JP2012002422A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat exchanger that shows high corrosion resistance under a water service environment, and is inexpensive and lightweight as compared with a heat exchanger having an inner pipe and an outer pipe both composed of only Cu metal.SOLUTION: The heat exchanger includes: a first heat transfer tube 20 serving as an outer pipe where water flows, and a second heat transfer tube 30 disposed inside the first heat transfer tube 20 and serving as an inner tube where a refrigerant flows. The heat exchanger is a double tube type heat exchanger that exchanges heat between the water and the refrigerant. The double tube type heat exchanger is configured such that at least one of the first heat transfer tube 20 and the second heat transfer tube 30 is Al metal tube 21, 31 whose base material is composed of Al metal, and Cu metal layers 22, 32 are formed on the whole surface which is to be in contact with water.

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 a conventional water-refrigerant heat exchanger, there is a double-tube type heat exchanger in which an inner tube is arranged inside an outer tube (see, for example, Patent Documents 1 and 2). And in such a double pipe type heat exchanger, from the viewpoint of ensuring heat conductivity and corrosion resistance under a water supply environment, it is common that both the inner pipe and the outer pipe are made of Cu metal.

Japanese Patent No. 3922214 Japanese Patent No. 4200323

  However, since Cu metal has a high material cost and is heavy, a heat exchanger in which both the inner tube and the outer tube are made of Cu metal has a problem that the cost is high and heavy.

  In view of the above points, the present invention provides an inexpensive and lightweight heat exchanger as compared with the case where both the inner tube and the outer tube are made of only Cu metal while having high corrosion resistance under a water supply environment. For the purpose.

  In order to achieve the above object, according to the first aspect of the present invention, the first heat transfer tube (20) through which one of water and refrigerant flows and the other of water and refrigerant are disposed inside the first heat transfer tube (20). In a double-tube type heat exchanger that exchanges heat between water and refrigerant, at least of the first heat transfer tube (20) and the second heat transfer tube (30). One is characterized in that the base metal is an Al metal pipe (21, 31) made of Al metal, and a Cu metal layer (22, 32) is formed over the entire surface in contact with water.

  According to this, at least one of the first and second heat transfer tubes is made of Al metal, which has a material cost lower than that of Cu metal and is light, and a Cu metal layer having high corrosion resistance is formed over the entire surface in contact with water. An inexpensive and lightweight heat exchanger can be provided as compared with the case where both the first and second heat transfer tubes are made of only Cu metal while having high corrosion resistance in a water supply environment.

  In invention of Claim 2, in the invention of Claim 1, water flows through the first heat transfer tube (20), the refrigerant flows through the second heat transfer tube (30), and the first heat transfer tube ( 20) is an Al metal tube (21) whose base material is made of Al metal, and a Cu metal layer (22) is formed over the entire inner surface in contact with water, and the second heat transfer tube (30) is The base metal is an Al metal pipe (31) made of Al metal, and a Cu metal layer (32) is formed over the entire outer surface in contact with water.

  According to this, both the first and second heat transfer tubes are made of Al metal, which is cheaper than Cu metal and has a lighter material cost, and a Cu metal layer having high corrosion resistance is formed over the entire surface in contact with water. Compared to the case where both the first and second heat transfer tubes are made of only Cu metal, it is possible to provide an inexpensive and lightweight heat exchanger while having high corrosion resistance under the environment.

  In invention of Claim 3, in the invention of Claim 1, water flows through the first heat transfer tube (20), the refrigerant flows through the second heat transfer tube (30), and the first heat transfer tube ( 20) is a Cu metal tube (23) whose base material is made of Cu metal, and the second heat transfer tube (30) is an Al metal tube (31) whose base material is made of Al metal, A Cu metal layer (32) is formed over the entire outer surface in contact with water.

  According to this, the second heat transfer tube is made of Al metal, which is cheaper than Cu metal and has a lighter material, and a Cu metal layer with high corrosion resistance is formed over the entire surface in contact with water. Compared to the case where both the first and second heat transfer tubes are made of only Cu metal, an inexpensive and lightweight heat exchanger can be provided.

  In invention of Claim 4, in invention of Claim 1, a refrigerant | coolant flows through the 1st heat exchanger tube (20), water flows through the 2nd heat exchanger tube (30), and the 1st heat exchanger tube ( 20) is an Al metal tube (21) whose base material is made of Al metal, and the second heat transfer tube (30) is an Al metal tube (31) whose base material is made of Al metal, A Cu metal layer (32) is formed over the entire inner surface in contact with water.

  According to this, both the first and second heat transfer tubes are made of Al metal, which is cheaper than Cu metal and has a lighter material cost, and a Cu metal layer having high corrosion resistance is formed over the entire surface in contact with water. Compared to the case where both the first and second heat transfer tubes are made of only Cu metal, it is possible to provide an inexpensive and lightweight heat exchanger while having high corrosion resistance under the environment.

  According to a fifth aspect of the present invention, in the second, third, and fourth aspects of the invention, the second heat transfer tube (30) is a multi-hole tube (31) having a plurality of flow paths therein. It is said.

  Here, since Cu metal is difficult to finely process, it was difficult to manufacture a multi-hole tube with Cu metal. However, by forming the second heat transfer tube with Al metal that is easy to finely process, A multi-hole tube can be manufactured as the two heat transfer tubes. Thereby, compared with the case where a 2nd heat exchanger tube is comprised with Cu metal, the miniaturization and performance improvement of a heat exchanger is attained.

  In invention of Claim 6, the 1st heat exchanger tube (20) and the 2nd heat exchanger tube (30) are connected with the joint (40) for connecting with water piping and refrigerant piping, and it is made of Al and Cu. A Cu metal layer (22, 32) is brazed to the joint (40) using a filler material (43) having a melting point lower than the eutectic temperature.

  Thus, by brazing the Cu metal layer with the joint, it is possible to prevent the Al metal from being exposed to water and to ensure high corrosion resistance. Further, by using a filler material having a melting point lower than the eutectic temperature of Al and Cu, the Cu metal layer can be prevented 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 a longitudinal cross-sectional view of the coupling 40 in 1st Embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in a 2nd embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in a 3rd embodiment. It is a cross-sectional view of the 1st, 2nd heat exchanger tubes 20 and 30 in 4th Embodiment. It is a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the fifth embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in a 6th embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in a 7th embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in an 8th embodiment. It is a transverse cross section of the 1st and 2nd heat exchanger tubes 20 and 30 in a 9th embodiment. It is a longitudinal cross-sectional view of the coupling 40 in other embodiment.

  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 is of a double tube type, and specifically, a first heat transfer tube (outer tube) 20 disposed on the outside, and a first heat transfer tube. The second heat transfer tube (inner tube) 30 disposed inside the heat tube 20 is provided, and the first heat transfer tube 20 is spirally wound. The first heat transfer tube 20 constitutes the water flow path 15a, the second heat transfer tube 30 constitutes the refrigerant flow path 15b, and water flows inside the first heat transfer pipe 20 and outside the second heat transfer pipe 30. As the refrigerant flows through the second heat transfer tube 30, water and the refrigerant exchange heat through the second heat transfer tube 30.

  As shown in FIG. 3, the first heat transfer tube 20 and the second heat transfer tube 30 are both cylindrical tubes having a circular cross section, and one second heat transfer tube 30 is concentrically inside the first heat transfer tube 20. Has been placed.

  The first heat transfer tube 20 is an Al metal tube 21 whose base material is made of Al metal, and a Cu metal layer 22 is formed over the entire inner surface in contact with water. The second heat transfer tube 30 is an Al metal tube 31 whose base material is made of Al metal, and a Cu metal layer 32 is formed over the entire outer surface in contact with water.

  In the present embodiment, both of the Al metal tubes 21 and 31 are made of only Al metal. As long as the base metal is made of Al metal, the Al metal tubes 21 and 31 may have other metal layers or oxide films formed on the surface of the base metal. Incidentally, the base material as used in this specification means the main material which occupies half or more by weight ratio.

  The Cu metal layers 22 and 32 are formed by simultaneous drawing or coextrusion of a Cu metal material and an Al metal material. Note that the Cu metal layers 22 and 32 may be formed by metal processing using a clad material in which a Cu metal layer and an Al metal layer are bonded in advance, a plating method, or a thermal spraying method.

  Thus, in the present embodiment, both the first heat transfer tube 20 and the second heat transfer tube 30 are made of Al metal, which has a material cost lower than that of Cu metal and is light, and Cu metal having high corrosion resistance over the entire surface in contact with water. Layers 22 and 32 are formed. Thereby, compared with the case where both the 1st heat exchanger tube 20 and the 2nd heat exchanger tube 30 are comprised only with Cu metal, it can provide a cheap and lightweight heat exchanger, having high corrosion resistance in water supply environment. .

  Moreover, the 1st heat exchanger tube 20 and the 2nd heat exchanger tube 30 are connected with the joint (joint) 40 for connecting with water piping and refrigerant | coolant piping in the front end side. Here, FIG. 4 shows a longitudinal sectional view of the joint 40.

  The joint 40 is made of Cu metal or brass, and includes a first connection portion 41 connected to the first heat transfer tube 20 and a second connection portion 42 connected to the water pipe, as shown in FIG. Yes. The first connecting portion 41 has a double tube structure in which a cylindrical inner tube 41a and an outer tube 41b are arranged concentrically. A water channel is formed between the inner tube 41 a and the outer tube 41 b of the first connection portion 41, and the water channel is connected to the cylindrical second connection portion 42. The second connection part 42 extends in a direction intersecting (orthogonal) with the extending direction of the inner pipe 41 a and the outer pipe 41 b of the first connection part 41.

  In the connection state of the first heat transfer tube 20 and the second heat transfer tube 30 and the joint 40, the second heat transfer tube 30 penetrates the inside of the first connection portion 41 (inside the inner tube 41a), whereby the second heat transfer tube. The leading end side of 30 is taken out of the joint 40. Further, the first connection portion 41 is inserted inside the first heat transfer tube 20.

  The Cu metal layer 22 on the inner surface of the first heat transfer tube 20 is brazed to the outer tube 41b of the first connection portion 41, and the Cu metal layer 32 on the outer surface of the second heat transfer tube 30 is connected to the inner tube 41a of the first connection portion 41. By brazing, the space between the first heat transfer tube 20 and the second heat transfer tube 30 and the joint 40 is sealed.

  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 43 used for brazing, a material having a melting point lower than 548 ° C. which is a eutectic temperature of Al and Cu is used. Examples of such a filler material include Zn metal and Sn metal. Here, not the melting point of Al, but a temperature lower than the eutectic temperature of Al and Cu is set between the Al metal tubes 21 and 31 and the Cu metal layers 22 and 32 by heating during brazing. This is because the metal atoms diffuse. Thereby, it is possible to prevent the Cu metal layers 22 and 32 from melting during brazing.

  By the way, in connection with the 1st heat exchanger tube 20 and the 2nd heat exchanger tube 30, and the joint 40, unlike this embodiment, the state where the outer tube 41b of the 1st connection part 41 was located in the outside of the 1st heat exchanger tube 20, Then, the front end surface 50 of the first heat transfer tube 20 (Al metal tube 21) is exposed to water, and corrosion resistance against tap water cannot be ensured.

  On the other hand, in the present embodiment, the Cu metal layer 22 and the outer tube 41b on the inner surface of the first heat transfer tube 20 are in a state where the outer tube 41b of the first connection portion 41 is positioned inside the first heat transfer tube 20. Joined by brazing. Thereby, it can prevent that the front end surface 50 of the 1st heat exchanger tube 20 (Al metal tube 21) is exposed to water, and can ensure the corrosion resistance with respect to tap water.

(Second Embodiment)
FIG. 5 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 5 corresponds to FIG. As shown in FIG. 5, the present embodiment is different from the first embodiment (see FIG. 3) in that the number of second heat transfer tubes 30 arranged inside the first heat transfer tube 20 is one to a plurality (see FIG. 5). 5 is changed to 2). The Cu metal layer 31 of the second heat transfer tube 30 is manufactured in the same manner as in the first embodiment. For this reason, also in this embodiment, there exists an effect similar to 1st Embodiment.

(Third embodiment)
FIG. 6 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 6 corresponds to FIG. As shown in FIG. 6, in this embodiment, compared to the first embodiment (see FIG. 3), the Al metal tube 31 of the second heat transfer tube 30 disposed inside the first heat transfer tube 20 is finely multi-holed. It has been changed to a tube.

  The fine multi-hole tube 31 has a flat cross section, and a plurality of refrigerant channels 15b are formed in one tube. The fine multi-hole tube 31 is formed by extrusion or drawing of an Al metal material. In addition, a Cu metal layer 32 is formed on the outer surface of the fine multi-hole tube 31, and this Cu metal layer 32 is formed by a plating method or a thermal spraying method.

  According to the present embodiment, in addition to the effects of the first embodiment, the following effects are also achieved. That is, when the second heat transfer tube 30 is made of Al metal, the Al metal can be refined, so that the micro multi-hole tube 31 can be manufactured by extrusion or the like as in the present embodiment. Here, in the case where the same refrigerant flow rate is allowed to flow in the heat transfer tube, the refrigerant flow channel is more formed with a plurality of refrigerant flow channels than when one refrigerant flow channel is formed in the heat transfer tube. Since the cross-sectional area of the flow path becomes small, the heat exchange performance between the refrigerant and water is improved. Further, the size of the entire heat transfer tube can be reduced by forming it with one heat transfer tube, rather than forming a plurality of heat transfer tubes separately. Therefore, by configuring the second heat transfer tube 30 with the fine multi-hole tube 31, the water refrigerant heat exchanger 15 can be downsized and improved in performance.

(Fourth embodiment)
FIG. 7 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 7 corresponds to FIG. As shown in FIG. 7, in this embodiment, the first heat transfer tube 20 in the first embodiment (see FIG. 3) is changed from an Al metal tube 21 having a Cu metal layer 22 formed on the inner surface to a Cu metal tube 23. It is a thing. The Cu metal tube 23 has a base material made of Cu metal, and here, the entire tube is made of Cu metal. The second heat transfer tube 30 is the same as in the first embodiment.

  In this embodiment, one of the first heat transfer tube 20 and the second heat transfer tube 30 (second heat transfer tube 30) is made of Al metal, which is cheaper than Cu metal and light in material cost, and has corrosion resistance over the entire surface in contact with water. A high Cu metal layer 32 is formed. This also provides an inexpensive and lightweight heat exchanger as compared with the case where both the first heat transfer tube 20 and the second heat transfer tube 30 are made of only Cu metal while having high corrosion resistance in a water supply environment. it can.

(Fifth embodiment)
FIG. 8 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 8 corresponds to FIG. As shown in FIG. 8, in this embodiment, the first heat transfer tube 20 in the second embodiment (see FIG. 5) is replaced with an Al metal tube in which a Cu metal layer 22 is formed on the inner surface as in the fourth embodiment. 21 is changed to a Cu metal tube 23. The second heat transfer tube 30 is the same as in the second embodiment. For this reason, also in this embodiment, there exists an effect similar to 4th Embodiment.

(Sixth embodiment)
FIG. 9 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 9 corresponds to FIG. As shown in FIG. 9, in this embodiment, the first heat transfer tube 20 in the third embodiment (see FIG. 6) is replaced with an Al metal tube in which a Cu metal layer 22 is formed on the inner surface as in the fourth embodiment. 21 is changed to a Cu metal tube 23. The second heat transfer tube 30 is the same as in the third embodiment. For this reason, also in this embodiment, there exists an effect similar to 3rd and 4th embodiment.

(Seventh embodiment)
FIG. 10 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 10 corresponds to FIG.

  In the present embodiment, as in the first embodiment, the first heat transfer tube 20 and the second heat transfer tube 30 are cylindrical tubes, and the second heat transfer tube 30 is disposed concentrically inside the first heat transfer tube 20. However, contrary to the first embodiment, the first heat transfer pipe 20 constitutes the refrigerant flow path 15b, and the second heat transfer pipe 30 constitutes the water flow path 15a. For this reason, the refrigerant flows inside the first heat transfer tube 20 and outside the second heat transfer tube 30, and water flows inside the second heat transfer tube 30.

  And in this embodiment, the 1st heat exchanger tube 20 is comprised only with the Al metal tube 21, and Cu metal layer is not formed. The second heat transfer tube 30 is an Al metal tube 31, and a Cu metal layer 32 is formed on the entire inner surface in contact with water.

  The Cu metal layer 32 is formed by simultaneous drawing or coextrusion of a Cu metal material and an Al metal material. Note that the Cu metal layer 32 may be formed by metal processing using a clad material in which a Cu metal layer and an Al metal layer are bonded in advance, or by a plating method.

  Thus, in this embodiment, both the 1st heat exchanger tube 20 and the 2nd heat exchanger tube 30 are comprised with Al metal with a material cost cheaper than Cu metal, and the water in the 2nd heat exchanger tube 30 into which water flows, A Cu metal layer 32 having high corrosion resistance is formed over the entire surface in contact therewith. Thereby, compared with the case where both the 1st heat exchanger tube 20 and the 2nd heat exchanger tube 30 are comprised only with Cu metal, it can provide a cheap and lightweight heat exchanger, having high corrosion resistance in water supply environment. .

(Eighth embodiment)
FIG. 11 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 11 corresponds to FIG. As shown in FIG. 11, the present embodiment differs from the seventh embodiment (see FIG. 10) in that the number of second heat transfer tubes 30 arranged inside the first heat transfer tube 20 is one to a plurality (see FIG. 11). 11 is changed to 2). The Cu metal layer 31 of the second heat transfer tube 30 is manufactured in the same manner as in the seventh embodiment. For this reason, also in this embodiment, there exists an effect similar to 7th Embodiment.

(Ninth embodiment)
FIG. 12 shows a cross-sectional view of the first and second heat transfer tubes 20 and 30 in the present embodiment. FIG. 12 corresponds to FIG. As shown in FIG. 12, the present embodiment is a third embodiment in which the Al metal tube 31 of the second heat transfer tube 30 disposed inside the first heat transfer tube 20 is the third embodiment (see FIG. 10). Like the form, it is changed to a fine multi-hole tube. Therefore, in this embodiment, the same effect as in the third and seventh embodiments can be obtained.

  The fine multi-hole tube 31 has the same shape as that of the third embodiment, and is formed by extrusion or drawing of an Al metal material. In addition, a Cu metal layer 32 is formed on the entire inner surface of the fine multi-hole tube 31 in contact with water, and this Cu metal layer 32 is formed by a plating method or the like.

(Other embodiments)
(1) In the fourth to sixth embodiments, the first heat transfer tube (outer tube) 20 is changed to a Cu metal tube 23 with respect to the first to third embodiments, but the first to third embodiments. For the embodiment, the second heat transfer tube (inner tube) 30 may be changed to a Cu metal tube, and the first heat transfer tube (outer tube) 20 may be the same as in the first to third embodiments. .

  That is, one of the first heat transfer tube 20 and the second heat transfer tube 30 (the first heat transfer tube 20) is made of Al metal whose material cost is lower than that of Cu metal and has high corrosion resistance over the entire surface in contact with water. A layer may be formed, and the other (second heat transfer tube 30) may be made of Cu metal.

  (2) FIG. 13 shows a longitudinal sectional view of the joint 40 in the present embodiment. FIG. 13 corresponds to FIG. In the first embodiment, the sealing between the first heat transfer tube 20 and the second heat transfer tube 30 and the joint 40 is performed by brazing. However, as shown in FIG. It may be used and sealed.

  Also in this case, as shown in FIG. 13, the Cu metal layer 22 and the outer tube 41 b on the inner surface of the first heat transfer tube 20 with the outer tube 41 b of the first connection portion 41 positioned inside the first heat transfer tube 20. And a sealed structure through an O-ring 43. Thereby, it can prevent that the front end surface 50 of the 1st heat exchanger tube 20 (Al metal tube 21) is exposed to water, and can ensure the corrosion resistance with respect to tap water.

  (3) In each above-mentioned embodiment, as shown in FIG. 2, the water-refrigerant heat exchanger 15 is the one in which the first heat transfer tube (outer tube) 20 is spirally wound. The shape of the heat exchanger 15 may be changed to another 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.

15 Water refrigerant heat exchanger (heat exchanger)
15a Water channel
15b Refrigerant flow path 20 First heat transfer tube (outer tube)
21 Al metal pipe (base material)
22 Cu metal layer 23 Cu metal tube (base material)
30 Second heat transfer tube (inner tube)
31 Al metal pipe (base material)
32 Cu metal layer 40 Joint (joint)

Claims (6)

A first heat transfer tube (20) through which one of water and refrigerant flows;
A double-tube type heat exchanger that is disposed inside the first heat transfer tube (20) and includes a second heat transfer tube (30) through which the other of water and refrigerant flows, and exchanges heat between the water and the refrigerant. In
At least one of the first heat transfer tube (20) and the second heat transfer tube (30) is an Al metal tube (21, 31) whose base material is made of Al metal, and over the entire surface in contact with water. A heat exchanger in which a Cu metal layer (22, 32) is formed. Water flows through the first heat transfer tube (20), and refrigerant flows through the second heat transfer tube (30).
The first heat transfer tube (20) is an Al metal tube (21) whose base material is made of Al metal, and a Cu metal layer (22) is formed over the entire inner surface in contact with water,
The second heat transfer tube (30) is an Al metal tube (31) whose base material is made of Al metal, and a Cu metal layer (32) is formed over the entire outer surface in contact with water. The heat exchanger according to claim 1. Water flows through the first heat transfer tube (20), and refrigerant flows through the second heat transfer tube (30).
The first heat transfer tube (20) is a Cu metal tube (23) whose base material is made of Cu metal,
The second heat transfer tube (30) is an Al metal tube (31) whose base material is made of Al metal, and a Cu metal layer (32) is formed over the entire outer surface in contact with water. The heat exchanger according to claim 1. The first heat transfer tube (20) flows refrigerant, and the second heat transfer tube (30) flows water.
The first heat transfer tube (20) is an Al metal tube (21) whose base material is composed of Al metal,
The second heat transfer tube (30) is an Al metal tube (31) whose base material is made of Al metal, and a Cu metal layer (32) is formed over the entire inner surface in contact with water. The heat exchanger according to claim 1.   The heat exchanger according to any one of claims 2 to 4, wherein the second heat transfer tube (30) is a multi-hole tube (31) having a plurality of flow paths therein. The first heat transfer pipe (20) and the second heat transfer pipe (30) are connected to a joint (40) for connecting to a water pipe and a refrigerant pipe,
The Cu metal layer (22, 32) is brazed to the joint (40) using a filler material (43) having a melting point lower than the eutectic temperature of Al and Cu. The heat exchanger according to 2 or 3.

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