JP2009121738A - Air-cooled heat exchanger - Google Patents

Abstract

A high-performance air-cooled heat exchanger that can be manufactured by a relatively simple manufacturing process in which the contact thermal resistance between a heat transfer tube and a fin is reduced to the limit.
In an air-cooled heat exchanger in which a heat exchange medium is circulated inside a heat transfer tube, while heat is exchanged between the fins provided outside the heat transfer tube and air circulated outside the heat transfer tube. The heat transfer tube is constituted by an outer surface finned tube 10 in which outer surface fins 14 are integrally formed on the outer peripheral surface of the tube by integral molding, and the outer surface finned tube 10 includes an outer surface fin 14. the ratio of the surface area of the surface (a ₁₎ and the surface area when formed into a smooth form of distribution allowed is inner surface of the heat exchange medium _{(a 0) (a 1 /} a 0) is 10 or more, so as to be 25 or less Configured.
[Selection] Figure 6

Description

  The present invention relates to an air-cooled heat exchanger that performs heat exchange between a heat exchange medium and air, and in particular, air-conditioning equipment such as a home air conditioner, an automobile air conditioner, and a packaged air conditioner, a refrigerator, and a heat pump water heater The present invention relates to an air-cooled heat exchanger of a type that performs heat exchange between air and a refrigerant.

  Conventionally, heat exchangers that operate as evaporators or condensers have been used in air conditioning equipment such as home air conditioners, automotive air conditioners, and packaged air conditioners, and refrigerators. In commercial packaged air conditioners, cross fin tube type heat exchangers as disclosed in Patent Documents 1 and 2 have been most commonly used.

  In recent years, heat exchangers using natural refrigerants with a low global warming coefficient have been developed as heat exchange media in place of conventional chlorofluorocarbon refrigerants from the viewpoint of protecting the ozone layer and preventing global warming. Among them, hot water heaters using refrigerants mainly composed of carbon dioxide gas have been developed, but cross-fin tube type heat exchangers similar to the above are also used for such air heat exchangers. Yes.

  And the cross fin tube which comprises such a cross fin tube type heat exchanger is normally comprised by assembling | attaching the air-side aluminum fin and the heat exchanger medium (refrigerant) side heat exchanger tube integrally. The heat transfer tube has a structure in which a number of grooves, for example, a number of spiral grooves extending so as to extend with a predetermined lead angle with respect to the tube axis are formed on the inner surface thereof. While so-called inner surface grooved heat transfer tubes in which inner fins of a predetermined height are formed between the grooves are often used, aluminum fins on the surface are clearly disclosed in Patent Documents 3, 4, etc. What is formed by machining a shape having a heat transfer promoting effect, such as a slit, a louver, and a cut-and-raised portion, is used.

  In addition, such a cross fin tube type heat exchanger is manufactured as follows by a well-known process. That is, first, an aluminum plate fin in which a plurality of predetermined assembly holes are formed is formed by pressing or the like, and then, after the obtained aluminum plate fins are laminated, they are separately manufactured in the assembly holes. A heat transfer tube will be inserted. As heat transfer tubes, those obtained by subjecting the inner surface to grooving or the like by rolling or the like and subjecting it to regular cutting and hairpin bending must be used. It becomes. After that, the heat transfer tube is expanded and fixed to the aluminum plate fin, and the U-bend tube is brazed at the end of the heat transfer tube opposite to the side subjected to the hairpin bending process. A heat exchanger is manufactured.

  By the way, in order to improve the heat transfer performance of such a cross fin tube type heat exchanger, various efforts have been made so far, and in particular, the heat transfer tube is in the form of a groove formed on its inner surface. By making various improvements, the heat transfer coefficient in the tube is greatly improved. For this reason, for example, when the fins formed between the inner grooves of the heat transfer tube are raised, such fins are used. The more slim the tube is, the greater the problem of reduction of heat transfer coefficient in the tube due to fin deformation such as fin collapse and fin collapse in the assembly and expansion process of heat transfer tubes and aluminum plate fins. .

  For this reason, a proposal for an internally grooved tube (Patent Document 5) that can effectively suppress deformation of the fin, such as collapse of the fin and collapse of the fin during tube expansion, has also been made. However, in such a technique, although the fin deformation suppression effect is exhibited, it is difficult to eliminate the fin deformation, and the problem of fin collapse and fin collapse at the time of hairpin bending is the same, It is becoming difficult to improve the heat transfer coefficient in the tube by further improving the shape of the inner groove.

  On the other hand, it has been recognized that problems with aluminum plate fins often occur particularly in fin pressing and tube expansion processes. In particular, in recent years, thinning of fins has progressed, and in the fin press process that cuts and raises complicated slits and louver patterns, collar skipping, color cracking, burring of cut parts, etc. are likely to occur, and these The occurrence of this causes a problem that the heat transfer coefficient on the air side is lowered, and in the pipe expansion process, the angle from the fin to the root part often changes due to slight fluctuations in the pipe expansion conditions. There is also a problem that the heat transfer performance is lowered due to an increase in the contact thermal resistance between the aluminum plate fin and the heat transfer tube.

  In addition, the conventional cross fin tube type heat exchanger uses two parts, an aluminum plate fin and a heat transfer tube, and there is essentially a contact thermal resistance due to the assembly of these two parts. The underlying problem is inherent.

  As described above, the heat transfer coefficient in the heat transfer tube has been improved, and in the cross fin tube type heat exchanger, in order to improve the total heat exchange performance of the heat exchanger, the heat transfer performance of the aluminum plate fin and the heat transfer tube can be improved. It has become important to further reduce the contact heat resistance of the heat pipe, and therefore, an air-cooled heat exchanger that reduces such contact heat resistance to the limit is desired.

JP 2000-39283 A JP-A-11-190597 JP-A-2-203199 JP-A-11-108575 Japanese Patent Laid-Open No. 2002-90086

  Here, the present invention has been made in the background of such circumstances, the place to be solved is to reduce the contact thermal resistance between the heat transfer tube and the fin to the limit, An object is to provide a high-performance air-cooled heat exchanger that can be manufactured by a relatively simple manufacturing process.

  The present invention can be suitably implemented in various aspects as listed below in order to solve the problems described above or the problems grasped from the description of the entire specification and the drawings. Each aspect described below can be employed in any combination. It should be noted that the aspects or technical features of the present invention are not limited to those described below, and can be recognized based on the description of the entire specification and the inventive concept disclosed in the drawings. Should be understood.

(1) In the air-cooled heat exchanger in which the heat exchange medium is circulated inside the heat transfer tube, while heat is exchanged with the air circulated outside the heat transfer tube in the fin portion provided outside the heat transfer tube. The heat transfer tube is constituted by an outer finned tube in which the fin portion is integrally formed on the outer peripheral surface of the tube by integral molding, and the outer finned tube is formed on the surface area of the outer surface including the fin portion ( a ₁₎ and the ratio of the surface area when formed into a smooth form of distribution allowed is inner surface of the heat exchange medium _{(a 0) (a 1 /} a 0) is 10 or more, so that 25 or less, by being configured An air-cooled heat exchanger.

(2) The air-cooled heat exchanger according to the aspect (1), wherein heat transfer promotion means is provided inside the heat transfer tube.

(3) The air-cooling heat exchanger according to the aspect (2), wherein the heat transfer promoting means is a plurality of grooves formed on the inner surface of the heat transfer tube.

(4) The air-cooling type heat exchanger according to the aspect (2), wherein the heat transfer promotion means is a heat transfer promotion insert inserted and disposed in the heat transfer tube.

(5) The heat transfer tube is curved in a U shape, alternately connecting a plurality of parallel straight tube portions arranged at a predetermined interval and adjacent end portions of the plurality of straight tube portions. The hairpin-shaped tube portion having a smooth outer surface is formed in a meandering shape and in an integral shape, and the outer surface fin is integrally formed only on the outer peripheral surface of the plurality of straight tube portions. The air-cooled heat exchanger according to any one of the above aspects (1) to (4), wherein

(6) A plurality of straight pipe portions parallel to each other arranged at a predetermined interval and adjacent ends of the plurality of straight pipe portions are alternately connected, and the plurality of straight pipe portions are connected in series. The above-described aspects (1) to (5), wherein the straight pipe part and the header pipe part are each constituted by the pipe with the outer surface fin. The air-cooled heat exchanger according to any one of the above.

(7) The air-cooled heat exchanger according to any one of the above aspects (1) to (6), wherein the heat transfer tube is made of a material made of aluminum or an aluminum alloy.

(8) The air-cooled heat exchanger according to any one of the above aspects (1) to (6), wherein the heat transfer tube is made of a material made of copper or a copper alloy.

(9) The air-cooled heat exchanger according to any one of the above aspects (1) to (8), wherein the outer fins of the tube with outer fins are formed in a spiral shape by rolling.

(10) An air inlet portion is formed at one opening end of the rectangular rectangular tube and an air outlet portion is formed at the other opening end so that air to be heat-exchanged is circulated inside. The air-cooled heat according to any one of the above aspects (1) to (9), wherein the heat transfer tube is accommodated in an internal space of the shell. Exchanger.

  According to the configuration of the air-cooled heat exchanger according to the present invention as described above, a tube with an outer fin, in which fins are integrally formed on the outer peripheral surface, is used as a heat transfer tube, and is a main component of the heat exchanger. The contact heat resistance between the heat transfer tube and the fins provided on the outer peripheral surface, which has been a problem in the conventional cross fin tube type heat exchanger, becomes zero, which greatly improves the heat exchange performance. In addition to being able to improve, the surface area of the tube outer surface including the fin is configured to be 10 times or more of the surface area of the tube inner surface in the tube with the outer fin through which the heat exchange medium is circulated. Because the air-side heat transfer area is sufficiently large, the air-side heat exchange performance can be kept high, as with conventional cross-fin tube heat exchangers. It has a feature.

  Moreover, in such an air-cooled heat exchanger, the tube with the outer fins to be used is integrally formed, so that it is inevitably adopted in the manufacturing process of the conventional cross fin tube type heat exchanger. In other words, the tube expansion process for integrating the heat transfer tubes and the plate fins is completely unnecessary, and the omission of such a tube expansion process can simplify the manufacturing process, thus contributing only to cost reduction. In particular, when an internally grooved tube with grooves formed on the inner surface is used, the heat transfer coefficient in the tube is reduced due to deformation of the fin, such as fin collapse or fin collapse of the inner surface fin caused by the tube expansion process. The problem can be solved ugly.

  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 partially shows an outer finned tube 10 as a heat transfer tube used in an air-cooled heat exchanger according to the present invention in the form of a perspective view, and FIG. Such an externally finned tube 10 is partially shown in a longitudinal cross-sectional configuration having a cross section parallel to the tube axis direction. In these drawings, the tube 10 with the outer surface fin is constituted by an integrally molded product in which a spiral outer surface fin 14 is integrally formed on the outer peripheral surface of the tube portion 12 having a smooth tube inner surface. A heat exchange medium is circulated in the tube portion 12, while air is circulated between the outer surface fins 14 on the outer surface of the tube, so that the heat of the heat exchange medium contacts the outer surface fins 14. Is released to the air side.

  Further, the outer finned tube 10 is formed by using a known material as a heat transfer tube, in particular, a metal material having good thermal conductivity and workability such as aluminum, copper, and alloys thereof. The outer fins 14 are easily integrated with the outer peripheral surface of such a metal tube in accordance with various known processing methods, preferably using a rolling method. Will be formed.

  And the pipe 10 with an external fin in which such external fins 14 are integrally formed is simply composed of one kind of metal material having excellent recyclability, and its life cycle. Costs can be effectively reduced, and it is superior to conventional heat exchangers with a two-part assembly structure consisting of copper pipes and aluminum plate fins from the viewpoint of environmental impact. It will be a thing. Moreover, in the case of the conventional cross fin tube type heat exchanger, there is a problem of crushing grooves and fins provided on the inner surface in the tube expansion process, and this problem is further transmitted. When using a metal material with good workability, such as aluminum, copper, or an alloy thereof, as the material of the heat tube, it became more prominent, but with an integrally formed outer fin as described above By using the tube 10, such a problem does not occur at all.

Further, in the tube 10 with the outer surface fin, the surface area (A ₁ ) of the outer surface including the outer surface fin 14 and the smooth inner surface of the tube portion 12 in which the predetermined heat exchange medium is circulated. The ratio (A ₁ / A ₀ ) to the surface area (A ₀ ) is 10 or more and 25 or less. Here, when such a ratio (A ₁ / A ₀ ) is set to 10 or more, the heat transfer area on the air side that can be circulated through the exterior finned tube 10 is sufficiently increased. Therefore, the heat exchange performance on the air side can be kept high as in the conventional cross fin tube type heat exchanger. When the ratio (A ₁ / A ₀ ) is less than 10, heat exchange from the heat exchange medium circulated through the tube portion 12 of the outer finned tube 10 to the outside air can be effectively performed. The heat exchange capacity cannot be fully exhibited, and if the ratio (A ₁ / A ₀ ) exceeds 25, it is difficult to integrally form the target outer finned tube 10. Therefore, in the case of manufacturing relatively easily and at a low cost, in the present invention, the ratio (A ₁ / A ₀ ) is set to 25 or less.

In particular, in such a tube 10 with an external fin, the value of the ratio (A ₁ / A ₀ ) is set to 25 by increasing the fin height of the external fin 14 or decreasing the fin pitch. In addition, not only is it difficult to manufacture the fin, but if the fin height is too high, heat conduction to the tip of the fin is not sufficient, and the heat dissipation performance is good for the increase in fin surface area. In other words, there is a problem that the fin efficiency is deteriorated. Further, when the fin pitch is too small, there is a problem that a blockage due to frost formation is easily caused.

In addition, in this pipe 10 with an outer surface fin, the outer diameter of the pipe including the outer surface fin 14 integrally formed on the outer surface of the tube portion 12: Do, the inner diameter of the pipe: Di, the height of the outer surface fin 14: h, the outer surface The distance (pitch) between the fins 14 and the outer fins 14 is p, the average thickness of the outer fins 14 is tf, and the thickness (bottom thickness) of the tube portion 12 in the portion without the outer fins 14 is t. In order to satisfy the condition of the ratio (A ₁ / A ₀ ) and to achieve the object of the present invention advantageously, it is selected appropriately, but particularly preferably, Do = 6 to 30 mm, Di = 1-10 mm, h = 1-10 mm, p = 1.0-3.0 mm, tf = 0.1-1.0 mm, and t = 0.1-1.0 mm. desirable.

Here, the surface area (A ₁ ) of the tube outer surface including the outer fins 14 is the smooth portion (A) of the tube outer surface, the tip (B) of the outer fin 14, and the side surface (C) of the outer fin 14. It is the sum of all surface areas, and is represented by the surface area per unit length of the outer finned tube 10 as a heat transfer tube. Further, the surface area (A ₀ ) when the inner surface of the tube through which the heat exchange medium is circulated is made smooth is that the inner surface of the tube portion 12 of the tube 10 with the fins on the outer surface is smooth as shown in FIG. In the case of the inner surface, it is the surface area itself of the inner surface of the tube, and as will be described later, a predetermined heat transfer promoting means (see FIGS. 3 and 4) is provided in the tube of the tube portion 12. Does not consider the surface area of such heat transfer promoting means, and is expressed by the inner surface area of the inner surface smooth tube having the same inner diameter as Di, in the form excluding such heat transfer promoting means. is there.

  By the way, in the tube 10 with the outer fin used in the air-cooled heat exchanger according to the present invention, heat transfer promotion means is provided inside the tube for the purpose of promoting heat transfer on the heat exchange medium side that is circulated in the tube. The configuration will also be advantageously employed. As such heat transfer promoting means, for example, as shown in FIG. 3, a spiral groove 16 similar to a conventional inner surface grooved tube is formed on the outer surface finned tube 10 itself, and the groove In addition to the structure in which the portion located between 16 is formed as an inner fin 18 having a predetermined height, a known heat transfer promoting insert such as a twisted tape 20 is inserted into the tube portion 12 as shown in FIG. Various conventionally known structures such as a caulking structure will be appropriately employed.

  Moreover, in the air-cooled heat exchanger according to the present invention, a plurality of straight pipe portions arranged at a predetermined interval and parallel to each other, and adjacent ends of the straight pipe portions are alternately connected, U It is formed in a meandering shape and an integral shape from a hairpin-shaped tube portion that is curved in a letter shape and has a smooth outer surface, and the outer fin is integrated only on the outer peripheral surface of the plurality of straight tube portions The heat transfer tube having the structure formed in Fig. 5 is also advantageously used, and an example thereof is shown in Fig. 5. The eight straight pipe portions 22 are arranged in parallel to each other on the same plane, and adjacent straight pipe portions 22 are alternately arranged at both ends so that they are connected in series. The outer fins 26 of a predetermined height are integrally formed in a spiral shape on the outer peripheral surface of each straight tube portion 22, and are connected to the target transmission. A heat pipe is constructed. In addition, in that, the integral structure part of the straight pipe part 22 and the outer surface fin 26 is set as the structure corresponded to the tube 10 with an outer surface fin shown by FIG.

  In the heat transfer tube having such a structure, since the straight tube portion 22 and the hairpin-shaped portion 24 are integrally formed, there is no brazed joint as in a conventional cross fin tube heat exchanger. Therefore, the problem that the effect of improving the heat transfer performance due to the increase in the area of the outer peripheral surface of the heat transfer tube is obstructed is also effectively eliminated, and the problem that the heat exchange efficiency is reduced is also advantageously avoided. It was possible to do it. Furthermore, since the outer surface fins 26 in each straight tube portion 22 are configured as independent fins, a large number of heat transfer tubes are provided on one fin as in a conventional cross fin tube heat exchanger. Problems in the inserted structure can also be advantageously avoided. That is, in the conventional cross fin tube type heat exchanger, since a large number of heat transfer tubes are inserted into one fin, the temperature of the heat exchange medium is different between the upstream side and the downstream side of the heat transfer tubes, The problem is that heat is transferred from the high temperature side to the low temperature side through the fins, and heat is difficult to transfer from the heat exchange medium to the air side. However, in the structure shown in FIG. Is never evoked.

  When forming a heat transfer tube in which the locations (22) where the outer fins (26) are formed and the locations (24) where they are not formed are alternately provided, such as the heat transfer tube shown in FIG. For example, for a tubular body (material) having a straight tubular outer peripheral surface smoothed, a predetermined rolling process is performed only at a necessary portion, and the outer fin (26) is partially formed. In addition to the method of bending the portion not provided with the outer fin (26) into a hairpin shape, a heat transfer tube in which the outer fin is formed by rolling over the entire length of the tube (material), When bending into a meandering shape, the outer fin of the portion that becomes the hairpin-shaped tube portion 24 is scraped off by cutting and the outer peripheral surface is smoothed, and the portion where the outer fin is formed and the portion where it is not formed And alternate Method for forming a heat pipe or the like, various known methods can be adopted.

  Further, in the air-cooled heat exchanger according to the present invention, as shown in FIG. 6, a plurality of outer finned tubes 10 are arranged parallel to each other on one plane, and the tube ends on both sides thereof are alternately arranged on the header. It is also possible to employ a heat transfer tube structure having a structure in which the plurality of tubes 10 with external fins are connected in series by being connected by the tube 30. In addition, the header pipe | tube 30 is integrally formed with the outer surface fin 32 by the integral molding on the outer surface similarly to the pipe | tube 10 with an outer surface fin.

  In this way, by arranging the heat transfer tubes (tubes 10 with outer fins) as densely as possible, fins that contribute to heat transfer on the air side compared to the case of a conventional cross fin tube type heat exchanger. In addition, it is possible to make a heat exchanger that does not significantly reduce the area of the heat exchanger, and in addition, the contribution of the contact thermal resistance reduction part between the fin and the heat transfer tube improves the total heat exchange performance Can be achieved. In particular, here, the header pipe 30 is also integrally provided with the outer fins 32 to form a pipe structure with outer fins, so that the conventional cross fin tube type heat exchanger does not contribute to the heat exchanger. The heat exchange at the part can also be effectively utilized, and thereby the heat exchange performance can be further improved.

  Note that the air-cooled heat exchanger shown in FIG. 6 employs a structure in which the heat transfer tubes are arranged in one stage, but a structure in which such heat transfer tubes are arranged in a plurality of stages can also be adopted. For example, in the case of adopting a two-stage arrangement in the thickness direction of the heat exchanger, as shown in FIG. 7, the upper heat transfer tube 34 and the lower heat transfer tube 36 are provided as a heat exchanger. It is desirable that the center positions of the heat transfer tubes in the width direction be shifted by 1/2 pitch, and thereby the arrangement intervals of the heat transfer tubes 34 and 36 at the upper and lower stages are made closer. It is possible.

  Furthermore, in the present invention, the above-described heat transfer tube can be accommodated in the internal space of a predetermined box-shaped shell to constitute a target air-cooled heat exchanger. In this case, the box-shaped shell is generally formed with an air inlet portion formed at one opening end of the rectangular rectangular tube and an air outlet portion formed at the other opening end. The air to be heat exchanged is made to circulate.

  In FIG. 8 showing an example of the air-cooled heat exchanger having such a configuration, a heat transfer tube having an externally finned tube structure integrally formed as shown in FIG. 5 is formed in the internal space of the shell 40 having a rectangular box shape. Is provided on the outer surface of the heat transfer tube 42 by forcibly feeding air into the box-shaped shell 40 from one open end thereof. An air outlet provided at the other open end of the shell 40 is capable of efficiently exchanging heat between the heat exchange medium flowing through the heat transfer tube 42 and the air flowing through the shell 40 via the outer fins 26. The heat exchanged air is taken out from the section.

  In this way, in the air-cooled heat exchanger provided with the box-shaped shell 40 as described above, the heat exchange efficiency is further improved by allowing the cooling water to flow through the shell 40 as necessary. Since it is possible to operate as a water-cooled heat exchanger, it is also possible to configure so that the operation can be switched when necessary. And when it is set as the structure which can be drive | operated also as such a water cooling type heat exchanger, water will distribute | circulate inside the shell 40, Shell inner surface and outer surface fin which are the parts which contact this water The outer surface of the attached tube is preferably made of copper or a copper alloy having good corrosion resistance against water, and if necessary, tin plating is applied to the surface of the copper or copper alloy material in contact with the water. It is desirable to apply and further improve the corrosion resistance.

  Moreover, about the form of arrangement | positioning of the heat exchanger tube (tube with an outer surface fin) in the internal space of this box-shaped shell 40, the direction where the outer surface fin 26 extends from the straight tube part 22 which is a heat exchanger tube main body, ie, It is desirable to configure the straight pipe portion 22 so that the direction perpendicular to the pipe length direction substantially coincides with the direction of the fluid flow that flows through the inside of the shell 40, and this arrangement reduces the resistance to the fluid flow. The pressure loss can be reduced.

  As described above, the representative embodiments of the present invention have been described in detail. However, the embodiments are merely examples, and the present invention is not limited to specific descriptions according to such embodiments. It should be understood that this is not to be construed as limiting. The present invention is implemented in an embodiment to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art, and such an embodiment does not depart from the spirit of the present invention. Needless to say, all belong to the category of the present invention.

  In the following, one of the representative embodiments of the present invention will be shown to further clarify the features of the present invention. However, the present invention is not limited by the description of such embodiments. It should be understood that they are not subject to

First, as a heat transfer tube used as a refrigerant (heat exchange medium) side flow path constituting the air-cooled heat exchanger according to the present invention, the dimensions shown in FIG. 2 are Do = 21 mm, Di = 6 mm, h = 7 mm, p = 1.6 mm, t = 0.5 mm, tf = 0.5 mm, tube outer diameter of the tube part 12 without the outer fin 14 = 7 mm, A ₁ = 0.428 mm ² / m, A ₀ = 0.019 mm ² / m , A ₁ / A ₀ = 22.5 A heat transfer tube having a configuration as shown in FIG. 5 was manufactured by a known rolling process. As the material, phosphorus deoxidized copper (JIS-H-3300-C1220) was used.

  In this manufactured heat transfer tube (heat exchanger), the fins (straight tube portions) are arranged in one row and eight rows so that the fins (straight tube portions) are parallel to each other so that the distance (A) between the tips of the outer fins is 1 mm. On the other hand, the fin forming portion (straight tube portion) has 71 fins and its width (in FIG. 5 (a), the width in the horizontal direction in which the fin is formed) is 112 mm, and the length (FIG. 5 ( In a), the length in the vertical direction was set to 175 mm.

  On the other hand, a conventional cross fin tube heat exchanger was manufactured as a comparative example. Phosphorus deoxidized copper is used as the heat transfer tube material, and a heat transfer tube outer diameter = 7 mm, inner diameter = 6 mm, and wall thickness = 0.5 mm are used as bare tubes, while the fins are made of pure aluminum and the plate pressure = The number of fins was set to 1.6 mm and 71 pieces as described above.

  Then, using the two heat exchangers (heat transfer tubes) prepared as described above, the heat transfer performance was evaluated by a numerical fluid simulation. In the heat exchanger according to the present invention, the heat transfer performance was that of a comparative example. On the other hand, it was confirmed that the amount of heat transfer increased by 25% due to the reduction of contact thermal resistance, etc., despite the fact that the heat transfer area of the fins was reduced.

It is an isometric view explanatory drawing which shows an example of the pipe | tube with an outer surface fin used for the air-cooling type heat exchanger according to this invention. It is explanatory drawing which shows a part of longitudinal section of the pipe with an outer surface fin shown by FIG. It is a section explanatory view corresponding to Drawing 2 showing other examples of a pipe with an external fin used for an air cooling type heat exchanger according to the present invention. It is a section explanatory view corresponding to Drawing 2 showing another example of a pipe with an external fin used for an air cooling type heat exchanger according to the present invention. The example from which the heat exchanger tube used for the air-cooling type heat exchanger according to this invention differs is shown, Comprising: (a) is the plane explanatory drawing, (b) is the right side explanatory drawing. It is explanatory drawing which shows another example of the arrangement | positioning form of the heat exchanger tube used for the air-cooling type heat exchanger according to this invention, Comprising: (a) is the front explanatory drawing, (b) is the plane explanatory drawing, (c) is CC sectional explanatory drawing in (b). FIG. 7 is a cross-sectional explanatory view corresponding to FIG. 6C, although the heat transfer tube arrangement structure shown in FIG. In another different example of the air-cooled heat exchanger according to the present invention, it is an explanatory view showing a state in which a part of the shell is cut away, wherein (a) is a plan view, and (b) is a back surface. Each is shown in the form of a figure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tube with outer surface fin 12 Tube part 14, 26, 32 Outer surface fin 16 Groove 18 Inner surface fin 20 Torsion tape 22 Straight pipe part 24 Hairpin shape pipe part 30 Header pipe 34, 36 Heat transfer pipe 40 Shell

Claims (10)

In the air-cooled heat exchanger in which the heat exchange medium is circulated inside the heat transfer tube, while heat exchange is performed between the air that is circulated outside the heat transfer tube in the fin portion provided outside the heat transfer tube.
The heat transfer tube is constituted by an outer finned tube in which the fin portion is integrally formed on the outer peripheral surface of the tube by integral molding, and the outer finned tube is formed on the surface area of the outer surface including the fin portion ( a ₁₎ and the ratio of the surface area when formed into a smooth form of distribution allowed is inner surface of the heat exchange medium _{(a 0) (a 1 /} a 0) is 10 or more, so that 25 or less, by being configured An air-cooled heat exchanger.   The air-cooled heat exchanger according to claim 1, wherein heat transfer promoting means is provided inside the heat transfer tube.   The air-cooled heat exchanger according to claim 2, wherein the heat transfer promoting means is a plurality of grooves formed on an inner surface of the heat transfer tube.   The air-cooled heat exchanger according to claim 2, wherein the heat transfer promoting means is a heat transfer promoting insert inserted and disposed in the heat transfer tube.   The heat transfer tubes are curved in a U shape, alternately connecting a plurality of parallel straight tube portions arranged at a predetermined interval and adjacent ends of the plurality of straight tube portions. The outer surface fin is formed integrally with the meandering shape from the hairpin-shaped tube portion having a smooth outer surface, and only on the outer peripheral surface of the plurality of straight tube portions. The air-cooled heat exchanger according to any one of claims 1 to 4, wherein the air-cooled heat exchanger is characterized.   A plurality of straight pipe parts arranged in parallel with each other at a predetermined interval and headers that connect the adjacent ends of the plurality of straight pipe parts alternately and connect the plurality of straight pipe parts in series. 6. The pipe according to any one of claims 1 to 5, wherein the straight pipe part and the header pipe part are each constituted by the pipe with the outer surface fin. The air-cooled heat exchanger described.   The air-cooling heat exchanger according to any one of claims 1 to 6, wherein the heat transfer tube is made of a material made of aluminum or an aluminum alloy.   The air-cooled heat exchanger according to any one of claims 1 to 6, wherein the heat transfer tube is made of a material made of copper or a copper alloy.   The air-cooled heat exchanger according to any one of claims 1 to 8, wherein the outer surface fin of the tube with the outer surface fin is formed in a spiral shape by rolling.   Box body in which an air inlet portion is formed at one of the opposed opening ends of the rectangular rectangular tube shape and an air outlet portion is formed at the other opening end so that air to be heat-exchanged is circulated inside. The air-cooled heat exchanger according to any one of claims 1 to 9, wherein the heat transfer tube is housed in an inner space of the shell.

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