer tubes are arranged in a meandering form so as to sequentially penetrate the fin groups of the respective stages. (1) Each fin constituting the fin group is made of a metal plate having the same shape, and adjacent fins are arranged at intervals of 0.6 to 5.0 mm. And (2 A gist of a serpentine heat exchanger for an air conditioner, wherein adjacent ones of the plurality of fin groups are arranged with a distance of 2.0 mm or less in the z direction. Is. Here, as the shape of the fin, a shape such as a rectangle, a circle, or a polygon is preferably employed.

  By the way, according to one of the preferable embodiments of such a serpentine heat exchanger for an air conditioner according to the present invention, a difference in natural pitting potential between the heat transfer tube and each fin constituting the fin group is 30 mV or more. It will be comprised so that. This makes it possible to effectively reduce the corrosion of the heat transfer tube due to the electrolytic corrosion of the fins and the heat transfer tube.

  Further, in one of the desirable embodiments of the serpentine heat exchanger for an air conditioner of the present invention, the metal plate is made of aluminum or an aluminum alloy, and is another desirable one. Thus, the heat transfer tube is made of aluminum or an aluminum alloy.

  Furthermore, according to another preferred embodiment of the serpentine heat exchanger for an air conditioner according to the present invention, the heat transfer tube is made of aluminum or an aluminum alloy, and a sacrificial anode effect of zinc on the outer surface thereof Will be granted.

  According to another preferred embodiment of the present invention, the heat transfer tube is made of aluminum or an aluminum alloy, and a metal film having a sacrificial anode effect is formed on the outer surface thereof. In addition, the surface roughness Ra of the outer surface is configured to be 0.2 to 3.0 μm in the tube axis direction.

  Furthermore, according to another preferred embodiment of the serpentine heat exchanger for an air conditioner according to the present invention, the material of the metal plate is JIS A1050, JIS A1100, JIS A1200, JIS A7072, and JIS A1050, JIS. A1100 or JIS A1200 is an aluminum or aluminum alloy composed of any one of 0.1 to 0.5% by mass of Mn and / or 0.1 to 1.8% by mass of Zn, And the material of the said heat exchanger tube is aluminum or aluminum alloy which consists of any 1 type in JIS A1050, JIS A1100, JIS A1200, and JIS A3003.

  Furthermore, in another desirable aspect of the serpentine heat exchanger for an air conditioner according to the present invention, the heat transfer tube is made of copper or a copper alloy, and is still another desirable aspect. Accordingly, the material of the heat transfer tube is JIS H3300 C1220 or JIS H3300 C5010.

  In addition, in such a serpentine heat exchanger for an air conditioner according to the present invention, advantageously, the inner surface of the metal heat transfer tube has a predetermined length with respect to the straight groove and the tube axis parallel to the tube axis direction. It is comprised so that it may have any 1 type, or 2 or more types of the cross groove comprised by the spiral groove | channel which has the following twist angle, or the groove | channel cross | intersected in a pipe-axis direction.

  In another desirable aspect of the serpentine heat exchanger for an air conditioner according to the present invention, the fin has a plurality of embossed portions protruding in the thickness direction and having a circular or elliptical bottom portion. It is configured as such.

  Further, in the present invention, preferably, the fin is slit or louvered, and according to another desirable aspect, the projected area of the fin is It will be comprised so that it may become 3 to 30 times the cross-sectional area prescribed | regulated by the outer diameter of a heat exchanger tube.

Furthermore, in another desirable embodiment of the serpentine heat exchanger for an air conditioner according to the present invention, the projected area of the fin is 200 to 1000 mm ² .

  And according to another one of the preferable aspects of the serpentine heat exchanger for air conditioners according to this invention as mentioned above, the outer diameter of the said metal heat exchanger tube shall be 3-13 mm.

  In another advantageous aspect of the serpentine heat exchanger for an air conditioner of the present invention, a surface treatment layer is provided on the surface of the metal plate, and a single surface treatment layer is provided on the surface treatment layer. A layer or a multilayer coating layer is formed, and at least the outermost layer of the coating layer is a coating layer made of a hydrophilic resin or a water-repellent resin.

  Furthermore, according to another preferred embodiment of the serpentine heat exchanger for an air conditioner according to the present invention, the hydrophilic resin is a polyvinyl alcohol resin, a polyacrylamide resin, a polyacrylic acid resin, a cellulose resin. It will be selected from the group consisting of resins and polyethylene glycol resins.

  Furthermore, in another preferred embodiment of the serpentine heat exchanger for an air conditioner according to the present invention, the water-repellent resin is an epoxy resin, polyurethane resin, acrylic resin, melamine resin, fluorine It will be selected from the group consisting of a series resin, a silicone series resin, and a polyester series resin.

  In addition, in the present invention, a resin coating layer is advantageously formed on the surface of the metal heat transfer tube. Moreover, according to one of the other preferable aspects of this invention, the said resin-made coating-film layer contains a heat conductive filler.

By the way, in the present invention, there are provided a serpentine heat exchanger having the characteristic structure as described above, and fan means for circulating a heat exchange fluid in the x direction through the plurality of fin groups arranged in the z direction. In the equipped air conditioner,
An interval between adjacent fins in the fin group located in the first region where the wind speed during circulation of the heat exchange fluid by the fan means is large or a part thereof is defined as p _1, and 0 with respect to the wind speed in the first region. a .7 following wind speed, when the interval between adjacent fins in the fin group or a portion thereof located in a small second region of the wind speed was p _2, the following formula:
1.5 ≦ p ₂ / p ₁ ≦ 3.0
An air conditioner characterized in that the fin interval in the fin group or a part thereof is defined so as to satisfy the above is also the gist of the present invention.

  According to one of the preferred embodiments of the air conditioner according to the present invention, the fin group located in the first area or a part thereof and the fin group located in the second area or a part thereof Are positioned on different stages in the z-direction.

  Further, according to one of the other preferred embodiments of the air conditioner according to the present invention, the fin group located in the first region or a part thereof and the fin group located in the second region or A part thereof is configured to be located in the same step in the z direction.

  Thus, in the serpentine heat exchanger for an air conditioner according to the present invention, the fin shape constituting each fin group is the same, and the interval (fin pitch) between adjacent fins on the metal heat transfer tube is the same. In addition, the adjacent fin groups are 2 to 2 in the z direction, that is, the direction perpendicular to the flow direction of the heat exchange fluid, in the fin group arrangement direction. The dew condensation water generated on the fin surface or the like does not stay between the adjacent fins or between the adjacent fin group and the fin group, since it is disposed at a distance of 0.0 mm or less. As a result, it is effectively discharged smoothly out of the fin group, and even when used in an air conditioner, a decrease in heat exchange performance due to condensation can be effectively suppressed.

  Further, in such a serpentine heat exchanger for an air conditioner, one or two heat transfer tubes are penetrated through a large number of fins constituting the fin group, and are configured by independent fin groups. The fin efficiency can be advantageously increased, and the heat interference (conduction) through the fins of adjacent heat transfer tubes can be cut off. As a result, it is possible to improve the heat exchange performance, thereby It is possible to advantageously realize a compact exchanger.

  And in such a serpentine heat exchanger for an air conditioner, the difference between the natural pitting potential between the heat transfer tube and each fin constituting the fin group is 30 mV or more, so that the fin and the heat transfer tube Even if electrolytic corrosion occurs between the two, the fins are preferentially corroded, so that the possibility that the heat transfer tubes corrode can be effectively suppressed or eliminated. In this way, by suppressing or eliminating the corrosion of the heat transfer tube, it is possible to effectively suppress or eliminate the possibility that the refrigerant flowing through the heat transfer tube leaks from the heat transfer tube. It will be.

It is a perspective explanatory view showing an example of a serpentine heat exchanger for an air conditioner according to the present invention. It is a section explanatory view showing roughly an example at the time of applying the serpentine heat exchanger for air conditioners according to the present invention to the outdoor unit of an air conditioner. It is a section explanatory view showing roughly another example at the time of applying the serpentine heat exchanger for air conditioners according to the present invention to the outdoor unit of an air conditioner. It is sectional explanatory drawing which shows an example of the coating-film layer formed on the surface of the fin which comprises the serpentine heat exchanger for air conditioners according to this invention. It is an isometric view explanatory drawing which shows another different example of the serpentine heat exchanger for air conditioners according to this invention. It is an isometric view explanatory drawing which shows another different example of the serpentine heat exchanger for air conditioners according to this invention. It is an isometric view explanatory drawing which shows another different example of the serpentine heat exchanger for air conditioners according to this invention. It is explanatory drawing which shows another example of the fin which comprises the serpentine heat exchanger for air conditioners according to this invention, Comprising: (a) is a perspective explanatory drawing of the whole one fin, (b) is embossing It is a section explanatory view expanding and showing a section of a portion. It is explanatory drawing which shows the metal heat exchanger tube which comprises the serpentine heat exchanger for air conditioners according to this invention, (a) is sectional explanatory drawing which shows what was used for the heat exchanger shown in FIG. (B), (c), (d) is sectional explanatory drawing which each shows another different example used as a metal heat exchanger tube.

  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 serpentine heat exchanger for an air conditioner (hereinafter also simply referred to as a serpentine heat exchanger or a heat exchanger) according to the present invention in the form of a perspective view. . The heat exchanger 10 includes a plurality of fin groups 14 each including a plurality of rectangular fins 12 arranged in parallel to each other and spaced apart from each other by a plurality of fin groups 14 each having a predetermined distance. The metal heat transfer tubes 16 are arranged in a meandering manner, that is, arranged in a serpentine shape via a bent portion 18 so as to pass through the plurality of fin groups 14 in order. ing.

  More specifically, the fin 12 is a thin, substantially flat plate-like fin in which a metal plate made of a predetermined metal material is formed in a predetermined fin shape (here, a rectangular shape). An assembly hole through which the metal heat transfer tube 16 is inserted is provided at the site, and a collar portion having a predetermined height is provided integrally with the fin 12 at the peripheral portion of the assembly hole. In addition, it is preferable that the metal plate which provides this fin 12 is comprised with aluminum or aluminum alloy like the past, and among them, it is excellent in heat conductivity and can ensure the intensity | strength as a fin. In view of the above, in addition to materials such as JIS A1050, JIS A1100, and JIS A1200, JIS A1050, JIS A1100, or JIS A1200 has Mn in a proportion of about 0.1 to 0.5 mass% and / or Zn is 0. In the ratio of about 1 to 1.8% by mass, the material to be contained is advantageously used. Further, when priority is given to the strength as a fin, the material of JIS A7072 is advantageously employed. Here, a symbol represented by a combination of an alphabet of “JIS A” and a four-digit number indicates an aluminum or aluminum alloy material defined in the JIS standard.

The projected area of the fin 12 is 3 to 30 times the cross-sectional area defined by the outer diameter of the heat transfer tube (metal heat transfer tube 16) from the viewpoint of achieving both a reduction in size of the heat exchanger and heat exchange performance. It is preferable that The cross-sectional area defined by the outer diameter of the heat transfer tube indicates the cross-sectional area obtained from the outer diameter of the heat transfer tube after the metal heat transfer tube 16 is expanded and fixed to the assembly hole of the fin 12. For example, as shown in FIG. 1, in a serpentine heat exchanger in which one heat transfer tube passes through one fin, if the outer diameter of the expanded metal heat transfer tube 16 is 6.5 mm, The cross-sectional area is 33.2 mm ² . When the projected area of the fin is less than three times the cross-sectional area defined by the outer diameter of the heat transfer tube, the fin is too small for the heat transfer tube, so that sufficient heat exchange performance is achieved. On the other hand, if the cross-sectional area exceeds 30 times, the heat exchanger becomes large and not practical. In particular, the projected area of the fin is preferably 200 to 1000 mm ² from the viewpoint of achieving both a reduction in size of the heat exchanger and heat exchange performance. If the projected area of the fin is less than 200 mm ² , sufficient heat exchange performance may not be obtained. On the other hand, if it exceeds 1000 mm ² , the heat exchanger becomes large and impractical. Because.

  Then, as shown in FIG. 1, a plurality of such fins 12 are in a direction (y direction in FIG. 1) perpendicular to the flow direction of air as the heat exchange fluid (x direction in FIG. 1). In other words, the fins 12 and 12 that are parallel and adjacent to each other in such a manner that the thickness direction of the plate is perpendicular to the air flow direction (fin pitch), preferably 1 The fin group 14 is formed by arrange | positioning so that the space | interval of 0.0-4.0 mm may be separated. Furthermore, a plurality of such fin groups 14 composed of a large number of fins 12 are arranged so that each fin group 14 is 2.0 mm in the direction perpendicular to the x direction and the y direction (z direction in FIG. 1). Hereinafter, it is configured so as to exhibit a flat plate shape as a whole by being arranged in a row with a distance d of preferably 1.5 mm or less. In addition, the z direction which is the arrangement direction of the fin group 14 is set to be a vertical direction in a state where the heat exchanger 10 is used.

  On the other hand, the metal heat transfer tube 16 is a tube having a substantially circular cross section formed of a predetermined metal material as in the prior art. And as a metal material which comprises this metal heat exchanger tube 16, Preferably, aluminum or an aluminum alloy, or copper or a copper alloy will be used. The difference in natural pitting corrosion potential between the metal heat transfer tube 16 and each fin 12 constituting the fin group 14 is preferably configured to be 30 mV or more. Therefore, the natural pitting potential of the metal heat transfer tube 16 refers to the natural pitting potential of the material itself constituting such a heat transfer tube, and a coating layer is formed on the surface, It should be understood that it has not been modified. Moreover, even if it exists in the fin 12, the natural pitting potential points out the natural pitting potential of the raw material itself which comprises it.

  Here, in the case where the metal heat transfer tube 16 is made of an aluminum material or an aluminum alloy material, from the viewpoint of manufacturability (extrudability), among JIS A1050, JIS A1100, JIS A1200, and JIS A3003 Any one kind of material is advantageously employed, but in order to further improve the corrosion resistance of the heat transfer tube, the following is preferable.

That is, the metal heat transfer tube 16 is made of any one of aluminum or aluminum alloy of JIS A1050, JIS A1100, JIS A1200, and JIS A3003 as described above, and the outer surface thereof is zinc sprayed and contains zinc. It is possible to improve the corrosion resistance of the heat transfer tube by forming a sacrificial anode material layer by flux (KZnF ₄ ), zinc plating or the like on the outer surface of the heat transfer tube and imparting the sacrificial anode effect by zinc. Alternatively, the metal heat transfer tube 16 is made of any one of the materials of JIS A1050, JIS A1100, JIS A1200, and JIS A3003, and the metal plate constituting the fin 12 is made of these aluminum. Alternatively, the corrosion resistance of the heat transfer tube can be improved by using Zn-containing JIS A7072 material that is electrochemically lower than the aluminum alloy.

  Further, when the metal film having the sacrificial anode effect is formed on the outer surface of the heat transfer tube as described above, the surface roughness Ra of the outer surface is 0.2 to 3.0 μm in the tube axis direction. It is preferable that it is comprised so that it may become. This is because when the surface roughness Ra is lower than 0.2 μm, since the management of the surface accuracy of the tool for processing the heat transfer tube becomes strict, the manufacturing cost of the heat transfer tube increases. When Ra is higher than 3.0 μm, a gap is easily formed between the fin collar portion and the surface of the heat transfer tube, so that the heat transfer efficiency between the fin and the heat transfer tube is lowered. This is because moisture can enter the gaps and cause the heat transfer tubes to corrode.

  Further, the heat transfer tube 16 can be constituted by a clad tube having a double tube wall structure including an inner core material layer and an outer skin material layer in the radial direction. Therefore, the JIS A1050, JIS A1100, JIS A1200, JIS A3003 etc. are adopted as the material of the core material layer, and JIS A7072 etc. are adopted as the material of the skin material layer, and the same effect as above is obtained. It will be realized together. In addition, as a clad rate used as the thickness of an outer skin | leather material layer, the value used as 3 to 20% of the tube wall full thickness is employ | adopted. If this cladding ratio is less than 3%, the sacrificial anode effect of the skin material is small, the through-holes are likely to be clear, causing the problem of poor corrosion resistance, and if the cladding ratio exceeds 20%, the tube wall The ratio of the core material layer to the thickness is reduced, and problems such as a decrease in strength are likely to occur.

  On the other hand, when the metal heat transfer tube 16 is made of copper or a copper alloy, a material such as JIS H3300 C1220 or JIS H3300 C5010 is advantageously employed from the viewpoint of heat transfer. Become. In addition, the symbol consisting of the combination of “JIS H3300” and “C + four-digit number” used here also indicates the copper or copper alloy material defined in the JIS standard.

  In the metal heat transfer tube 16 made of such a predetermined metal material, the outer diameter is appropriately determined so as to satisfy both the demand for downsizing the target serpentine heat exchanger 10 and the heat exchange performance. Although it is a thing, Preferably it is 3-13 mm. This is because heat transfer tubes with an outer diameter of less than 3 mm are difficult to manufacture as tubes, and those with an outer diameter of more than 13 mm are larger for heat exchangers employing such thick heat transfer tubes. This is because it is not practical.

  In addition, the straight portion of such a single metal heat transfer tube 16 sequentially passes through the assembly holes formed in the substantially central portions of the plurality of fins 12 constituting the fin group 14 described above, and the metal The outer peripheral surface of the heat transfer tube 16 and the collar inner peripheral surface of the peripheral edge of the assembly hole of the plurality of fins 12 are brought into close contact with each other and fixed (coupled). It should be noted that, for such a connection between the fin 12 and the metal heat transfer tube 16, various conventionally known methods are appropriately selected and used. An assembly hole with a collar having an inner diameter slightly larger than the outer diameter of the heat transfer tube 16 is opened, and after inserting the metal heat transfer tube 16 into such an assembly hole, the inside of the metal heat transfer tube 16 By inserting a tube expansion plug into the metal heat transfer tube 16 to increase the outer diameter of the metal heat transfer tube 16, the outer peripheral surface of the metal heat transfer tube 16 and the inner peripheral surface of the assembly hole provided in the fin 12 (collar inner peripheral surface) The method of adhering to each other is preferably employed.

  In this way, as shown in FIG. 1, the metal heat transfer tube 16 is perpendicular to the flow direction (x direction) of the air as the heat exchange fluid and the arrangement direction (y direction) of the multiple fins 12. So as to penetrate through a plurality of fin groups 14 arranged in a certain direction (z direction) in order, and in a meandering form, in other words, by being arranged in a serpentine shape, the entire plate is substantially flat. A serpentine heat exchanger 10 for an air conditioner having a shape is configured.

  By the way, the following method can be illustrated in order to make the metal heat exchanger tube 16 meander shape and make it the shape of the target heat exchanger 10. That is, first, a plurality of fin groups 14 are arranged at a predetermined interval with respect to one long straight metal heat transfer tube 16. Thereafter, a portion where the fin group 14 of the metal heat transfer tube 16 is not disposed is bent into a U shape, thereby forming a bent portion 18 to have a meandering shape, as shown in FIG. Thus, this is a method of forming the desired shape of the heat exchanger 10.

  In addition, the serpentine heat exchanger 10 for air conditioners which exhibits the substantially flat shape illustrated here is suitably employ | adopted as a heat exchanger for outdoor units of an air conditioner as shown, for example in FIG. It will be. That is, in FIG. 2, the outdoor unit 20 of the air conditioner is schematically shown in the form of a sectional view, in which the serpentine heat exchanger 10 for an air conditioner disposed in the outdoor unit 20. On the other hand, heat is exchanged between the refrigerant and the air by circulating air as a heat exchange fluid by the fan 22.

  Moreover, the example which used this serpentine heat exchanger 10 for air conditioners as a heat exchanger which takes the form which bent the flat plate so that the side view may become L shape is shown by FIG. . There, two such L-shaped heat exchangers (10, 10 ′) are used in combination so that the heat exchangers 10, 10 ′ have a rectangular shape in plan view. In addition, the fan 22 is installed on the upper part of the outdoor unit 20 so as to be positioned above the rectangular shape. Then, by the operation of the fan 22, the air as the heat exchange fluid is circulated through the two heat exchangers 10 and 10 ′ combined in a rectangular cylindrical shape as indicated by arrows, Heat exchange between the refrigerant and the air can be performed.

  Therefore, in the serpentine heat exchanger 10 for an air conditioner having a structure according to the present invention as described above, the fins 12 are spaced on the metal heat transfer tube 16 at intervals of 0.6 to 5.0 mm (fin pitch). ) To form the fin group 14, even when used in an air conditioner, a decrease in heat exchange performance due to condensation is effectively suppressed. . That is, if the fin pitch is less than 0.6 mm, water (condensation liquid) generated by dew condensation is unlikely to fall from the fin surface even when the film layer described later is provided on the fin. While the exchange performance is degraded, such condensed liquid may be pushed out by the air blown to cause water splashing in the room. On the other hand, if the fin pitch exceeds 5.0 mm, the fin pitch is too large. Therefore, in the heat exchanger of the same size, the number of fins is inevitably reduced, and the heat exchange performance may be deteriorated.

  Furthermore, in this heat exchanger 10, in the vertical direction which is the z direction, adjacent ones of the plurality of fin groups 14 are separated by a distance (d) of 2.0 mm or less, preferably 1.5 mm or less. Therefore, the dew condensation liquid generated on the surface of the fin 12 can be smoothly flowed downward and discharged to the outside, so that the heat exchange performance of the heat exchanger 10 is effective. It becomes possible to demonstrate to. On the other hand, when the interval (d) between the fin groups 14 and 14 adjacent to each other in the vertical direction is larger than 2.0 mm, the condensed liquid generated on the surface of the fin 12 flows down from the surface of the fin 12. There is a risk of staying between the adjacent fin groups 14 and 14 or at the end of the fin 12, and such dew condensation liquid causes problems such as deterioration in heat exchange performance and water splash as described above. There is a fear of being done.

  Further, in the heat exchanger 10, the heat exchanger is configured by a plurality of independent fin groups 14, and the fins are configured by assembling a large number of heat transfer tubes on one fin.・ Fin efficiency can be increased more favorably than an and-tube heat exchanger, and thermal interference (conduction) through the fins of adjacent heat transfer tubes can be effectively suppressed or cut off. The heat exchange performance can be advantageously improved. As a result, the advantage that the heat exchanger 10 can be made compact is also exhibited.

  As described above, one of the representative embodiments of the heat exchanger according to the present invention has been described in detail. However, these are merely examples, and the present invention is specific to such an embodiment. It should be understood that this description is not to be construed as limiting in any way.

  For example, in the above-described embodiment, the fin 12 is a pre-coating in which an unpainted metal plate is formed in a predetermined fin shape, but a single-layer or multi-layer coating layer is formed on the surface of the metal plate. The fins 12 may be formed using a metal plate. At this time, at least the outermost layer of the coating layer is a coating layer made of a hydrophilic resin or a water-repellent resin. Thus, by forming the fin 12 with the pre-coated metal plate on which the coating layer made of hydrophilic resin or water-repellent resin is formed, the temperature difference between the set temperature of the air conditioner and the outside air temperature is significant, and the fin 12 The heat exchange performance of the heat exchanger 10 can be advantageously maintained even under conditions where dew condensation occurs on the surface of the heat exchanger 10.

  In such a pre-coated metal plate, when the coating layer made of a hydrophilic resin is provided as the outermost layer, the water generated by the dew condensation is formed into a film on the surface of the outermost layer. It is possible to effectively suppress an increase in ventilation resistance (resistance when air passes between the fins) and to stably maintain high heat exchange performance. On the other hand, even when a coating layer made of a water-repellent resin is provided as the outermost layer, the water generated by condensation on the surface of the outermost layer falls smoothly from the fin surface as fine water droplets. Since it can be effectively discharged out of the fin, the increase in ventilation resistance due to condensed water is effectively suppressed, as in the case where a coating layer made of hydrophilic resin is provided as the outermost layer. Thus, the heat exchange performance of the heat exchanger 10 can be maintained.

  In the coating layer formed on the surface of the fin 12 in this way, at least the outermost layer is made of a hydrophilic resin or a water repellent resin, examples of the hydrophilic resin include polyvinyl alcohol resins (polyvinyl alcohol and its derivatives). ), Polyacrylamide resins (polyacrylamide and derivatives thereof), polyacrylic acid resins (polyacrylic acid and derivatives thereof), cellulose resins (carboxymethylcellulose sodium, carboxymethylcellulose ammonium, etc.), polyethylene glycol resins (polyethylene glycol, Polyethylene oxide, etc.). Examples of the water repellent resin include an epoxy resin, a polyurethane resin, an acrylic resin, a melamine resin, a fluorine resin, a silicon resin, and a polyester resin.

  Furthermore, it is of course possible to use a pre-coated metal plate provided with a single coating layer made of a hydrophilic resin or a water-repellent resin as the fins 12, but preferably, a metal plate serving as a substrate is used. First, a corrosion-resistant coating layer made of epoxy resin, urethane resin, polyester resin, vinyl chloride resin or the like is formed on the surface, and further, a coating layer made of the above-mentioned hydrophilic resin or the like is formed on the surface. A pre-coated metal plate provided with a plurality of coating layers obtained by the formation is used. Thus, it becomes possible to improve the corrosion resistance of the fin 12 by providing such a corrosion-resistant coating layer on the surface of the metal plate to be the substrate. In addition, it is preferable that the thickness of each coating film layer formed on the surface of a metal plate in this way is 0.1-5.0 micrometers per single layer. This is because when the thickness of each coating layer is less than 0.1 μm, the effects of each coating layer may not be enjoyed advantageously. On the other hand, even if a coating layer having a thickness of more than 5.0 μm is provided, the effect of each coating layer is already in a saturated state, so it is only costly to form such a coating layer. It becomes.

  In addition, when a coating layer made of a hydrophilic resin or a water-repellent resin or a corrosion-resistant coating layer is provided on the surface of the metal plate constituting the fin 12, a base treatment layer 32 is previously formed on the surface of the metal plate 30. It is preferable that this is done (see FIG. 4). By providing such a base treatment layer 32, it is possible to improve the adhesion between the metal plate and each of the coating layers (34, 36) described above. Here, as such a base treatment layer, chromate treatment using phosphate chromate, chromate chromate, etc., and other than chromium compounds, titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, titanium oxide, oxidation Examples thereof include a film layer obtained by a chemical film treatment (chemical conversion treatment) such as non-chromate treatment using zirconium or the like. The chemical film treatment method includes a reaction type and a coating type. In the present invention, any method can be adopted.

  Furthermore, in the illustrated embodiment, the intervals (fin pitches) between the adjacent fins 12 and 12 are all equally spaced. However, in one heat exchanger 10, the arrangement site of the fin group 14 and the fins are arranged. Of course, it is possible to set different fin pitches between the fin groups 14 or within one fin group 14 depending on the fin 12 arrangement site in the group 14.

  Specifically, in the refrigerant flowing through the metal heat transfer tube 16, the gas phase region and the liquid phase region in the vicinity of the refrigerant inlet / outlet are compared with the gas / liquid two-phase region in the intermediate portion of the refrigerant. Since the exchangeability is low and the heat transfer coefficient is clearly low, it is possible to increase the heat exchange efficiency by expanding the heat exchange area by narrowing the fin pitch at such a part.

  Further, in the outdoor unit 20 of the air conditioner as shown in FIG. 3, when air is circulated to the heat exchangers 10, 10 ′ by the fan 22, the upper region that is the closest region to the fan 22. The flow velocity of the air flowing between the fins 12 of the fin group 14 located at A is larger than the flow velocity of the air flowing between the fins 12 of the fin group 14 located in the lower region B, which is the region farthest from the fan 22. Become.

For example, the flow velocity Va of the air flowing between the fins 12 in the fin group 14 in the upper region A: Va is 1.5 to 2 times the flow velocity of the air flowing between the fins 12 in the fin group 14 in the lower region B: Vb. In such a case, the interval between the adjacent fins 12 and 12 (fin pitch: p ₁ ) in the fin group 14 in the upper region A is narrowed for the purpose of improving the heat exchange performance. On the other hand, if the spacing (fin pitch: p ₂ ) between adjacent fins 12 in the fin group 14 in the lower region B is also set to the same fin pitch as the fin pitch: p ₁ , the fin group in the lower region B In 14, the ventilation resistance becomes too large, and the problem arises that the heat exchange performance as a whole deteriorates.

Then, to avoid the occurrence of such a problem, the fin pitch of the fin group 14 located farther lower region B from the fan 22: the p _2, the fin group 14 located in the upper region A close to the fan 22 It is preferable to expand the fin pitch at an appropriate ratio with respect to p ₁ . Therefore, in the present invention, paying attention to the flow velocity (wind velocity) of the air that is the heat exchange fluid in the regions A and B, the upper region A (first region) in which the wind velocity during air circulation by the fan 22 is large. a plurality of fins sites fin pitch in the group of fins 14 located) and p _1, is 0.7 or less of the wind against the wind speed at the upper stage region a, a small lower region B of the wind speed (second region) By restricting the relationship between the fin pitch 14 in the fin group 14 located at p ₂ and p ₂ , the ratio p ₂ / p ₁ is 1.5 or more and 3.0 or less (1.5 ≦ p ₂ / p ₁ ≦ 3.0), advantageously adopting a configuration that adjusts the fin pitch of the fin group 14 in each region to control the ventilation resistance and improve the overall heat exchange performance Will be.

When the value of p ₂ / p ₁ is less than 1.5, the effect of changing the ratio of the two fin pitches becomes insufficient, and it is difficult to expect improvement in heat exchange performance. When the value of p ₂ / p ₁ exceeds 3.0, the interval between adjacent fins 12 and 12 of the fin group 14 located in the upper region A of each heat exchanger 10 and 10 ′: p _{When 1} is 0.6 mm, which is the lower limit of the appropriate range for the fin pitch, an increase in ventilation resistance due to the attachment of condensed water on each fin 12 during heating operation causes a decrease in air-side heat transfer coefficient In addition, the air-side heat transfer coefficient is reduced, which causes a reduction in heat exchange performance.

Here, the above-described fin pitch: p ₁ is set as an interval between adjacent fins in at least one fin group 14 located in the upper region A that is the region closest to the fan 22. In general, however, the upper region A close to the fan 22 is positioned close to the fan 22 among the plurality of (n-step) fin groups 14 arranged in the z direction. The fin group 14 having n / 4 stages is included. Similarly, the fin pitch: p ₂ is adopted as an interval between adjacent fins in at least one fin group located in the lower region B, which is the region farthest from the fan 22. Among the plurality of (n-stage) fin groups 14 constituting the heat exchangers 10 and 10 ′, it is advantageous to the n / 4-stage fin group 14 located in the region farthest from the fan 22. It will be applied to. In addition, even in the fin region 14 (n / 2 steps) in the intermediate region located between the upper region A and the lower region B, the wind speed of the fin group 14 is 0.7 times or less than the wind speed in the upper region A. In this case, the fin pitch (p ₂ ) is defined so as to satisfy the inequality related to p ₂ / p ₁ described above. The p ₁ is shown as an average fin pitch of at least one fin group 14 located in the upper region A, and p ₂ is at least one fin group 14 located in the lower region B. It is shown as the average fin pitch at.

Furthermore, the air in the fin group 14 located in the intermediate region between the upper region A and the lower region B of the plurality of (n stages) fin groups arranged in the z direction in each heat exchanger 10, 10 ′. Since Vc has a relationship of Vb ≦ Vc ≦ Va, the fin pitch of the fin group 14 of the intermediate region of the plurality of fin groups 14 (generally, the number of stages of n / 2) is: p ₃ is preferably p ₁ ≦ p ₃ ≦ p ₂ .

The change in the flow velocity (wind speed) of the heat exchange fluid (air) as described above occurs between the fin groups 14 and 14 located at different stages in the z direction, and different fin arrangements in the fin groups 14 of the same stage. The relationship between the fin pitches p ₁ and p ₂ described above is that they occur also between the fins 12 of one fin group 14 arranged at different positions in the tube axis direction of the heat transfer tubes 16. In either case, it will be applied.

  Moreover, in the heat exchanger 10 in this embodiment, although the one metal heat exchanger tube 16 penetrated with respect to the one fin 12, as shown in FIG. The heat exchanger 40 having a structure in which the two fins 44 are formed by passing the two metal heat transfer tubes 16 and 16 through the fins 42 may be used.

  Furthermore, a shape in which a plurality of heat exchangers 10 are overlapped with respect to the flow direction of the heat exchange fluid (air), for example, as shown in FIGS. It is also possible to constitute one serpentine heat exchanger 46, 48 for an air conditioner by overlapping each other at intervals. Thus, in the case where a plurality of flat plate-shaped heat exchangers 10 are overlapped with respect to the air flow direction, the fins of adjacent heat exchangers 10, such as the heat exchanger 46 shown in FIG. 6, are used. In other words, one of the fin groups 14 of the front heat exchanger 10 is adjacent to one of the fin groups 14 of the rear heat exchanger 10 in the flow direction of the heat exchange fluid. 7, so that one of the fin groups 14 of the front heat exchanger 10 is adjacent to the two fin groups 14 of the rear heat exchanger 10, as in the heat exchanger 48 shown in FIG. 7. It is also possible to arrange them so that the fins 12 of the adjacent heat exchangers 10 are staggered. However, from the viewpoint of heat exchange performance, as shown in FIG. 7, better heat exchange efficiency can be expected by superimposing them in a zigzag pattern. Further, in the case where a plurality of heat exchangers 10 are stacked in the flow direction of the air that is the heat exchange fluid in this way, the ventilation resistance is lowered by widening the fin pitch in a portion where high heat exchange efficiency cannot be expected. Is also possible. By reducing the ventilation resistance in this way, the flow of air, which is a heat exchange fluid, is improved, and sufficient air also flows through the heat exchanger 10 disposed on the rear side with respect to the air flow direction. It becomes possible to improve the heat exchange efficiency of the whole exchanger.

  As the fins constituting the heat exchanger 10 (40, 46, 48), in addition to the illustrated fin 12 (42) having a substantially flat rectangular shape, for example, as shown in FIG. A fin 50 having a plurality of embossed portions 52 protruding on the surface in the thickness direction of the fin and having a bottom or outer shape of a circle or an ellipse is preferably used. By forming the embossed portion 52 on the fin surface in this manner, after the heat exchange air passing between the stacked fins 50 comes into contact with the embossed portion 52, the stacking direction (longitudinal direction) of the fins 50 and It is converted into a direction (lateral direction) perpendicular to the stacking direction, and these become an appropriate longitudinal spiral (hereinafter referred to as longitudinal vortex) and lateral spiral (hereinafter referred to as lateral vortex). The air between the fins is appropriately disturbed by such an appropriate spiral flow, and as a result, the heat exchange performance can be improved. When a fin-and-tube heat exchanger (serpentine heat exchanger) is used as an evaporator in a low-temperature environment as an outdoor unit in a cold region, such an appropriate swirl flow, particularly a vertical flow The vortex suppresses the retention of relatively low temperature air in the vicinity of the fin surface, and allows relatively high temperature air that tends to stay in the central part between the fins to contact the fin surface. Suppression of frost formation or growth of frost that has formed frost can be effectively suppressed.

  The improvement of the heat exchange performance due to the presence of the embossed portion 52 as described above can be similarly realized by a cut-and-raised slit or a louver slit formed by slit processing or louver processing. Accordingly, such slit processing and louver processing are performed on the fins (12, 42) in accordance with a conventional method together with or instead of the embossing for forming the embossed portion 52.

  The pipe diameter of the metal heat transfer pipe 16 may be different depending on the part of the heat exchanger 10 depending on the flow characteristics of the refrigerant flowing in the pipe. For example, a heat transfer tube with a relatively small outer diameter is used in the liquid phase region, while a heat transfer tube with a relatively large outer diameter is used in the gas phase region, thereby improving the heat transfer coefficient in the tube and reducing the pressure loss. This can be advantageously achieved. When adopting a metal heat transfer tube having a different pipe diameter depending on the part of such a heat exchanger, a single long metal heat transfer pipe whose pipe diameter is appropriately changed at a desired part in the tube axis direction is used. In addition to using, for example, a metal heat transfer tube having a pipe diameter appropriately selected for each fin group 14 may be connected by a U-bend tube or the like to form a metal heat transfer tube having a meandering shape.

  Further, in the embodiment exemplified above, a tubular body (see FIG. 9A) having a smooth inner surface is used as the metal heat transfer tube 16, but in the longitudinal direction on the inner surface of the heat transfer tube. It is also possible to employ a so-called internally grooved heat transfer tube in which parallel straight grooves, spiral grooves having a twist angle, or cross grooves having a groove shape in which the grooves intersect at a predetermined angle are formed. In this way, it is possible to further increase the heat exchange performance of the heat exchanger 10 by increasing the heat transfer area on the inner surface of the heat transfer tube and further complicating the flow of the refrigerant flowing through the heat transfer tube. It becomes. In addition, in the serpentine heat exchanger 10 that employs the inner surface grooved heat transfer tube as described above, the entire groove type inner surface grooved heat transfer tube may be employed, but other than that, for example, It is also possible to use an internally grooved heat transfer tube of a type having a different groove shape for each path constituting the fin group 14. Note that the groove formed on the inner surface of the heat transfer tube in this way preferably has a groove depth of 0.05 to 1.0 mm, and the number of grooves is preferably in a cross section perpendicular to the longitudinal direction of the heat transfer tube. It is possible to effectively improve the heat exchange performance by setting the length to 15 to 150.

  Furthermore, the metal heat transfer tube 16 used in the present invention only needs to have an outer surface having a substantially circular shape. For example, as shown in FIGS. 9B, 9C, and 9D, the cross section is 1. In addition to the multi-hole pipes 54, 56, and 58 partitioned by two partition boards 55, two parallel partition boards 57 and 57, and two crossing partition boards 59 and 59, various known multi-hole pipes Can be suitably employed.

  In addition, as the metal heat transfer tube 16 constituting the serpentine heat exchanger 10, one having a resin coating layer formed on its surface is preferably used. The serpentine heat exchanger 10 described above is assembled by bringing the metal heat transfer tubes 16 and the fins 12 into close contact with each other by a method such as a mechanical tube expansion method, and assembling them. If the contact portion of the heat tube is viewed microscopically, a certain amount of air gap exists between the metal heat transfer tube 16 and each of the fins 12. However, if such voids are present, the contact thermal resistance between the fins and the heat transfer tubes is increased, and the heat exchange performance may be degraded. Therefore, in order to reduce the contact thermal resistance between them and effectively exhibit the performance of the heat exchanger, it is preferable that there is no gap between the metal heat transfer tubes 16 and the fins 12, Therefore, by forming a resin coating layer on the surface of the metal heat transfer tube 16, the generation of such voids is advantageously suppressed.

  And as resin which comprises such a resin-made coating-film layer, other than thermoplastic resins, such as a polyethylene resin, the hydrophilic resin and water-repellent resin similar to what is formed in the fin 12 surface mentioned above, And epoxy resins, urethane resins, polyester resins, vinyl chloride resins, and the like. By forming a coating layer made of these various resins on the surface of the metal heat transfer tube 16, the following effects can be obtained. That is, for a thermoplastic resin such as a polyethylene resin, after assembling the fins 12 provided with collared holes to the metal heat transfer tube 16 having a coating layer made of a thermoplastic resin such as a polyethylene resin as the outermost layer, When heated above the melting point of a thermoplastic resin such as polyethylene resin and then cooled, the gap between the collar skirt formed on the periphery of the hole with the collar and the metal heat transfer tube is advantageous by the thermoplastic resin such as polyethylene resin. Since the contact area between the fins 12 and the metal heat transfer tubes 16 can be ensured larger, the heat exchange performance of the heat exchanger can be further improved. Further, by forming a coating film layer made of a hydrophilic resin or a water repellent resin on the metal heat transfer tube 16 as an outermost layer, the exposed portions (portions where no fins are assembled) of the metal heat transfer tube 16 are formed on the fin 12. It is possible to have the same function as. Furthermore, by providing a coating layer made of epoxy resin, urethane resin, polyester resin, vinyl chloride resin or the like on the surface of the metal heat transfer tube 16, the corrosion resistance of the metal heat transfer tube 16 can be improved. Is possible.

  Moreover, it is preferable that this resin-made coating-film layer contains a heat conductive filler from a viewpoint of improving heat conductivity. Examples of such thermally conductive fillers include boron nitride, aluminum nitride, silicon nitride, silicon carbide, alumina, zirconia, titanium oxide, fine carbon powder, and the like.

  In the present invention, a structure in which a single coating layer made of various resins as described above is provided on the surface of the metal heat transfer tube 16 can be employed. First, a corrosion-resistant coating layer made of epoxy resin, urethane resin, polyester resin, vinyl chloride resin, or the like is formed on the surface of the heat transfer tube 16, and a thermoplastic resin such as polyethylene resin is further formed thereon. The structure which forms the resin-made coating-film layer which consists of hydrophilic resin or water-repellent resin is employ | adopted. Moreover, it is preferable that the thickness of this resin-made coating-film layer is 0.1-5.0 micrometers per single layer. If the thickness of the resin coating layer is less than 0.1 μm, the effects of each of the resin coating layers described above may not be enjoyed. On the other hand, a resin coating layer having a thickness exceeding 5.0 μm is provided. However, the effect of each coating layer is already in a saturated state, and it is only costly.

  Furthermore, when a resin coating layer made of the above-described resin is provided on the surface of the metal heat transfer tube 16, it is preferable that a base treatment layer is formed on the surface of the metal heat transfer tube 16 in advance. By providing such a base treatment layer, the adhesion between the metal heat transfer tube 16 and each coating layer described above can be improved. Here, as the base treatment layer, chromate treatment using phosphate chromate, chromate chromate, etc., and other than chromium compounds, titanium phosphate, zirconium phosphate, molybdenum phosphate, zinc phosphate, titanium oxide, zirconium oxide Examples thereof include a film layer obtained by chemical film treatment (chemical conversion treatment) such as non-chromate treatment using the like. The chemical film treatment method includes a reaction type and a coating type. In the present invention, any method can be adopted.

  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.

  Hereinafter, representative examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited by the description of such examples. It goes without saying.

-Experimental example 1-
First, an aluminum alloy (JIS A3003) is extruded as a heat transfer tube used to construct a serpentine heat exchanger for an air conditioner according to the present invention. Various types of inner surface grooved heat transfer tubes having a predetermined groove formed on the inner surface of the tube at 0 mm were formed. That is, tube outer diameter: 8.0 mm, tube wall thickness: 0.65 mm, fin height of fins formed between adjacent grooves: 0.65 mm, number of grooves: 30, lead angle with respect to tube axis : 0 ° inner surface grooved heat transfer tube with straight groove formed on the inner surface, tube outer diameter: 8.0 mm, wall thickness: 0.42 mm, fin height: 0.28 mm, number of grooves: 50 , Lead angle: 34 °, inner surface grooved heat transfer tube with spiral groove formed on the inner surface, tube outer diameter: 8.0 mm, wall thickness: 0.42 mm, fin height between primary grooves: 0.28 mm , Fin height between secondary grooves: 0.10 mm, number of primary and secondary grooves: 50 each, lead angle of primary groove: 34 °, lead angle of secondary groove: 10 °, pipe inner surface Three types were formed: an internally grooved heat transfer tube in which a cross groove was formed. In addition, as a manufacturing method of such an internally grooved tube, various known methods are appropriately selected and used. For example, JP-A-8-49992 and JP-A-2004-301495 are used. The method disclosed in (1) is preferably adopted.

  And after spraying zinc metal powder with respect to each outer surface of the heat transfer tube with an inner surface groove formed in this way, a long straight line in which a zinc concentrated layer is formed in a surface layer range of 200 μm by heat treatment Three types of metal heat transfer tubes (14) were prepared. That is, the heat transfer tube A1 is formed from the internally grooved heat transfer tube having a straight groove shape, the heat transfer tube A2 is formed from the internally grooved heat transfer tube having a spiral groove shape, and the internally grooved heat transfer tube having a groove shape is a cross groove. , Heat transfer tubes A3 were prepared. The surface roughness (Ra) of the outer surfaces of the heat transfer tubes A1 to A3 was all Ra: 1.0 μm.

  Another heat transfer tube is an internally grooved heat transfer tube formed of a copper alloy (phosphorus deoxidized copper: JIS H3300 C1220) and having an outer diameter of 8.0 mm, and a spiral groove is formed on the inner peripheral surface thereof. What was formed was prepared as a heat transfer tube A4. The heat transfer tube A4 has a tube outer diameter of 8.0 mm, a wall thickness of 0.3 mm, a fin height of 0.12 mm, a groove number of 80, a lead angle with respect to the tube axis: 43 °, and an outer surface. The surface roughness (Ra) was Ra: 0.3 μm. Furthermore, similarly to the heat transfer tubes A1 to A3, two inner surface grooved heat transfer tubes having an outer diameter of 8.0 mm, in which predetermined straight grooves are formed on the inner surface by extruding an aluminum alloy, are prepared. A zinc-concentrated layer is not formed on the outer surface of one of them, and a heat transfer tube A5 having a surface roughness (Ra) of Ra: 0.3 μm is prepared as the outer surface of the other. In the same manner as the heat transfer tubes A1 to A3, a zinc concentrated layer is formed in the range of the surface layer of 200 μm, and the outer surface roughness (Ra) is set to Ra: 5.0 μm as heat transfer tubes A6, respectively. did. In addition, the shape, dimension, etc. of the inner surface groove | channel of these heat exchanger tubes A5 and A6 were made the same as heat exchanger tube A1.

  On the other hand, as fin materials, plate material: 0.1 mm aluminum material: JIS A1100 plate material B1, plate thickness: 0.1 mm aluminum material: JIS A7072 plate material B2, and the surface of such plate material B2 are shown in FIG. Three types of plate material B3 formed with the three-layer surface treatment film shown in FIG. Therefore, the plate material B3 is formed by subjecting the plate material B2 to a phosphoric acid chromate immersion treatment to form a chemical conversion film (32) made of phosphoric acid chromate on the surface of the plate material B2, and then the conversion film (32). On top, an epoxy resin is applied using a roll coater and heated at a temperature of 220 ° C. for 10 seconds to form a corrosion-resistant coating film (34) having a film thickness of 1 μm. Further, after air cooling, a polyvinyl alcohol resin ( A coating for a hydrophilic coating film made of PVA resin) is applied on the corrosion-resistant coating film (34) and heated at a temperature of 220 ° C. for 10 seconds, whereby a hydrophilic coating film having a film thickness of 1.5 μm (36 ) Was formed as a fin material. Then, the three types of fin materials prepared in this way are each cut into a rectangular shape having a size of 12 mm in the x direction and 16 mm in the z direction, and a heat transfer tube is inserted through the substantially central portion thereof. A large number of three types of fins were prepared by providing through holes (through holes with a 0.5 mm collar on the periphery).

  And the target fin group was formed on one heat exchanger tube as follows using the various heat exchanger tubes and fins which were prepared in this way. That is, a plurality of such fins are arranged so that the respective through holes are parallel to each other with a predetermined interval, and the heat transfer tubes are sequentially inserted through the through holes, and then the heat transfer tubes are expanded. Thus, the heat transfer tubes and the fins were integrated to form a fin group on the heat transfer tubes. At this time, the tube diameter (D) of the heat transfer tube after the tube expansion was 8.75 mm so that one heat transfer tube penetrated substantially the center of one fin. Further, the fin interval (fin pitch) was set to 1.0 mm with respect to the straight tube portion of the heat transfer tube. Here, 300 fins are prepared, divided into groups of 60 sheets, and the fins are arranged in parallel in each fin group and joined to each other, so that one heat transfer tube is predetermined. Five fin groups having the same width were formed at intervals.

  Next, bending is performed on a portion of the heat transfer tube where the fin group is not formed so that the heat transfer tube has a U-shape, and the fin group is arranged at a predetermined interval (d). The serpentine heat exchangers having the shape shown in FIG. 1 arranged in a meandering form so that the heat transfer tubes sequentially pass through the arranged fin groups were produced. As shown in Table 1, the distance (d) between the fin groups is within the scope of the present invention. No. 1 to 10 heat exchangers and those outside the range. 11 and 12 heat exchangers were used.

  In addition, each heat exchanger No. prepared in this way. 1-No. Table 1 below shows the measured pitting corrosion potentials of the cores and fins of 12 heat transfer tubes and the pitting corrosion potential difference between the fins and the heat transfer tubes. Here, the conditions at the time of measuring each pitting potential were 5% NaCl aqueous solution (pH = 3, acetic acid acid) as a test solution, test temperature: 25 ° C., electrode material serving as counter electrode at the time of measurement: The measurement was performed with SCE, sweep rate: 20 mV / m.

For each heat exchanger prepared in this manner, a test solution of 5% salt water adjusted to pH: 3 with acetic acid was sprayed at a spray chamber temperature: 35 ° C., spray amount: 1-2 ml / 80 cm ² / A corrosion test consisting of spraying for 4 weeks under the conditions of h was carried out. After this corrosion test, for each heat exchanger, pitting corrosion of the heat transfer tube after peeling the fins was observed with a microscope, and the number of the pitting corrosion was comparatively evaluated. The results are shown in the table below, where x is a case where pitting corrosion is noticeable, Δ is a case where pitting corrosion is slightly observed, ○ is a case where pitting corrosion is hardly observed, and ◎ is a case where pitting corrosion is not observed at all. It was shown in 1.

  Moreover, in order to evaluate the water | moisture content contained in each heat exchanger, each water exchanger immersed in the water tank was pulled up, the water content after standing still for 1 minute was measured, and this was made into water retention amount. Here, the weight of the heat exchanger having a fin pitch of 1.0 mm is set as 100%, and relative comparison is made, and 150% or less is regarded as acceptable.

  As is clear from the results in Table 1, the heat exchanger No. 1 in which the distance (d) between the fin groups was 1.0 mm or 1.5 mm. In each of Nos. 1 to 10, it was recognized that the water retention amount (moisture amount) was low, and therefore, the condensed water could be smoothly discharged from the heat exchanger. In addition, heat exchanger No. 1 to 3, 5 and 7, even in a combination of an Al heat transfer tube and an Al fin, the natural pitting potential difference between them is 30 mV or more. However, almost no pitting corrosion was observed in the heat transfer tube. Furthermore, heat exchanger No. 4 and no. 6 is configured so that the natural pitting potential difference between the heat transfer tube made of Cu material and the fin made of Al material is larger than 30 mV, so even if the corrosion test is performed. No pitting corrosion was observed on the heat transfer tube. On the other hand, the heat exchanger No. 2 in which the distance (d) between the fin groups is made to exceed 2 mm. 11 and no. In No. 12, the amount of water retained was large, and therefore, dew condensation was not sufficiently discharged and pitting corrosion was observed in the heat transfer tube. Further, the heat exchanger No. 1 formed using the heat transfer tube A6 in which the surface roughness (Ra) of the outer surface of the heat transfer tube is outside the scope of the present invention is Ra: 5.0 μm. In No. 9, although the pitting potential difference was made larger than 92 mV and 30 mV, a little pitting corrosion was observed. That is, since the surface roughness of the outer surface is large, moisture (condensation water) stays in the gap formed between the fin collar portion and the heat transfer tube surface, and thus pitting corrosion is likely to occur.

-Experimental example 2-
Serpentine heat exchanger No. having a fin group of 16 stages and having various fin pitches of the fin group in the upper region A, the lower region B and the intermediate region thereof. 21-No. 27, heat exchanger No. 27 in Experimental Example 1. 1 was manufactured using A1 as the heat transfer tube and B2 as the fin. In each heat exchanger, the fin group located in the upper stage area A has four stages, and the fin group located in the lower stage area B has four stages, while an intermediate stage between them has an eight-stage fin group. The fin pitches (p ₁ , p ₂ , p ₃ ) of the respective regions are configured so as to have the values shown in Table 2 below in consideration of the wind speed at the respective positions.

  Next, heat exchanger No. 1 manufactured as described above was used. 21-No. In order to compare the heat exchange performance of No. 27, the following experiment was conducted. Specifically, in the configuration shown in FIG. 3, with each heat exchanger set in the wind tunnel device, the fan is operated at a predetermined rotational speed and ventilated, while all the inlet / outlet conditions on the refrigerant side are constant. The refrigerant mass flow rate (kg / s) was measured. And the heat exchange amount (W) was calculated by multiplying the measured refrigerant mass flow rate by the specific enthalpy difference (J / kg) at the refrigerant inlet / outlet. In this experiment, heat exchanger No. The wind speed of the upper region A at 21 was 3.0 m / s, the lower region B was 1.0 m / s, and the middle region was 1.5 m / s. Also, in this experiment, the air side heat transfer area varies depending on the number of fins, and therefore, using the value obtained by dividing the calculated heat exchange amount by the air side heat transfer area, heat exchanger No. It was calculated as a performance ratio when the value of 21 was 1.0. The results are shown in Table 2 below.

As is clear from the results in Table 2, the heat exchanger No. No. 21 has a fin pitch of 3.0 mm from the upper region A to the lower region B, and has a heat exchange amount that can withstand practical use as an air conditioner. In addition, heat exchanger No. Nos. 22, 25 and 26 have a value of p ₂ / p ₁ within the preferred range defined in the present invention, and the overall heat exchanger does not have excessive ventilation resistance, and the heat exchange performance is particularly preferred. confirmed. Furthermore, heat exchanger No. Nos. 23 and 24 are heat exchanger Nos. As in FIG. 21, the value of p ₂ / p ₁ is out of the preferred range. Therefore, when appropriate operating conditions are set in the upper fin group, the ventilation resistance increases excessively in the lower fin group, and the air Although it can withstand practical use as a conditioner, the effect of improving the heat exchange performance of the heat exchanger as a whole has not been recognized as sufficient. In addition, heat exchanger No. 27, the value of p ₂ / p ₁ is too large, and the fin pitch (p ₂ ) in the lower region is larger than the appropriate fin pitch, so that the heat exchange performance is low. Is recognized.

-Experimental Example 3-
As the heat transfer tube, an internally grooved heat transfer tube made of phosphorous deoxidized copper (JIS H3300 C1220) in which a large number of inner surface grooves were formed as spiral grooves extending with a predetermined lead angle with respect to the tube axis was prepared. In addition, each dimension of this inner surface grooved heat transfer tube was as follows: outer diameter: 6.35 mm, bottom wall thickness: 0.23 mm, groove depth: 0.15 mm, number of grooves: 58, lead angle: 30 ° .

  On the other hand, as the fin material, a plate material of 0.13 mm thick, pure aluminum (JIS A1050) was prepared, and the surface of the fin material was subjected to a surface treatment consisting of three layers as in Experimental Example 1. . Further, as the resin applied to the surface of the corrosion-resistant coating film (34), instead of the above-described hydrophilic coating film (36), a water-repellent coating film made of an epoxy resin is used, and this is applied to the corrosion-resistant coating film. By coating on the surface of (34) and heating at a temperature of 220 ° C. for 10 seconds, another fin material on which a water-repellent coating film (36) having a film thickness of 1.5 μm was formed was prepared.

  Then, the two types of fin materials prepared in this way are each cut into a rectangular shape having a size of 12 mm in the x direction and 16 mm in the z direction in FIG. 1, and a heat transfer tube is inserted through the substantially central portion thereof. A large number of two types of fins were prepared by providing through holes (through holes with a 0.5 mm collar on the periphery).

  And the target fin group was formed on one heat exchanger tube as follows using the heat exchanger tube and fin prepared in this way. That is, a plurality of such fins are arranged so that the respective through holes are parallel to each other with a predetermined interval, and the heat transfer tubes are sequentially inserted through the through holes, and then the heat transfer tubes are expanded. Thus, the heat transfer tubes and the fins were integrated to form a fin group on the heat transfer tubes. At this time, the tube diameter (D) of the heat transfer tube after the tube expansion was 6.75 mm, so that one heat transfer tube penetrated the substantial center of one fin. In addition, by arranging and joining the fins in parallel in order so that the fin interval (fin pitch) and the number of fins are as shown in Table 3 below and joined to the straight pipe portion of the heat transfer tube, all from the same width The target fin group was formed.

  Next, after forming 16 fin groups so formed in the length direction of the heat transfer tubes at a predetermined interval, the heat transfer tube fin groups are subjected to bending processing, The heat transfer tubes are configured to be U-shaped, the fin groups are arranged at a predetermined interval, and the heat transfer tubes are arranged in a meandering form so that the heat transfer tubes sequentially pass through the arranged fin groups. A serpentine heat exchanger as shown in FIG. 1 was produced. In addition, the space | interval (distance between centers) of the heat exchanger tube bent in parallel is 18 mm, and the clearance gap between fins is 1 mm.

  Nine types of heat exchangers No. 1 thus obtained were obtained. 31-No. As shown in FIG. 2, each of 39 was set in a predetermined outdoor unit, a refrigerant (R410A) was passed through the heat transfer tube, a cooling operation was performed by rotating the fan, and the presence or absence of water splash was observed. As a result, heat exchanger no. In 35 and 37, spattering of water was observed even though a coating layer of hydrophilic resin or water repellent resin was provided on the fin surface. On the other hand, heat exchanger No. having a fin interval of 1.0 mm or more. In 31-34, 36, and 38, no water splashing was observed, and a good operating state was confirmed.

  Furthermore, no. For the heat exchangers (total 6 types) having a fin interval of 1.0 mm or more of 31 to 34, 36, and 38, the following experiments were performed in order to compare the heat exchange performance. Specifically, as shown in FIG. 2, in a state where it is set in a predetermined outdoor unit, air is flowed at a constant speed and wind speed with a fan, and all the inlet / outlet conditions on the refrigerant side are constant, and the refrigerant mass flow (kg / s ) Was measured. Then, the heat exchange amount (W) was calculated by multiplying the measured refrigerant mass flow rate by the specific enthalpy difference (J / kg) at the refrigerant inlet / outlet.

  As a result, heat exchanger no. 31 and 33, the heat exchange amounts thereof are both about 1500 W and the heat exchanger No. 3 having a fin interval of 3.0 mm. In 32 and 34, both were about 750 W, and from this, it was recognized that these heat exchangers are heat exchange amounts that can withstand practical use as an air conditioner. However, heat exchanger no. In 36 and 38, the amount of heat exchange was as low as about 100 W, and it was recognized that these were heat exchangers that were difficult to use as an air conditioner.

These heat exchangers No. In 31 to 34, the cross-sectional area defined by the outer diameter of the heat transfer tube, when obtaining a projected area of the fins, respectively, cross-sectional area (ST): 31.7mm ^2, the projected area (SF): at 192 mm ² Therefore, the area ratio (SF / ST) is 6.1 times, which is within an appropriate range defined by the present invention (3 to 30 times), and both heat exchange performance and downsizing of the heat exchanger are achieved. It was confirmed that it was preferable from the viewpoint.

DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Fin 14 Fin group 16 Metal heat exchanger tube 18 Bending part 20 Outdoor unit 22 Fan

Claims (23)

A plurality of fin groups consisting of a plurality of fins arranged in parallel with each other at a predetermined interval in the direction (y direction) perpendicular to the flow direction (x direction) of the heat exchange fluid are the x direction and y A plurality of fin groups are arranged in a row at a predetermined distance from each other in a direction perpendicular to the direction (z direction), and one or two metal heat transfer tubes are formed in one fin. In the serpentine heat exchanger having a structure in which the metal heat transfer tubes are arranged in a meandering form so as to sequentially penetrate the fin groups of each stage in the form of being penetrated,
Each fin constituting the fin group is made of a metal plate having the same shape, and adjacent fins are arranged at intervals of 0.6 to 5.0 mm.
Adjacent ones of the plurality of fin groups are disposed at a distance of 2.0 mm or less in the z direction.
A serpentine heat exchanger for an air conditioner.   The serpentine heat exchanger for an air conditioner according to claim 1, wherein a difference in natural pitting potential between the heat transfer tube and each fin constituting the fin group is 30 mV or more.   The serpentine heat exchanger for an air conditioner according to claim 1 or 2, wherein the metal plate is made of aluminum or an aluminum alloy.   The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 3, wherein the heat transfer tube is made of aluminum or an aluminum alloy.   The air according to any one of claims 1 to 4, wherein the heat transfer tube is made of aluminum or an aluminum alloy, and a sacrificial anode effect of zinc is given to an outer surface thereof. Serpentine heat exchanger for harmonic machines.   The heat transfer tube is made of aluminum or an aluminum alloy, a metal film having a sacrificial anode effect is formed on the outer surface thereof, and the surface roughness Ra of the outer surface is 0. 0 in the tube axis direction. The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 5, wherein the serpentine heat exchanger is configured to be 2 to 3.0 µm.   The material of the metal plate is JIS A1050, JIS A1100, JIS A1200, JIS A7072, and JIS A1050, JIS A1100 or JIS A1200, 0.1 to 0.5 mass% of Mn and / or 0.1 to 1.8. Aluminum or aluminum alloy made of any one of those containing Zn of mass%, and the material of the heat transfer tube is any one of JIS A1050, JIS A1100, JIS A1200, and JIS A3003. The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 6, wherein the serpentine heat exchanger is an aluminum or aluminum alloy made of seeds.   The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 3, wherein the heat transfer tube is made of copper or a copper alloy.   The serpentine heat exchanger for an air conditioner according to claim 8, wherein a material of the heat transfer tube is JIS H3300 C1220 or JIS H3300 C5010.   Either a straight groove parallel to the tube axis direction, a spiral groove having a predetermined twist angle with respect to the tube axis, or a cross groove configured by a groove intersecting in the tube axis direction on the inner surface of the metal heat transfer tube The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 9, wherein the serpentine heat exchanger has one type or two or more types.   The serpentine heat for an air conditioner according to any one of claims 1 to 10, wherein the fin has a plurality of embossed portions protruding in a thickness direction and having a bottom or outer shape of a circle or an ellipse. Exchanger.   The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 11, wherein the fin is slit or louvered.   13. The air conditioner according to claim 1, wherein a projected area of the fin is 3 to 30 times a cross-sectional area defined by an outer diameter of the heat transfer tube. Serpentine heat exchanger. Projected area of the fins, a serpentine heat exchanger for an air conditioner according to any one of claims 1 to 13, characterized in that it is 200 to 1000 mm ^2.   The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 14, wherein an outer diameter of the metal heat transfer tube is 3 to 13 mm.   A surface treatment layer is provided on the surface of the metal plate, and a single-layer or multiple-layer coating layer is formed on the surface treatment layer, and at least the outermost layer of the coating layer is hydrophilic. The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 15, wherein the serpentine heat exchanger is a coating layer made of a functional resin or a water-repellent resin.   The serpentine heat for an air conditioner according to claim 16, wherein the hydrophilic resin is selected from the group consisting of polyvinyl alcohol resin, polyacrylamide resin, polyacrylic acid resin, cellulose resin, and polyethylene glycol resin. Exchanger.   The water-repellent resin is selected from the group consisting of an epoxy resin, a polyurethane resin, an acrylic resin, a melamine resin, a fluorine resin, a silicon resin, and a polyester resin. Serpentine heat exchanger for air conditioners.   The serpentine heat exchanger for an air conditioner according to any one of claims 1 to 18, wherein a resin coating layer is formed on a surface of the metal heat transfer tube.   The serpentine heat exchanger for an air conditioner according to claim 19, wherein the resin coating layer contains a thermally conductive filler. 21. An air comprising a serpentine heat exchanger according to any one of claims 1 to 20 and fan means for circulating a heat exchange fluid in the x direction through a plurality of fin groups arranged in the z direction. In the harmony machine,
An interval between adjacent fins in the fin group located in the first region where the wind speed during circulation of the heat exchange fluid by the fan means is large or a part thereof is defined as p _1, and 0 with respect to the wind speed in the first region. a .7 following wind speed, when the interval between adjacent fins in the fin group or a portion thereof located in a small second region of the wind speed was p _2, the following formula:
1.5 ≦ p ₂ / p ₁ ≦ 3.0
An air conditioner characterized in that the fin interval in the fin group or a part thereof is defined so as to satisfy the above.   The air according to claim 21, wherein the fin group or a part thereof located in the first region and the fin group or a part thereof located in the second region are located at different stages in the z direction. Harmony machine. The fin group or a part thereof located in the first region and the fin group or a part thereof located in the second region are located in the same step in the z direction. 22. An air conditioner according to 22.

Images