JP6360791B2 - Heat transfer tube for fin-and-tube heat exchanger and fin-and-tube heat exchanger using the same - Google Patents

Description

  The present invention relates to a heat transfer tube for a fin-and-tube heat exchanger and a fin-and-tube heat exchanger using the same, and more particularly to a fin-and-tube in an air conditioner such as a home air conditioner or a packaged air conditioner. The present invention relates to a heat transfer tube suitably used for a mold heat exchanger and a fin-and-tube heat exchanger using the same.

  Conventionally, in addition to air conditioning equipment such as home air conditioners, automotive air conditioners, and packaged air conditioners, refrigerators, heat pump water heaters, and the like have used heat exchangers that operate as evaporators or condensers, among them. In home indoor air conditioners and commercial packaged air conditioners, fin-and-tube heat exchangers having a structure in which fins are assembled to heat transfer tubes have been most commonly used.

  In recent years, heat exchangers using natural refrigerants with a low global warming potential have been developed in place of conventional chlorofluorocarbon refrigerants from the viewpoint of protecting the ozone layer and preventing global warming. Among them, hot water heaters using a refrigerant mainly composed of carbon dioxide gas have attracted attention and have been developed. However, the same fin-and-tube as described above is also used for air heat exchangers in such water heaters. A mold heat exchanger is used.

  By the way, such a fin-and-tube heat exchanger is generally used in a structure in which a fin (outer surface fin) subjected to predetermined processing and a heat transfer tube are used and the fin and the heat transfer tube are joined. It is becoming. And in the heat exchanger having such a structure, while circulating the refrigerant in the heat transfer tube, by flowing air as a heat exchange fluid along the fins in a direction perpendicular to the heat transfer tube, Heat exchange is performed between the refrigerant and the air.

  Further, as one of the heat transfer tubes used in such a fin-and-tube heat exchanger, a flat tube having a structure in which a flat tube interior is divided into a plurality of flow paths by a plurality of partition walls. Hole tubes are known. The flat multi-hole tube is usually obtained by porthole extrusion of aluminum or an aluminum alloy. The cross-sectional shape of such a flat multi-hole tube is, for example, As disclosed in Japanese Laid-Open Patent Publication No. 6-142755 (Patent Document 1), a pipe having a rectangular flow path is generally used. Furthermore, in such a flat multi-hole tube, in order to improve the heat exchange efficiency, it is effective to increase the surface area of the flow path. In JP-A-5-222480 (Patent Document 2), a square is used. A structure that increases the surface area by forming a large number of minute irregularities on the inner surface of the hole has been clarified. By increasing the surface area of the flow path in this way, the contact area between the coolant that can circulate inside the hole and the surface of the hole is increased, and the heat transfer coefficient on the coolant side, that is, the heat between the coolant and the heat transfer tube. By improving the transfer rate, the heat exchange efficiency is improved.

  However, when forming a flat multi-hole tube from aluminum or an aluminum alloy by extrusion such as porthole extrusion, the size of the irregularities formed on the inner surface of the hole cannot be made sufficiently small. In addition, the surface area cannot be increased sufficiently. In particular, if the flat multi-hole tube is made smaller for the purpose of reducing the size of the heat exchanger, the number of holes formed is also smaller, so the heat based on the increase in surface area due to the formation of such irregularities. The effect of improving the transmission rate was not sufficient.

  Further, in FIG. 9 (c) of the above-mentioned Patent Document 1 (Japanese Patent Laid-Open No. 6-142755) and Japanese Patent Laid-Open No. 9-72680 (Patent Document 3), the hole shape of the flat multi-hole tube is a triangular cross-sectional shape. What has been made clear. That is, Patent Document 1 aims at extending the life of a multi-hole tube extrusion die and improving the size and accuracy of a product when performing extrusion molding of a multi-hole tube. As an example of the hole shape of a multi-hole tube manufactured using a die for extruding a hole tube, a triangular cross-sectional shape is merely mentioned. Patent Document 2 relates to a porous flat tube that can obtain a predetermined thickness and a flat surface by rolling or compression, and that can improve tensile strength by work hardening to give appropriate hardness and elasticity. As a structure of a porous flat tube capable of obtaining such characteristics, it has been clarified that the hole shape is a cross-sectional shape of an isosceles triangle.

  However, in the flat multi-hole pipes disclosed in those Patent Documents 1 and 3, the hole shape of the multi-hole pipe formed by extrusion processing is simply a triangular cross-sectional shape, In order to improve the hardness and elasticity of the multi-hole tube, the hole shape is merely a cross-sectional shape of an isosceles triangle. In other words, no consideration has been given to the specific shape of the triangle or the heat transfer coefficient of the heat transfer tube. Furthermore, when the hole formed in the flat multi-hole tube by the extrusion process has a triangular shape, the metal flow at the time of the extrusion process is not good, and the target triangular hole is formed. The manufacturing problem of difficulty is inherent.

JP-A-6-142755 Japanese Patent Laid-Open No. 5-222480 JP-A-9-72680

  Here, the present invention has been made in the background of such circumstances, and the problem to be solved is that the heat transfer coefficient on the refrigerant side can be effectively improved and the extrudability can be improved. Is to provide excellent heat transfer tubes for fin-and-tube heat exchangers, and fins for air conditioners and the like manufactured using such heat-transfer tubes for fin-and-tube heat exchangers・ Providing an and-tube heat exchanger is also an issue to be solved.

  And in the present invention, in order to solve such problems, a heat transfer tube for a fin-and-tube heat exchanger to which a fin made of aluminum or an alloy thereof is assembled is made of aluminum or an alloy thereof. The multi-hole tube having a flat cross-sectional shape as a whole, and a number of trapezoidal cross-sectional holes extending in the tube axis direction provided in the multi-hole tube are arranged in parallel to each other at a distance in the width direction. And the length of the upper base of the hole is less than or equal to 1/2 of the length of the lower base, and the height of the hole is equal to or greater than the length of the lower base and the thickness of the multi-hole tube. The hydraulic diameter defined by dividing the cross-sectional area of such a hole by four times the sum of the lengths of the sides of the hole: D and the height of the hole: The ratio (D / h) to h is in the range of 0.40 to 0.85. The fin-and-tube heat exchanger heat transfer tube, characterized by being made, is to its gist.

  In addition, in one of the desirable modes of the heat transfer tube for a fin-and-tube heat exchanger according to the present invention, adjacent ones of a plurality of holes provided in the multi-hole tube are mutually upside down. The trapezoidal cross-sectional shape is arranged.

  Moreover, in one of the other desirable modes of the heat transfer tube for a fin-and-tube heat exchanger according to the present invention, the cross-sectional shape of the hole is an isosceles trapezoidal shape. In one case, the hole has a trapezoidal shape in which the inner angle between the lower base and one leg is 90 °.

  Furthermore, the present invention provides a fin-and-tube heat exchanger in which a fin made of aluminum or an alloy thereof and a multi-hole tube made of aluminum or an alloy thereof and having a flat cross-sectional shape as a whole are assembled. The multi-hole tube is configured by arranging a large number of trapezoidal cross-sectional holes extending in the tube axis direction and arranged parallel to each other in the width direction, and the length of the upper base of the holes is The length of the bottom is ½ or less, and the height of the hole is equal to or more than the length of the bottom, and is 0.5 to 0.8 times the thickness of the multi-hole tube, Then, the ratio (D / h) of hydraulic diameter: D defined by dividing four times the cross-sectional area of the hole by the sum of the lengths of the side of the hole and the height of the hole: h (D / h) is 0. .. Fin-and-characterized by being configured to be in the range of 40 to 0.85 Also cube-type heat exchanger, and the gist thereof.

  Further, according to one of the preferred embodiments of the fin-and-tube heat exchanger according to the present invention, a rectangular plate-like fin is used as the fin, and the fin is opened at one end of the plate-like fin. The multi-hole tube and the plate-like fin are assembled by fitting and fixing the multi-hole tube in a slit having a predetermined length provided on the plate.

  Furthermore, in another preferred embodiment of the fin-and-tube heat exchanger according to the present invention, a corrugated fin having a corrugated shape is used as the fin, and a plurality of the corrugated fins and the multi-holes are used. A plurality of tubes are stacked alternately and joined together to be assembled.

  Therefore, according to the fin-and-tube heat exchanger heat transfer tube configured according to the present invention, the hole having a trapezoidal cross-sectional shape is a ratio of the length of the upper base and the lower base in the trapezoidal shape. And the ratio of the height of the hole to the thickness of the heat transfer tube, and also the hydraulic diameter defined by dividing the hole cross section by four times the sum of the lengths of the sides of the hole: D and the hole When the refrigerant flows through the hole in the heat transfer tube from where it is formed, the ratio (D / h) to the height: h is set to an appropriate range. The portion with a small hole, such as a portion with a small angle in the portion sandwiched between the bottom) and the leg, a portion sandwiched between the upper base and the two legs, which are less than half the length of the lower bottom, and the like Circulates, the area of the inner surface of the multi-hole tube that contacts the unit volume of the refrigerant increases, and the heat between the refrigerant and the heat transfer tube increases. Itaruritsu, i.e. the heat exchange efficiency of the heat transfer tube, it become possible to effectively improve. In addition, when the refrigerant passes through such a narrow hole portion, a local flow state can be induced, and thus the heat exchange efficiency can be increased more effectively.

  Further, in the fin-and-tube heat exchanger heat transfer tube configured according to the present invention, since the hole shape is a trapezoidal shape, when manufacturing the heat transfer tube by extrusion, a triangular shape is used. It is easier to produce a metal flow than manufacturing a flat multi-hole tube having a shape hole, and the extrudability can be advantageously improved.

  In the fin-and-tube heat exchanger manufactured using the heat transfer tube for the fin-and-tube heat exchanger configured as described above, the heat transfer coefficient on the refrigerant side in the heat-transfer tube is From the point of being advantageously improved, the high heat exchange performance is exhibited, and the effects such as downsizing and weight reduction of the heat exchanger and reduction of the manufacturing cost are advantageously exhibited.

It is a perspective explanatory view showing an example of a fin and tube type heat exchanger according to the present invention. It is a perspective explanatory view which shows the fin which comprises the fin and tube type heat exchanger shown by FIG. FIG. 2 is an explanatory cross-sectional view showing an enlarged part of a cross section of a flat multi-hole tube constituting the fin-and-tube heat exchanger shown in FIG. 1. It is front explanatory drawing which shows roughly the fin and tube type heat exchanger for heat exchange performance evaluation used in the Example. It is explanatory drawing which shows the cross section of the flat multi-hole tube prepared in order to comprise the heat exchanger used in the Example, (a) is a thing whose hole shape is an isosceles trapezoid shape, (b) Fig. 8 shows a trapezoidal shape in which the hole shape is a base and the inner angle of one leg is a right angle, and (c) shows a trapezoidal shape having a dimension different from that in (b). It is explanatory drawing which shows the cross section of the flat multi-hole tube prepared in order to comprise the heat exchanger used for the comparison in an Example, Comprising: (a) is a thing with a square-shaped hole shape, ( b) shows a circular hole shape. It is explanatory drawing which shows the cross section of the flat multi-hole tube further prepared in order to comprise the heat exchanger used for the comparison in the Example, (a) And (b) is this invention specification, respectively. An outer trapezoidal hole shape is shown.

  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.

  FIG. 1 is a perspective view schematically showing one embodiment of a fin-and-tube heat exchanger using a heat-transfer tube for a fin-and-tube heat exchanger according to the present invention. Has been. In the heat exchanger 10, two flat multi-hole tubes 14 and 14 are slits provided in the fins 12 with respect to the plurality of fins 12 arranged in parallel to each other and at a predetermined distance. It is configured by being inserted into and fixed to the assembly hole 16.

  More specifically, the fin 12 is formed of a metal material made of aluminum or an aluminum alloy, for example, an aluminum material having a JIS designation of A1000 series, A3000 series, A7000 series or the like, as shown in FIG. As shown, it is composed of thin plate-like fins having a rectangular planar shape. Further, in the fin 12, an assembly hole 16 into which the flat multi-hole tube 14 is assembled is formed as a slit extending from one end of the rectangular fin 12 in the width direction of the fin 12 (left and right direction in FIG. 2). Has been. Further, around the assembly hole 16, a collar portion 18 having a predetermined height is formed integrally with the fin 12 and is erected in a U-shape.

  On the other hand, as is well known, the flat multi-hole tube 14 is formed of a metal material made of aluminum or an aluminum alloy, for example, an aluminum material such as JIS name A1000 series, A3000 series, A6000 series, It is composed of a multi-hole tube having a flat shape in which ten holes 20 extending in the tube axis direction are formed. The hole 20 has a trapezoidal cross-sectional shape as shown in FIG. 3 in which a cross-section in a direction perpendicular to the tube axis, that is, a part of a so-called cross-section is enlarged. Of these, the length of the upper base: a is less than or equal to 1/2 of the length of the lower base: b, and the height: h is equal to or greater than the length of the lower base: b. The height: h is set to be 0.5 to 0.8 times as long as the thickness: H of the flat multi-hole tube 14. And here, the trapezoidal shape of the hole 20 is such that the height of the hole: h and the length of the lower base: b are the same length, and the length of the upper base: a is the length of the lower base: b. The shape is an isosceles trapezoid in which the length is ½ and the inner angles of both ends of each base (upper base, lower base) are equal. In addition, as shown in the figure, adjacent holes 20 of the holes 20 having such a shape are mutually spaced apart at a predetermined interval in the width direction of the flat multi-hole tube 14 in a form in which the vertical direction is inverted. They are arranged in parallel.

  Furthermore, in such a hole 20, the ratio of hydraulic diameter D defined by dividing four times its cross-sectional area by the sum of the lengths of the sides of the hole and the height of the hole: h ( D / h) is configured to be within a range of 0.40 to 0.85. That is, here, the hole 20 has the same hole height (h) and lower base length (b), and the upper base length (a) is 1/2 of the lower base length (b). Therefore, D / h = 0.84, which is within the range of D / h defined above.

  In this way, the hole shape of the hole 20 of the flat multi-hole tube 14 is changed to the trapezoidal upper base length: a, lower base length: b, hole height: h, and flat multi-hole tube 14 thickness. The ratio of the length: H, and further the ratio (D / h) of the hydraulic diameter: D to the height of the hole: h (D / h) is set to be a value within the above range, whereby the narrow portion of the hole 20 is cooled. Is effectively passed, and the area of the inner surface of the hole in contact with the unit volume of the refrigerant increases, and the heat transfer coefficient between the refrigerant and the heat transfer tube is advantageously improved. Moreover, since a local fluid state generate | occur | produces because a refrigerant | coolant passes the narrow part of such a hole 20, it also becomes possible to raise a heat transfer rate more effectively.

  By the way, in the flat multi-hole tube 14 described above, the length (a) of the upper base exceeds 1/2 of the length (b) of the lower base, or the hole height (h) is the length of the lower base (b ), The refrigerant easily passes through the hole 20, so that it is difficult to sufficiently transfer the heat between the refrigerant and the heat transfer tube. In addition, when the hole height (h) is less than 0.5 times the thickness (H) of the heat transfer tube, the hole becomes too small, which makes it difficult to manufacture. On the other hand, even when the hole height (h) is larger than 0.8 times the thickness (H) of the heat transfer tube, the upper and lower thicknesses of the flat multi-hole tube 14 become too thin. This makes it difficult to manufacture. The length (a) of the upper base of the trapezoidal shape of the hole 20 is preferably 0.1 mm or more. This is because if the length (a) is smaller than 0.1 mm, the metal flow during the extrusion process deteriorates, and it becomes difficult to produce the intended flat multi-hole tube. .

  Furthermore, even if there is a relationship between the hydraulic diameter: D and the hole height: h, if the value of D / h is smaller than 0.40, the hole 20 becomes too small and is flat. Since it becomes difficult to manufacture a multi-hole tube, it becomes impractical. On the other hand, when the value of D / h is larger than 0.85, the increase in the contact area per unit volume of the refrigerant is not sufficient, and the effect of improving the heat transfer coefficient is hardly exhibited.

  Then, using such flat multi-hole tube 14 and fins 12, a plurality of such fins 12 are separated from each other in parallel and at a constant distance in a state where the assembly holes 16 formed in each of them are aligned. The target fin-and-tube heat exchanger 10 is configured by fitting the flat multi-hole tube 14 into the assembly holes 16 that are aligned with each other and fixedly assembling them. It is. As is well known, the flat assembly of the multi-hole tube 14 and the fins 12 is performed by various known methods such as joining by caulking or brazing or fixing by an adhesive. Thus, it will be completed as an integral fin and tube heat exchanger. Further, both end portions of the flat multi-hole tube 14 which is a heat transfer tube constituting such a fin-and-tube heat exchanger are respectively connected to a header (not shown), and the flat multi-hole tube 14 10 The ten holes 20, that is, the ten flow paths through which the refrigerant extending in the tube axis direction is circulated are combined on the refrigerant inlet side and the outlet side to form the fin-and-tube heat exchanger 10. It is.

  Accordingly, in the fin-and-tube heat exchanger 10 configured according to the present invention, the shape of the hole 20 formed in the flat multi-hole tube 14 is simply the contact between the refrigerant and the inner surface of the hole. The flat multi-hole tube 14 has a trapezoidal shape that not only increases the area but also increases the contact area per unit volume of the refrigerant to advantageously improve the heat transfer coefficient on the refrigerant side. In this case, the heat exchange efficiency between the refrigerant circulating in the pipe and the heat transfer pipe is effectively improved, and as a result, the heat exchange performance of the heat exchanger 10 can be advantageously enhanced. Further, since the hole 20 formed in the flat multi-hole tube 14 has a trapezoidal shape, the problem that the metal flow deteriorates and the workability deteriorates at the time of extrusion is advantageously solved. Or it will be avoided and high extrudability will be exhibited. Further, by using the flat multi-hole tube 14 exhibiting such a high heat transfer rate, the heat exchanger 10 can be reduced in size and weight, and the effect of reducing the manufacturing cost can be advantageously exhibited. .

  As described above, one of the representative embodiments of the present invention has been described in detail. It should be understood that this is not to be construed as limiting.

  For example, in the above-described embodiment, the fin-and-tube heat exchanger 10 is illustrated in which the flat multi-hole tube 14 is assembled in the assembly hole 16 provided in the plate-like fin 12. For example, as shown in FIG. 4, a corrugated fin type fin-and-tube heat exchanger 30 constructed by assembling corrugated (corrugated) fins 24 between flat multi-hole tubes 22, 22. It is also possible.

  Further, the shape of the hole 20 formed in the flat multi-hole tube 14 is the same as the hole height (h) and the length of the lower base (b) in the above embodiment, and the length of the upper base. (A) is an isosceles trapezoidal shape in which the length of the bottom base (b) is ½ and the inner angles of both ends of each base are the same, but the hydraulic diameter: D and the hole If the ratio of height: h (D / h) is a trapezoidal shape within the specified range in the present invention, in addition to the isosceles trapezoid illustrated, the angles of the inner angles at both ends of the base (lower base) Various trapezoidal shapes such as trapezoids having different angles and trapezoids in which the inner angle between the base (lower base) and one leg is a right angle are appropriately selected. Furthermore, in the illustrated trapezoidal shape, each side (base, leg) of the trapezoid is linear, but if D / h satisfies the relationship described above, a circle having a predetermined radius of curvature. It can also be an arcuate side.

  In addition, the inner surface of the hole 20 is a flat surface here, but may be a surface on which minute irregularities (grooves and protrusions) are formed. By forming such irregularities, the contact area between the refrigerant per unit volume and the surface of the hole 20 can be further increased, and the heat transfer coefficient between the refrigerant and the heat transfer tube can be improved more effectively. Become.

  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.

  First, as a heat transfer tube for a fin-and-tube heat exchanger according to the present invention, an aluminum alloy (JIS A3003) is extruded to exhibit a cross-sectional shape as shown in FIG. : Extruded flat multi-hole tube 40 having a thickness of 16 mm, a thickness (H) of 1.9 mm, and a number of holes of 12 was prepared. It was set to 1. Such a heat transfer tube No. The shape of the twelve holes (42) provided in 1 is as follows: upper base (a): 0.6 mm, lower base (b): 1.2 mm, height (h): 1.2 mm (heat transfer tube thickness It was made to be an isosceles trapezoid. Other specifications such as the hydraulic diameter were as shown in Table 1 below. In Table 1 below, the hole height (h) is the hole height in the thickness direction of the flat multi-hole tube (40), and the flow path area is the per-hole in the cross section perpendicular to the axial direction. The cross-sectional area of the hole portion and the wet edge length indicate the length of the side of the hole per hole in the cross section.

  Further, as another example of the heat transfer tube for the fin-and-tube heat exchanger according to the present invention, flat multi-hole tubes 44 and 46 having a cross-sectional shape as shown in FIGS. 5 (b) and 5 (c) are prepared. The heat transfer tube No. 2. Heat transfer tube no. It was set to 3. Here, heat transfer tube no. 2 is an extruded flat multi-hole tube having a width (W): 16 mm, a thickness (H): 1.9 mm, and the number of holes: 20, and the hole shapes thereof are an upper base: 0.1 mm and a lower base: 0.0. 7 mm, height: 1.5 mm (0.79 times the thickness of the heat transfer tube), and a trapezoidal shape with an inner angle of 90 ° between the base (lower base) and one leg. In addition, heat transfer tube No. 3 is an extruded flat multi-hole tube having a width (W): 16 mm, a thickness (H): 1.9 mm, and a number of holes: 14, and the hole shapes thereof are an upper base: 0.4 mm and a lower base: 0.0. 7 mm, height: 1.5 mm, and a trapezoidal shape with an inner angle of 90 ° between the base and one leg. That is, the heat transfer tubes 2 and 3 are flat multi-hole tubes that have the same width (W) and thickness (H) as the heat transfer tubes 1 but differ in the hole shape and the number of holes. The heat transfer tube No. 2 and 3 are heat transfer tube Nos. 1 was produced by extruding an aluminum alloy (JIS A3003). In addition, the heat transfer tube No. The specifications such as the channel area and hydraulic diameter in 2 and 3 are shown in Table 1 below.

  As a heat transfer tube for comparison, a flat multi-hole tube 50 having a quadrangular shape (one side length: 1 mm square) as shown in FIG. 6 (a) and FIG. 6 (b). As shown in the figure, a flat multi-hole tube 52 having a circular hole shape (a circle having a diameter of 1.2 mm) is prepared. 4. Heat transfer tube no. It was set to 5. Further, although the hole shape is a trapezoidal shape, the flat multi-hole tube having a hole shape as shown in FIGS. 7 (a) and 7 (b) assuming that the value of D / h is outside the scope of the present invention. 54 and 56 were prepared. 6. Heat transfer tube no. It was set to 7. Here, heat transfer tube no. The hole shape of No. 6 is: upper base: 0.2 mm, lower base: 0.5 mm, height: 1.5 mm (0.79 times the thickness of the heat transfer tube), and the inner angle between the base and one leg is 90 ° The trapezoidal shape is as follows. In addition, heat transfer tube No. The hole shape of No. 7 is: upper base: 0.8 mm, lower base: 1.2 mm, height: 1.2 mm (0.63 times the heat transfer tube thickness), and the inner angle between the base and one leg is 90 ° The trapezoidal shape is as follows. In addition, those heat exchanger tubes No. 4 to 7, the heat transfer tube No. 1 to 3 are produced by extruding an aluminum alloy (JIS A3003). 1 (width (W): 16 mm, thickness (H): 1.9 mm). However, in terms of the number of holes, the heat transfer tube No. Nos. 4, 5 and 7 have 12 heat transfer tubes. 6 was 18 pieces. In addition, the heat transfer tube No. The specifications such as the channel area and hydraulic diameter in 4 to 7 are shown in Table 1 below.

  Then, using each of the flat multi-hole tubes (heat transfer tubes No. 1 to 7) prepared in this way, a plurality of flat multi-hole tubes (22) are arranged in parallel with each other as shown in FIG. A heat exchanger (30) in which corrugated fins (24) molded into a corrugated shape are joined between flat multi-hole tubes (22, 22) that match each other is referred to as a heat exchanger No. 1, respectively. It produced as 1-7. In this heat exchanger (30), both ends of the arranged flat multi-hole pipes (22) are respectively connected to the header (26), and the respective holes (in the axial direction of the flat multi-hole pipe (22) ( Are formed on the refrigerant inlet side and the outlet side to form a refrigerant flow path. In each heat exchanger (30) manufactured here, the fins (24) are all corrugated processed brazing sheets using JIS A3703 alloy as the core material and JIS A4045 alloy as the skin material. When preparing one heat exchanger, 75 flat multi-hole tubes (24) were used. The fin (24) and the flat multi-hole tube (22) are joined to the fin (24) and the flat multi-hole tube (22) laminated and assembled in the shape of the target heat exchanger (30). The assembly (2) is heated and held at 600 ° C. for 3 minutes in a brazing furnace (the highest temperature reached) for 3 minutes, and then cooled, whereby the fin (24) and the flat multi-hole tube (22) are brazed. It was made to join. The length of the flat multi-hole tube (22) between the headers (26, 26) is 610 mm, and the overall size of the heat exchanger (30) is width: 650 mm and height: 610 mm. I did it.

  Thereafter, the heat exchanger No. prepared in this way. 1-7 were used to perform a unit performance evaluation test of each heat exchanger. In the test method, each heat exchanger is installed in a wind tunnel device provided in a constant temperature and humidity test chamber, and the air temperature in the test chamber (dry bulb: 35 ° C., wet bulb: 24 ° C.), wind speed (1.5 m / s), the refrigerant (R-410A) is subjected to the conditions of heat exchanger inlet temperature: 64 ° C. (SH = 20K), condensing temperature: 44 ° C., heat exchanger outlet temperature: 39 ° C. (SC = 5K). The amount of heat exchange in a state where the heat balance between air and refrigerant was set was measured. The test results for each heat exchanger are shown in Table 2 below. In addition, the test result shown in this Table 2 shows heat exchanger No.2 whose hole shape of a flat multi-hole pipe is a square. It is shown in a ratio to the case where the heat exchange amount of 4 is 100.

  From the above results, the heat exchangers No. 1 having the same flow path area but having different hole shapes formed in the flat multi-hole tube. In contrast of 1, 4 and 5, the heat exchanger No. 1 having a trapezoidal hole shape according to the present invention. No. 1 is a heat exchanger No. 1 having a square hole shape. 4 or circular heat exchanger No. 4 It was confirmed that the condensation performance was greatly improved than 5. Further, the hole shape is a trapezoidal shape, and the ratio of hydraulic diameter: D to hole height: h: D / h is configured using flat multi-hole tubes 40, 44, 46 within the scope of the present invention. Each heat exchanger No. 1, heat exchanger no. 2 and heat exchanger no. No. 3 is a heat exchanger No. 3 in which the hole shape of the flat multi-hole tube is a general square. Compared to 4, an improvement in heat exchange performance of 2% or more was confirmed. On the other hand, although the hole shape is trapezoidal, D / h is outside the scope of the present invention. 6 and 7, heat exchangers No. 6 having a square hole shape (square). The performance was lower than 4, and it was confirmed that the effect of improving the heat transfer coefficient on the refrigerant side in the flat multi-hole tube due to the trapezoidal hole shape was not exhibited effectively.

DESCRIPTION OF SYMBOLS 10 Heat exchanger 12 Fin 14 Flat multi-hole pipe 16 Assembly hole 18 Collar part 20 Hole

Claims (6)

A heat transfer tube for a fin-and-tube heat exchanger to which fins made of aluminum or its alloy are assembled,
Obtained by extrusion of aluminum or its alloys, is constituted by extruded flat multi-hole tubes of flattened cross-sectional shape as a whole, and a large number of trapezoidal cross-sectional shape extending in the axial direction of the tube provided in said extrusion flat multihole pipe the hole, it becomes arranged in parallel to each other at a distance from each other in the width direction, transverse cross-sectional shape of the hole, a trapezoidal internal angle between the lower base and one leg is 90 °, also in the hole the length of the upper base is less than half of the length of the lower base, further the height of the hole is the length of the lower base equal to or greater than, and the thickness of the extruded flat multi-hole tubes 0.5 The ratio of hydraulic diameter: D and the height of the hole: h defined by dividing the cross-sectional area of such a hole by 4 times the sum of the side lengths of the hole. (D / h) is configured to be within a range of 0.40 to 0.85. Over Bed heat exchanger heat transfer tube.   The fin-and-tube heat exchanger according to claim 1, wherein adjacent ones of a plurality of holes provided in the multi-hole tube are arranged in a relationship of trapezoidal cross-sectional shapes that are reversed upside down. Heat transfer tube. The heat transfer tube for a fin-and-tube heat exchanger according to claim 1 or 2, wherein the height of the trapezoidal hole is greater than the length of the bottom of the trapezoidal shape. . A fin-and-tube heat exchanger in which fins made of aluminum or an alloy thereof and an extruded flat multi-hole tube having a flat cross-sectional shape as a whole obtained by extrusion processing of aluminum or an alloy thereof is assembled.
The extruded flat multi-hole tubes, the number of holes in the trapezoidal cross-sectional shape extending in the tube axis direction, and arranged parallel to one another at a distance from each other in the width direction, with is configured, the cross-sectional shape of the hole, the lower a trapezoidal shape internal angle between the bottom and one leg is 90 °, and the length of the upper base of the hole is equal to or less than half of the length of the lower base, yet the height of the hole, the lower the length of the bottom equal to or more and is 0.5 to 0.8 times the thickness of the extruded flat multi-hole tube, and the sum of the lengths of the sides of the hole four times the cross-sectional area of such holes The ratio (D / h) of the hydraulic diameter defined by dividing by D and the height of the hole: h (D / h) is configured to be within a range of 0.40 to 0.85. Fin-and-tube heat exchanger. By using rectangular plate-like fins as the fins, and fitting and fixing the extruded flat multi-hole tube in a slit of a predetermined length provided so as to open at one end of the plate-like fins, The fin-and-tube heat exchanger according to claim 4 , wherein the extruded flat multi-hole tube and the plate-like fin are assembled. As the fin, the use of corrugated fins waveform, and a plurality of said plurality of said corrugated fins extruded flat multi-hole tubes are disposed alternatively, by bonding to each other, according to claim 4 which are assembled Fin-and-tube heat exchanger.

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