JP2007263469A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat exchanger which heats water by heat exchange made between water and a refrigerant, and prevents scale from adhering to a part where hot water comes into contact to maintain the heat exchange performance. <P>SOLUTION: This heat exchanger 10 includes: a heat exchange part 1 for making heat exchange between water and a refrigerant; a water inflow pipe 6a for causing water to flow into the heat exchange part 1; a water outflow pipe 6b for causing water heat-exchanged by the refrigerant to flow out from the heat exchange part 1; a refrigerant inflow pipe 9a for causing the refrigerant to flow into the heat exchange part 1; and a refrigerant outflow pipe 9b for causing the refrigerant heat-exchanged by water to flow out from the heat exchange part 1. At least one of the water inflow part 6a and the water outflow part 6b has a flat part 7 provided with a set of flat surfaces formed along the pipe axial direction in a part thereof, a magnetic field generating means M is installed on the flat surfaces so that N pole and S pole are opposite to each other with the flat part 7 interposed between them, and the magnetic flux density of the magnetic field generating means M is 3,000 gauss or more. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat exchanger for exchanging heat between water and a refrigerant, and particularly used for applications such as hot water supply and floor heating.

  Recently, a heat exchanger in which water is heated by a supercritical carbon dioxide refrigerant or a chlorofluorocarbon refrigerant has been put into practical use, and has come to be widely used in applications such as hot water supply and floor heating. In such a heat exchanger, the water stored in the hot water storage tank is heated in the heat exchanging section, and the heated water becomes warm water and returns to the hot water storage tank again. Supplied.

  In such a heat exchanger, since water is circulated and heated, the carbonate compound contained in the water in the hot water storage tank is concentrated, and compared with a normal gas type instantaneous water heater, the heat exchange section, piping There has been a problem that scales mainly composed of calcium carbonate easily adhere to the inside of the (water inflow pipe, water outflow pipe) and hot water storage tank. In addition, the installation space for the heat exchanger is often limited, and the flow rate of the heated water is generally designed to be small so that water as hot as possible can be obtained with a limited volume. For this reason, calcium carbonate or a scale mainly composed of this easily adheres to the portion of the heat exchanger that comes into contact with water.

  Furthermore, since the solubility of calcium carbonate in water decreases as the water temperature increases, calcium carbonate is particularly likely to precipitate in the portion where the water temperature increases. For this reason, scale adhesion tends to occur as the temperature of the water becomes higher. In the portion where the scale has once adhered, the scale further adheres 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 in the piping, an increase in pump pressure, and an increase in power consumption of the pump. There is a need for improvement in scale adhesion.

  Conventional heat exchangers that circulate water as a cooling medium or a heating medium are scales such as polymers having carboxyl groups obtained by polymerizing maleic acid, acrylic acid, itaconic acid, etc. to prevent calcium carbonate scales. An inhibitor is added to the circulating water.

On the other hand, in a heat exchanger for heating hot water for drinking or bathing, a scale inhibitor cannot be added due to its nature. Therefore, as a method for preventing the adhesion of scale other than the addition of the scale inhibitor, Patent Document 1 describes that the inner surface of the heat exchanger is coated with fluorosilicone or a fluororesin. Patent Document 2 describes that in a double-tube heat exchanger, the bend radius of the outer tube is set to be three times or more the inner diameter of the outer tube, thereby extending the period until the tube is blocked by the scale. Has been. Further, Patent Document 3 describes that a torsion plate is rotatably provided in a pipe through which cooling water flows, and scale adhesion is prevented by turbulent flow formed by the torsion plate.
JP 61-149794 (2nd page, upper right column, lines 5 to 17) JP 2005-69620 A (paragraph 0015) Japanese Utility Model Laid-Open No. 2-109190 (page 3, line 17 to page 4, line 5, FIGS. 1 and 5)

  However, the invention described in Patent Document 1 has been made in order to prevent scale adhesion of a radiator of an automobile, and has no effect on prevention of scale mainly composed of calcium carbonate. Further, the invention described in Patent Document 2 does not actively prevent scale adhesion, but is intended to extend the usable period of the heat exchanger on the assumption that the scale adheres. Actually, the scale mainly composed of calcium carbonate is unavoidably attached to the portion where the water temperature is high, and it is difficult to prevent the heat exchange performance and the flow rate from decreasing due to this. Furthermore, the invention described in Patent Document 3 is to install a rotatable torsion plate in the pipe, but it is applicable when the double pipe heat transfer pipe, the pipe has a bent portion, or the inner diameter of the pipe is small. Not practical.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to prevent a scale from adhering to a portion where hot water contacts in a heat exchanger that heats water by exchanging heat between water and a refrigerant. An object of the present invention is to provide a heat exchanger in which the heat exchange performance does not deteriorate.

  In order to solve the above-mentioned problem, the invention of claim 1 is directed to a heat exchange part that exchanges heat between water and a refrigerant, a water inflow pipe that flows the water into the heat exchange part, and water that is heat-exchanged by the refrigerant. Heat exchange comprising a water outflow pipe flowing out from the heat exchange section, a refrigerant inflow pipe through which the refrigerant flows into the heat exchange section, and a refrigerant outflow pipe through which the refrigerant heat-exchanged with the water flows out from the heat exchange section And at least one of the water inflow pipe and the water outflow pipe has a flat portion in which a set of flat surfaces is formed along a tube axis direction at a part thereof, and sandwiches the flat portion. The magnetic field generating means is installed on the flat surface so that the N pole and the S pole face each other, and the magnetic flux density of the magnetic field generating means is configured as a heat exchanger of 3000 gauss or more.

With this configuration, the magnetic field generating means is installed on at least one of the water inflow pipe and the water outflow pipe with the flat portion of the pipe interposed therebetween, so that a perpendicular magnetic field acts on the water flowing inside the pipe. Then, a magnetic field is applied to the water circulating inside the heat exchanger. As a result, even if Ca ²⁺ and CO ₃ ^2- ions are contained in the circulating water, Ca (HCO ₃ ) that is soluble in water is generated, and CaCO ₃ (calcium carbonate), which is the cause of scale, is generated. Generation is prevented. As a result, the adhesion of the scale mainly composed of calcium carbonate to the inside of the heat exchanger is suppressed. In addition, since it is not necessary to install a magnetic field generating means in the heat exchange part, the degree of freedom in designing the heat exchange part is increased.

The invention of claim 2 is configured as a heat exchanger in which a large number of fins are formed on the inner surface of the flat portion.
If comprised in this way, since the fin is formed in the inner surface of a flat part, a magnetic field will generate | occur | produce between fin tips, the distance between the N pole of a magnetic field, and a S pole will become short, and a heat exchanger The magnetic field applied to the water circulating inside becomes stronger.

The invention of claim 3 is configured as a heat exchanger in which a film of magnetic metal or alloy is formed on the inner surface of the flat portion.
If comprised in this way, attenuation | damping of the magnetic field inside a flat part will decrease with the magnetism of the film | membrane formed in the inner surface of a flat part, and the magnetic field provided to the water which circulates the inside of a heat exchanger will become strong.

  In the heat exchanger according to claim 1, at least one of a water inflow pipe that flows water into a heat exchange section that exchanges heat between water and a refrigerant, and a water outflow pipe that flows out heat-exchanged water from the heat exchange section. A heat exchanging unit, a water outflow pipe, and a heat exchanging unit for heat exchange between water and a refrigerant are provided by providing a flat part in the pipe and installing magnetic field generation means having a magnetic flux density of 3000 gauss or more across the flat part. It becomes possible to semi-permanently prevent the scale from adhering to a portion where hot water contacts, such as a hot water storage tank for storing water (hot water).

  In addition, the heat exchanging section for exchanging heat between water and the refrigerant is a double pipe type depending on the type of the heat exchanger, a type in which the refrigerant pipe and the water pipe are brought into contact, and a refrigerant pipe and a box through which water flows inside. There are various types, such as types, but it is not necessary to install magnetic field generating means in these heat exchange units. For example, it is only necessary to install magnetic field generating means in the water inflow pipe. It becomes higher and contributes to the downsizing of the heat exchanger (heat exchanger).

  In the heat exchanger according to claim 2, since a large number of fins are formed on the inner surface of the flat portion where the magnetic field generating means is installed, the magnetic field between the fin tips facing each other becomes stronger, and the effect of preventing scale adhesion is achieved. Becomes even larger.

  In the heat exchanger according to claim 3, the effect of the magnetic field applied to the water is strengthened by forming a magnetic metal or alloy film on the inner surface of the flat portion where the magnetic field generating means is installed. Therefore, the effect of preventing scale adhesion is further increased.

  Further, in the heat exchanger of the present invention, scale adhesion of the heat exchanging part and the water outflow pipe can be effectively prevented, and scale adhesion in the hot water storage tank is also prevented. Occurrence of problems such as a decrease in water flow rate, a decrease in the amount of circulating water due to a reduction in the cross-sectional area of the water passage, an increase in pump pressure, and an increase in power consumption of the pump can be prevented.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a view schematically showing a hot water supply system using the heat exchanger of the present invention, FIG. 2 (a) is a cross-sectional view along the tube axis direction of a water inflow pipe (water outflow pipe), and FIG. ) In the X1-X1 line, (c) is a cross-sectional view along the tube axis direction showing another form of the flat part, and FIG. 3 (a) is along the tube axis direction showing another form of the flat part. (B) is an end view taken along line X2-X2 of (a), FIG. 4 is a partially enlarged view of the fin of FIG. 3 (b), and FIG. 5 (a) is a partially broken view showing an example of a heat exchange section. The perspective view, (b) is a cross-sectional view perpendicular to the tube axis showing another form of the small-diameter pipe of (a), FIG. 6 (a) is a side view showing another form of the heat exchange section, and (b) is (a). FIG. 7: (a), (b) is a perspective view of the heat exchange part which has a winding part.

<Heat exchanger>
As shown in FIG. 1, the heat exchanger 10 of the present invention is used in, for example, a hot water supply system 30, and water supplied from a hot water storage tank 23 of a water unit 21 is supplied from a refrigerant unit 22. The hot water (warm water) is made by heat exchange with (CO _{2 in} FIG. 1), and the hot water (warm water) is returned to the hot water storage tank 23.

  The heat exchanger 10 includes a heat exchange unit 1, a water inflow pipe 6a, a water outflow pipe 6b, a refrigerant inflow pipe 9a, and a refrigerant outflow pipe 9b. Each configuration will be described below.

(1) Heat Exchanger The heat exchanger 1 that can be applied to the heat exchanger 10 of the present invention includes the following forms, but any form can be used as long as the heat exchanger is of a type in which water is heated by a refrigerant. It can be applied regardless of Note that the refrigerant that exchanges heat with water includes carbon dioxide (CO ₂ ), a fluorocarbon refrigerant, and the like.

(Double tube heat exchange part)
As shown in FIG. 5A, the small diameter pipe 3A is inserted into the large diameter pipe 2, and the medium W (water) flowing in the large diameter pipe 2 and the refrigerant X flowing in the small diameter pipe 3A exchange heat. When the superheated CO ₂ or the like is used as a refrigerant in the heat exchange section 1A of the type, CO ₂ is circulated in the small diameter pipe 3A, and water is supplied into the large diameter pipe 2 (region outside the small diameter pipe 3A). Distribution is usually performed.

  In order to increase the heat transfer amount of the heat exchanging portion 1A, the number of the small diameter pipes 3A is set to two or more, and the flow direction of the medium W flowing in the large diameter pipe 2 and the flow of the refrigerant X flowing in the small diameter pipe 3A is reversed. It is desirable to set the direction (opposite flow). Further, although not shown in the drawing, a large diameter is provided in which a linear / spiral groove or the like is provided inside the small diameter pipe 3A or / and the large diameter pipe 2 or a linear or helical fin is provided outside the small diameter pipe 3A. The area in the tube may be increased to promote heat transfer by a method such as making the tube 2 or / and the small diameter tube 3A into a corrugated tube. Further, although not shown, heat transfer may be promoted by inserting a baffle material or the like into the large-diameter pipe to disturb the flow of the fluid (medium W).

Further, when the inside of the small-diameter pipe is torn due to corrosion or the like, the fluid in the pipe mixes with the fluid in the large-diameter pipe. Therefore, in order to avoid this, it is preferable that the small-diameter pipe has a double structure having a detection structure. Specifically, as shown in FIG. 5B, a small-diameter tube in which an inner tube 3b having an outer diameter smaller than that of the outer tube 3a is fitted inside the outer tube 3a so that a space 4 is formed. 3B is preferable. Moreover, in order to form the space part 4, it is preferable to provide a linear / spiral groove on the inner side of the outer tube 3a and / or the outer side of the inner tube 3b.
In the above configuration, the fluid in the large-diameter pipe 2 and the small-diameter pipe 3A and the small-diameter pipe 3B (inner pipe 3b) are reversed, that is, the refrigerant X and the small-diameter pipe 3A (inner pipe 3b) in the large-diameter pipe 2. The medium W may flow inside.

  As shown in FIGS. 7A and 7B, a winding part 5A spirally wound around at least a part of the large-diameter tube 2, a winding part 5B spirally wound, and the like are provided. You may save the space of the exchange part 1A. The cross-sectional shape orthogonal to the winding axis Y of the winding portions 5A and 5B is a circular shape (see FIG. 7A), a straight path and a semicircular curve formed on both sides of the straight path. It is preferable that it is an oval shape (refer FIG.7 (b)) which consists of a road.

(Heat exchange part in which refrigerant pipe and water pipe are in contact)
This type of heat exchanging part is a heat exchanging part 1B in which a small diameter pipe 3C is fitted in a groove provided outside the large diameter pipe 2 as shown in FIGS. 6 (a) and 6 (b). It is a heat exchanging part or the like in which a small diameter pipe is brazed to the outside of the diameter pipe. When supercritical CO ₂ or the like is used as a refrigerant, it is usually performed that CO ₂ is circulated in the small-diameter pipe 3C and water is circulated in the large-diameter pipe 2 (region outside the small-diameter pipe 3C).

  In order to increase the heat transfer amount of the heat exchanging section 1B, the number of the small diameter pipes 3C is set to two or more, and the direction of the flow of water flowing in the large diameter pipe 2 and the flow of the refrigerant flowing in the small diameter pipe 3C is reversed ( It is preferable to use a counter flow. Although not shown, by increasing the area in the tube and promoting heat transfer by a method such as providing a linear / spiral groove inside the small-diameter tube 3C or / and inside the large-diameter tube 2, etc. Also good. Although not shown, heat transfer may be promoted by inserting a baffle material or the like into the large-diameter tube to disturb the flow of water. Furthermore, in order to lengthen the contact between the large diameter pipe 2 and the small diameter pipe 3C and increase the heat transfer area, it is preferable to arrange the small diameter pipe 3C in a spiral shape outside the large diameter pipe 2. And like the above-mentioned heat exchanging part 1A, at least a part of the large-diameter pipe 2 of the heat exchanging part 1B has a winding part such as a spiral shape or a spiral to save space of the heat exchanging part 1B. Is preferable.

(Heat exchange part in which the tube contacts the box-shaped housing and the box-shaped housing)
Although this type of heat exchange section is not shown in the figure, for example, there is a combination in which a tube of an appropriate size is wound around a box-shaped housing and brazed, and water is supplied into the box-shaped housing and a refrigerant is passed through the tube. In addition, heat exchange efficiency is improved by providing a baffle material or the like in the box-shaped housing and determining the flow path of water.

  The large diameter pipe 2, small diameter pipes 3A, 3B (outer pipe 3a, inner pipe 3b), 3C, and the casing have heat conductivity, bending workability, brazing property, corrosion resistance against water, refrigerant, installation environment, etc. From the viewpoint of pressure resistance and the like, it is preferable to use copper or a copper alloy. That is, it contains copper, such as oxygen-free copper and deoxidized copper, or an element selected from Sn, P, Ni, Fe, Co, Zn, Zr, Cr, Ti, Mg, Mn, Si, etc., and satisfies the above characteristics An appropriate material may be selected from copper alloys.

(2) Water inflow pipe, water outflow pipe The water inflow pipe is a pipe for flowing water into the heat exchange part of the heat exchanger, and the water outflow pipe heats the water (hot water) heat-exchanged in the heat exchange part. It is piping for flowing out from the exchange part. For example, as shown in FIG. 1, in the hot water supply system 30, the water inflow pipe 6 a flows water into the heat exchange unit 1 (1 </ b> A, 1 </ b> B) from the hot water storage tank 23, water pipe (not shown) of the water unit 21. The water outflow pipe 6b is a pipe through which heat-exchanged water (hot water) flows out to the hot water storage tank 23. The water inflow pipe 6a and the water outflow pipe 6b are joined to the large-diameter pipe 2 (see FIGS. 5 and 6) of the heat exchange unit 1 (1A, 1B) and a box-shaped housing (not shown). Yes. The tube shapes of the water inflow tube 6a and the water outflow tube 6b are not particularly limited as long as they can be joined to the large diameter tube and the box-type housing.

  As shown in FIGS. 1, 2 (a), and 2 (b), at least one of the water inflow pipe 6a and the water outflow pipe 6b is a part of the flat surface 7a along the tube axis direction. The flat portion 7 is formed. It is advantageous for prevention of scale adhesion that the water inflow pipe 6a provided upstream of the heat exchange part 1 (1A, 1B) has the flat part 7. The reason why the flat portion 7 is provided is that the contact area between the magnetic field generating means M (magnet or the like) described later and the water inflow pipe 6a or / and the water outflow pipe 6b is increased and installed on the outer surface (flat surface 7a) of the flat portion 7. This is because a stronger magnetic field is transmitted to the water in the tube by reducing the distance between the N pole and the S pole of the magnetic field generating means M.

  As the material of the water inflow pipe 6a and the water outflow pipe 6b, since corrosion resistance is required, it is preferable to use copper, copper alloy, stainless steel or the like. The thinner the tube, the smaller the magnetic field attenuation in the tube, and the more advantageous. The tube thickness may be determined in consideration of the water pressure in the tube and the decrease in wall thickness after prolonged use. Usually, a thickness of about 0.2 to 1.5 mm may be employed.

  As shown in FIGS. 2 (a) and 2 (b), the magnetic field of the magnetic field generating means M becomes wider as the width D1 of the flat portion 7A and the length L in the tube axis direction are larger (a large magnet may be installed). Therefore, it is advantageous for preventing scale adhesion. The outer diameters of the water inflow pipe 6a and the water outflow pipe 6b are usually about 7 to 30 mm, and a part of these pipes has a width D1 of the flat portion 7A of 5 to 12 mm and a space D2 between the pipe inner surfaces of about 1 to 10 mm. What is necessary is just to make it flat. Note that the length L of the flat portion 7A may be about 20 to 200 mm. Or you may incorporate the pipe | tube which has the flat part 7A of the said dimension in the water inflow pipe 6a or / and the water outflow pipe 6b by methods, such as brazing.

  As shown in FIG. 2A, the flat portion 7A preferably has a flat surface 7a facing in parallel. However, if a sufficient magnetic field is applied to the water in the tube, as shown in FIG. 2C, the flat surface 7a is inclined along the tube axis direction, that is, the outer diameter of the flat portion 7A is water (medium It may be a form enlarged or reduced in the flow direction of W).

  As shown in FIG. 1, when the magnetic field generating means M is installed in the flat part 7, the magnetic lines of force inside the flat part draw a trajectory that connects the shortest distance. If a large number of fins 7b are provided on the inner surface of the flat portion 7B, the magnetic field in the tube becomes stronger, which is advantageous for preventing scale adhesion. The fins 7b may be formed, for example, by a method of rolling an internally grooved tube.

  As shown in FIG. 4, the fin height h from the inner surface of the fin 7b may be about 0.1 to 1.0 mm. When the fin height h is less than 0.1 mm, the effect of preventing scale adhesion due to the provision of the fins 7b is small. When the fin height h exceeds 1.0 mm, particularly when the distance between the fin tips on the inner surface of the pipe is small, Increased pressure loss for flow. The pitch Pf at the tip of the fin is assumed to be the pitch Pf = π × (D−2) where the number of fins n, the fin height h, the bottom wall thickness T, and the tube outer diameter D (the tube outer diameter before the flat portion 7 is formed). Xh-2 × T) / n), and may be about 0.2 to 3 mm. When the pitch Pf at the fin tip exceeds 3 mm, the effect of preventing scale adhesion due to the provision of the fin 7b is small, and when the pitch Pf at the fin tip is less than 0.2 mm, the distance between the fin tips on the inner surface of the pipe is particularly small. , The pressure loss with respect to the flow of water increases. A thinner bottom wall thickness T of the groove 7c formed between the fins 7b is advantageous because the magnetic field in the tube is less attenuated. Further, the lead angle θ of the groove 7c (see FIG. 3A) does not have a large magnetic effect, and an appropriate value may be selected from the range of 0 to 45 ° (θ = 0 ° is a tube). Meaning a groove parallel to the axis).

  As shown in FIG. 2B, when a magnetic metal or alloy film 8 is formed on the inner surface of the flat part 7A, the attenuation of the magnetic field in the tube is small, which is further advantageous for preventing scale adhesion. The metal or alloy may be selected from ferromagnetic materials having good corrosion resistance, for example, Ni, Ni—Co, or the like. As shown in FIG. 3B, even when a large number of fins 7b (grooves 7c) are formed inside the flat portion 7B, a magnetic film (not shown) is provided on the surfaces of the fins 7b and the grooves 7c. It is preferable to form.

(3) Refrigerant inflow pipe, refrigerant outflow pipe The refrigerant inflow pipe is a pipe for flowing the refrigerant into the heat exchange part of the heat exchanger, and the refrigerant outflow pipe flows out the heat exchanged refrigerant from the heat exchange part. It is piping for. For example, as shown in FIG. 1, in the hot water supply system 30, the refrigerant inflow pipe 9 a is a pipe for allowing the refrigerant to flow into the heat exchanger 10 from the compressor 25 of the refrigerant unit 22, and the refrigerant outflow pipe 9 b This is a pipe for allowing the exchanged refrigerant to flow out to the expansion valve 26. And the refrigerant | coolant inflow tube 9a and the refrigerant | coolant outflow tube 9b are joined to the small diameter pipe | tube 3A, 3B, 3C (refer FIG. 5, FIG. 6) of the heat exchange part 1 (1A, 1B). The pipe shapes of the refrigerant inflow pipe 9a and the refrigerant outflow pipe 9b are not particularly limited as long as they can be joined to the small diameter pipes 3A, 3B, and 3C.

(4) Magnetic field generating means As shown in FIGS. 2A and 2B, the magnetic field generating means M is installed on the flat surface 7a so that the N pole and the S pole face each other across the flat portion 7A. . The magnetic field generating means M is not particularly limited as long as it generates a magnetic field, and a permanent magnet or an electromagnetic coil (electromagnet) is preferable. Since the installation method of the magnetic field generating means M is preferably installed with no gap from the flat surface 7a, it is fixed to the flat surface 7a with a vise or the like.

  The magnetic flux density of the magnetic field generating means M needs to be 3000 gauss (0.3 Tesla) or more. It is known that irradiating water flowing in a pipe with magnetism is effective in preventing scale adhesion. In the heat exchanger for exchanging heat between the water and the refrigerant of the present invention, the flow rate of water is generally small, and when the hot water in the hot water storage tank is circulated and heated, the concentration of Ca and Si contained in the water increases. Also, since the water temperature is high, the scale is more easily adhered as compared to normal water piping. Therefore, if the magnetic flux density is less than 3000 gauss (0.3 Tesla), it is difficult to prevent scale adhesion over a long period of time. Therefore, in the present invention, the magnetic flux density of the magnetic field generating means is 3000 gauss (0.3 Tesla)

<Hot water supply system>

Next, an example in which the heat exchanger of the present invention is used in a hot water supply system will be described with reference to FIG. In the heat exchanger 10, water is circulated through a large diameter pipe (not shown) of the heat exchange section 1 (1A, 1B), and CO _{2 is} passed through a small diameter pipe (not shown) of the heat exchange section 1 (1A, 1B). Circulate. The CO ₂ absorbs atmospheric heat in the evaporator 24 of the refrigerant unit 22, is then compressed by the compressor 25, and is sent to the refrigerant inflow pipe 9 a of the heat exchanger 10 as a high-temperature and high-pressure fluid. The CO ₂ supplied to the small diameter pipe via the refrigerant inflow pipe 9a exchanges heat with the water in the large diameter pipe and becomes a low-temperature fluid and is sent to the expansion valve 26 of the refrigerant unit 22 via the refrigerant outflow pipe 9b. . CO ₂ expands by the expansion valve 26 and absorbs heat again by the evaporator 24. On the other hand, the water in the hot water storage tank 23 of the water unit 21 is sent to the water inflow pipe 6 a of the heat exchanger 10 by the pump P. The water sent to the water inflow pipe 6 a is magnetized by the magnetic field generating means M installed in the flat part 7. The low-temperature water to which magnetism has been applied is supplied to the large-diameter pipe via the water inflow pipe 6a, heated by contacting with the small-diameter pipe, and becomes hot water (hot water) through the water outflow pipe 6b. Return to the hot water storage tank 23 of the water unit 21. Here, since magnetism is imparted to the water circulating inside the heat exchanger 10 (heat exchanging unit 1), a scale is formed inside the heat exchanging unit 1, the water outflow pipe 6b and the hot water storage tank 23 in contact with the hot water. It is prevented from adhering.

Examples of the present invention will be described.
As an example (No. 1-6), the heat exchanger provided with the following heat exchange parts, a water inflow pipe, a water outflow pipe, a refrigerant inflow pipe, a refrigerant outflow pipe, and a magnetic field generation means was produced.

<Heat exchange part>
As a heat exchange part, a double pipe type heat exchange part (see FIG. 5A) in which three small diameter pipes were arranged inside a large diameter pipe was produced. In addition, the spiral winding part (refer FIG. 7 (a)) with an internal diameter of 250 mm was provided in a part of large diameter pipe | tube.

(1) Large-diameter pipe A smooth pipe made of JIS-regulated phosphorus-deoxidized copper (C1220) having an outer diameter of 15 mm, a thickness of 0.8 mm, and a length of 8 m was used.

(2) Small-diameter pipe As shown in FIG. 5B, a double pipe having a detection structure (space part) composed of an outer pipe and an inner pipe was used.

(Outer pipe)
Made of JIS stipulated phosphorous deoxidized copper (C1220), outer diameter 5.5mm, bottom thickness (T) 0.5mm, fin height (h) 0.25mm, number of grooves 50, groove lead angle (θ) 18 An internally grooved tube with a peak angle (δ) of 35 ° and a length of 8 m was used (the groove shape is the same as the flat portion shown in FIGS. 3A and 4).

(Inner pipe)
A smooth tube made of JIS-defined phosphorous deoxidized copper (C1220) having an outer diameter of 4.0 mm, a thickness of 0.5 mm, and a length of 8 m was used.

<Water inflow pipe>
A smooth tube made of JIS-defined phosphorous deoxidized copper (C1220) having an outer diameter of 15 mm, a wall thickness of 0.8 mm, and a length of 2 m was used. A flat water pipe having a flat part of various dimensions was brazed to the central part in the length direction of the water inflow pipe. Next, a magnetic field generating means (permanent magnet), which will be described later, is fixed to the flat portion of the flat water tube so that the N pole and the S pole face each other with the flat portion interposed therebetween, thereby forming a magnetic installation portion.

(Flat water pipe)
A smooth tube having a length of 200 mm, an outer diameter of 15 mm, and a wall thickness of 0.8 mm made of JIS-defined phosphorous deoxidized copper (C1220) was prepared. Next, as shown in FIGS. 2 (a) and 2 (b), a flat water tube (No. 1) in which a flat portion having a width (D1) of 5 to 12 mm and a length (L) of 120 mm is processed at the center of the smooth tube. -3) Further, a flat water tube (No. 4) in which a Ni film having a thickness of 1.5 μm was formed on the inner surface of the tube by electroplating after the flat part was processed was produced.

  Moreover, the inner surface grooved tube which prepared the grooved process on the inner surface of the said smooth tube was prepared. A flat water tube (No. 5) in which a flat portion having a width (D1) of 12 mm and a length (L) of 120 mm is processed at the center portion of the inner grooved tube, and the inner surface of the tube is electroplated to a thickness of 1 after the flat portion is processed. A flat water tube (No. 6) on which a 5 μm Ni film was formed was prepared. The groove shape of the internally grooved tube is fin height (h) 0.4 mm, number of grooves 80, groove lead angle (θ) 18 °, peak angle (δ) 25 °, bottom wall thickness (T) 0.4 mm. The fin pitch (Pf) was 0.5 mm (see FIGS. 3A and 4).

<Water outflow pipe>
A smooth tube made of JIS-defined phosphorous deoxidized copper (C1220) having an outer diameter of 15 mm, a wall thickness of 0.8 mm, and a length of 2 m was used.

<Refrigerant inflow pipe, refrigerant outflow pipe>
A smooth tube made of JIS stipulated phosphorous deoxidized copper (C1220) having an outer diameter of 5.5 mm, a wall thickness of 0.75 mm, and a length of 2 m was used.

<Magnetic field generation means>
A permanent magnet having a length of 100 mm, a width of 25 mm, and a thickness of 25 mm was used. The magnetic flux density of the permanent magnet was 3000 to 6000 gauss (0.3 to 0.6 Tesla).

<Production of heat exchanger>
Connect the water inflow pipe (with a flat water pipe and braze the magnetic field generator) and the water outflow pipe to the large diameter pipe of the heat exchange section, and connect the refrigerant inflow pipe and the refrigerant outflow pipe to the small diameter pipe. did.

  As a comparative example (No. 7), a heat exchanger was produced in the same manner as in Example (No. 2) except that a permanent magnet having a magnetic flux density of 2000 gauss (0.2 Tesla) was used. Moreover, the heat exchanger was produced like Example (No. 1) except not using a flat water pipe and a permanent magnet as a comparative example (No. 8).

  Next, the heat exchangers (No. 1 to 8) were operated for 4000 hours under the following conditions, and hot water was circulated. After the test, the scale adhesion state of the heat exchange part where the scale is most likely to adhere was confirmed. In addition, the flow of the medium which distribute | circulates the inside of the small diameter pipe | tube of a heat exchange part and a large diameter pipe | tube was made into the reverse direction mutually.

<Operating conditions of heat exchanger>
-CaCO ₃ concentration in water: 800 mg / l
・ Water flow rate (large diameter pipe): 1.2 l / min
・ Refrigerant (small-diameter pipe): Supercritical CO ₂
-Refrigerant flow rate (small diameter pipe): 1.3kg / min
・ Water inlet side temperature of heat exchanger: 20 ℃
・ Water outlet temperature of heat exchanger: 85 ℃

<Evaluation method of scale adhesion>
The mass of the heat exchanger before and after operation was measured, and the amount of mass increase after operation was taken as the amount of scale adhesion. When the scale adhesion amount exceeded 5 g / m, the scale adhesion was judged as “Yes”, and when it was 5 g / m or less, the scale adhesion was judged as “None”.
The mass before the operation was measured by measuring the mass of the heat exchange part (total length: 8 m) and converted to a mass per 1 m. The mass after operation was cut out by about 1 m in length from the water discharge side of the heat exchanging part where the water temperature becomes high, the mass was measured, and divided by the length to obtain the mass per 1 m. The results are shown in Table 1.

  As shown in Table 1, in the heat exchangers of Examples (Nos. 1 to 6), scale adhesion did not occur in the heat exchange part. On the other hand, since the magnetic flux density of the magnet of the heat exchanger of the comparative example (No. 7) is smaller than the lower limit value of the present invention, a scale is generated in the heat exchange part. Since the flat part and the magnet were not installed in the heat exchanger of the comparative example (No. 8), a large amount of scale was generated in the heat exchange part.

  About the heat exchange part of these heat exchangers, when the large-diameter pipe inner surface and the small-diameter pipe outer surface were visually observed, scale adhesion was hardly seen in the examples (Nos. 2 to 6). In the example (No. 1), slight scale adhesion was observed. On the other hand, in the comparative example (No. 7), a large amount of scale adheres as compared to the example (No. 1), and in the comparative example (No. 8), a larger amount of scale adheres as the flow path of the water in the pipe becomes narrower. It was observed.

It is a figure which shows typically the hot water supply system which uses the heat exchanger of this invention. (A) is sectional drawing along the pipe-axis direction of a water inflow pipe (water outflow pipe), (b) is an end view in the X1-X1 line | wire of (a), (c) is a pipe | tube which shows the other form of a flat part It is sectional drawing along an axial direction. (A) is sectional drawing along the pipe-axis direction which shows the other form of a flat part, (b) is an end elevation in X2-X2 line of (a). It is the elements on larger scale of the fin of FIG.3 (b). (A) is a partial fracture perspective view which shows an example of a heat exchange part, (b) is a pipe axis orthogonal sectional view which shows the other form of the small diameter pipe | tube of (a). (A) is a side view which shows the other form of a heat exchange part, (b) is an end elevation in the X3-X3 line of (a). (A), (b) is a perspective view of the heat exchange part which has a winding part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 1A, 1B Heat exchange part 6a Water inflow pipe 6b Water outflow pipe 9a Refrigerant inflow pipe 9b Refrigerant outflow pipe 7, 7A, 7B Flat part 7a Flat surface 10 Heat exchanger M Magnetic field generation means

Claims (3)

A heat exchanging section for exchanging heat between water and the refrigerant, a water inflow pipe for flowing the water into the heat exchanging section, a water outflow pipe for flowing out the water heat-exchanged with the refrigerant from the heat exchanging section, and the refrigerant. A heat exchanger comprising a refrigerant inflow pipe flowing into the heat exchange section and a refrigerant outflow pipe for flowing out the refrigerant heat-exchanged with the water from the heat exchange section,
At least one of the water inflow pipe and the water outflow pipe has a flat portion in which one set of flat surfaces is formed along a tube axis direction in a part thereof,
Magnetic field generating means is installed on the flat surface so that the N pole and the S pole face each other across the flat portion,
The heat exchanger according to claim 1, wherein the magnetic field generating means has a magnetic flux density of 3000 gauss or more.   The heat exchanger according to claim 1, wherein a large number of fins are formed on an inner surface of the flat portion.   The heat exchanger according to claim 1 or 2, wherein a film of magnetic metal or alloy is formed on an inner surface of the flat portion.

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