JP2011220582A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat exchange performance than before while preventing a hole from being formed by electrolytic corrosion of a tube on the side of refrigerant in a water-refrigerant heat exchanger that uses Cu metal as a base material of a tube on the side of water and Al metal as a base material of the tube on the side of refrigerant.SOLUTION: An Al metal layer 22 is formed on the entire outer surface of a water-side tube 20 the base material 21 of which includes Cu metal, and the Al metal layer 22 of the water-side tube 20 and a refrigerant-side tube 30 the base material 31 of which is Al metal are joined using metal by brazing. Owing to this, both the tubes are joined by the same kind of metal, and therefore, it is possible to prevent the occurrence of electrolytic corrosion caused by the use of different kinds of metal and to prevent a hole from being formed by corrosion of the refrigerant-side tube 30. Further, both the tubes are joined using metal by brazing, and therefore, it is possible to considerably reduce the thermal resistance at the joined part compared to the case where both tubes are contacted mechanically and to improve heat exchange performance.

Description

  The present invention relates to a heat exchanger that performs heat exchange between water and a refrigerant, and a water refrigerant heat exchanger mounted on a heat pump water heater that heats water by exchanging heat between water and a refrigerant. It is suitable for use.

  As disclosed in Patent Document 1, a general water-refrigerant heat exchanger includes tap water as a constituent material of a water-side tube that forms a water channel and a refrigerant-side tube that forms a coolant channel. Cu metal with a proven track record in the environment is used. However, since Cu metal is expensive and difficult to miniaturize, for example, a fine multi-hole tube cannot be formed, and it is difficult to improve the size and performance of the water-refrigerant heat exchanger.

  On the other hand, in the water refrigerant heat exchanger disclosed in Patent Document 2, the water side tube is made of Cu metal and the refrigerant side tube is made of Al metal. According to this, since the refrigerant | coolant side tube is comprised with Al metal cheaper than Cu metal, cost reduction is attained. Furthermore, since Al metal can be refined, it is possible to manufacture micro multi-hole tubes by extrusion processing. By configuring the refrigerant tubes with micro multi-hole tubes, the water refrigerant heat exchanger can be made smaller and more efficient. It becomes possible.

  In the water-refrigerant heat exchanger disclosed in Patent Document 2, a plating layer made of the same metal as the other tube is formed on the outer surface of one tube, and mechanically contacts each other with the plating layer in between. I am letting. This is because when different metals such as Cu metal and Al metal come into contact with each other, the adhesion of the electrolyte solution such as moisture causes corrosion of different metals (electro-corrosion). Therefore, both the contact surfaces are made of the same metal to prevent this electrolytic corrosion. Even when different metals are not in contact, if moisture exists between the different metals, corrosion occurs due to an electrochemical reaction between the different metals.

  Moreover, although it is not a water-refrigerant heat exchanger, the technique which joins Al metal and Cu metal metallicly is disclosed by patent document 3, 4. FIG.

Japanese Patent No. 39548891 Japanese Patent No. 3796172 Japanese Patent Laid-Open No. 2001-87866 JP 2004-1069 A

  However, in the water-refrigerant heat exchanger disclosed in Patent Document 2, since the water-side tube and the refrigerant-side tube are merely mechanically contacted with each other, there is a gap between them, for example. There is a problem in that the heat resistance at is large and the heat exchange performance deteriorates.

  Patent Documents 3 and 4 do not describe prevention of electrolytic corrosion. Even if the joining technique disclosed in Patent Documents 3 and 4 is applied to the water refrigerant heat exchanger disclosed in Patent Document 2, Corrosion may occur in the refrigerant side tube due to the joining between different kinds of metals.

  In view of the above points, the present invention prevents perforation due to corrosion of the refrigerant side tube in the water refrigerant heat exchanger using Cu metal as the base material of the water side tube and Al metal as the base material of the refrigerant side tube. However, it aims at improving heat exchange performance rather than before.

In order to achieve the above object, according to the first aspect of the present invention, one of the water side tube (20) and the refrigerant side tube (30) is disposed on the entire outer surface of the heat exchange site between water and the refrigerant. A metal layer (22, 33) made of the same metal as the base material is formed,
The water side tube (20) and the refrigerant side tube (30) are characterized in that they are metallicly joined by brazing.

  According to this, a metal layer composed of the same metal as the base material of the other tube is formed on the outer surface of one tube, and both tubes are joined between the same type of metal. It is possible to prevent the occurrence of electrolytic corrosion due to different kinds of metals and to prevent perforation due to corrosion of the refrigerant side tube.

  And since both tubes are metallically joined by brazing, compared to the case where both tubes are mechanically contacted, the thermal resistance at the connection point can be significantly reduced, and the heat exchange performance is improved. be able to.

  In the invention described in claim 1, for example, as described in claim 2, the water side tube (20) has an Al metal layer (22) formed on the outer surface thereof, and the Al metal layer (22). The structure joined with the refrigerant | coolant side tube (30) through can be employ | adopted.

  Furthermore, in this case, as a filler material used in brazing, as described in claim 3, the natural potential of the metal constituting the joint between the water side tube and the refrigerant side tube is lower than that of Al metal. It is preferable to use one.

  As a result, even if moisture exists between the outer surface of the refrigerant side tube and the joint, and electric corrosion occurs, the Al metal constituting the refrigerant side tube has a higher natural potential than the metal constituting the joint. The refrigerant side tube can be prevented from corroding.

  Moreover, in invention of Claim 2, 3, as described in Claim 4, Al metal layer (22) is a simultaneous drawing process or simultaneous extrusion process of Cu metal material and Al metal material, Cu metal. It is preferable that the layer and the Al metal layer are formed by metal processing using a clad material in which a layer is bonded in advance or by thermal spraying on the outer surface of the base material. Further, among these, formation by thermal spraying is preferable, and simultaneous drawing processing or simultaneous extrusion processing and metal processing using a clad material are more preferable. This is because the Al metal layer can be formed by plating, but the formation by spraying can suppress the generation of defects compared to the case of forming by plating, and simultaneous drawing, simultaneous extrusion, and cladding. This is because the formation of defects can be further suppressed by forming by metal working using a material. Thereby, the electrolytic corrosion which arises between a base material and Al metal layer by the penetration | invasion of the water | moisture content from a defect part can be suppressed.

  Moreover, in invention of Claim 1, as described in Claim 5, for example, as for the refrigerant | coolant side tube (30), Cu metal layer (33) is formed in the outer surface, Cu metal layer ( The structure joined with the water side tube (20) through 33) is employable.

  Further, in this case, as a filler material used in brazing, as described in claim 6, the natural potential of the metal constituting the joint portion of the water side tube and the refrigerant side tube is lower than that of Cu metal. It is preferable to use one.

  As a result, even if moisture exists between the outer surface of the refrigerant side tube and the joint, and electric corrosion occurs, the Cu metal constituting the outer surface of the refrigerant side tube has a higher natural potential than the metal constituting the joint. Therefore, the refrigerant side tube can be prevented from corroding.

  Moreover, in invention of Claim 5, 6, as described in Claim 7, Cu metal layer (33) is a simultaneous drawing process or simultaneous extrusion process of Cu metal material and Al metal material, Cu metal. It is preferable that the layer and the Al metal layer are formed by metal processing using a clad material in which a layer is bonded in advance or by thermal spraying on the outer surface of the base material. Further, among these, as in the invention described in claim 4, formation by thermal spraying is preferable, and simultaneous drawing processing or simultaneous extrusion processing or metal processing using a clad material is more preferable.

  In the invention according to claim 8, the water side tube (20) and the refrigerant side tube (30) are brazed using a filler material having a melting point lower than the eutectic temperature of Al and Cu. It is characterized by being.

  Thereby, it is possible to prevent the metal layer formed on the outer surface of one of the tubes from melting during brazing.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole lineblock diagram of the heat pump type hot water heater in a 1st embodiment of the present invention. It is a front view of the water refrigerant heat exchanger in FIG. It is the III-III sectional view taken on the line in FIG. It is sectional drawing of the water refrigerant | coolant heat exchanger in 2nd Embodiment. It is sectional drawing of the water refrigerant | coolant heat exchanger in 3rd Embodiment. (A), (b), (c) is the front view of the water-refrigerant heat exchanger in 4th Embodiment, sectional drawing of a water side tube, and sectional drawing of a refrigerant | coolant side tube, respectively. (A), (b), (c) is the front view of the water refrigerant | coolant heat exchanger in the modification of 4th Embodiment, sectional drawing of a water side tube, and sectional drawing of a refrigerant | coolant side tube, respectively. It is sectional drawing of the water refrigerant | coolant heat exchanger in 5th Embodiment. It is sectional drawing of the water refrigerant | coolant heat exchanger in 6th Embodiment. (A), (b), (c) is the front view of the water-refrigerant heat exchanger in 7th Embodiment, sectional drawing of a water side tube, and sectional drawing of a refrigerant | coolant side tube, respectively. (A), (b), (c) is the front view of the water-refrigerant heat exchanger in the modification of 7th Embodiment, sectional drawing of a water side tube, and sectional drawing of a refrigerant | coolant side tube, respectively. (A), (b) is the front view and sectional drawing of the water-refrigerant heat exchanger in other embodiment, respectively.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are given the same reference numerals in the drawings in order to simplify the description.

(First embodiment)
In this embodiment, the heat exchanger according to the present invention is applied to a water-refrigerant heat exchanger of a heat pump type water heater. In FIG. 1, the whole block diagram of the heat pump type water heater in this embodiment is shown.

  As shown in FIG. 1, the heat pump type hot water heater includes a hot water storage tank 10 for storing hot water, a water circulation passage 11 for circulating hot water in the hot water storage tank 10, and a heat pump cycle device 12 for heating the hot water. I have.

  The hot water storage tank 10 is a hot water tank that can retain hot hot water for a long time. Hot water stored in the hot water storage tank 10 is discharged from a hot water outlet 10a provided in the upper part of the hot water storage tank 10 and supplied to a kitchen or a bath. Tap water is replenished from a water supply port 10 b provided in the lower part of the hot water storage tank 10.

  An electric water pump 13 that circulates hot water is disposed in the water circulation passage 11. The hot water is supplied from the hot water outlet 10 c at the lower part of the hot water tank 10 → the electric water pump 13 → the water refrigerant heat exchanger 15 → the hot water tank 10. It flows in the order of the upper hot water supply inlet 10d.

  The heat pump cycle device 12 has an electric compressor 14, a water refrigerant heat exchanger 15, an expansion valve 16, an evaporator 17, and the like sequentially connected by piping, and constitutes a known refrigeration cycle.

  The water-refrigerant heat exchanger 15 has a water flow path 15a through which hot-water supply flows and a refrigerant flow path 15b through which high-temperature and high-pressure refrigerant flows after discharging the electric compressor 14, and high-temperature after discharging hot water and the electric compressor 14 This is a heating heat exchanger that heats hot water by causing heat exchange with a refrigerant.

  Next, a specific structure of the water refrigerant heat exchanger 15 of the present embodiment will be described. FIG. 2 shows a front view of the water-refrigerant heat exchanger 15, and FIG. 3 shows a cross-sectional view taken along line III-III in FIG.

  As shown in FIGS. 2 and 3, the water-refrigerant heat exchanger 15 includes a water-side tube 20 in which a water flow path 15 a is formed, and a refrigerant-side tube 30 in which a refrigerant flow path 15 b is formed. Yes.

  As shown in FIG. 2, the water-refrigerant heat exchanger 15 of the present embodiment has a shape in which a plurality of (two in this example) water-side tubes 20 are spirally wound, and the refrigerant-side tube 30 The water-side tube 20 is spirally wound around.

  Water-side headers 20a are provided at both ends of the water-side tube 20 to distribute water to a plurality of water channels or to collect outflow water from the plurality of water channels. Similarly, a refrigerant side header 30a is provided at both ends of the refrigerant side tube 30 to distribute the refrigerant to a plurality of refrigerant flow paths or to collect refrigerant flowing out from the plurality of refrigerant flow paths.

  The water side tube 20 is made of Cu metal having high corrosion resistance in a tap water environment, and the refrigerant side tube 30 is made of Al metal.

  Specifically, as shown in FIG. 3, the water-side tube 20 is a cylindrical tube having a circular cross section and one water flow path 15a formed inside. The water side tube 20 uses Cu metal as a base material (core material) 21, and an Al metal layer 22 is formed on the outer surface thereof. The base material is a material mainly constituting the tube, and forms at least the inner surface of the tube.

  The Al metal layer 22 is formed on the entire outer surface of the water side tube 20 in the cross section of the water side tube 20, and completely covers the base material 21 made of Cu metal.

  The Al metal layer 22 is formed in a heat exchange part (heat exchange core part) where heat exchange between water and the refrigerant is performed, that is, in a range where the water side tube 20 and the refrigerant side tube 30 are connected. Has been. Note that the Al metal layer 22 may be formed or omitted except for the heat exchange site.

  The water side tube 20 is formed by simultaneous drawing or coextrusion of a Cu metal material and an Al metal material. It should be noted that metal processing such as pressing using a clad material in which a Cu metal layer and an Al metal layer are bonded together in advance, or Al metal is sprayed on the outer surface of a tube formed of Cu metal, The side tube 20 may be formed.

  On the other hand, the refrigerant side tube 30 is a fine multi-hole tube having a flat cross section and having a plurality of refrigerant flow paths 15b formed in one tube. The refrigerant side tube 30 uses Al metal as the base material 31 and is formed by extrusion or drawing of an Al metal material.

  The refrigerant side tube 30 has a sacrificial corrosion layer 32 made of an Al—Zn alloy or the like formed on the outer surface thereof. The sacrificial corrosion layer 32 is formed on the Al tube surface by Zn spraying or the like. The sacrificial corrosion layer 32 is used to prevent the base material 31 from being corroded by making it more easily corroded than the base material 31 of the refrigerant side tube 30, but may be omitted.

  The water side tube 20 and the refrigerant side tube 30 are metallicly joined by brazing. That is, in the state where the water side tube 20 and the refrigerant side tube 30 are in contact with each other, the two are joined by the joint portion 40.

  By the way, “brazing” is a technique for joining base materials using filler metal (brazing material or solder) as described in “Connection / Joint Technology” (Tokyo Denki University Press). means. When joining using a filler material having a melting point of 450 ° C. or higher is called brazing, the filler material at that time is called brazing material, and when joining using a filler material having a melting point of less than 450 ° C. is soldered The filler material at that time is called solder.

  In the present embodiment, as the filler material used for brazing, the melting point is lower than 548 ° C., which is the eutectic temperature of Al and Cu, and the joint portion 40 between the water side tube 20 and the refrigerant side tube 30 is configured. A metal whose natural potential is lower than that of Al metal is used. Examples of such a filler material include Zn metal and Sn metal.

  Here, not the melting point of Al but the temperature lower than the eutectic temperature of Al and Cu is set between the base material 21 of the water side tube 20 and the Al metal layer 22 by heating during brazing. This is because the metal atoms diffuse. Thereby, it is possible to prevent the Al metal layer 22 of the water side tube 20 from being melted during brazing.

  Moreover, if the natural potential of the metal constituting the joint 40 is lower than that of the Al metal, the moisture is assumed to cover the Al metal constituting the base material 31 of the refrigerant side tube 30 and the metal constituting the joint 40. Even if it exists and an electrochemical reaction occurs, it is possible to prevent the joint portion having a low natural potential from corroding and the base material 31 of the refrigerant side tube 30 from corroding. As a result, perforation due to corrosion of the refrigerant side tube 30 can be prevented. In addition, Sn metal alone has a higher natural potential than Al metal, but when Sn solder is brazed using Sn metal as a filler material, Sn and Al diffuse to form a Sn / Al alloy. This Sn / Al alloy has a lower natural potential than Al metal.

  Next, main features of the present embodiment will be described.

  (1) In the water refrigerant heat exchanger 15 of the present embodiment, the water side tube 20 is mainly made of Cu metal, and the refrigerant side tube 30 is made of Al metal which is cheaper than Cu metal. Compared with the case where the tube is made of Cu metal, the cost can be reduced.

  In addition, since Al metal can be refined, it is possible to produce a fine multi-hole tube by extrusion or the like. Here, when the same refrigerant flow rate is allowed to flow through the tube, the flow path of the refrigerant flow path is better when the plurality of refrigerant flow paths are formed than when one refrigerant flow path is formed within the tube. Since the area is reduced, the heat exchange performance between the refrigerant and water is improved. In addition, the size of the entire tube can be reduced by forming a single tube rather than forming a plurality of tubes separately. Therefore, the water-side refrigerant heat exchanger can be reduced in size and performance by configuring the refrigerant side tube 30 with a fine multi-hole tube.

  (2) When Cu metal and Al metal are brought into contact with each other, if an electrolyte solution is present, electrolytic corrosion due to dissimilar metals occurs, and corrosion of Al metal having a low natural potential among both metals occurs.

  On the other hand, in this embodiment, the Al metal layer 22 is formed on the entire outer surface of the water side tube 20 in which the base material 21 is made of Cu metal. And the water side tube 20 is joined to the refrigerant | coolant side tube 30 whose base material 31 is Al metal through this Al metal layer 22. FIG.

  As described above, since the water-side tube 20 and the refrigerant-side tube 30 are joined between the same type of metals, the occurrence of electrolytic corrosion due to the dissimilar metal between the two tubes can be prevented, and holes due to corrosion of the refrigerant-side tube 30 can be prevented. Can prevent perforation.

  When the sacrificial corrosion layer 32 is not formed on the outer surface of the refrigerant side tube 30, the base material (Al metal) 31 of the refrigerant side tube 30 and the Al metal layer 22 of the water side tube 20 are joined. The water side tube 20 and the refrigerant side tube 30 are joined between the same kind of metals. Further, when the sacrificial corrosion layer 32 is formed on the outer surface of the refrigerant side tube 30, the base material (Al metal) 31 of the refrigerant side tube 30 and the Al metal layer of the water side tube 20 are interposed via the sacrificial corrosion layer 32. 22 can be said to be joined between the same kind of metals.

  In addition, when the Cu metal and the Al metal are brazed, a filler material capable of obtaining a good bond with both metals must be selected. Since it is only necessary to select a material, joining by brazing becomes easy.

  Further, unlike the present embodiment, when Cu metal and Al metal are directly joined metallically by brazing, the joining material of the filler material used for brazing is diffused at the joining portion of both by the diffusion of metal atoms. In addition to an alloy of a metal component and Cu or Al, an alloy of Cu and Al (Al / Cu alloy) is formed. Since this Al / Cu alloy is brittle, there is a problem that when the Cu metal and the Al metal are directly joined metallically by brazing, good joining between the tubes cannot be obtained.

  On the other hand, in the present embodiment, Al metal and Al metal are joined metallically by brazing (if the sacrificial corrosion layer 32 is present, the Al metal and Al / Zn alloy are joined), so the joined portion It is possible to prevent the Al / Cu alloy from being formed on 40 and to obtain good bonding between the tubes.

  (3) Since the water refrigerant heat exchanger 15 of this embodiment has joined the water side tube 20 and the refrigerant | coolant side tube 30 metalically by brazing, it is making patent documents 2 which have made both tubes contact mechanically. Compared with the technique described in (1), the thermal resistance at the connection point can be significantly reduced. As a result, the amount of heat conduction between both tubes can be increased, so that the heat exchange performance can be improved.

  (4) By the way, in the water-refrigerant heat exchanger disclosed in Patent Document 2, a plating layer made of the same metal as the other tube is formed on the outer surface of one tube. Generally, the plating layer has many defects, and the base material of the tube is exposed from the plating layer at the defect portion. For this reason, if moisture enters the defective portion, electrolytic corrosion due to dissimilar metals occurs between the base material of the tube and the plating layer.

  On the other hand, in this embodiment, the water side tube 20 is formed by simultaneous drawing process or simultaneous extrusion process of Cu metal material and Al metal material. As a result, the Al metal layer 22 formed on the outer surface of the water side tube 20 has fewer or almost no defects as compared with the plating layer, so the base material 21 of the water side tube 20 and the Al metal layer 22 are not present. It is possible to suppress the occurrence of electrolytic corrosion due to dissimilar metals.

  Even when the water-side tube 20 is formed by metal processing using a clad material in which a Cu metal layer and an Al metal layer are bonded in advance, or when the Al metal layer 22 is formed on the outer surface of the base material by thermal spraying. A similar effect can be obtained. However, for the formation of the Al metal layer 22, the case of performing simultaneous drawing or coextrusion or the case of using a clad material is preferable to thermal spraying. This is because in these cases, generation of defects can be suppressed more than spraying.

  Patent Document 2 describes a water-refrigerant heat exchanger in which a Cu plating layer is formed on the outer surface of a refrigerant-side tube among a water-side tube made of Cu and a refrigerant-side tube made of Al. For this reason, when water permeates into a defective portion of the Cu plating layer, electrolytic corrosion due to a dissimilar metal occurs between the base material (Al metal) of the refrigerant side tube and the Cu plating layer.

  Here, in the dissimilar metal contact corrosion, when the contact area between the cathode side metal and the electrolyte solution is large, the corrosion amount of the anode side metal tends to increase. From this, when the Cu plating layer is formed on the outer surface of the refrigerant side tube, the Cu plating layer located on the outermost surface is the cathode side, and the exposed area of the Cu plating layer is large. As a result, there is a problem that the refrigerant side tube is easily perforated to reach the refrigerant flow path.

  On the other hand, in this embodiment, the Al metal layer 22 is formed on the outer surface of the water side tube 20 among the water side tube 20 and the refrigerant side tube 30. For this reason, even if defects occur in the AL metal layer 22, the surface of the Cu metal on the cathode side is almost covered with the Al metal layer 22, and the exposed area of the Cu metal is small. Less corrosion. Therefore, even if the Al metal layer 22 of the water side tube 20 is corroded, the amount of corrosion is small, and therefore, the refrigerant side tube 30 is hardly corroded, so that the refrigerant side tube 30 reaches the refrigerant flow path. There is no perforation.

(Second Embodiment)
FIG. 4 shows a cross-sectional view of the water refrigerant heat exchanger in the present embodiment. Below, a different point from 1st Embodiment is demonstrated.

  In the present embodiment, in the water side tube 20, the intermediate metal layer 23 is formed between the base material 21 and the Al metal layer 22. The intermediate metal layer 23 is made of a metal different from the base material 21 and the Al metal layer 22. As the metal constituting the intermediate metal layer 23, it is preferable to use a metal having a eutectic temperature with Al higher than the eutectic temperature of Al and Cu (548 ° C.), for example, Fe metal.

  In the present embodiment, as the filler material used for brazing, a material having a melting point lower than the eutectic temperature of the metal constituting the intermediate metal layer 23 and Al is used, but 548 which is the eutectic temperature of Al and Cu. Those having a melting point higher than ° C. can be used.

(Third embodiment)
FIG. 5 shows a cross-sectional view of the water refrigerant heat exchanger in the present embodiment.

  In the first embodiment, the refrigerant side tube 30 is a fine multi-hole tube, but in this embodiment, the refrigerant side tube 30 has an elliptical cross section and one refrigerant channel 15b is formed inside. is there. The refrigerant side tube 30 is composed only of the base material 31.

  On the other hand, the water side tube 20 also has an elliptical cross section and has one water flow path 15a formed therein. The water side tube 20 is formed by the same manufacturing method as in the first embodiment.

  The water refrigerant heat exchanger has a shape in which one water side tube 20 and one refrigerant side tube 30 are arranged in parallel to each other. Thus, the shape of the water side tube 20 and the refrigerant | coolant side tube 30 and the shape of a water refrigerant | coolant heat exchanger can be changed.

  Moreover, in this embodiment, the water side tube 20 and the refrigerant | coolant side tube 30 are metal-joined by brazing, and both joining joins Al metal layer 22 of the water side tube 20 via the junction part 40. And between the Al metal in the refrigerant side tube 30. Thereby, also in this embodiment, the effect similar to 1st Embodiment is acquired.

(Fourth embodiment)
FIG. 6A shows a front view of the water-refrigerant heat exchanger in this embodiment, FIG. 6B shows a cross-sectional view of the water-side tube in FIG. 6A, and FIG. Sectional drawing of the refrigerant | coolant side tube in 6 (a) is shown.

  In the present embodiment, both the water-side tube 20 and the refrigerant-side tube 30 have a circular cross section and are formed as cylindrical tubes in which one flow path 15a, 15b is formed. The refrigerant side tube 30 is spirally wound around the outer surface of the water side tube 20 having a straight shape (straight pipe).

  Also in this embodiment, as shown in FIG. 6B, the water side tube 20 has an Al metal layer 22 formed on the outside of the base material 21. The water side tube 20 is formed by the same manufacturing method as in the first embodiment. As in the first embodiment, the water-side tube 20 and the refrigerant-side tube 30 are metallicly joined by brazing, and the joining of the two is performed by the Al metal layer 22 on the outer surface of the water-side tube 20 and the refrigerant. This is performed between the side tube 30 and the Al metal. Thereby, also in this embodiment, the effect similar to 1st Embodiment is acquired.

  FIGS. 7A, 7B, and 7C are a front view of a water refrigerant heat exchanger, a cross-sectional view of a water-side tube, and a cross-sectional view of a refrigerant-side tube, respectively, in a modification of the present embodiment. . In the water-refrigerant heat exchanger 15 shown in FIG. 6, a cylindrical tube is used as the refrigerant-side tube 30. However, as shown in FIG. 7C, a fine multi-hole tube can be used as the refrigerant-side tube 30.

(Fifth embodiment)
FIG. 8 shows a cross-sectional view of the water refrigerant heat exchanger in the present embodiment. In the water refrigerant heat exchanger 15 of the present embodiment, the water side tube 20 and the refrigerant side tube 30 have the same shape as that shown in FIG. 2 described in the first embodiment, but the water side tube 20 and the refrigerant side. The structure in the cross section of the tube 30 differs from 1st Embodiment. Hereinafter, differences from the first embodiment will be described.

  As shown in FIG. 8, the refrigerant side tube 30 is a fine multi-hole tube as in the first embodiment, but a Cu metal layer 33 is formed on the entire outer surface thereof. The refrigerant side tube 30 uses Al metal as a base material 31. After forming a tube by extrusion or drawing of an Al metal material, a Cu metal layer 33 is formed by thermal spraying or the like.

  On the other hand, the water side tube 20 is comprised only with the base material 21 which consists of Cu metal, and the outer surface is formed with Cu metal.

  And the water side tube 20 and the refrigerant | coolant side tube 30 are metal-joined by brazing via the Cu metal layer 33. FIG. That is, in the state where the water side tube 20 and the refrigerant side tube 30 are in contact with each other, the two are joined by the joint portion 50.

  In the present embodiment, as the filler material used for brazing, the melting point is lower than 548 ° C., which is the eutectic temperature of Al and Cu, and the joint portion 50 between the water side tube 20 and the refrigerant side tube 30 is configured. A metal whose natural potential is lower than that of Cu metal is used. Examples of such a filler material include Zn metal and Sn metal.

  Thereby, it is possible to prevent the Cu metal layer 33 of the refrigerant side tube 30 from being melted at the time of brazing, and it is assumed that moisture is present between the outer surface of the refrigerant side tube 30 and the metal constituting the joint portion 50. Even if there is galvanic corrosion, the joint 50 having a low natural potential is corroded and the refrigerant side tube 30 is not corroded.

  As described above, the water refrigerant heat exchanger 15 of the present embodiment forms the Cu metal layer 33 on the entire outer surface of the refrigerant side tube 30 in which the base material 31 is made of Al metal, and the Cu metal layer of the refrigerant side tube 30. 33 and the water side tube 20 made of Cu metal are joined by brazing.

  As described above, since the water-side tube 20 and the refrigerant-side tube 30 are joined between the same type of metals, the occurrence of electrolytic corrosion due to the dissimilar metal between the two tubes can be prevented, and holes due to corrosion of the refrigerant-side tube 30 can be prevented. Can prevent perforation.

  Moreover, in this embodiment, since the Cu metal layer 33 of the refrigerant side tube 30 is formed by thermal spraying, it is possible to suppress the occurrence of a defective portion and to infiltrate moisture from the defective portion as compared with the case where it is formed by plating. It is possible to suppress the electrolytic corrosion generated between the base material (Al metal) 31 and the Cu metal layer 33 caused by the above.

(Sixth embodiment)
FIG. 9 shows a cross-sectional view of the water refrigerant heat exchanger in the present embodiment.

  In this embodiment, the water refrigerant heat exchanger 15 of the fifth embodiment is changed to the shape of the third embodiment. That is, the refrigerant side tube 30 has an elliptical cross section and has one refrigerant channel 15b formed therein. Similarly, the water-side tube 20 also has an elliptical cross section and a single water channel 15a formed therein.

  For this reason, in this embodiment, the refrigerant | coolant side tube 30 can be formed by simultaneous drawing or a simultaneous extrusion process of Cu metal material and Al metal material. In addition, the metal processing such as press processing using a clad material in which a Cu metal layer and an Al metal layer are pasted together in advance, or spraying Cu metal on the outer surface of a tube formed of Al metal, The side tube 30 may be formed. However, from the viewpoint of suppressing defects generated in the Cu metal layer 33, the case of performing simultaneous drawing or coextrusion or the case of using a clad material is preferable to thermal spraying.

  Moreover, in this embodiment, the water side tube 20 and the refrigerant | coolant side tube 30 are metal-joined by brazing, and both joining is Cu metal which comprises the water side tube 20 via the junction part 50. And the Cu metal layer on the outer surface of the refrigerant side tube 30. Thereby, also in this embodiment, the effect similar to 5th Embodiment is acquired.

(Seventh embodiment)
FIG. 10A shows a front view of the water refrigerant heat exchanger in the present embodiment, FIG. 10B shows a cross-sectional view of the water-side tube in FIG. 10A, and FIG. Sectional drawing of the refrigerant | coolant side tube in 10 (a) is shown.

  In the present embodiment, the water-refrigerant heat exchanger 15 of the fifth embodiment has a shape in which the refrigerant-side tube 30 is spirally wound around the outer surface of the straight water-side tube 20 as in the fourth embodiment. It has been changed.

  Also in this embodiment, as shown in FIG. 10C, the coolant side tube 30 has a Cu metal layer 33 formed on the outside of the base material 31. The refrigerant side tube 30 is formed by the same manufacturing method as in the sixth embodiment. Similarly to the fifth embodiment, the water-side tube 20 and the refrigerant-side tube 30 are metallicly joined by brazing, and the joining of both is performed by the Cu metal of the water-side tube 20 and the refrigerant-side tube 30. This is performed between the Cu metal layer 33 on the outer surface. Thereby, also in this embodiment, the effect similar to 5th Embodiment is acquired.

  Moreover, Fig.11 (a), (b), (c) is the front view of the water refrigerant heat exchanger in the modification of this embodiment, sectional drawing of a water side tube, and sectional drawing of a refrigerant side tube, respectively. . In the water-refrigerant heat exchanger 15 shown in FIG. 10, a cylindrical tube is used as the refrigerant-side tube 30. However, as shown in FIG. A tube can also be used.

(Other embodiments)
(1) The front view and sectional drawing of the water-refrigerant heat exchanger in other embodiment are shown to Fig.12 (a), (b). The water-refrigerant heat exchanger of each of the above-described embodiments can be formed in a serpentine shape as shown in FIG.

  In this water-refrigerant heat exchanger 15, the water-side tube 20 meanders in the up-down direction while being folded back in the left-right direction in FIG. 12A, and the refrigerant-side tube 30 is in the direction perpendicular to the plane of FIG. It snakes up and down while turning up.

  Moreover, as shown in FIG.12 (b), the water side tube 20 is a cylindrical tube with a cylindrical cross section, and Cu metal is used as a base material. The refrigerant side tube 30 is a fine multi-hole tube, and Al metal is used as a base material.

  And the metal layer comprised with the same metal as the other base material is formed in the whole outer surface of one side of both tubes, and both tubes are joined metallic by brazing.

  (2) From the viewpoint of reducing thermal resistance by metallic bonding, in each of the above-described embodiments, the same metal layers 22 and 33 as the other base material are formed on the outer surface of the water-side tube 20 or the refrigerant tube 30. Plating may be used as a technique for this.

  (3) Like each above-mentioned embodiment, if the water side tube 20 and the refrigerant | coolant side tube 30 form the flow path, they can be changed into what kind of shape.

  (4) In each above-mentioned embodiment, although the present invention was applied to the water refrigerant heat exchanger used for a heat pump type hot water heater, the present invention can be applied also to the water refrigerant heat exchanger used for other uses.

DESCRIPTION OF SYMBOLS 15 Water refrigerant | coolant heat exchanger 15a Water flow path 15b Refrigerant flow path 20 Water side tube 21 Base material of water side tube 22 Al metal layer 30 Refrigerant side tube 31 Base material of refrigerant side tube 33 Cu metal layer 40 Joining part 50 Joining part

Claims (8)

A water-side tube (20) in which a Cu channel is used as a base material (21) forming a water flow path (15a) inside and forming an inner surface;
A refrigerant channel (15b) is formed inside, and includes a refrigerant side tube (30) in which Al metal is used as a base material (31) forming an inner surface,
In the heat exchanger (15) for exchanging heat between water and the refrigerant,
One of the water-side tube (20) and the refrigerant-side tube (30) has a metal layer made of the same metal as the other base material on the entire outer surface at the heat exchange site between water and the refrigerant ( 22 and 33) are formed,
The said water side tube (20) and the said refrigerant | coolant side tube (30) are metal-joined by brazing, The heat exchanger characterized by the above-mentioned.   The water side tube (20) has an Al metal layer (22) formed on the outer surface thereof, and is joined to the refrigerant side tube (30) via the Al metal layer (22). The heat exchanger according to claim 1.   The heat exchanger according to claim 2, wherein the metal constituting the joint (40) between the water side tube (20) and the refrigerant side tube (30) has a lower natural potential than Al metal. .   The Al metal layer (22) is formed by simultaneous drawing or coextrusion of a Cu metal material and an Al metal material, metal processing using a clad material in which a Cu metal layer and an Al metal layer are pasted together, or a base material. The heat exchanger according to claim 2 or 3, wherein the heat exchanger is formed by thermal spraying on an outer surface.   The refrigerant side tube (30) has a Cu metal layer (33) formed on the outer surface thereof, and is joined to the water side tube (20) via the Cu metal layer (33). The heat exchanger according to claim 1.   6. The heat exchanger according to claim 5, wherein the metal constituting the joint (50) between the water side tube (20) and the refrigerant side tube (30) has a lower natural potential than Cu metal. .   The Cu metal layer (33) is formed by simultaneous drawing or co-extrusion of a Cu metal material and an Al metal material, metal processing using a clad material in which a Cu metal layer and an Al metal layer are bonded together, or a base material. The heat exchanger according to claim 5 or 6, wherein the heat exchanger is formed by thermal spraying on an outer surface.   The water side tube (20) and the refrigerant side tube (30) are brazed using a filler material having a melting point lower than the eutectic temperature of Al and Cu. Item 8. The heat exchanger according to any one of Items 1 to 7.

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