JP2014218590A - Heat storage container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat storage container having excellent reliability to copper damage, in a heat storage container for a heat storage device provided at an air conditioner.SOLUTION: In a heat storage container 1 made of a resin in a heat storage device including an alkaline or neutral heat storage material 3 and metallic refrigerant piping 2 at the inside, by adding a chelate agent 5 to the heat storage material 3, copper ions generated in the case the metallic refrigerant piping 2 is corroded are instantaneously chelated, namely, are instantaneously made harmless, the contact and infiltration of the copper ions on the heat storage container 1 are prevented, thus deterioration in the heat storage container 1 can be prevented.

Description

  The present invention relates to a heat storage container used in a heat storage device provided in an air conditioner.

  Polyolefin resin typified by polypropylene has a phenomenon of copper damage that accelerates the cutting of the polymer in a contact environment with metal, particularly copper, and accelerates deterioration. Therefore, when polypropylene is used in an environment where it comes into contact with copper, an additive called a metal deactivator, also known as a copper damage inhibitor, is often added to the resin to seal the metal. For example, in order to use a polyolefin resin for a plastic part of a coating such as an electric wire coated with a copper wire, a copper damage inhibitor is added to the resin (for example, see Patent Document 1).

JP-A-46-23896

  However, polyolefin resin is a plastic with excellent mechanical properties such as impact resistance, strength and elongation, and heat resistance, low specific gravity, low cost, excellent moldability and recyclability, but it is in contact with metals, especially copper. As a result, there was a problem that the degradation of polymer cutting accelerated.

  When the structure of the above prior art is used to use a polyolefin resin, even if a copper damage inhibitor is added to the resin to a certain level or more, a phenomenon called bleed out occurs in which the inhibitor elutes on the surface over time. There is an upper limit for the addition amount of the harm preventing agent, and the amount of the copper harm preventing agent that can be added to the resin has been limited. Therefore, there is a limit to suppressing copper damage when excess copper contacts and permeates the resin.

  In addition, when there is a copper tube or the like in a polyolefin resin container that encloses the heat storage material, the copper tube corrodes and copper ions diffuse into the heat storage material and contact / penetrate into the container, causing copper damage in the polyolefin resin. In addition to the consumption of the inhibitor, it is also assumed that the copper damage inhibitor is eluted into the heat storage material, and the above configuration alone is not sufficient in reliability against copper damage.

  Accordingly, an object of the present invention is to solve the above-described problem, and an object of the present invention is to provide a heat storage container with excellent reliability against copper damage in a heat storage container for a heat storage device provided in an air conditioner. .

  In order to solve the above-mentioned conventional problems, the heat storage container of the present invention is a resin heat storage container of a heat storage device including an alkaline or neutral heat storage material and a metal refrigerant pipe inside, and a chelating agent is added to the heat storage material. It is a thing.

  As a result, even if copper ions are generated when the metal refrigerant pipe (copper pipe) in the polyolefin resin heat storage container containing the heat storage material is corroded, the hydroxide is maintained by keeping the heat storage material alkaline or neutral. High concentration of ions makes it possible to precipitate and remove copper ions. Furthermore, by adding a chelating agent that forms a complex with copper ions to the heat storage material, copper ions are immediately chelated even in an acidic environment, that is, detoxified, so that the copper ions can contact the inner wall of the resin heat storage container. It is possible to prevent the resin heat storage container from being deteriorated by making it difficult to penetrate.

Copper hydroxide (Cu (OH) 2) produced in the presence of alkaline, neutral, and copper ions has a small solubility product of 1.9 × 10 ^−19, and there is almost no presence of copper ions in alkaline or neutrality. To be judged. On the other hand, the chelating agent also has a high chelating ability with copper ions and can capture and detoxify 99.9% or more of the copper ions. The risk of copper damage can be greatly reduced. Even if the oil for evaporation is decomposed and the pH is lowered due to the formation of organic acid, the chelating agent can detoxify the copper ions. As a result, the heat storage material has almost no copper ions in any environment, so it uses a polypropylene heat storage container, has excellent strength and heat resistance, is highly reliable, inexpensive and comfortable. A heat storage container for a heat storage device can be provided.

Schematic of the heat storage container in Embodiment 1 of the present invention Schematic showing the copper ion chelated by the triazole compound Schematic showing copper ions chelated by ethylenediaminetetraacetic acid

  According to a first aspect of the present invention, in a resin heat storage container of a heat storage device that includes an alkaline or neutral heat storage material and a metal refrigerant pipe, the metal refrigerant pipe is corroded by adding a chelating agent to the heat storage material. Even in this case, it can be immediately removed from the system as copper hydroxide or chelated copper ions. Therefore, since there is almost no copper ion in the heat storage material, the copper ion penetrating into the resin can be greatly reduced, and deterioration of the resin heat storage container can be prevented.

  In the second invention, in particular, when the heat storage container of the first invention is constituted by using a polyolefin resin, even when the metal refrigerant pipe is corroded, it is instantly used as copper hydroxide or chelated copper ions. Can be removed outside. Therefore, since there is almost no copper ion in a heat storage material, the copper ion which permeate | transmits resin can be reduced significantly, and deterioration of a resin-made heat storage container can be prevented.

  In the third invention, in particular, the property of the resin can be greatly customized by using the polyolefin resin of the second invention as a resin containing polypropylene. Polypropylene is a general-purpose resin that is often used as an automobile material, and not only has excellent chemical resistance and heat resistance, but also has a molecular weight design, that is, moldability, glass filler, talc / calcium carbonate as additives, their compatibilizers, and antioxidants. The physical properties and characteristics can be significantly changed by adjusting the addition amount of the agent, copper damage inhibitor, pigment and the like. For this reason, it is effective because the design according to the structure to be used becomes possible.

  In the fourth invention, in particular, by setting the pH value of the heat storage material of the second or third invention to 6 or more, even when copper ions are eluted in the heat storage material solution, it can be immediately precipitated and discharged out of the system. Deterioration of the resin heat storage container can be suppressed.

  In particular, the fifth invention is a benzoate having the effect of reducing corrosion by forming a film on the copper surface as a chelating agent by using a triazole compound as the chelating agent of any one of the first to fourth inventions. By using triazole, mercaptobenzotriazole, tolyltriazole and other triazole compounds such as citric acid, ethylenediaminetetraacetic acid (EDTA), sebacic acid and terephthalic acid, the amount of copper ions acting as copper damage is drastically reduced. be able to.

In the sixth invention, in particular, the heat storage material of any one of the first to fifth inventions is a mixture of water and ethylene glycol, so that the specific heat is large, so that the heat storage amount can be increased, and the heat storage material is frozen even in a sub-freezing atmosphere. Therefore, there is no excessive stress applied to the container due to freezing and expansion, and it is possible to provide a heat storage container including a low-cost excellent heat storage material that hardly generates bacteria and mold.

  In the seventh invention, in particular, the metal refrigerant pipe according to any one of the first to sixth inventions is made of copper and a copper alloy, so that a metal containing copper and aluminum, stainless steel, iron, or an alloy thereof is used as a refrigerant pipe. By using it, it is possible to provide an excellent heat storage container that can sufficiently withstand a high-pressure and high-temperature environment without leaking a refrigerant and can efficiently transfer heat in the heat storage container.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 shows a schematic diagram of a heat storage container according to Embodiment 1 of the present invention.
In FIG. 1, the refrigerant | coolant piping 2 enters from the exterior of the polyolefin heat storage container 1, passes through the heat storage material 3 in the container, and comes out of the container. Polyolefin can be used as the polyolefin, and any of homopolymers, random copolymers, and block copolymers among polypropylenes can be used. Other examples include α-olefin, polyethylene, cross-linked polyethylene, cyclic olefin, and polybutene, and alloy materials such as modified polyphenylene ether polymer-alloyed with polypropylene can also be used. In order to adjust the mechanical strength, talc, calcium carbonate, glass filler and the like can be added. In addition, it is more preferable to contain a copper damage inhibitor in the resin, because even if the metal ion 4 reaches the resin, it is rendered harmless by the copper damage inhibitor that is a chelate in the resin.

  Examples of the heat storage material include a sensible heat storage material and a latent heat storage material, which are liquid or solid depending on the temperature. For sensible heat storage materials, water, ethylene glycol, propylene glycol, mineral oil, bricks, etc. For latent heat storage materials, paraffin, sugar alcohol, sodium sulfate 10 water with a melting point between the temperature of the compressor that is the heat source and the temperature of the refrigerant Japanese hydrate, calcium chloride hexahydrate, sodium acetate trihydrate, sodium carbonate decahydrate and the like can be used. Although melting | fusing point can be used to about -10-50 degreeC, when the temperature difference of the compressor and a refrigerant | coolant by heat storage and heat radiation is considered, about 0 to 40 degreeC is preferable. Since the copper ion concentration can be lowered in an alkaline or neutral environment where the concentration of hydroxide ions 7 is high, it is preferable to maintain alkalinity or neutrality by adding caustic soda or a pH adjuster. The pH is preferably 6 or more, and preferably 9 or more is always kept in consideration of time-series changes. Since the heat storage material is likely to evaporate at a high temperature, it is possible to dispose hydrocarbon or silicon-based oil having a specific gravity lower than that of the heat storage material on the heat storage material.

  The metal of the refrigerant pipe 2 is copper, a copper alloy belonging to a broad sense, aluminum, aluminum alloy, stainless steel, carbon steel that forms a passive film in the alkaline region, etc., which exhibits excellent corrosion resistance due to the passive film in the neutral region. it can. PH adjustment and rust preventive agent according to each characteristic are needed.

It has been clarified that the copper ion promotes the resin deterioration as described in Minakawa Gennobu, Organic Synthetic Chemistry, Vol. 31, No. 5 (1973). Thus, when metal ions 4 are generated in the container due to corrosion, copper damage occurs due to contact with the resin and permeation. However, by maintaining a high pH, the copper ion concentration can be lowered to a ppm level or less, and if there is a chelating agent 5, the metal ion 4 is immediately chelated to become a chelated metal ion 6 and detoxified. Is done. As the chelating agent, it is preferable to use a compound containing a pyrrole ring, a pyrazole ring, a thiazole ring and an imidazole ring in addition to the triazole compound 9 which is a heterocyclic compound having an effect of reducing corrosion by forming a film on the copper surface. . For example, 1.2.3-benzotriazole, 1.2.3-benzotriazole sodium salt, mercaptobenzotriazole, tolyltriazole, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium salt, and benzotriazole. In addition, ethylenediaminetetraacetic acid 11 (EDTA), hydroxyethylenediaminetriacetic acid (EDTA-OH), glycol etherdiaminetetraacetic acid (GEDT), hydroxyethyliminodiacetic acid (HIDA), iminodiacetic acid (IDA) ), Nitrilotriacetic acid (NTA) can also be used. The type of chelating agent is not limited to the above, and any chelating agent can be used as long as it does not chelate with copper ions and adversely affect corrosion.

  Further, it can be used in a state where a chelating agent is held in a fiber or the like. Furthermore, not only chelate but also ion exchange resin or activated carbon that captures or adsorbs copper ions can be used.

  FIG. 2 is a schematic diagram showing copper ions chelated by triazole compound 9 as an example of chelation, and FIG. 3 is a schematic diagram showing copper ions chelated by ethylenediaminetetraacetic acid 11 (EDTA). It is. The chelate formation constant of ethylenediaminetetraacetic acid 11 and copper ion 12 is said to be 18.8. See Equation 1 below.

  This indicates that when ethylenediaminetetraacetic acid 11 and copper ions are present in the same number of moles, 99.99% or more of the copper ions are chelated, and the copper ions that cause copper damage are brought into contact with the resin. Can be greatly reduced.

  Table 1 shows the results of experiments conducted to verify the above hypothesis.

  The heat storage material is an aqueous solution of various pHs consisting of ethylene glycol and benzotriazole (with additives), pH adjuster, etc., and copper chloride is added to the glass container containing the heat storage material to simulate copper pipe corrosion. The manufactured dumbbell test piece was immersed at 100 ° C. for 1 year. The copper concentration in the supernatant of the test solution after the test was quantitatively analyzed by inductively coupled plasma emission spectrometry, and the residual amount of benzotriazole was quantitatively analyzed by liquid chromatography. Since the measured copper concentration is not necessarily all copper ions, it is considered to be the maximum amount of copper ion concentration. For production of dumbbells, J705UG pellets made of prime polymer not containing copper damage inhibitor and reinforcing material were used. The dumbbell shape was based on JIS, and the tensile strength was measured at 23 ° C. at a tensile speed of 50 mm / min.

  Test result No. with no benzotriazole added From 1-4, in an environment where the concentration of hydroxide ions 7 at pH 4 is small, when copper ions are mixed into the heat storage material, copper ions are present in the liquid as they are (No. 1), but as the pH increases, hydroxylation occurs. It was clarified that when the product ions 7 increased, a precipitate presumed to be a copper hydroxide was generated in the liquid, and the copper concentration in the liquid was decreased (No. 2-4).

  On the other hand, when benzotriazole was added, In No. 5-24, a precipitate that appeared to be benzotriazole copper was formed with the addition of copper, and at the same time, a decrease in the benzotriazole concentration in the liquid was observed. Even at pH 4, when the benzotriazole was not added, the copper concentration of 998 ppm (No. 1) was 10 ppm (No. 8), and a clear decrease in the copper concentration in the liquid was observed.

The strength of polypropylene immersed for 1 year at 100 ° C. is No. having a copper concentration of 600 ppm or more. 1 and No. Although a significant decrease was observed in No. 9, it was judged that there was no problem if a copper damage inhibitor was added to the resin while maintaining the pH at 6 or higher.

  From these results, even if copper ions are mixed into the liquid due to corrosion, the precipitate containing copper is generated by hydroxide and benzotriazole, so that it does not penetrate into the resin and cause deterioration of the resin. That was proved.

  As described above, in the present embodiment, in a resin heat storage container of a heat storage device that includes an alkaline or neutral heat storage material and a metal refrigerant pipe, heat is stored by adding a chelating agent to the heat storage material. Even if copper ions are generated when the metal refrigerant pipe (copper pipe) in the polyolefin resin heat storage container enclosing the material corrodes, high concentration of hydroxide ions is maintained by keeping the heat storage material alkaline or neutral. Then, copper ions can be precipitated and removed. Furthermore, by adding a chelating agent that forms a complex with copper ions to the heat storage material, copper ions are immediately chelated even in an acidic environment, that is, detoxified, so that the copper ions can contact the inner wall of the resin heat storage container. It is possible to prevent the resin heat storage container from being deteriorated by making it difficult to penetrate.

  As described above, the polyolefin heat storage container of the air conditioner according to the present invention is excellent in mechanical strength such as copper damage and impact resistance, and thus has high reliability without being damaged by dropping. In addition, the specific gravity is small, light, inexpensive, and excellent in moldability and water vapor permeability. Therefore, it can be applied to any air conditioner for shortening the defrosting time during heating.

DESCRIPTION OF SYMBOLS 1 Polyolefin thermal storage container 2 Refrigerant piping 3 Thermal storage material 4 Metal ion 5 Chelating agent 6 Chelated metal ion 7 Hydroxide ion 8 Copper hydroxide 9 Triazole compound 10 Copper ion chelated by triazole compound 11 Ethylenediamine Tetraacetic acid 12 Copper ion chelated by ethylenediaminetetraacetic acid

Copper hydroxide (Cu (OH) 2) produced in the presence of alkalinity, neutrality and copper ions has a small solubility product of 1.9 × 10-19, and there is almost no presence of copper ions in alkalinity and neutrality. To be judged. On the other hand, the chelating agent also has a high chelating ability with copper ions and can capture and detoxify 99.9% or more of the copper ions. The risk of copper damage can be greatly reduced. Even if the oil for evaporation is decomposed and the pH value is lowered due to the generation of organic acid, the chelating agent can detoxify copper ions. As a result, the heat storage material has almost no copper ions in any environment, so it uses a polypropylene heat storage container, has excellent strength and heat resistance, is highly reliable, inexpensive and comfortable. A heat storage container for a heat storage device can be provided.

Examples of the heat storage material include a sensible heat storage material and a latent heat storage material, which are liquid or solid depending on the temperature. For sensible heat storage materials, water, ethylene glycol, propylene glycol, mineral oil, bricks, etc. For latent heat storage materials, paraffin, sugar alcohol, sodium sulfate 10 water with a melting point between the temperature of the compressor that is the heat source and the temperature of the refrigerant Japanese hydrate, calcium chloride hexahydrate, sodium acetate trihydrate, sodium carbonate decahydrate and the like can be used. Although melting | fusing point can be used to about -10-50 degreeC, when the temperature difference of the compressor and a refrigerant | coolant by heat storage and heat radiation is considered, about 0 to 40 degreeC is preferable. Since the copper ion concentration can be lowered in an alkaline or neutral environment with a high concentration of hydroxide ions 7, it is preferable to maintain the alkali ion or neutrality by adding caustic soda or a pH value adjusting agent. It is desirable that the pH value is always 6 or more, preferably 9 or more in consideration of the time series change. Since the heat storage material is likely to evaporate at a high temperature, it is possible to dispose hydrocarbon or silicon-based oil having a specific gravity lower than that of the heat storage material on the heat storage material.

The metal of the refrigerant pipe 2 is copper, a copper alloy belonging to a broad sense, aluminum, aluminum alloy, stainless steel, carbon steel that forms a passive film in the alkaline region, etc., which exhibits excellent corrosion resistance due to the passive film in the neutral region. it can. Adjustment of pH value and rust preventive agent according to each characteristic are required.

It has been clarified that the copper ion promotes the resin deterioration as described in Minakawa Gennobu, Organic Synthetic Chemistry, Vol. 31, No. 5 (1973). Thus, when metal ions 4 are generated in the container due to corrosion, copper damage occurs due to contact with the resin and permeation. However, by maintaining a high pH value , the copper ion concentration can be lowered to a ppm level or less, and if there is a chelating agent 5, the metal ion 4 is immediately chelated to become a chelated metal ion 6 and harmless. It becomes. As the chelating agent, it is preferable to use a compound containing a pyrrole ring, a pyrazole ring, a thiazole ring and an imidazole ring in addition to the triazole compound 9 which is a heterocyclic compound having an effect of reducing corrosion by forming a film on the copper surface. . For example, 1.2.3-benzotriazole, 1.2.3-benzotriazole sodium salt, mercaptobenzotriazole, tolyltriazole, 2-mercaptobenzothiazole, 2-mercaptobenzothiazole sodium salt, and benzotriazole. In addition, ethylenediaminetetraacetic acid 11 (EDTA), hydroxyethylenediaminetriacetic acid (EDTA-OH), glycol etherdiaminetetraacetic acid (GEDT), hydroxyethyliminodiacetic acid (HIDA), iminodiacetic acid (IDA) ), Nitrilotriacetic acid (NTA) can also be used. The type of chelating agent is not limited to the above, and any chelating agent can be used as long as it does not chelate with copper ions and adversely affect corrosion.

The heat storage material is an aqueous solution of various pH values consisting of ethylene glycol and benzotriazole (with and without additives), pH value adjusting agent, etc. The polypropylene dumbbell test piece was immersed in 100 ° C. for 1 year. The copper concentration in the supernatant of the test solution after the test was quantitatively analyzed by inductively coupled plasma emission spectrometry, and the residual amount of benzotriazole was quantitatively analyzed by liquid chromatography. Since the measured copper concentration is not necessarily all copper ions, it is considered to be the maximum amount of copper ion concentration. For production of dumbbells, J705UG pellets made of prime polymer not containing copper damage inhibitor and reinforcing material were used. The dumbbell shape was based on JIS, and the tensile strength was measured at 23 ° C. at a tensile speed of 50 mm / min.

Test result No. with no benzotriazole added From 1-4, in an environment where the concentration of hydroxide ions 7 having a pH value of 4 is small, if copper ions are mixed into the heat storage material, copper ions are present in the liquid as they are (No. 1), but the pH value is increased. Accompanying this, when the hydroxide ions 7 increased, it was clarified that a precipitate presumed to be a copper hydroxide was generated in the liquid, and the copper concentration in the liquid decreased (No. 2-4).

On the other hand, when benzotriazole was added, In No. 5-24, a precipitate that appeared to be benzotriazole copper was formed with the addition of copper, and at the same time, a decrease in the benzotriazole concentration in the liquid was observed. Even at a pH value of 4, when the benzotriazole was not added, the copper concentration of 998 ppm (No. 1) was 10 ppm (No. 8), and a clear decrease in the copper concentration in the liquid was observed.

The strength of polypropylene immersed for 1 year at 100 ° C. is No. having a copper concentration of 600 ppm or more. 1 and No. Although a significant decrease was observed in No. 9, it was judged that there was no problem if a copper damage inhibitor was added to the resin while maintaining the pH value at 6 or higher.

Claims (7)

A resin heat storage container of a heat storage device including an alkaline or neutral heat storage material and a metal refrigerant pipe therein, wherein a chelating agent is added to the heat storage material. The heat storage container according to claim 1, wherein the heat storage container is configured using a polyolefin resin.   The heat storage container according to claim 2, wherein the polyolefin resin is a resin containing polypropylene. The pH value of the said heat storage material was 6 or more, The heat storage container of Claim 2 or 3 characterized by the above-mentioned. The heat storage container according to any one of claims 1 to 4, wherein the chelating agent is a triazole compound. The heat storage container according to any one of claims 1 to 5, wherein the heat storage material is a mixture of water and ethylene glycol. The heat storage container according to claim 1, wherein the metal refrigerant pipe is made of copper and a copper alloy.