JP2008274426A - Copper alloy member and heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copper alloy member with a function of inhibiting the deposition of scale, which makes a scale containing calcium carbonate as a main component hardly deposit thereon, and makes the scale not to deposit on a part contacting with water, does not lower a heat exchange performance in a process of being used and does not cause a pitting corrosion that is rarely formed though depending on a quality of the water, even when used in a heat exchanger that indirectly or directly heats the water, and to provide the heat exchanger which incorporates the member. <P>SOLUTION: The copper alloy member includes Co in a parent phase as a solid solution, a simple substance and/or a compound in an amount of 0.02 to 0.5 mass% (in terms of Co in the case of compound), P in a parent phase as a solid solution, a simple substance and/or a compound in an amount of 0.005 to 0.2 mass% (in terms of P in the case of compound), and the balance Cu with unavoidable impurities; and has a remaining carbon in an amount of 10 mg/m<SP>2</SP>or less on the surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a copper alloy member having a function of suppressing scale mainly composed of calcium carbonate and a heat exchanger incorporating the member, and particularly easily occurs in a cold water section when groundwater containing a large amount of free carbonic acid is used. The present invention relates to a copper alloy member and a heat exchanger that make it difficult to produce type II pitting corrosion that tends to occur in hot water portions of 50 ° C. or higher with tap water and the like containing 0.5 mg / L or more of residual type I pitting corrosion and residual chlorine.

  Recently, heat exchangers in which water is heated by a supercritical carbon dioxide refrigerant or a chlorofluorocarbon refrigerant have been put into practical use and have been widely used for applications such as hot water supply and floor heating. As a member constituting such a heat exchanger, since the pressure of the refrigerant becomes extremely high, in order to maintain necessary strength and thermal efficiency, it has necessary thermal conductivity, so a copper or copper alloy member Is used.

  In such a heat exchanger, the installation space is often limited. For example, in a hot water storage water heater heat pump system, the flow rate of heated water is generally 1 L so that water having a limited volume can be obtained. Designed as small as / min. Since the flow rate of water is small, calcium carbonate or a scale mainly composed of this tends to adhere to the portion of the heat exchanger that comes into contact with water. Since the solubility of calcium carbonate in water decreases as the water temperature increases, calcium carbonate is particularly likely to precipitate at portions where the water temperature increases. For this reason, scale adhesion tends to occur as the temperature of the water becomes higher. Further, in the portion where the scale is once adhered, the scale is further adhered due to the high temperature of the adhered scale and the low flow rate of water, and the scale grows thick. The scale formed in this way causes problems such as a decrease in heat exchange efficiency, a decrease in the amount of circulating water due to a decrease in the cross-sectional area of the water passage, an increase in pump pressure, and an increase in power consumption of the pump. Yes.

  In heat exchangers that circulate and use water as a cooling medium or heating medium, prevent scales such as polymers with carboxyl groups polymerized with maleic acid, acrylic acid, or itaconic acid to prevent calcium-based scales. The agent is added to the circulating water.

  On the other hand, in a heat exchanger or the like for heating hot water for drinking or bathing, a scale inhibitor cannot be added due to its nature. As a method of preventing scale adhesion in heat exchangers other than the addition of scale inhibitors, the inner surface of the heat exchanger is coated with fluorosilicone or fluororesin (Patent Document 1), or the outer tube is bent in a double-tube heat exchanger. By setting the radius to 3 times or more of the inner diameter of the outer tube, the period until the tube is blocked by the scale is extended (Patent Document 2), or a torsion plate is rotatably provided in the tube through which the cooling water flows. Magnetism that prevents the scale from adhering to the turbulent flow formed by the twisted plate (Patent Document 3) or forms a magnetic field in at least a part of the pipe in a pipe that forms a circulation path for circulating cooling water as an aqueous fluid. In addition to providing a treatment unit, a magnetic substance is added to the cooling water (Patent Document 4), an inner pipe having a refrigerant flow passage formed therein, and an outer pipe provided between the inner pipe and the inner pipe. Water channel is formed In a double-tube heat exchanger that is formed in a spiral shape and has an outer tube, an inner-wound double tube that is formed so that water flows in a spiral shape in the water flow path. And a heat exchange unit having an outer-wound double pipe formed so that water flows in a spiral shape in the water flow path to the outside. The heat exchange unit on the side has a structure in which an externally wound double tube is provided (Patent Document 5), or a portion made of a copper or copper alloy base material and at least a surface that can come into contact with water during use is hydrophilic. Forming a heat-resistant coating (Patent Document 6), enlarging the cross-sectional area of the flow path at a high-temperature region near the flow path outlet side to prevent the hot water supply function from being impaired even if some scale accumulates (Patent Document 7), Various methods have been proposed, such as prevention of scale adhesion by treatment. To have.

  Further, Patent Document 8 discloses an inner tube that forms a first fluid channel inside, and an outer tube that is provided outside the inner tube and forms a second fluid channel between the inner tube and the inner tube. And the first fluid flowing through the inner tube is a refrigerant in a double-pipe heat exchanger in which a leakage detection groove is provided at the boundary surface between the first fluid channel and the second fluid channel, A heat exchanger in which the second fluid flowing in the outer pipe is water, and the ratio of the cross-sectional area of the water flow path to the cross-sectional area of the refrigerant flow path is 3.5 to 24.5. A heat exchanger has been proposed (Claim 3) and put into practical use. Furthermore, in the heat exchanger described in Patent Document 8, by specifying the ratio of the cross-sectional area of the water flow path to the cross-sectional area of the refrigerant flow path, the outer tube is attached by the scale while maintaining the heat exchange performance. It has been disclosed that the service life until closure can be extended.

On the other hand, depending on the composition of the water-soluble component that varies in tap water nationwide, it is derived from the lubricating oil remaining on the inner surface of the water flow portion when the water temperature is 15 mg / L or more at a low temperature portion of about 15 ° C. or less. Type I pitting corrosion that tends to occur when the amount of residual carbon is 5 mg / m ² or more, and Type II pitting corrosion that tends to occur when residual chlorine is 0.5 mg / L or more in warm water at a water temperature of 50 ° C. or more, Rarely occurs depending on the type of the phosphorous deoxidized copper member and the copper alloy member, which may cause problems due to leakage of hot water or refrigerant.

  For such a problem, a copper alloy member having improved pitting corrosion resistance by adding an element such as Zr, P, Sn, or Ag to the copper alloy member has been proposed, and partly put into practical use. (Patent Documents 9 and 10).

JP-A 61-149794 JP 2005-69620 A Japanese Utility Model Publication No. 2-109190 Japanese Patent Application Laid-Open No. 2005-238023 JP 2005-147469 A JP 2002-98496 A JP 2002-147469 A JP 2005-69620 A Japanese Patent No. 3374398 JP-A-6-184669

  However, the invention described in Patent Document 1 may cause a decrease in thermal conductivity because a film having an appropriate thickness is formed. The invention described in Patent Document 2 does not actively prevent scale adhesion, and is intended to extend the usable period of the heat exchanger on the assumption that the scale adheres. Actually, in the prior art described in Patent Document 2, it is inevitable that the scale mainly composed of calcium carbonate adheres to the part where the water temperature is high, thereby preventing a decrease in heat exchange performance and a decrease in the amount of circulating water. Difficult to do. In addition, the invention described in Patent Document 3 installs a rotatable torsion plate in the pipe, but can be applied to a double pipe refrigerant pipe, a pipe having a bent portion, or a small inner diameter of the pipe. Not practical. The prior art described in Patent Document 4 is not suitable for the purpose of use in which water comes into contact with the human body because metal ions such as zinc are eluted and contaminated in water. The invention described in Patent Document 5 can suppress sedimentation of scale floating in the water by lengthening the straight portion of the copper tube on the outlet side of the heat exchanger, but suppresses the scale deposition on the copper tube wall. It cannot be done and the effect is insufficient. In the invention described in Patent Document 6, the effect of eliminating the local high-temperature portion due to the hydrophilic film tends to appear when the water temperature is relatively low, but the effect is insufficient because the high-temperature water becomes the scale generation temperature as a whole. It is. The inventions described in Patent Documents 7 and 8 sacrifice the heat exchange rate at the site where the water temperature is high, and in order to ensure a heat exchange rate equivalent to the case where the cross-sectional area of the flow channel is not widened, further flow channels. The length had to be taken, which hindered the downsizing of the equipment and the freedom of design.

  In addition, the magnetic processing method is to install a strong magnet in a part of the heat exchanger and try to prevent the adhesion of scale by applying a magnetic force to the water in the tube. There are problems such as being expensive and difficult to incorporate magnets in a limited space of the heat exchanger housing.

  The conventional techniques described in Patent Documents 9 and 10 correspond to type II pitting corrosion among type I pitting corrosion and type II pitting corrosion, which have different forms depending on the water quality and use environment. The number of households that use groundwater is increasing due to the rise in the number of people, and there are increasing opportunities for use in environments where there is a risk of I-type pitting corrosion. These copper alloy materials are manufactured by the same method as the phosphorous deoxidized copper member, and have not yet been able to prevent type I pitting corrosion due to residual carbon remaining on the surface, and still have problems. I left it.

  The present invention has been made in view of such a problem, and a scale in which calcium carbonate as a main component hardly adheres, and even in a heat exchanger in which water is indirectly or directly heated, a portion in contact with water Provides a copper alloy member with a scale adhesion control function that does not cause scale adhesion, does not deteriorate heat exchange performance during use, and does not generate pitting corrosion that occurs rarely due to water quality, and a heat exchanger incorporating the copper alloy member The purpose is to do.

  In addition, another object of the present invention is 50 for tap water containing 0.5 mg / L or more of type I pitting corrosion and residual chlorine, which is likely to occur in a cold water part, especially when groundwater containing a large amount of free carbonic acid is used. An object of the present invention is to provide a copper alloy member that is less likely to cause type II pitting corrosion that is likely to occur in a hot water portion at or above ° C. and a heat exchanger incorporating the copper alloy member.

  Still another object of the present invention is to provide a heat exchanger that has a refrigerant pipe through which a refrigerant flows and a water passage through which water flows, and heats the water in the water passage by the refrigerant in the refrigerant pipe. An object of the present invention is to provide a heat exchanger having a function of suppressing the adhesion of scale without lowering the heat exchange rate.

The copper alloy member according to the present invention contains Co as a solid solution, a simple substance and / or a compound in the matrix phase in an amount of 0.02 to 0.5% by mass (in the case of a compound, Co equivalent value), and P is a matrix. The solution contains 0.005 to 0.2% by mass (in terms of P in the case of a compound) as a solid solution, a simple substance and / or a compound, the balance is made of Cu and inevitable impurities, and the amount of residual carbon on the surface is 10 mg. / M ² or less.

By containing Co and P in the copper alloy, it is possible to suppress the adhesion of scale to the surface of the copper alloy material. The Co and P are present in the copper alloy matrix as a solid solution, a simple substance, or a compound. The Co and P compounds include a Co—P compound such as Co ₂ P, a Cu—Co—P compound, or These oxides, other compounds formed by added elements and Co or P, oxides thereof, composite oxides, and the like can be given. However, the Co and P compounds are not limited to these types, and any form that contributes to prevention of scale adhesion can be used as long as it exists in the matrix in the form of precipitates. Moreover, it contributes to prevention of scale adhesion even when it is not a precipitate but in a solid solution state in the matrix and when it is present as Co alone. However, the Co and P compounds are more effective when concentrated in the vicinity of the surface in the form of precipitates.

  This copper alloy member preferably further contains 0.005 to 0.3% by mass (in the case of a compound, Zr equivalent value) of Zr as a solid solution, a simple substance and / or a compound in the matrix phase.

  Furthermore, it is preferable that Sn is contained in an amount of 0.03 to 3.0% by mass and the average crystal grain size is 30 μm or less.

  Further, it is preferable to contain 0.03 to 5.0% by mass of Zn.

  Furthermore, at least one element selected from the group consisting of Ni: 0.005 to 0.2 mass%, Mg: 0.005 to 0.2 mass%, and Fe: 0.005 to 0.2 mass% Is preferably 0.005 to 0.5 mass% in total, and the average crystal grain size is preferably 10 μm or less.

  A heat exchanger according to the present invention has a water flow path through which water flows and a refrigerant pipe through which a refrigerant flows, and is in contact with water in a heat exchanger that heats water in the water flow path with the refrigerant in the refrigerant pipe. The water flow path and / or at least a part of the refrigerant pipe is made of the copper alloy member described above.

  In another heat exchanger according to the present invention, when the channel cross-sectional area of the water channel is A and the channel cross-sectional area of the refrigerant tube is B, the water channel cross-sectional area is relative to the refrigerant tube channel cross-sectional area. The ratio A / B is 1.0 to 12.3.

  Furthermore, it is preferable that a ratio A / B of the water channel cross-sectional area to the refrigerant pipe channel cross-sectional area is 1.0 to 3.5.

  In the heat exchanger according to the present invention, the water flow path is, for example, a water flow pipe. And it is preferable that the said refrigerant | coolant pipe | tube is arrange | positioned inside the said water flow pipe | tube. Moreover, it is preferable that the said water flow pipe is an internal grooved pipe.

  In addition, the refrigerant pipe can be configured to have a large-diameter pipe through which the water flows on the outer surface and a small-diameter pipe that is disposed in the large-diameter pipe and through which the refrigerant flows. And it is preferable that the detection part which detects the leakage of the said water or the said refrigerant | coolant is provided between the said large diameter pipe | tube and the said small diameter pipe | tube. Furthermore, it is preferable that a plurality of grooves having parallel or twist angles in the tube axis direction are formed on the inner surface of the small diameter tube. Furthermore, it is preferable that fins are formed on at least a part of the outer surface of the large-diameter pipe in the refrigerant pipe.

  ADVANTAGE OF THE INVENTION According to this invention, the adhesion of the scale which has calcium carbonate as a main component can be suppressed in the copper alloy member with high calcium hardness which contacts high temperature water, or self becomes high temperature. In addition, by making this a heat exchanger used for the water flow part or the outer surface of the refrigerant pipe, more water is generated at the site where the water temperature becomes 80 ° C. or more, and the calcium carbonate scale adheres to the water flow part or the outer surface of the refrigerant pipe. Providing a heat exchanger that contributes to energy saving by preventing problems such as reduced heat exchange efficiency, reduced heat exchange performance, reduced circulating water volume, increased pump pressure, and increased pump power consumption. can do. In addition, the copper alloy member has a function of suppressing the adhesion of calcium carbonate scale to the surface when used as it is, so no special treatment for incorporation into a heat exchanger is required, and the practicality is excellent. ing.

  In addition, when groundwater containing a large amount of free carbonic acid is used, type I pitting corrosion that tends to occur in the cold water part and tap water that contains 0.5 mg / L or more of residual chlorine is likely to occur in hot water parts of 50 ° C. or higher II. Mold pitting corrosion can be made difficult to occur. For this reason, the copper alloy member of the present invention is extremely versatile.

  Furthermore, according to the heat exchanger of the present invention, in the heat exchanger that has the refrigerant pipe through which the refrigerant flows and the water flow path through which water flows, and heats the water in the water flow path with the refrigerant in the refrigerant pipe, the water temperature is high. Thus, a heat exchanger having a function of suppressing the adhesion of scale can be obtained without reducing the heat exchange rate at the site. Furthermore, by specifying the relationship between the flow path cross-sectional area of the water flow path and the flow path cross-sectional area of the refrigerant pipe through which the refrigerant flows, it is advantageous for downsizing the equipment in which this heat exchanger is incorporated and the degree of freedom in design. It is possible to increase.

  Hereinafter, embodiments of the present invention will be described in detail.

The calcium carbonate scale is generated by a reaction of Ca (HCO ₃ ) ₂ → CO ₂ + H ₂ O + CaCO ₃ , and this reaction proceeds more rapidly as the water temperature is higher. As a mechanism for the scale to adhere to the copper pipe, the generated CaCO ₃ fine particles adhere to the copper pipe wall, and it is considered that the scale grows as a nucleus. Therefore, if the CaCO ₃ fine particles are prevented from adhering to the copper tube wall, the scale adhesion can be suppressed. It is known that the surface of CaCO ₃ is negatively charged. On the other hand, Cu ₂ O present on the surface of copper is positively charged, and attractive force acts on each other, and as a result, CaCO ₃ scale adheres to and accumulates on the surface of the copper member.

On the other hand, the inventor of the present application is that any precipitate generated when Zr is contained in the copper base material is negatively charged as in the CaCO ₃ scale, and the copper alloy containing this contains CaCO ₃ fine particles. It was found that it did not adhere and no scale was deposited.

  In addition, Sn, which is an effective additive element for type II pitting corrosion, which is likely to occur in water quality containing, for example, 1 ppm or more of residual chlorine in a high temperature region where the water temperature is 50 to 90 ° C., contains an appropriate amount of oxygen. However, it has been found that, by heat treatment in an inert gas or reducing gas atmosphere, the oxide of the additive element can be properly concentrated on the surface, and both scale resistance and pitting corrosion resistance can be provided at the same time.

On the other hand, in the case of a phosphorous deoxidized copper member that is often used in the market, it adheres to the surface when it comes into contact with water containing 15 mg / L or more of free carbonic acid at a low temperature of 15 ° C. or less. If the amount of residual carbon exceeds 5.0 mg / m ² , it is said that type I pitting corrosion is likely to occur. On the surface of the copper alloy member of the present invention, it has been found that if the amount of carbon remaining on the surface is 10.0 mg / m ² or more, the possibility of generating copper I-type pitting corrosion increases. The copper alloy member has excellent pitting corrosion resistance against type II pitting corrosion by having a distribution in the depth direction of the appropriate additive element, but is insufficient for the type I pitting corrosion. The surface residual carbon amount is preferably 10.0 mg / m ² or less.

  As a method for producing a copper alloy member having a surface whose residual carbon amount is not more than a specified amount, the processing lubricating oil remaining on the surface is burned mainly in the annealing process or heat treatment process to generate residual carbon. However, this is not necessarily the case. That is, a method of performing annealing or similar heat treatment in an inert gas or reducing gas atmosphere mixed with predetermined oxygen, a method of performing annealing or similar heat treatment in a hydrogen atmosphere, an organic solvent or a degreasing cleaner, etc. Various methods such as a method of performing a normal annealing process after washing the oil, or a method in which the member temperature reaches the annealing temperature in a relatively short time, such as induction heating annealing or electric heating annealing, can be applied. .

  In order to obtain the scale adhesion preventing function more effectively, it is sufficient to contain more additive elements. However, due to the accompanying increase in the strength of the raw material, particularly in the case of pipe materials, there is a lack of strength in the extrusion process, and drawing in the drawing process. Failures due to additional equipment such as breakage occur frequently. In order to obtain an effective function with as little additive element amount as possible, it is better to mix and process 10 to 200 ppm of oxygen in the atmosphere during the annealing or heat treatment process. By exposing to a high temperature in the presence of a small amount of oxygen, oxygen enters into the vicinity of the surface of the base material while suppressing excessive oxidation of the copper base material, the added elements are oxidized, and internal oxidation occurs. Thereby, since the additive element in the metallic state is deficient in the surface layer of the base material, the additive element is diffused from the inside of the material, and the diffusion of the additive element is continued and the additive element is concentrated on the surface. Since the concentrated additive element has a function of preventing scale adhesion, a great effect can be obtained instead of the addition amount.

  Hereinafter, the reasons for limiting the composition of the copper alloy member of the present invention will be described in detail.

“Co: 0.02 to 0.5% by mass (in the case of a compound, Co equivalent value) as a solid solution, a simple substance and / or a compound”
Co forms a phosphide and exhibits a scale adhesion preventing effect. In addition, it itself dissolves in copper to improve strength and proof stress. When the Co content is less than 0.02% by mass, the scale adhesion preventing effect cannot be obtained. On the other hand, if the Co content exceeds 0.5% by mass, coarsening of precipitates or generation of crystallized matter is likely to occur, and ductility is lowered.

“P: 0.005 to 0.2% by mass (in the case of a compound, converted to P) as a solid solution, a simple substance and / or a compound”
P is an element necessary for forming the phosphide. When the P content is less than 0.005% by mass, a phosphide effective for preventing scale adhesion cannot be obtained sufficiently. On the other hand, if the P content exceeds 0.2% by mass, the ductility tends to decrease due to the formation of coarse crystals.

“Residual carbon content is 10 mg / m ² or less”
When the copper alloy member of the present invention is used in a stream of I-type pitting corrosion, if the amount of residual carbon adhering to the surface exceeds 10.0 mg / m ² , I-type pitting is likely to occur. The smaller the amount of residual carbon attached, the lower the possibility of causing type I pitting corrosion, more preferably less than 5.0 mg / m ² and even more preferably less than 2.0 mg / m ² .

“Zr: 0.005 to 0.3% by mass (in the case of a compound, converted to Zr) as a solid solution, simple substance and / or compound in the matrix”
Zr has an effect of preventing scale adhesion, and the effect of preventing scale adhesion can be further improved as compared with the case of using only Co-P. Further, Zr exhibits the same effect as Co—P even when added in a small amount, and is effective in preventing the ductility from being reduced by increasing the amount of Co—P. Furthermore, Zr is effective in preventing pitting corrosion and improving strength. When the Zr content is less than 0.005% by mass, the above-mentioned scale adhesion preventing effect, ductility reduction preventing effect, pitting corrosion preventing effect and strength improving effect are small. When Zr exceeds 0.3% by mass, a coarse crystallized product is produced and ductility is lowered.

The compounds of Zr, Cu-Zr compound such as _{Cu 3 Zr, ZrP 3, P} -Zr compounds such ZrP, Zr oxides such ZrO _3, ZrCu ₃ O ₄ ZrCu over O composite oxides such like However, the Zr compound is not limited to this, and any form that contributes to the prevention of scale adhesion can be used as long as it is present in the matrix in the form of precipitates. In addition, it contributes to the prevention of scale adhesion even when it is dissolved in the matrix rather than the precipitate and when it is present as Zr alone. However, it is more effective that Zr is concentrated near the surface in the form of precipitates.

“Sn: 0.03 to 3.0 mass%”
Sn imparts type II pitting resistance to copper alloy members. Sn has an effect of increasing elongation in mechanical properties, improving strength, and preventing crystal grain coarsening at high temperatures up to 900 ° C. If the Sn content is less than 0.03% by mass, the type II pitting resistance and other effects become insufficient. When the Sn content exceeds 3.0% by mass, wrinkles appear during bending due to changes in mechanical properties. In addition, work hardening is increased and wear and breakage of rolling mandrels and drawing plugs / dies in the case of pipes and loss of grooved plugs are increased. Moreover, when Sn is excessive, thermal conductivity will also fall.

“Average grain size is 30 μm or less”
Addition of Sn can suppress grain coarsening. When the average crystal grain size exceeds 30 μm, the yield ratio of the copper alloy member decreases. When the yield ratio is lowered, the yield strength value is reduced with respect to the fracture strength, and plastic deformation is likely to occur. In addition, due to the influence of P that tends to gather at the crystal grain boundaries, a non-uniform state of P on the surface is formed, and thus corrosion resistance begins to be affected.

“Zn: 0.03 to 5.0 mass%”
Zn imparts excellent workability to the copper alloy member of the present invention in which workability may be reduced by containing various elements. It is an element that improves its strength by dissolving in the parent phase of the copper alloy member. Further, Zn has an effect of suppressing wear of processing tools (plugs, mandrels, dies, etc.). Since the copper alloy member of the present invention has a large amount of hard phosphide and Sn that is easy to work harden, and tool wear tends to occur, it is preferable to add Zn. The effect is small when Zn is less than 0.03% by mass. If the Zn content exceeds 5.0% by mass, the corrosion resistance starts to deteriorate during use in an aqueous environment, and the dezincification corrosion resistance and stress corrosion cracking susceptibility begin to be affected. Note that, as the Zn content increases, the copper alloy tube is more easily work-hardened. Therefore, particularly when processing a copper alloy tube, the number of annealing increases as compared with phosphorous-deoxidized copper, resulting in an increase in processing cost.

“At least one selected from the group consisting of Ni, Mg, and Fe: 0.005 to 0.2 mass% individually, and 0.005 to 0.5 mass% in total”
Ni, Mg, and Fe form a solid solution or phosphide and contribute to improving the strength and heat resistance of the copper alloy member. If the content of each element is less than 0.005% by mass individually (and therefore in total), the effect is insufficient. Moreover, when content of each element exceeds 0.2 mass% individually, or exceeds 0.5 mass% in total, a precipitate will coarsen and bending workability will fall. Therefore, Ni, Mg, and Fe are individually 0.2% by mass or less and the total amount is 0.5% by mass or less.

“Average crystal grain size: 10 μm or less”
When the average crystal grain size of the copper alloy member exceeds 10 μm, the yield ratio decreases. When the yield ratio decreases, the proof stress value is low with respect to the fracture strength, and plastic deformation easily occurs. Since the corrosion resistance is not affected unless the average crystal grain size of the copper alloy member exceeds 30 μm, the yield ratio and the corrosion resistance are good if the average crystal grain size is 10 μm or less.

Such a member can be used for, for example, a water heat exchanger for a heat pump water heater using CO ₂ as a refrigerant. Water heat exchangers for heat pump water heaters (EcoCute (registered trademark)) that use CO ₂ as a refrigerant, cook hot water at 80 to 90 ° C at night using low-cost electricity at night, and store hot water Since it is stored in the tank, the water temperature is much higher than the conventional gas water heater and instantaneous water heater. In the water heat exchanger for a CO ₂ refrigerant heat pump type hot water heater, a calcium carbonate scale generated at a high water temperature is attached to the pipe wall by a reaction between a hardness component such as calcium and a carbonic acid component depending on the water quality. This is continued, and the flow path of the water flow section may be blocked or the pressure loss may increase. By using the member, since the adhesion of the calcium carbonate scale is suppressed with respect to the problem of clogging due to the calcium carbonate scale and an increase in pressure loss, the clogging and the increase in pressure loss can be suppressed.

  In the form of the heat exchanger, for example, a member constituting the water flow path of the heat exchange portion is a tube (water flow tube). One or more refrigerant tubes are wound around the outer surface, and heat exchange is performed between the inner surface and the outer surface of the water flow tube. A heat exchanger (FIG. 1), a heat exchanger (FIG. 2) in which a refrigerant pipe is present inside the water flow pipe and water is directly heated by the refrigerant pipe, and a box-shaped housing having a complicated path therein A heat exchanger (FIG. 3) for exchanging heat between the inner surface and the outer surface of the water flow portion between the water flow portion of the water flow portion and the refrigerant pipe that is brought into contact with the box-shaped housing, for example. If the heat exchanger such as a heat exchanger that directly heats water by causing one or more refrigerant pipes along a complicated path to exchange heat with the flow path through which the refrigerant flows and the flow path through which the water flows is used, the present invention is used. Applicable.

  Moreover, when the member which comprises a water flow part is a pipe | tube, it can be set as the inner surface grooved pipe | tube which formed many groove | channels in the water flow pipe inner surface. By using the inner grooved tube, the efficiency of heat exchange between the water flowing through the water flow portion and the outer surface of the water flow tube can be improved (FIG. 4). The groove shape is not particularly limited, and the fin height, the number of grooves, the bottom wall thickness, the peak angle, the twist angle, the twist groove, the straight groove, the cross groove, and It can be in any form such as a cut groove.

It was considered from the beginning that the CO ₂ refrigerant heat pump water heater started to spread, but the heat flow performance due to the scale adherence and the heat exchange performance due to the scale adherence were considered to make the water flow pipe into an internally grooved pipe. It has been impossible to put it to practical use because of a significant decrease in the above. However, the present invention has made it possible to suppress the adhesion of scales to the surface of the material, thereby increasing the degree of freedom in design and making it possible to change the bold idea of improving the performance of the heat exchanger. It is possible for the first time that the water flow pipe is an internally grooved pipe.

In the case of FIG. 2, when supercritical CO ₂ or the like is used as the refrigerant, it is usually performed that CO ₂ is circulated in the refrigerant pipe and water is circulated in the water flow pipe (region outside the refrigerant pipe). Regardless, the water in the water flow pipe and the refrigerant in the refrigerant pipe may be reversed. In order to increase the amount of heat transfer, it is desirable that the number of refrigerant tubes be two or more, and the direction of the flow of water flowing in the water flow tube and the flow of refrigerant flowing in the small diameter tube be reversed (opposite flow). In addition, the refrigerant pipe is a double pipe composed of a large diameter pipe and a small diameter pipe disposed inside the large diameter pipe, and further, the outside of the large diameter pipe is provided between the large diameter pipe and the small diameter pipe. It is also possible to provide a structure for detecting leakage of flowing water or refrigerant flowing through the small-diameter pipe (FIGS. 5A, 5B, and 5C). Further, a plurality of grooves having a parallel or twist angle in the tube axis direction may be formed on the inner surface of the small diameter tube (FIG. 5D).

  That is, as shown in FIGS. 5 (a) and 5 (b), this heat transfer tube 1 has four small diameter tubes 3 arranged inside a large diameter tube 2, and each small diameter tube 3 is shown in FIG. As shown in (c), the inner surface of the outer tube 4 is formed with irregularities having a triangular cross section, and the inner tube 5 is fitted inside thereof. For this reason, a space 6 is formed between the outer tube 4 and the inner tube 5. For this reason, when a hole due to corrosion or the like occurs in the outer tube or the inner tube, the fluid flowing outside the outer tube, the outer flow path 7 or the inner tube leaks into the space 6. This leakage flows in the tube axis direction through the space 6 and can be detected when it leaks outside the heat exchanger. FIG. 5D shows a case where a groove is formed on the inner surface of the inner tube 5.

  A straight / spiral groove may be provided inside the water flow tube. Also, whether a straight / spiral groove or the like is provided inside the refrigerant pipe (FIGS. 5E to 5G), or a linear or spiral fin is provided outside the small-diameter pipe (FIG. 6), Heat transfer may be promoted by increasing the area in the pipe by disturbing the flow of the fluid in the pipe by a method such as making the water flow pipe and / or the refrigerant pipe a corrugated pipe. When the inside of the refrigerant pipe is torn due to corrosion or the like, the fluid in the pipe mixes with the fluid in the water flow pipe. Therefore, in order to avoid this, it is desirable that the refrigerant pipe has a double structure having a detection structure. Further, such a heat exchanger may be wound in a spiral shape or a spiral shape to save space.

  FIG. 7 shows a baffle spacer, FIG. 8 shows an inner material, FIG. 9 shows an inner material, FIG. 10 shows a baffle ring, FIG. 11 shows a baffle ring and a spacer, and FIG.

As a heat exchanger similar to the configuration of FIG. 1, for example, a refrigerant pipe is fitted in a groove provided outside the water flow pipe (FIG. 13), and the refrigerant pipe is brazed to the outside of the water flow pipe. There are things that have been. When supercritical CO ₂ or the like is used as the refrigerant, it is usually performed that CO ₂ is circulated in the refrigerant pipe and water is circulated in the water pipe. However, the refrigerant in the water pipe and the refrigerant pipe are reversed regardless of this. May be. In order to increase the amount of heat transfer, it is desirable that the number of refrigerant pipes be two or more, and the flow direction of the medium flowing in the water flow pipe and the flow direction of the medium flowing in the refrigerant pipe be reversed (opposite flow). Also, the area inside the pipe is increased by a method such as providing a linear or spiral groove inside the refrigerant pipe and / or inside the water flow pipe, and heat transfer is promoted by disturbing the fluid flow in the pipe. May be. Moreover, it arrange | positions helically on the outer side of a water flow pipe, the contact length of a water flow pipe and a refrigerant pipe may be lengthened, and a heat transfer area may be increased. Further, such a heat exchanger may be wound in a spiral shape, a spiral shape or the like in order to save space.

  Further, in such a heat exchanger, the water temperature becomes high by setting the ratio A / B of the flow passage cross-sectional area A of the water flow passage to the flow passage cross-sectional area B of the refrigerant pipe to 1.0 to 12.3. A heat exchanger having a function of suppressing scale adhesion can be obtained without reducing the heat exchange rate at the site. Furthermore, since the cross-sectional area of the water flow path is specified with respect to the flow-path cross-sectional area of the refrigerant, it is advantageous for downsizing the equipment in which this heat exchanger is incorporated, and the degree of freedom in design can be increased. It is. When A / B is less than 1.0, the flow passage cross-sectional area A of the water flow pipe is small, so that the average flow velocity of the water flowing in the water flow pipe increases and the pressure loss increases. Further, when a scale mainly composed of calcium carbonate adheres to the inner surface of the water pipe or the outer surface of the refrigerant pipe, the average flow velocity of the water flowing in the water pipe further increases and the pressure loss increases. When A / B exceeds 12.3, the heat flow per unit length decreases, so the heat transfer performance decreases. Therefore, the ratio A / B of the channel cross-sectional area A of the water channel to the channel cross-sectional area B of the refrigerant pipe is 1.0 to 12.3. In order to obtain higher heat exchange performance, the ratio A / B of the channel cross-sectional area A of the water channel to the channel cross-sectional area B of the refrigerant pipe is preferably 1.0 to 3.5.

The copper alloy tube of the present invention can exert its effect by using it in a water heat exchanger for a heat pump type hot water heater that seeks to obtain higher temperature water using CO ₂ as a refrigerant. The use in copper alloy pipes is not limited to this, but the water temperature is relatively high, such as gas water heaters or baths with gas burner heating, and heat exchangers for additional cooking, as well as boiler piping and water heaters. It can also be applied to piping for hot water supply.

  In the manufacturing method, the copper alloy member of the present invention, in the case of a plate material, is manufactured by a process of melting, casting, hot rolling, cold rolling, leveling, annealing and winding (coil material), or finally. It is cut to a standard length. In the case of tube material, it is melted, cast, hot extruded, cold rolled, cold drawn and straight cut (straight tube material) or wound (long coil material) and then packed through annealing. The Meanwhile, in order to obtain a desired element distribution, an appropriate annealing treatment is performed.

  During the annealing process, the atmosphere to be brought into contact with the surface on the inner surface or the outer surface on which the desired characteristics are desired is an inert gas or reducing gas containing 5 to 200 ppm of oxygen, and the annealing temperature is 550 to 700 ° C., By adjusting the heating time from 10 to 200 minutes, a surface additive element distribution having desired characteristics can be obtained. It is desirable to adjust the open-air point in the furnace at 5 to 15 ° C.

  Hereinafter, the effects of the present invention will be described with respect to the characteristics of the examples of the present invention in comparison with comparative examples that are out of the scope of the present invention. Hereinafter, although the copper alloy member of an Example comparative example is a pipe material, the characteristic is fundamentally the same also with a board | plate material.

(Residual carbon adhesion measurement method)
The method for measuring the amount of residual carbon adhered to the copper member was as follows. In the evaluation in this example, since the inner surface was evaluated in the state of the copper alloy tube, the amount of residual carbon adhering to the inner surface of the copper alloy tube was measured. The oil on the inner surface of the tube was extracted with hexane, and then the inner and outer surfaces of the tube were washed with acetone and dried. Next, a mixed acid of hydrochloric acid and nitric acid (1 + 1) was added to the inner surface of the tube to extract the adhering carbon. The extracted mixed acid was suction filtered using quartz filter paper, and carbon was collected on the filter paper. And the filter paper was put into the dryer set to 80 degreeC, and it was made to dry. After drying, it was cooled in a desiccator. Carbon was quantified by a combustion infrared absorption method using a carbon / sulfur simultaneous analyzer: EMIA-610 type (combustion temperature: 1200 ° C., time: 100 seconds) manufactured by Horiba, Ltd.

(Scale adhesion evaluation method)
The evaluation method of the amount of scale adhesion is as follows. A mixed aqueous solution of NaHCO ₃ (0.018 mol / L) and CaCl ₂ .2H ₂ O (0.009 mol / L) was prepared at 20 ° C. to obtain a scale generation solution containing Ca (HCO ₃ ) ₂ . As the standard dimensions of the evaluation member, a plate adjusted to a width of 60 mm × a length of 50 mm × a plate thickness of 0.5 mm, and a tube having an outer diameter of 9.52 mm × a length of 50 mm × a thickness of 0.5 mm Each was produced. Thereby, the surface area of the member for evaluation which contacts a scale production | generation solution can be unified to about 6.0 * 10 < ³ > mm < ² >, even if it is a board | plate material or a pipe material. The prepared member for evaluation was immersed in 100 ml of the scale generation solution, and the temperature was raised to 90 ° C. This operation was repeated 5 times for each sample using a new scale production solution. Then, it took out from the liquid, washed and dried, weighed, and calculated the amount of scale adhesion from the weight before and after the scale adhesion. The phosphorous deoxidized copper pipe produced in the same manner as the evaluation member was also evaluated, and the respective materials were compared and evaluated based on the amount of scale attached to the phosphorous deoxidized copper pipe.

  The case where the amount of scale adhered was less than half that of the phosphorous deoxidized copper was judged as “◯”. In the copper alloy member having the structure according to claim 1, the result of the scale adhesion test is “◯”.

  In addition, the case where the scale adhesion amount in the scale adhesion test was 5/12 or less of the phosphorous-deoxidized copper was designated as “◎”.

(Type I pitting corrosion evaluation method)
In the type I pitting corrosion evaluation method, a field test using a groundwater flow in a region where type I pitting corrosion frequently occurs in a phosphorus-deoxidized copper pipe was conducted for 12 months. The analysis results of the water quality components used are shown in Table 1 below. The evaluation material used was a copper alloy tube having an outer diameter of 12.7 mm, a thickness of 0.71 mm, and a length of 1 m. The evaluation material was controlled by an electromagnetic valve so that water was allowed to pass through the evaluation material only for 30 minutes per day, and the rest was retained while the water remained in the pipe. The flow rate in the tube was adjusted with a flow meter so as to be 0.2 m / sec.

  At the same time, it was evaluated using a phosphorous deoxidized copper tube. As a result of the investigation after 12 months, "X" was obtained when the maximum pitting depth was more than half of the phosphorous deoxidized copper tube, and "○" " To evaluate the maximum pitting corrosion depth, the copper alloy tube or phosphorous-deoxidized copper tube after 12 months has been extracted and divided in the axial direction of the tube, and the inner surface is acid cleaned and then the inner surface is observed visually or using a stereomicroscope. The cross-section of the most corroded part that is observed and confirmed is observed, and the remaining thickness of the bottom of the corrosion hole and the outer surface of the pipe is subtracted from the original thickness of the pipe (0.71 mm) did.

(Type II pitting corrosion evaluation method)
It was based on checking the generation | occurrence | production situation of II type pitting corrosion by allowing the evaluation water adjusted to II type pitting corrosion reproduction conditions to flow in a pipe | tube using the said evaluation member. Using the running water test apparatus shown in FIG. 14, the test water shown in Table 2 below is heated to 60 ° C. in the main tank and allowed to pass through the evaluation material for 30 minutes a day, and otherwise, water is retained in the pipe. I stopped it. The flow rate in the tube was adjusted with a flow meter so as to be 0.2 m / sec. The pH and residual chlorine were constantly measured, and residual chlorine was added with sodium hypochlorite and the pH was adjusted with dilute sulfuric acid by a metering pump. The test water to be circulated was renewed once a month, and the test was continued until 12 months to examine the corrosion status of the specimen. In parallel, a phosphorus-deoxidized copper tube was used for evaluation. As a result of investigation after 12 months, "XX" if the maximum pitting depth is more than half of the phosphorous deoxidized copper tube, "X" if less than half, "△" if less than 1/3, If it was 1/4 or less, it was set as “◯”. To evaluate the maximum pitting corrosion depth, the copper alloy tube or phosphorous-deoxidized copper tube after 12 months has been extracted and divided in the axial direction of the tube, and the inner surface is acid cleaned and then the inner surface is observed visually or using a stereomicroscope. The cross-section of the most corroded part that is observed and confirmed is observed, and the remaining thickness of the bottom of the corrosion hole and the outer surface of the pipe is subtracted from the original thickness of the pipe (0.71 mm) did.

(Yield ratio evaluation)
The yield ratio was evaluated by conducting a tensile test on a copper alloy tube to be evaluated having an outer diameter of 9.52 mm, a thickness of 0.8 mm, and a length of 300 mm, and measuring the tensile strength and the yield strength. As a result of the tensile test, the ratio of the yield strength to the tensile strength is defined as the yield ratio. If the yield ratio is 0.40 or more, “◎”, if it is 0.30 or more and less than 0.40, “◯”, less than 0.30. Then, it was set as “x”.

(Bending evaluation)
The evaluation of the bending workability was based on the hairpin bending process using a pipe bender for hairpin bending process (FIG. 15). After adjusting the outer diameter of the mandrel 21 and the front / rear position of the mandrel with the same size phosphorous deoxidized copper pipe and adjusting the strength of the clamp 22 to confirm that no bending wrinkles occur inside the hairpin bend The copper alloy pipe to be evaluated was bent.

  If the bending wrinkle does not disappear even if the clamping strength is changed without changing the mandrel front and back position, it is judged that the bending is not defective.

  In the bending workability evaluation, an inner grooved tube having an outer diameter of 7 mm produced in the inner grooved tube rolling process evaluation was used as a test material, and the bending pitch 23 of hairpin bending was set to 21.0 mm.

(Inner grooved tube rolling process evaluation)
After annealing an inner smooth element tube with an outer diameter of 10.0 mm and a wall thickness of 0.37 mm in an induction heating furnace, using a carbide tool steel grooved plug, plug / die reduction, and subsequent rolling process, No plug / Dies reduced diameter, outer diameter 7mm, groove bottom thickness 0.25mm, number of grooves 65, fin height 0.23mm, helix angle 35 °, peak angle 22 °, groove bottom R0.04mm inner groove A tube was made.

  When the groove plug is broken during the continuous rolling process, it is detected by the fracture of the pipe material. In order to roll one coil, a length of about 4300 m was continuously rolled, and up to 5 coils were continuously rolled with the same grooved plug. “△” indicates that only one coil has been rolled (breakage or plug defect found in the second coil), “○” indicates that it has been rolled to 3 coils, and “◎” indicates that it has been rolled to 5 coils. "

(Dezincification corrosion evaluation test) (JBMA T303, Japan Copper and Brass Association Technical Standard-Dezincification test method for brass bars)
As the test aqueous solution, a solution prepared by dissolving 0.40 g of sodium hydrogen carbonate and 29.22 g of sodium chloride in water to make 1000 ml was used. A platinum electrode and an electrode sample are set in an aqueous solution saturated with a gas mixed with N ₂ : O ₂ : CO ₂ = [70 ± 1.5]: [20 ± 1.0]: [10 ± 0.5]. Then, constant current electrolysis was performed at a current density of 1.0 mA / cm ^{2 for} 24 hours. During the test, the mixed gas was continuously injected to maintain a saturated state. The aqueous solution was maintained at 60 ± 2 ° C. in a thermostatic bath. After constant current electrolysis for 24 hours, the sample was observed in cross section, and the maximum erosion depth (= dezincing depth + dissolution corrosion depth) was measured. Phosphorus deoxidized copper measured as a comparison had a maximum erosion depth of 10 μm due to the action of only melt corrosion. Of the specimens, those having a maximum erosion depth of 15 μm or more were judged as “x” because of the influence of dezincification corrosion.

(First embodiment)
In this first example, Co, P, Zr, and Sn are added singly or in combination, and the composition and characteristic test results are shown in Table 3 (Tables 3-1, 3-2, and 3-3) below. Show.

  A scale adhesion test, a type I / type II pitting corrosion test, a tensile test, and a bending work test were carried out for the examples of the present invention and comparative examples outside the scope of the present invention by the following methods. It was shown in 3.

  Co, Zr, and Sn are pure metal pellets, and P is added by 15% by mass P copper alloy pellets in the casting process, followed by hot drawing and cold rolling, and a cold drawing process for various tests. Repeatedly, a sample having a predetermined size was annealed and cut into a predetermined length to prepare a specimen.

  The amount of residual carbon attached is standard after the cold drawing process of the copper alloy tube to the final dimension is cleaned with acetone and hexane and then annealed. After applying an oil having the same composition as in Example 1, annealing was performed.

  No. shown in Table 3 Examples 2 and 3 satisfy the first aspect. Items underlined in the table indicate numerical values outside the scope of claim 1 of the present invention. No. 61 is a phosphorus deoxidized copper pipe (JIS H3300 C1220-T) annealed material, which was used to determine a reference value as a comparative material in the scale adhesion evaluation test and the I type / II type pitting corrosion test.

  In addition, No. No. 21, 45, 49, 53, 57 could not adjust the crystal grains. No. 61 was not effective with only a small amount of P.

  Example No. In both 2 and 3, the content of Co was within the scope of the claims, and the adhesion to scale and the bending workability of the tube were excellent. Comparative Example No. In No. 1, the Co content was below the claimed range, the compound of Co and P was small, and the amount of scale adhesion was large. Comparative Example No. No. 4 had a large Co content and a small amount of scale adhered, but a coarse crystallized product was formed, the ductility was lowered, and the bending workability was lowered.

  Example No. In all of Nos. 5 to 7, the contents of Co and P were within the scope of the claims, and exhibited excellent properties of scale adhesion resistance, pipe bending workability, and I-type pitting corrosion resistance. In Comparative Example 8, since the amount of residual carbon was too much, the type I pitting corrosion exceeded half of DHP. Comparative Example No. No. 9 had a Zr content lower than the range of claim 2 and could not maintain the corrosion resistance against type II pitting corrosion. On the other hand, Example No. Nos. 10 and 11 had a Zr content satisfying claim 2, and the scale adhesion amount was reduced. Comparative Example No. In No. 12, since the content of Zr exceeds the range of claim 2, a coarse crystallized product was generated, the ductility was lowered and the bending workability was lowered.

  Example No. In any of 13 to 15, the contents of Co, P and Zr are within the scope of the present invention, and the excellent scale adhesion resistance of the copper alloy member satisfying claim 1 of the present invention is further improved. In addition, it showed excellent bending workability and type II pitting corrosion resistance. Comparative Example No. No. 16 had a large amount of residual carbon, and the I-type pitting depth exceeded half of the comparative material DHP. In Comparative Example 17, the content of Sn was small and there was no effect of type II corrosion resistance. Since Examples 18 and 19 satisfied Claim 3, the type II corrosion resistance was also excellent. In Comparative Example 20, tool breakage occurred during bending with work hardening. In Comparative Example 21, the crystal grains could not be adjusted. In Comparative Example 24, the type II pitting corrosion resistance decreased due to segregation of P accompanying the coarsening of crystal grains. Comparative Example 25 does not satisfy claim 2. Since the Sn content is small, the type II pitting resistance is low. Comparative Example 28 did not satisfy claim 2, and tool breakage occurred during bending by work hardening. The comparative example 29 is satisfied up to claim 3, but is not satisfied with claim 5. Therefore, there is no strength improvement effect by adding the element of claim 5. Comparative Example 32 was satisfied up to claim 3, but a coarse crystallized product was produced, elongation did not occur, and bending workability deteriorated.

  On the other hand, the effect of adding the element contained in the claim was obtained in the example of each claim. Other examples and comparative examples are combinations of the above examples and comparative examples.

(Second embodiment)
As shown in claim 4, the second embodiment contains Zn. Table 4 below shows the composition of the copper alloy tube of the second embodiment. According to the following methods, the grooved tube rolling processability evaluation and the dezincification corrosion evaluation test were performed with and without the requirements shown in claim 4.
Add pure metal pellets of Zn in the casting process, go through hot extrusion and cold rolling, repeat the cold drawing process for various tests, anneal to a predetermined size, cut to a predetermined length And produced.

  Example No. shown in Table 4 above. Reference numerals 64 to 67 are embodiments that satisfy claim 4 of the present invention. Items underlined in Table 4 indicate numerical values outside the scope of claim 4 of the present invention. Comparative Example No. 69 is an annealed material of a phosphorus deoxidized copper pipe (JIS H3300 C1220-T), and was used to determine a reference value as a comparative material in a scale adhesion evaluation test and a type I / type II pitting corrosion test.

  Comparative Example No. with no added Zn Comparative Example No. 62 with Zn content of less than the claims. In No. 63, friction of the grooved plug at the time of groove rolling was increased due to the influence of other elements, and the first coil was finished and the tube broke in the middle of the second coil. In addition, the groove plug was deficient.

  Example No. with a small amount of Zn added. 64 and 65 could be rolled continuously up to the third coil due to the effect, and the tube broke in the middle of the fourth coil. Furthermore, Example No. In Nos. 66 to 68, Zn was further added, and the fifth coil was finished and no fracture occurred. However, Comparative Example No. No. 68 had a large Zn content, and therefore, a sign of dezincification corrosion was observed in the dezincification corrosion evaluation, and it was judged to be impractical for use in the present invention.

(Third embodiment)
Next, an example demonstrating the durability effect of the heat exchanger of the present invention will be described in comparison with a comparative example that is out of the scope of the present invention.
(1) Form of double tube heat exchanger Water flow tube: outer diameter 12.7 mm, wall thickness 0.8 mm, length 8 m
Refrigerant tube: detection structure double tube, inserted into two water tubes Outer tube: outer diameter 5.5mm, bottom thickness 0.5mm, peak height 0.25mm, number of peaks 50
Inner tube: Outer diameter 4.0mm, wall thickness 0.5mm
Structure: Drum winding type FIG. 16 shows a schematic view of this double tube heat exchanger.
(2) Examples and Comparative Examples: Copper alloy tubes having the composition of Example 30 in Table 3 were used as outer tubes of water flow tubes and refrigerant tubes.
Comparative Example: All phosphorus deoxidized copper (H3300 C1220-T)
(3) Test conditions Water flow rate: 1.0 liter / min Refrigerant flow rate: 1.3 kg / min Water side temperature: 20 ° C
Water temperature: 85 ° C
(4) Evaluation method of test About the heat exchanger of an Example and a comparative material, the pressure loss of the heat exchanger was measured before and after the test period. A product in which the pressure loss after the test was doubled compared with the pressure loss before the test period was regarded as a defective product, and a product that did not become a good product.
(5-1) Test conditions and results (scale adhesion evaluation)
CaCO ₃ concentration of the test water: 800CaCO ₃ mg / liter test time: 350 hours

  In Examples 70 and 71, scale adhesion did not progress and the pressure loss did not increase significantly. The increase in pressure loss was not serious even in the internally grooved tube, which was thought to be prone to scale accumulation. On the other hand, Comparative Examples 72 and 73 did not have an effect of preventing scale adhesion, and the pressure loss increased more than doubled after a 350-hour test period. In Comparative Example 73, in which the water flow tube was an internally grooved tube, the pressure loss increased significantly.

(5-2) Test conditions and results (I-type pitting corrosion resistance evaluation)
Operating conditions: Test water by the same field test as in the first example: Ground water in Table 1 (first example)
Test time: 12 months Evaluation method: Maximum corrosion depth by cross-sectional observation

In Examples 70 and 71, since the amount of residual carbon on the inner surface was small, the progression of type I pitting corrosion was small. On the other hand, Comparative Examples 72 and 73 are phosphorous deoxidized copper which does not have pitting corrosion resistance in the first place, and since the residual carbon adhesion amount exceeds a critical value of 5 mg / m ² , the progress of pitting corrosion is large. It was.

(5-3) Test conditions and results (type II pitting corrosion resistance evaluation)
Operating conditions: The same running water test as in the first example Test water: Test water in Table 2 (first example)
Test time: 12 months Evaluation method: Maximum corrosion depth by cross-sectional observation

  In Examples 70 and 71, the alloy composition had type II pitting corrosion resistance, and the progression of type II pitting corrosion was small. Comparative Examples 72 and 73 did not have pitting corrosion resistance, and the progress of pitting corrosion was large.

(Fourth embodiment)
Next, an example demonstrating the effects of heat exchange performance and durability in a heat exchanger composed of a water flow pipe and a refrigerant pipe of the present invention will be described in comparison with a comparative example that is out of the scope of the present invention.
(1) Form of double tube heat exchanger Water flow tube: outer diameter 12.7 mm, wall thickness 0.8 mm, length 8 m, flow path cross-sectional area A
Refrigerant tube: Detection structure double tube, inserted into one water tube Outer tube: Bottom wall thickness 0.5mm, peak height 0.25mm, number of peaks 50
Inner tube: wall thickness 0.5mm, channel cross-sectional area B
Structure: Drum winding type FIG. 17 shows a schematic view of this double tube heat exchanger.
(2) Examples and Comparative Examples Outer pipe of water flow pipe and refrigerant pipe: Inner pipe of copper alloy pipe refrigerant pipe having composition of Example 30 in Table 3: JIS H3300 C1220 Phosphorus deoxidized copper pipe (3) Test conditions Water flow rate : 1.0 liter / min Water-filled side temperature: 20 ° C
(4-1) Test evaluation method (heat exchange performance evaluation)
About the heat exchanger before the test period of an Example and a comparative example, the heat exchange performance was measured. In the double-tube heat exchangers of the example and the comparative example, water is allowed to flow in the water flow pipe, supercritical CO ₂ is allowed to flow in the refrigerant pipe in the direction opposite to the water flow in the water flow pipe, ) Side water temperature was measured. And the influence which the change of a flow-path cross-sectional area exerts on the heat exchange performance of a heat exchanger was measured. FIG. 18 shows a test apparatus for this heat exchange performance test. The case where the temperature of the tapping water was 80 ° C. or higher was rated as “◎”, the case where it was 70 ° C. or higher and lower than 80 ° C. was marked as “◯”, and the case where it was lower than 70 ° C. was marked as “X”.
(5-1) Test conditions and results Entry-side refrigerant pressure: 9 MPa
Refrigerant flow rate: 1.0 kg / min

  Example No. shown in Table 8 above. 75 to 81 are embodiments which satisfy the scope of claim 7 of the present invention. Comparative Example 74 and Examples 75 to 81 had a hot water temperature of 70 ° C. or higher, and showed excellent heat exchange properties as compared with Comparative Example 82.

  Example No. shown in Table 8 above. 75 to 79 are embodiments which satisfy the scope of claim 8 of the present invention. Comparative Example 74 and Examples 75 to 79 had a tapping temperature of 80 ° C. or higher, and exhibited excellent heat exchange properties as compared with Comparative Examples 80 to 82.

(4-2) Test evaluation method (scale adhesion evaluation)
About the heat exchanger of an Example and a comparative example, the pressure loss before and behind test time was measured. A product whose pressure loss after a test time of 350 hours exceeded 1.5 times the pressure loss before the test time was regarded as a defective product, and a product that did not become a defective product. Further, a product whose pressure loss after the test time of 700 hours exceeded 2.0 times the pressure loss before the test time was regarded as a defective product and a product that did not become a defective product.
(5-2) Test conditions and results Refrigerant flow rate: 1.3 kg / min Water discharge side temperature: 85 ° C
CaCO ₃ concentration of the test water: 800CaCO ₃ mg / l Test time: 350 hours, 700 hours

  Example No. shown in Table 9 above. 75 to 81 are embodiments which satisfy the scope of claim 7 of the present invention. In Examples 75 to 81 and Comparative Example 82, scale adhesion did not progress and the pressure loss did not increase significantly. The increase in pressure loss was not serious even in the internally grooved tube, which was thought to be prone to scale accumulation. On the other hand, Comparative Example 74 has no scale adhesion preventing effect, the pressure loss exceeds 1.5 times after 350 hours of test time, and the pressure loss increases to 2.0 times or more after 700 hours of test time. did.

(A), (b) is a member that constitutes the water flow path of the heat exchange portion is a tube (water flow tube). Heat that exchanges heat between the inner surface and the outer surface of the water flow tube by winding one or more refrigerant tubes around the outer surface. It is a figure which shows an exchanger. (A) thru | or (c) is a figure which shows the heat exchanger which a refrigerant | coolant pipe | tube exists in the inside of a water flow pipe, and heats water directly with the said refrigerant | coolant pipe | tube. A heat exchanger that exchanges heat between the inner surface and the outer surface of the water flow portion with a water flow portion of the box-shaped housing having a complicated path inside and a refrigerant pipe that is brought into contact with the box-shaped housing by wrapping or the like. FIG. It is a figure which shows the inner surface grooved pipe | tube which formed many groove | channels in the water flow pipe inner surface. In (a) to (g), the refrigerant pipe is a double pipe composed of a large diameter pipe and a small diameter pipe disposed inside the large diameter pipe, and further between the large diameter pipe and the small diameter pipe. It is a figure which shows the heat exchanger which provided the structure which detects the leakage of the water which distribute | circulates the outside of a large diameter pipe, or the refrigerant | coolant which distribute | circulates the inside of a small diameter pipe. It is a figure which shows what provided the linear or spiral fin on the outer side of a small diameter pipe | tube. (A) thru | or (e) are figures which show a baffle spacer. It is a figure which shows an inner material. (A) thru | or (c) is a figure which shows an inner material. It is a figure which shows a baffle ring. It is a figure which shows a baffle ring and a spacer. It is a figure which shows what corrugated. It is a figure which shows the heat exchanger with which the refrigerant pipe is fitted by the groove | channel provided in the outer side of the water flow pipe. It is a figure which shows a flowing water test apparatus. (A) thru | or (c) is a figure which shows a hairpin bending process evaluation apparatus. It is the schematic of a double tube type heat exchanger. It is the schematic of a double pipe type heat exchanger. This is a test apparatus for heat exchange performance test.

Explanation of symbols

1: Heat transfer tube, 2: Large diameter tube, 3: Small diameter tube, 4: Outer tube, 5: Inner tube, 6: Space part, 7: Outer channel, 8: Inner grooved tube, 9: Box-type housing 10: heat exchanger, 10a: double tube heat exchanger, 11: refrigerant tube, 110: double tube refrigerant tube with detection groove, 110a: leakage detection groove, 12: water flow tube, 13: baffle spacer, 14: inner material, 15: baffle ring, 16: spacer, 17: corrugated pipe, 18: groove, 21: mandrel, 22: clamp, 23: bending pitch, 24: compressor, 25: evaporator, 26: expansion valve , 81: groove, 82: fin, 83: twisted groove, 84: straight groove, 85: crossing groove

Claims (15)

Co is contained in the matrix as a solid solution, simple substance and / or compound in an amount of 0.02 to 0.5% by mass (in the case of a compound, Co equivalent value), and P is contained in the matrix as a solid solution, simple substance and / or The compound contains 0.005 to 0.2% by mass (in the case of a compound, converted to P), the balance is made of Cu and inevitable impurities, and the amount of residual carbon on the surface is 10 mg / m ² or less. A copper alloy member. The copper according to claim 1, further comprising 0.005 to 0.3% by mass (in the case of a compound, Zr converted value) of Zr as a solid solution, a simple substance and / or a compound in the matrix. Alloy member. The copper alloy member according to claim 1, further comprising 0.03 to 3.0 mass% of Sn and having an average crystal grain size of 30 μm or less. The copper alloy member according to any one of claims 1 to 3, further comprising 0.03 to 5.0 mass% of Zn. Furthermore, at least one element selected from the group consisting of Ni: 0.005 to 0.2 mass%, Mg: 0.005 to 0.2 mass%, and Fe: 0.005 to 0.2 mass% The copper alloy member according to any one of claims 1 to 4, wherein a total amount of 0.005 to 0.5 mass% is contained and an average crystal grain size is 10 µm or less. In the heat exchanger which has a water flow path through which water flows and a refrigerant pipe through which a refrigerant flows, and heats the water in the water flow path with the refrigerant in the refrigerant pipe, the water flow path and / or the refrigerant in contact with water A heat exchanger, wherein at least a part of the pipe is made of the copper alloy member according to any one of claims 1 to 5. When the channel cross-sectional area of the water channel is A and the channel cross-sectional area of the refrigerant pipe is B, the ratio A / B of the water channel cross-sectional area to the refrigerant pipe channel cross-sectional area is 1.0 to 12. The heat exchanger according to claim 6, wherein the heat exchanger is 3. When the channel cross-sectional area of the water channel is A and the channel cross-sectional area of the refrigerant pipe is B, the ratio A / B of the water channel cross-sectional area to the refrigerant pipe channel cross-sectional area is 1.0 to 3. The heat exchanger according to claim 6, wherein the heat exchanger is 5. The heat exchanger according to claim 6, wherein the water flow path is a water flow pipe. The heat exchanger according to claim 9, wherein the refrigerant pipe is disposed inside the water flow pipe. The heat exchanger according to claim 10, wherein the water flow pipe is an internally grooved pipe. 12. The refrigerant pipe according to claim 6, wherein the refrigerant pipe has a large-diameter pipe through which the water flows, and a small-diameter pipe arranged in the large-diameter pipe and through which the refrigerant flows. Or a heat exchanger according to claim 1. The heat exchanger according to claim 12, wherein a detection unit that detects leakage of the water or the refrigerant is provided between the large-diameter pipe and the small-diameter pipe. The heat exchanger according to claim 12 or 13, wherein a plurality of grooves having a parallel or twist angle in a tube axis direction are formed on an inner surface of the small diameter tube. The heat exchanger according to any one of claims 12 to 14, wherein fins are formed on at least a part of an outer surface of the large-diameter pipe in the refrigerant pipe.

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