JP2005351600A - Aluminum heat exchanger and its scale deposition preventing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum heat exchanger of a parallel flow type to be advantageously used as a heat exchanger for a building air conditioning system which can be smaller and lighter while using heat medium water, and to provide a scale deposition preventing method for preventing the deposition of scale which results in lower heat exchanging efficiency and heat exchanger pipe clogging. <P>SOLUTION: A plurality of heat exchanger pipes formed of aluminum or aluminum alloy are constituted by flat tubes which have partition walls e sectioned in the pipes to form a plurality of sectioned flow paths in approximate parallel and which have thicknesses (a) of 1.5-3 mm and hole widths (c) 3 mm or less. They have hydromechanical diameters of 1.3-3.0 mm. Corrugated fins formed of aluminum or aluminum alloy are arranged between the heat exchanger pipes, and they have heights (h) of 6-12 mm. The aluminum heat exchanger uses water as heat medium. The scale deposition preventing method uses the heat medium water which is produced by adding aluminum anticorrosive agent to treatment water subjected to previous scale deposition preventing treatment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aluminum heat exchanger using hot water or cold water as a heat medium and a method for preventing scale adhesion, and is not particularly limited, but is a parallel flow type aluminum heat exchanger using water as a heat medium. In particular, the present invention relates to an aluminum heat exchanger suitable for use in an air conditioner in a large-scale indoor space such as a building or an office, and a method for preventing scale adhesion.

  In general, heat exchangers used for air conditioning equipment in relatively large indoor spaces that manage the air conditioning of the entire building or the air conditioning of each office (hereinafter referred to as “heat exchangers for building air conditioning systems”). )) Uses fresh water such as tap water, industrial water, and groundwater as a heat medium, and requires materials with excellent thermal conductivity and corrosion resistance. A copper heat exchanger having a pipe is used, and as a heat medium used in such a copper heat exchanger, since the hydraulic diameter of the heat exchange pipe is usually 8 mm or more, a scale component in water (mainly Calcium and magnesium) are less likely to adhere to the inner wall of the heat exchange tube as scale, and there is relatively little risk of clogging the heat exchange tube, and measures to prevent scale adhesion are relatively easy. To be Required by taking steps of the scale adhesion prevention as follows water (hot and cold water) is used.

  That is, for example, an H-type cation exchange resin and a pH detection means are provided as means for preventing scale adhesion of a copper heat exchanger that uses water as a heat medium in this way, and part or all of the cooling water is H-type cation exchange. A method of suppressing the generation of scale by removing the scale component in the cooling water through the resin and detecting the pH value of the cooling water and controlling the amount of the cooling water passing through the H-type cation exchange resin by this pH value (See Japanese Patent Publication No. 55-28,759), a method of preventing the generation of scale by adding a chelating agent such as EDTA to water as a heat medium at a predetermined ratio (Japanese Patent Laid-Open Nos. 61-174,990 and 2000-2000). No. 246,286), cooling water is brought into contact with calcium carbonate particles and / or silica gel particles to remove scale components and the gelatinous film is viscous on a solid surface in water in cooling water A method of adding a slime control agent that prevents the formation of (slime) (see JP-A-2002-273,477) is known.

  On the other hand, air-conditioning equipment used for vehicles is required to be small and lightweight, and therefore uses the workability, heat conductivity, and lightness of aluminum or aluminum alloy (hereinafter referred to as “aluminum material”). A pair of header pipes arranged parallel to each other at a predetermined interval and having a heat medium inlet and outlet, and a plurality of aluminum pipes formed between the pair of header pipes and parallel to each other. A parallel flow type aluminum heat exchanger having a plurality of heat exchange tubes (condensation tubes) forming a heat medium flow path is used. Further, in this parallel flow type aluminum heat exchanger, the hydraulic diameter of the heat exchange pipe is usually up to 0.38 mmφ in order to efficiently secure the heat transfer area, so that the scale due to the scale component in the water is heated. It is easy to adhere to the inner wall surface of the exchange pipe, and the heat exchange pipe is easily clogged. Further, the heat exchange pipe made of aluminum also has a problem of corrosion. An aqueous heat medium is used (see, for example, Japanese Patent Publication No. 5-87,752, Japanese Patent Publication No. 7-62,596, Japanese Patent Application Laid-Open No. 9-68,395, etc.).

  However, in recent years, demands for higher performance, space saving, lighter weight, simplified recycling, and the like are also increasing in the heat exchangers for building air conditioning systems because of the conservation of the global environment. However, in conventional air-conditioning equipment, the use of water as a heat medium is not particularly problematic, but the heat transfer area of the heat exchange tube cannot be increased easily, making it difficult to achieve higher performance and space saving. There was a situation.

  Therefore, it is conceivable to use a parallel flow type aluminum heat exchanger having excellent workability and heat conductivity and a large heat transfer area of the heat exchange tube. However, since this parallel flow type aluminum heat exchanger was originally developed for use in air conditioning in automobiles, non-aqueous materials such as chlorofluorocarbon were used as the heat medium, and high performance and space saving were promoted. . For this reason, the heat medium flow path of the heat exchange pipe through which the heat medium passes is a collection of extremely thin tube bundles in order to make the heat transfer area as large as possible, and the aluminum material is comparatively tap water or industrial water. Therefore, a parallel flow type aluminum heat exchanger using hot water or cold water as a heat medium has not been tried as a heat exchanger for a building air conditioning system.

Further, for vehicle radiators and the like, flat tubes made of aluminum material are used as heat exchange tubes (for example, JP-A Nos. 2004-17, 116, 8-134,574, 7-83,594, etc.). (See the publications). However, since the flat tubes used in these vehicle radiators are electric sewing tubes and brazing tubes formed from thin plates, the inside of the tube has a long hole structure of about one or two holes. Therefore, it cannot withstand the pump pressure (usually 0.5 MPa or more) necessary for the movement of water as the heat medium of the heat exchanger for the building air conditioning system.
Japanese Patent Publication No.55-28,759 JP 61-174,990 JP 2000-246,286 Japanese Patent Laid-Open No. 2002-273,477 Japanese Patent Publication No. 5-87,752 Japanese Patent Publication No.7-62,596 JP-A-9-68,395 Japanese Unexamined Patent Publication No. 2004-17,116 Japanese Patent Laid-Open No. 8-134,574 JP-A-7-83,594

  Accordingly, the present inventors are aluminum heat exchangers such as a parallel flow type that can be reduced in size and weight using hot water or cold water as a heat medium, and are advantageously used as heat exchangers for building air conditioning systems. As a result of intensive studies on an aluminum heat exchanger that can be used and a method for preventing scale adhesion, a heat exchange tube formed of an aluminum material having a hydraulic diameter of 1.3 to 3.0 mm is used. The inventors have found that the purpose can be achieved by using heat transfer water obtained by adding an aluminum anticorrosive to treated water that has been subjected to scale adhesion prevention treatment in advance, thereby completing the present invention.

  Accordingly, an object of the present invention is a parallel flow type aluminum heat exchanger that can be reduced in size and weight using water as a heat medium, and is advantageously used as a heat exchanger for a building air conditioning system. It is to provide an aluminum heat exchanger that can be used.

  In addition, another object of the present invention is to enable the adhesion of scales that cause a decrease in heat exchange efficiency and blockage of heat exchange pipes in a parallel flow type aluminum heat exchanger using hot water or cold water as a heat medium. It is intended to provide a method for preventing scale adhesion of an aluminum heat exchanger that can be reduced in size, reduced in weight, etc., and can be advantageously used as a heat exchanger for a building air conditioning system. .

  That is, the present invention is formed of a pair of header pipes arranged at predetermined intervals and having a heat medium inlet and outlet, and aluminum or an aluminum alloy, and spanned between the pair of header pipes. Aluminum having a plurality of heat exchange pipes forming a plurality of heat medium flow paths and fins formed of aluminum or aluminum alloy and disposed between the heat exchange pipes, and using water as a heat medium Each of the heat exchange tubes is a flat plate having a thickness a1.5 to 3 mm and a hole width c3 mm or less provided with partition walls e that are partitioned from each other to form a plurality of substantially parallel partitioned flow paths. An aluminum heat exchanger characterized in that it is made of a tube and has a hydraulic diameter of 1.3 to 3.0 mm, and the fin is a corrugated fin having a height of h6 to 12 mm.

  In addition, the present invention is a pair of header pipes arranged at a predetermined interval and having a heat medium inlet and outlet, and formed of aluminum or an aluminum alloy, and spanned between the pair of header pipes. A plurality of heat exchange pipes forming a plurality of heat medium flow paths, and corrugated fins formed of aluminum or aluminum alloy and disposed between the heat exchange pipes. This is a method for preventing scale adhesion of an aluminum heat exchanger having a diameter of 1.3 to 3.0 mm, and heat medium water obtained by adding an aluminum anticorrosive to treated water that has been previously treated to prevent scale adhesion as a heat medium. A method for preventing scale adhesion of an aluminum heat exchanger.

  The heat exchanger of the present invention is formed of a pair of header pipes arranged at predetermined intervals and having a heat medium inlet and outlet, and aluminum or aluminum alloy, and is installed between the pair of header pipes. An aluminum heat exchanger having a plurality of heat exchange tubes that form a plurality of heat medium flow paths and corrugated fins formed of aluminum or an aluminum alloy and disposed between the heat exchange tubes. Preferably, it is a so-called parallel flow type aluminum heat exchanger in which a pair of header pipes are arranged in parallel to each other and a plurality of heat exchange pipes are laid in parallel between the pair of header pipes.

  Here, for each of the heat exchange tubes, it is necessary to be a flat tube in order to achieve a desired heat exchange efficiency, and inside the tube has a partition wall e that partitions the inside of the tube from each other, As a result, the inside of the tube is preferably formed into a plurality of partitioned flow paths having a substantially square cross section and substantially parallel to each other. Further, the hole width c of the partition channel needs to be at least 3 mm or less, and is preferably 1.5 mm or more and 2.5 mm or less, although it depends on the thickness d of the flat tube. As for the hole width c of the partition channel, it is necessary to increase the thickness d as the hole width c is increased. When the hole width c exceeds 3 mm, the thickness d of the flat tube is not set to 0.4 mm or more. As long as the pressure strength 0.5MPa desired for a building air conditioner heat exchanger cannot be satisfied, conversely, if the thickness d of the flat tube is made too thick, not only the weight of the heat exchanger increases, but also the thickness of the flat tube Unless the hydraulic diameter a is changed, the hydraulic diameter is inevitably reduced, and if this hydraulic diameter is smaller than 1.5 mm, the adverse effects described later occur, and if the thickness a of the flat tube is increased without changing the passage cross-sectional shape, This is not preferable because problems such as a reduction in air-side heat transfer area and an increase in ventilation resistance occur.

  Further, the thickness a of the flat tube used as the heat exchange tube needs to be 1.5 mm or more and 3 mm or less, preferably 1.5 mm or more and 2.5 mm or less, and the tube thickness a is 1.5 mm. If it is smaller, the height of the partition channel is inevitably lowered, the hydraulic diameter becomes smaller, the transition flow velocity during cooling operation exceeds 3 m / sec, and erosion occurs, and the tube thickness a is If it exceeds 3 mm, the ratio of flat tube thickness a / tube pitch (h + a) increases unless the fin height h is increased, the air side resistance increases, and the air heat transfer area decreases, When the same fan is used, the heat exchange performance is degraded due to insufficient air volume and insufficient heat transfer area on the air side. If the fin height h is increased beyond 12 mm, the fin efficiency (the entire surface of the fin is a flat tube). The immediate vicinity of The actual heat exchange amount on the fin surface with respect to the heat exchange amount when it is assumed to be equal to the temperature of (2) is lower than 0.8, and the heat exchange efficiency is lowered.

  And about the corrugated fin arrange | positioned between each heat exchange pipe, the height h needs to be 6 mm or more and 12 mm or less, and when this fin height h is lower than 6 mm, it is required on heat exchange efficiency. It becomes difficult to satisfy the condition that the ratio of thickness a / pitch tube (h + a) of the flat tube to be 0.2 or less. On the contrary, when the fin height h exceeds 12 mm, the fin efficiency is more than 0.8. It becomes low and heat exchange efficiency falls.

In the aluminum heat exchanger of the present invention, each of the heat exchange tubes must have a hydraulic diameter of 1.3 mm to 3.0 mm. If the hydraulic diameter is less than 1.3 mm, the pressure loss on the water side is reduced. It becomes large and it becomes difficult for water as a heat medium to flow, and there is a problem that erosion occurs because a flow rate of 3 m / sec or more is required as a transition flow rate during cooling operation. The heat transfer area on the water side is reduced with respect to the cross-sectional area, the heat exchange efficiency is lowered, and it becomes difficult to use it as a heat exchanger for a large-scale indoor air conditioner. Here, the “hydraulic diameter” is the value (mm) obtained by multiplying the cross-sectional area (mm ² ) of the flow path of the heat exchange pipe by 4 and dividing the obtained value by the wet perimeter of the flow path (mm). is there.

  Here, when the heat exchange tube is formed of a flat tube and the hydraulic diameter exceeds 3.0 mm, (1): only the hydraulic diameter without increasing the thickness a of the flat tube If the size is increased, the shape of the hole becomes very large with respect to the short side, and the pressure resistance that can be used as a heat exchanger for a building air conditioning system cannot be expressed. (2): Flat tube thickness a When the hydraulic diameter is increased by increasing the thickness of the fin, if the fin height h is constant, the ratio of the fin height h + the fin height h to the flat tube thickness a decreases, and the air-side pressure loss increases. If the air volume decreases or the air side heat transfer area decreases, the heat exchange efficiency decreases, and (3): If the ratio of the fin height h is not changed in the case of (2) above, the fin height As h increases, fin efficiency decreases. Exchange efficiency is reduced.

  Further, in the present invention, the thickness d of the flat tube is preferably 0.2 mm or more and 0.5 mm or less, and preferably 0.3 mm or more and 0.4 mm or less. If the thickness is less than 2 mm, the pressure resistance of the flat tube decreases, and it becomes difficult to achieve a desired pressure resistance (for example, 0.5 MPa). Conversely, even if the tube thickness d is greater than 0.5 mm, The material cost increases and the product weight only increases, and if the tube thickness d is increased in the direction of reducing the cross-sectional area of the flow path, the desired hydraulic diameter cannot be maintained.

  In the present invention, water is used as the heat medium, but the water as the heat medium contains additives such as antifreeze liquids such as ethylene glycol and propylene glycol and various aluminum anticorrosives as necessary. Also good.

By the way, the heat conductivity in the heat exchange pipe varies greatly depending on the flow of the heat medium flowing in the pipe, and it is necessary to make the flow in the pipe turbulent in order to increase the heat conductivity. For this reason, the Reynolds number (Re) represented by the following formula needs to be 2,700 or more, preferably 3,000 or more.
Re = ρ · u · De / η
(Ρ: density of the heat medium, η: viscosity coefficient of the heat medium, De: hydraulic diameter of the hole of the heat exchange pipe, u: flow velocity of the heat medium in the heat exchange pipe)
And in the heat exchanger for building air conditioning systems using water as a heat medium, the temperature of the heat medium is 5 to 10 ° C., preferably 7 ° C. during cooling, and 40 to 50 ° C., preferably 45 ° C. during heating. .

  Therefore, when using a heat exchange tube with a hydraulic diameter of 1.3 to 3.0 mm, in order to become turbulent during cooling, a flow velocity of about 2.5 m / sec or more when the hydraulic diameter is 1.3 mm. In addition, when the hydraulic diameter is 3.0 mm, a flow velocity of about 1.2 m / second or more is required. Furthermore, erosion of the inner surface of the heat exchange tube is likely to occur at a flow velocity of 3 m / second or more. The flow rate during cooling is preferably 1.2 m / second or more and 3.0 m / second or less. Also, in order to become turbulent during heating, a flow velocity of about 1.1 m / sec or more is required when the hydraulic diameter is 1.3 mm, and about 0.5 m / sec or more when the hydraulic diameter is 3.0 mm. Since the erosion of the inner surface of the heat exchange tube is likely to occur at a flow rate of 3 m / second or more, the flow velocity during heating is 0.5 m / second or more and 3.0 m / second or less. Is good.

  When the above-described aluminum heat exchanger of the present invention is actually used, for example, as a heat exchanger for a building air conditioning system, water is used as a heat medium. It is necessary to prevent clogging, and in the present invention, as a method for preventing scale adhesion of this aluminum heat exchanger, a heat medium obtained by adding an aluminum anticorrosive to treated water that has been subjected to scale adhesion prevention treatment in advance. Water is used as the heating medium.

  Here, the treated water that has been subjected to the scale adhesion prevention treatment in advance is a small amount of scale components obtained by descaling untreated water such as tap water or industrial water by an appropriate method, preferably calcium ions. In addition to fresh water with a concentration of 5 mg / L or less, more preferably with a calcium ion concentration of 3 mg / L or less, in the heat medium path of the heat exchange cycle in which the aluminum heat exchanger of the present invention is incorporated, or this heat medium Appropriate processing means is provided outside the path, and fresh water obtained by preferentially precipitating the scale component prior to precipitation of the scale component in each heat exchange tube of the aluminum heat exchanger in this processing means is also included. If the calcium ion concentration of the treated water obtained by descaling exceeds 5 mg / L, the scale mainly composed of calcium may be deposited and the heat exchange tube may be blocked when the operation is continued for a long time.

  Specific examples of the treated water that has been subjected to scale adhesion prevention treatment in advance include fresh water obtained by decalcifying untreated water with an ion exchange resin. Examples of the ion exchange resin used for this purpose include weakly acidic or strongly acidic cation exchange resins and monovet ion exchange resins. Specifically, for example, an ion exchange resin Amberlite trade name manufactured by Organo Corporation, IRC50, IR120B, MB-2 etc. can be illustrated.

  Other treated water includes fresh water obtained by adding an acid to untreated water and precipitating a scale component to separate and remove (acid addition treatment). Examples of acids used for this purpose include mineral acids such as phosphoric acid, nitric acid, chloric acid, and sulfuric acid, and organic acids such as oxalic acid, citric acid, and acetic acid. From the viewpoint of the corrosiveness of the aluminum material, Phosphoric acid and oxalic acid are preferred.

  In addition, as other treated water, a chelate compound that is easily soluble in water is formed by combining with the scale component in untreated water, and an appropriate chelating agent that suppresses the precipitation of the scale component is added. The fresh water obtained by the chelating agent addition process which suppresses as much as possible can be mentioned. Examples of the chelating agent added for this purpose include iminodiacetic acid, nitrilotriacetic acid, ethylenediaminetetraacetic acid (EDTA), cyclohexanediaminetetraacetic acid, ethyl etherdiaminetetraacetic acid, glycol etherdiaminetetraacetic acid, propylenediaminetetraacetic acid, Examples include aminocarboxylic acids such as diethylenetriaminepentaacetic acid and triethylenetetraminehexaacetic acid or metal salts thereof, polyvalent carboxylic acids such as oxalic acid and citric acid or metal salts thereof, inorganic acids such as phosphoric acid or metal salts thereof, and the like. it can. The amount of the chelating agent to be added is determined by the amount of the scale component contained in the untreated water. For example, the amount is usually 10 to 5000 mmol, preferably 100 to 1000 mmol, per 1 mmol of alkaline earth metal ion as the scale component. .

  As another example of treated water that has been subjected to scale adhesion prevention treatment in advance, untreated water is heated with a heater to a predetermined temperature, usually 60 ° C. or higher and 100 ° C. or lower, preferably 70 ° C. or higher and 80 ° C. or lower. Examples thereof include heat-treated fresh water that preferentially deposits a water scale component on the heat transfer surface of the heater. Examples of the heater used for this purpose include stainless steel-coated electric heaters, and in consideration of removal of scales deposited on the heat transfer surface later, the heat transfer surface is preferably coated with a fluororesin. The product name U-Freon heater is good.

  Furthermore, as another example of the treated water, the scale component of the untreated water is obtained by flowing the untreated water into the high-speed flow path that flows at a flow rate faster than the flow rate in the heat medium flow path formed by each heat exchange pipe. Examples thereof include fresh water that is preferentially deposited in a high-speed flow path and is subjected to a high-speed water flow treatment. Here, the flow rate in the high-speed flow path may be a little faster than the flow rate in the heat medium flow path formed by each heat exchange pipe, but is preferably about 1.1 to 5.0 times, more preferably 1 .5 to 5.0 times is preferable.

The aluminum anticorrosive added to the treated water is not particularly limited as long as it is added to fresh water in a system where aluminum and fresh water are in contact with each other and can prevent corrosion of aluminum. What is used more as this kind of aluminum corrosion inhibitor can be used, for example, phosphoric acid type | system | groups, such as Otsuka Chemical Co., Ltd. brand name "Shadan R", Chiyoda Chemical Co., Ltd. brand name "Thiolite C-412", etc. Anti-corrosive agent, sodium silicate 3 (Na ₂ O 3SiO ₂ ; manufactured by Nippon Kagaku Kogyo Co., Ltd.), Nikuri Co., Ltd. trade name “cold hot water 20-L”, etc. Examples thereof include chromic acid-based anticorrosives such as “Alsurf # 1200” and amine-based anticorrosives such as “Thiolite C-372A” manufactured by Chiyoda Chemical Co., Ltd. Among these, phosphoric acid-based anticorrosives and silicic acid-based anticorrosives are particularly preferable because they are not only excellent in anticorrosion performance against aluminum materials but also have high safety for animals, humans, and the environment.

In the scale adhesion prevention method of the present invention, the amount of the aluminum anticorrosive added to the treated water constituting the heat transfer water varies depending on the type of the aluminum anticorrosive and is an effective amount that exhibits anticorrosion performance. For example, in the case of the above-mentioned Shadan R (trade name, manufactured by Otsuka Chemical Co., Ltd.), it is usually 0.1 g / L or more and 100 g / L or less, preferably 0.1 g / L or more and 10 g / L or less. In the case of acid soda No. 3 (Na ₂ O · 3SiO ₂ ), it is usually 0.1 g / L or more and 100 g / L or less, preferably 0.1 g / L or more and 10 g / L or less.

  In addition, in the heat transfer water used in the method of the present invention, in addition to the above-mentioned aluminum anticorrosive agent, for example, antifreezing agents such as ethylene glycol, preservatives such as paraoxybenzoic acid (paraben), etc. It can be added as appropriate.

  The aluminum heat exchanger of the present invention is superior in performance per volume as compared with a heat exchanger of a copper pipe having a large diameter, and can be downsized and reduced in weight. It is useful as a heat exchanger (a heat exchanger for a building air-conditioning system) used for air conditioning equipment in a relatively large-scale indoor space such as a building that uses water.

  In addition, according to the method for preventing scale adhesion of an aluminum heat exchanger according to the present invention, even if an aluminum heat exchanger such as a parallel flow type using hot water or cold water as a heat medium is used, the heat exchange efficiency is reduced or the heat exchange tube is used. It is possible to prevent the scale from causing blockage as much as possible, reduce the size and weight, and solve the problem of corrosion of aluminum materials. Heat exchange for building air conditioning system It can be suitably applied to a vessel.

  Hereinafter, preferred embodiments of the present invention will be specifically described based on experimental examples, examples, and comparative examples.

[Experimental example 1: Relationship between hydraulic diameter and pressure loss]
Using an aluminum alloy (JIS A1050), a flat tube (heat exchange tube) having the shape, size, and number of holes shown in Table 1 is prepared by extrusion molding. If the hole shape is a round hole, it is 1 m / sec. When the hole shape was a square hole, water was allowed to flow at a flow rate of 1 m / second, and the pressure loss with respect to the hydraulic diameter of each heat exchange tube was examined.
The results are shown in Table 1 and FIG.

  As is apparent from the results of Table 1, it can be seen that the pressure loss is remarkably increased when the hydraulic diameter is 1.0 mm or less. When the pressure loss increases, a large pump as a heat transfer medium or a pump for transporting liquid mainly composed of water is required. Therefore, from this point of pressure loss, the hydraulic diameter should be 1.0 mm or more, preferably 1.3 mm or more.

[Experimental example 2: Relationship between shape of heat exchange tube and pressure resistance]
Using aluminum alloy (JIS A1050), 12 types of flat tubes (heat exchange tubes) A to L having the shape shown in FIG. 2 (square holes and the number of holes 4) and the sizes shown in Table 2 were prepared by extrusion molding. Increase amount of tube thickness a when an internal pressure of 0.5 MPa is applied to each flat tube A to L (thickness increase amount during pressurization), and residual tube thickness a when the internal pressure is subsequently returned to zero The amount of increase (residual amount of thickness when opened) was measured with a micrometer, and the internal pressure (deformation pressure) when each flat tube A to L caused plastic deformation was examined.
The results are shown in Table 2.

[Experimental Example 3: Relationship between heat exchange tube (flat tube) thickness a and air-side pressure loss]
The flat tube and the corrugated fin are both 16 mm wide and the heat exchange area has a front area of 0.3 m × 0.6 m = 0.18 m ² , and the fin height shown in Table 3 below. A heat exchanger having five types of flat tubes having a length h and a fin pitch was manufactured, and the pressure loss on the air side when air was passed at a wind speed of 2 m / sec and 5 m / sec was obtained.
The results are shown in FIG.

[Experimental Example 4: Relationship between fin height h, heat exchange tube (flat tube) thickness a, and air side heat transfer area]
The flat tube and corrugated fins are both 16mm wide and 1.4mm wide, and the heat exchange area has a front area of 1m x 1m = 1m ^2. The heat transfer area is calculated using 15 types of heat exchangers consisting of combinations of 5 types of tube thickness a and 3 types of fin height h shown in 4 as models, and the tube thickness a of flat tubes and fins of corrugated fins are calculated. The effect of the height h on the heat transfer area on the air side was investigated.
The results are shown in FIG.

  As is clear from the results of Experimental Example 3 and Experimental Example 4, when the tube thickness a of the flat tube is increased without changing the fin height h, the ratio of the fin height h decreases and the ventilation area decreases. In addition, the pressure loss on the air side increases, the heat transfer area on the air side decreases, and the heat exchange performance also decreases. Further, when the tube thickness a is increased and the fin height h is increased, the pressure loss on the air side and the heat transfer area on the air side are not reduced, but the fin efficiency is lowered and the heat exchange performance is also lowered.

[Experimental example 5: Relationship between fin height h and fin efficiency]
Using aluminum alloy (JIS A3003) with a thermal conductivity of 190 W / m · K, six corrugated fins with fin plate thickness of 0.1 mm and fin width of 16 mm and different fin heights h were prepared and used as flat tubes. Joining was performed with a joining width of 14 mm, and the fin efficiency with respect to the fin height h of the corrugated fin was examined with the thermal conductivity on the air side being 50 W / m ² · K.
The results are shown in FIG.

  As is clear from the results shown in FIG. 5, it was found that increasing the fin height h to lower the pressure loss on the air side decreases the fin efficiency and the performance of the heat exchanger.

[Experimental example 6: Examination of preferable flow velocity in pipe]
The relationship between water temperature (° C.) and viscosity (μPa · s) is as shown in FIG. 6, and the relationship between water temperature (° C.) and density (kg / m ³ ) is as shown in FIG. In order to increase the thermal conductivity in the heat exchange tube, it is necessary to make the flow in the heat exchange tube turbulent. For this reason, the Reynolds number is 2,700 or more, preferably 3,000 or more. When the relationship between the temperature (° C) and the transition flow velocity (m / s) when the hydraulic diameter is 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm, As shown in FIG.

[Experimental Example 7: Examination of hole width c and thickness a of flat tube]
Using aluminum alloy (JIS A3003) with thermal conductivity of 190 W / m · K, wall thickness d0.3mm-hole width c1.3mm, wall thickness d0.3mm-hole width c3.2mm, and wall thickness d0.2mm-hole Three types of heat exchange tubes with a width of c1.3mm were manufactured, and the increase in tube thickness a when an internal pressure of 0.5 MPa was applied, and the residual increase in tube thickness a when the internal pressure was subsequently returned to zero Each amount was examined with a micrometer.
The results are shown in FIG.

[Experiment 8: Comparison with conventional fin plate heat exchanger]
As shown in FIG. 10, the heat exchanger of the present invention is configured by alternately laminating flat tubes 10 and corrugated fins 11, and has a front area: width 600 mm × height 300 mm, flat tube 10: material. A1050, thickness a2mm, width 21mm, number of holes 8, pitch 10mm, and corrugated fin 11: material A3003, parallel flow type (PF type) aluminum with width 21mm, height h8.0mm, and pitch 1.4mm Using a heat exchanger, using a duct having the same cross-sectional shape and size as the front area of the heat exchanger on the air side, installing a heat exchanger in this duct, and configuring a heat exchange performance test device, On the side, air at a temperature of 25 ° C. flows at a wind speed (Va) of 2.0 to 4.5 m / s, and on the water side, water at a temperature of 15 ° C. flows at a flow rate of 0.8 m / s, 1.2 m / s, and When flowing at 2.0 m / s and passing air at a uniform temperature at a uniform wind speed The amount of heat exchange was measured, the heat transfer coefficient was determined from the result, and the relationship of the heat transfer coefficient to the wind speed on the air side was determined.
The result is shown by a solid line in FIG.

Also, for comparison, front area: width 600 mm × height 300 mm, heat exchanger thickness: 88 mm, copper 1 hole tube: material: phosphorous deoxidized copper seamless tube, 4 rows, diameter 9.53 mm, and Using a conventional fin plate type (T & F type) heat exchanger with a pitch of 25.4 mm and fins: material A3003 and a pitch of 3.6 mm, a heat exchange performance test apparatus exactly as in the case of the present invention described above. The amount of heat exchange was measured, the heat transfer coefficient was obtained from the result, and the relationship of the heat transfer coefficient to the wind speed on the air side was obtained.
As in the case of the present invention, the results are shown in broken lines in FIG.

  As is apparent from a comparison between the results of the parallel flow type (PF type) aluminum heat exchanger of the present invention shown in FIG. 11 and the results of the conventional fin plate type (T & F type) heat exchanger, the heat exchange of the present invention. The heat exchanger shows the same heat transfer coefficient value as the conventional heat exchanger when the flow velocity of water, which is the heat medium, is around 1 m / s, but when the flow velocity of water is 2 m / s, it is higher than that of the conventional heat exchanger. It clearly showed a high heat transfer coefficient. In this experimental example 8, in order to compare as a heat exchanger exhibiting substantially the same air-side pressure loss, the heat exchanger of the present invention is a PF type heat exchanger having a heat exchanger thickness of 21 mm and a fin pitch of 1.4 mm. An exchanger is used, and as a conventional heat exchanger, a T & F type heat exchanger having a heat exchanger thickness of 100 mm and a fin pitch of 3.6 mm is used. In view of the above, it can be seen that the heat exchanger of the present invention exhibits a performance equivalent to that of a conventional heat exchanger with a volume of about 1/5.

[Example of scale adhesion prevention method and comparative example]
[Configuration of aluminum heat exchanger]
The aluminum heat exchanger used in the following examples and comparative examples is a pair of header pipes (size: diameter 25 mmφ × thickness) formed in a cylindrical shape by aluminum alloy (JIS 3003) and arranged parallel to each other. 1.6 heat) and 20 heat exchange tubes (one size: 218mm x 22mm x thickness) formed in a porous flat tube with aluminum alloy (JIS 1050) and spanned between the pair of header pipes. 21 heat exchange fins (one size), formed in a corrugated plate made of aluminum alloy (JIS BAS272P) with 2mm hydraulic diameter: 1.5mm and mounted between heat exchange tubes arranged in parallel : 864mm × 22mm × thickness 0.1mm) parallel flow type aluminum heat exchanger, with one header pipe having a heat medium inlet and the other header pipe having a heat medium outlet ing.

[Operation test equipment]
In addition, the basic structure of the operation test apparatus used in the following examples and comparative examples is between the heat medium tank that stores the heat medium water used as the heat medium and the heat medium inlet of the aluminum heat exchanger. It is connected by a pipeline through a pump, and it is also configured by connecting a pipeline between the heat medium outlet of the aluminum heat exchanger and the heat medium tank. Heat medium tank → pump → aluminum heat exchange The heat medium inlet of the vessel → the heat medium outlet of the aluminum heat exchanger → the heat medium flow path of the heat medium tank.

〔Test method〕
In the above operation test apparatus, the scale adhesion prevention methods of the following examples and comparative examples are applied, and the test method: internal circulation test, the amount of heat transfer water: 100 L, the circulating fluid temperature: 7: 00 to 17 ： 60 ° C during 00, heater off, otherwise liquid circulation: heat exchange pipe flow rate 1m / sec (φ25mm pipe 24mm / min) 8 hours (9: 00-17: 00) / 1 day In 6 months, heat transfer water is passed through and the calcium ion concentration (Ca concentration: mg / L) of the heat transfer water is measured. I investigated.

About the scale adhesion prevention effect and anticorrosion effect of the heat medium flow path, after 1 month, 3 months, and 6 months, take out the heat exchanger as a test product and cut out so that the inner surface of the heat exchange tube can be observed Then, measure the thickness reduction using a micro gauge to confirm the presence or absence of overall corrosion, and then use the optical microscope with a focal scale to focus on the maximum pitting depth without contact from the surface using the focal depth method. In addition to examining the thickness (μm), the heat exchange tube used for the measurement was checked for clogging of the tube by visual observation. The clogging of this tube was checked: ○: no scale adhered, Δ: scale adhered It is evaluated in three stages, that is, it is not recognized until the tube is clogged, and x: the tube is clogged due to the scale, and from the result of the above maximum pitting corrosion depth (μm) and the clogged state of the tube. ○: There is no corrosion and the scale C: No clogging is observed, Δ: No corrosion occurs, but scale adherence is observed, and X: Corrosion occurs, or clogging due to scale is observed. It was.
In the following examples and comparative examples, no overall corrosion was observed.

Examples 1 to 4 and Comparative Example 1
Weakly acidic cation exchange resin (trade name: Amberlite IRC50, manufactured by Organo Corporation) or monobet ion exchange resin (trade name: MB-2, manufactured by Organo Corporation), and tap water [analytical value (mg / L): Ca: 30, Mg: 5.8, Na: 9.0, Fe: 0.03, Cu <0.005, SiO 2: 23.4, Cl -: 12.4, SO 4 2-: 28, PO 4 2-: <0.2; resistivity (Omega · cm): 4200] to prepare treated water A with a Ca concentration below the detection limit (<0.01 mg / L), and tap water is added to the treated water A below this Ca concentration detection limit. Treated water B with a Ca concentration of 3 mg / L, treated water C with 5 mg / L, and treated water D with 10 mg / L were prepared.

Next, in 4 types of treated waters A to D having different Ca concentrations, phosphoric acid-based anticorrosive as aluminum anticorrosive [trade name: Shadan R (composition; PO4: 173g / L, K: 122g / L, NO2: 17 g / L, Na: 9 g / L, NO3: 0.2 g / L)] 6 g / L or silicic acid-based anticorrosive agent [Nippon Chemical Industry Co., Ltd. sodium silicate 3 (Na ₂ O 3SiO ₂ ) 0.5 g / L was added to prepare heat transfer water for each of Examples 1 to 4 and Comparative Example 1.

In each of the parallel flow type aluminum heat exchangers, the obtained heat transfer water of each of Examples 1 to 4 and Comparative Example 1 was filled in the test operation apparatus, and an internal circulation test was performed by the test method. The effect of preventing scale adhesion was investigated.
The results are shown in Table 5.

Example 5
To the tap water, 0.01 g / L of phosphoric acid was added and allowed to stand for 1 day with gentle stirring. Thereafter, sodium hydroxide (NaOH) was added to adjust the pH to 8, and the precipitated calcium phosphate was filtered with a filter having a mesh size of 1 μm, and the obtained filtrate was used as treated water E.
To this treated water, 6 g / L of a phosphoric acid-based anticorrosive (trade name: Shadan R, manufactured by Otsuka Chemical Co., Ltd.) was added as an aluminum anticorrosive, and the heat transfer water of Example 5 was obtained.
Using the obtained heat transfer water of Example 5, the scale adhesion preventing effect in the parallel flow type aluminum heat exchanger was examined in the same manner as in Example 1.
The results are shown in Table 5.

Example 6
Except for using 0.001 mol / L of oxalic acid instead of phosphoric acid, the calcium content was removed as calcium oxalate to obtain treated water F in the same manner as in Example 5 above. Chemical brand product name: Shadan R) 6 g / L was added to obtain the heat transfer water of Example 6.
Using the obtained heat transfer water of Example 6, the scale adhesion preventing effect in the parallel flow type aluminum heat exchanger was examined in the same manner as in Example 1.
The results are shown in Table 5.

Examples 7-11
0.1 mol / L of EDTA (Example 7), iminodiacetic acid (Example 8), oxine (Example 9), malic acid (Example 10), or tartaric acid (Example 11) as a chelating agent in tap water Further, 6 g / L of a phosphoric acid anticorrosive (trade name: Shadan R, manufactured by Otsuka Chemical Co., Ltd.) was added to obtain heat transfer water of Examples 7 to 11.
Using the obtained heat transfer water of Examples 7 to 11, the scale adhesion preventing effect in the parallel flow type aluminum heat exchanger was examined in the same manner as in Example 1.

Example 12
As shown in FIG. 12, in the basic structure of the test operation apparatus configured by connecting the parallel flow type aluminum heat exchanger 1, the heat medium tank 2, and the pump 3 with a pipeline 4. The heat medium tank 2 was provided with a heat medium heating device configured by connecting the pump 5 and the heat treatment tank 6 with a pipeline 7. The heat medium tank 2 and the heat treatment tank 6 were provided with Taniguchi U-Flon heaters 2a and 6a, respectively, whose surfaces were coated with a fluororesin.

In addition, 6 g / L of phosphate-based anticorrosive (trade name: Shadan R, manufactured by Otsuka Chemical Co., Ltd.) is added to tap water to make a heat transfer water, and 100 L of this heat transfer water is a test operation device provided with a heat transfer medium heating device. In the heat medium tank 2, the heating medium tank 2 is heated to 60 ° C., and the heat treatment tank 6 is heated to 80 ° C. In the same manner as in Example 1, the parallel flow aluminum heat exchanger is used. The effect of preventing scale adhesion was investigated.
The results are shown in Table 5.

Example 13
As shown in FIG. 13, in the same basic structure of the test operation apparatus as described above, a high-speed water flow treatment constituted by connecting a pump 5 and a dummy heat exchanger 8 to the heat medium tank 2 through a pipeline 7. A device was attached. The heat medium tank 2 is provided with a Taniguchi U-Freon heater 2a.

In addition, 6 g / L of phosphate-based anticorrosive (trade name: Shadan R, manufactured by Otsuka Chemical Co., Ltd.) is added to tap water to make heat transfer water, and 100 L of this heat transfer water is a test operation with a high-speed water treatment device. In the aluminum heat exchanger 1, the heat transfer water flows through the heat exchange pipe at a flow rate of 1 m / sec. In the dummy heat exchanger 8 of the high-speed water treatment apparatus, the heat exchange pipe passes through the heat exchange pipe. The heat transfer water was allowed to flow at a flow rate of 2 m / second, and the scale adhesion preventing effect in the parallel flow type aluminum heat exchanger was examined in the same manner as in Example 1.
The results are shown in Table 5.

Comparative Examples 2-6
As a heat medium, tap water itself (Comparative Example 2), heat medium water obtained by adding 6 g / L of a phosphoric acid-based anticorrosive (trade name: Shadan R, manufactured by Otsuka Chemical Co., Ltd.) to tap water (Comparative Example 3) , Heat medium water (Comparative Example 4) obtained by adding 0.5 g / L of silicic acid-based anticorrosive agent (Nippon Chemical Industry Co., Ltd. sodium silicate 3) to tap water, treated water below the Ca concentration detection limit A (Comparative Example 5) and heat medium water (Comparative Example 6) in which tartaric acid 0.1 mol / L was added as a chelating agent to treated water A below the Ca concentration detection limit were used in the same manner as in Example 1 above. The effect of preventing scale adhesion in a parallel flow aluminum heat exchanger was investigated.
The results are shown in Table 5.

  From the results of Examples 1 to 6 and Comparative Examples 1 to 5, the calcium ion concentration in the treated water was reduced to 5 mg / L or less and an aluminum anticorrosive was added to the parallel flow type aluminum heat exchanger as a heat medium. It has been found that even when water is used, scale adhesion in the heat exchange tube can be prevented and corrosion of the aluminum heat exchange tube can be reliably prevented.

  Further, from the results of Examples 7 to 11, the effect of preventing scale adhesion can be obtained by using both the addition of the chelating agent and the addition of the aluminum anticorrosive agent. It has also been found that corrosion of the aluminum heat exchange tube can be reliably prevented by preferentially depositing the scale in a place other than the aluminum heat exchanger by water treatment.

  The aluminum heat exchanger of the present invention is a parallel flow type aluminum heat exchanger that can be reduced in size and weight using water as a heat medium, and is used for large-scale indoor spaces such as buildings and offices. It can be advantageously used as a heat exchanger for air-conditioning equipment.

  In addition, according to the method for preventing scale adhesion of an aluminum heat exchanger according to the present invention, in a parallel flow type aluminum heat exchanger using hot water or cold water as a heat medium, an aluminum material heat exchange tube which is easily corroded is used. Corrosion can be completely prevented, scale heat can be reduced as much as possible, which can reduce heat exchange efficiency and block the heat exchange tube, and can be reduced in size and weight. It can be suitably applied to a heat exchanger of a large-scale indoor space air conditioner such as a building or office.

FIG. 1 is a graph showing the relationship between hydraulic diameter and pressure loss investigated using heat exchange tubes (flat tubes) having different shapes, sizes and numbers of holes. FIG. 2 is a partial perspective explanatory view showing the shape of a heat exchange tube (flat tube) formed in Experimental Example 2 of the present invention.

FIG. 3 is a graph showing the relationship between the ratio of the tube thickness a / tube pitch and the ventilation resistance obtained in Experimental Example 3 of the present invention. FIG. 4 is a graph showing the relationship between the tube thickness a and the air-side heat transfer area obtained in Experimental Example 4 of the present invention.

FIG. 5 is a graph showing the relationship between the fin height h and the fin efficiency obtained in Experimental Example 5 of the present invention. FIG. 6 is a graph showing the relationship between the temperature and viscosity of the heat medium (water) used in Experimental Example 6 of the present invention.

FIG. 7 is a graph showing the relationship between the temperature and density of the heat medium (water) used in Experimental Example 6 of the present invention. FIG. 8 is a graph showing the relationship between the hydraulic diameter of the heat exchange tube (flat tube), the temperature of the heat medium (water), and the transition flow velocity obtained in Experimental Example 6 of the present invention.

FIG. 9 is a graph showing the relationship between the hole width c and the thickness a of the heat exchange tube (flat tube) obtained in Experimental Example 7 of the present invention. FIG. 10 is a partial perspective explanatory view showing the main part of the parallel flow type aluminum heat exchanger used in Experimental Example 7 of the present invention (a heat exchanging part composed of a flat tube and a corrugated fin). FIG. 11 is a graph showing the relationship between the heat exchange passing wind speed and the heat transfer coefficient of the heat exchanger obtained in Experimental Example 8 of the present invention.

FIG. 12 is an explanatory view showing a test operation device provided with a heat medium heating device according to Example 12 of the present invention. FIG. 13 is an explanatory view showing a test operation device provided with a high-speed water flow treatment device according to Example 13 of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Parallel flow type aluminum heat exchanger, 2 ... Heat-medium tank, 2a, 6a ... Heater, 3, 5 ... Pump, 4, 7 ... Pipeline, 6 ... Heat processing tank, 8 ... Dummy heat exchanger, 10 …… flat tube, 11 …… corrugated fin.

Claims (11)

A pair of header pipes arranged at predetermined intervals and having a heat medium inlet and outlet, and formed of aluminum or an aluminum alloy, and a plurality of heat medium flow paths installed between the pair of header pipes A heat exchanger tube made of aluminum or an aluminum alloy, and fins disposed between the heat exchanger tubes and using water as a heat medium.
Each of the heat exchange pipes is composed of a flat tube having a thickness a1.5 to 3 mm and a hole width c3 mm or less provided with partition walls e which are partitioned from each other to form a plurality of substantially parallel partition flow paths. The hydraulic diameter is 1.3-3.0 mm, and
The aluminum heat exchanger, wherein the fin is a corrugated fin having a height of h6 to 12 mm.   2. The aluminum heat exchanger according to claim 1, wherein each heat exchange tube has a wall thickness d of 0.2 to 0.5 mm.   The aluminum heat exchanger according to claim 1 or 2, wherein a flow rate of water as a heat medium in the heat exchange pipe is 1.2 to 3.0 m / s during cooling.   The aluminum heat exchanger according to claim 1 or 2, wherein a flow rate of water as a heat medium in the heat exchange pipe is 0.5 to 3.0 m / s during heating. A pair of header pipes arranged at predetermined intervals and having a heat medium inlet and outlet, and formed of aluminum or an aluminum alloy, and a plurality of heat medium flow paths installed between the pair of header pipes A plurality of heat exchange tubes, and corrugated fins formed of aluminum or aluminum alloy and disposed between the heat exchange tubes, the hydraulic diameter of each of the heat exchange tubes is 1.3 to It is a method for preventing scale adhesion of an aluminum heat exchanger that is 3.0 mm,
A method for preventing scale adhesion of an aluminum heat exchanger, wherein a heat medium water obtained by adding an aluminum anticorrosive agent to treated water that has been subjected to scale adhesion prevention treatment in advance is used as the heat medium.   The method of preventing scale adhesion of an aluminum heat exchanger according to claim 5, wherein the treated water is fresh water having a calcium ion concentration of 5 mg / L or less.   The method for preventing scale adhesion of an aluminum heat exchanger according to claim 6, wherein the treated water is fresh water obtained by decalcifying untreated water with an ion exchange resin.   The method for preventing adhesion of scale in an aluminum heat exchanger according to claim 6, wherein the treated water is fresh water obtained by an acid addition treatment in which an acid is added to untreated water to precipitate and remove a scale component.   The method for preventing adhesion of scale in an aluminum heat exchanger according to claim 5, wherein the treated water is water obtained by a chelating agent addition treatment that suppresses precipitation of scale components by adding a chelating agent to untreated water.   The scale adhesion prevention treatment is a heat treatment in which untreated water is heated to a predetermined temperature with a heater, and scale components of the untreated water are preferentially precipitated and removed on the heat transfer surface of the heater. To prevent scale adhesion of aluminum heat exchangers.   The scale adhesion prevention treatment is a high-speed water flow treatment in which untreated water is flowed into a high-speed flow path that flows at a flow rate faster than the flow velocity in the heat medium flow path formed by each heat exchange pipe. The method for preventing adhesion of scale in an aluminum heat exchanger according to claim 5, wherein the aluminum heat exchanger is preferentially deposited and removed in a high-speed flow path.

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