JP2010032183A - Heat exchanger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pipe type heat exchanger with superior heat exchange performance without extending the piping length of the heat exchanger. <P>SOLUTION: In the pipe type heat exchanger, a plurality of inner pipes 5 carrying CO<SB>2</SB>coolants 4 through their interiors and spirally twisted to one another are disposed in an outer pipe 3 carrying water 2 through its interior, and a plurality of grooves 6 extending in an axial direction of the inner pipe 5 and a plurality of recessed parts 7 positioned at predetermined intervals in the axial direction of the inner pipe 5 are formed on an outer surface of the inner pipe 3. A temperature boundary layer of a wall surface neighborhood is disturbed by the water 2 swirlingly flowing over the recessed parts 7 of the outer surface of the inner pipe 5, and a heat exchange area is enlarged by the plurality of grooves 6. By this, efficient heat exchange can be performed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat exchanger for exchanging heat between a fluid such as water and two kinds of fluids such as a refrigerant, such as a heat pump type hot water heater, etc., used in equipment such as an air conditioner and a hot water heater. It is.

  Conventionally, this type of heat exchanger is composed of an inner pipe in which a refrigerant flow path is formed and an outer pipe that is provided outside the inner pipe and forms a water flow path between the inner pipe and the inner pipe. A double-tube type is known (for example, see Patent Document 1).

  6 and 7 show a conventional heat exchanger described in Patent Document 1. FIG.

  As shown in FIGS. 6 and 7, the heat exchanger 101 is a double-pipe heat exchanger, and is provided on the outer side of the inner pipe 103 and the inner pipe 103 having the inside as the refrigerant flow path 102. In this heat exchanger 101, two inner tubes 103 are provided. The outer tube 105 is made of copper and forms a water flow path 104 between the inner tube 103 and the inner tube 103.

  The inner pipe 103 includes a copper refrigerant pipe 106 and a copper leak detection pipe 107 provided on the outer periphery of the refrigerant pipe 106, and expands the refrigerant pipe 106 or contracts the leak detection pipe 107. As a result, the refrigerant pipe 106 and the leak detection pipe 107 are in close contact with each other.

  A large number of leak detection grooves (not shown) are formed on the inner surface of the leak detection pipe 107 along the pipe direction, and an air layer is formed in the leak detection grooves. Furthermore, the leak detection groove is connected to a leak detection sensor (not shown) provided outside, and the refrigerant or water leaking from the inner tube 103 or the outer tube 105 leaks to the outside through the leak detection groove. However, it is detected by the leak detection sensor.

  The operation of the heat exchanger configured as described above will be described below.

The heat exchanger 101 is formed by a double tube of an inner tube 103 and an outer tube 105, and water flows through the outer periphery of the inner tube 103 and refrigerant flows through the refrigerant tube 106, and is made of copper having good thermal conductivity and Heat is exchanged between the refrigerant and water through the refrigerant pipe 106 and the leak detection pipe 107 which are in close contact with each other.
JP 2005-69620 A

  However, in the above-described conventional configuration, the outer surface area of the inner tube 103 is a heat transfer area on the water side in contact with water. Therefore, in order to improve heat exchange performance, the inner tube 103 and the outer tube of the heat exchanger 101 are improved. For example, the capacity and weight of the heat exchanger 101 should be increased by extending the lengths 105 together to improve the performance.

  This invention solves the said conventional subject, and it aims at providing the tubular heat exchanger which can improve heat exchange performance, without extending the pipe length of a heat exchanger. .

  In order to solve the above-described conventional problems, the heat exchanger according to the present invention has a configuration in which a plurality of second tubes through which the fluid B flows are arranged inside the first tube through which the fluid A flows. On the outer surface of the second tube, there are provided at least a large number of recesses recessed inward in the radial direction of the second tube, and further on the outer surface of the second tube, in the axial direction of the second tube. In this configuration, a number of extending grooves are provided.

  With this configuration, the large number of recesses and grooves provided on the outer surface of the second pipe increase the heat transfer area for the fluid A and disturb the flow of the fluid A flowing along the outer surface of the second pipe. Is something that can be done.

  Accordingly, the heat exchange performance can be improved by expanding the heat transfer area, and by disturbing the flow of the fluid A in the vicinity of the outer surface of the second pipe, the temperature boundary layer with the main flow in the fluid A is disturbed, Heat can be diffused into the mainstream of A.

  The tubular heat exchanger of the present invention can increase the heat transfer area and disturb the flow of the fluid A by a large number of recesses and grooves provided on the outer surface of the second tube. The entire heat can be efficiently transferred to the fluid A through the second pipe.

  Therefore, heat exchange performance can be improved without extending the tube length of the heat exchanger.

  The invention according to claim 1 is a heat exchanger comprising a first pipe through which a fluid A flows, and a plurality of second pipes through which the fluid B flows and which are arranged in the first pipe. The outer surface of the second tube is provided with a large number of concave portions recessed at least in the axial direction on the radially inner side of the second tube, and the second tube is formed on the outer surface of the second tube. A plurality of grooves having a predetermined depth extending in the axial direction are provided.

  By adopting such a configuration, the recesses and grooves provided on the outer surface of the second pipe enable expansion of the heat transfer area and disturbance of the flow of the fluid A flowing in the first pipe. As a result, the heat exchange performance can be improved by expanding the heat transfer area, and by disturbing the flow near the outer surface of the second pipe of the fluid A, the temperature boundary layer with the main flow in the fluid A is disturbed, Heat can be diffused into the main stream of the fluid A, and the heat exchange performance can be further improved.

  According to a second aspect of the present invention, in the first aspect of the invention, the plurality of second tubes are entangled with each other and twisted in a spiral shape.

  With such a configuration, the fluid A flowing around the second tube becomes a swirling flow along the wavy shape of the surface of the second tube, and not only accelerates the temperature mixing of the fluid A but also spirals with each other. A plurality of grooves form a gap through which the fluid A flows with respect to a water stop region formed between the second pipes twisted together. As a result, the temperature boundary layer between the second tubes can be disturbed, and more efficient heat exchange can be realized.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the second pipe defines a low temperature portion in which the temperature of the second pipe is relatively low, and the groove is formed in the second pipe. 2 is provided in the low temperature part of the tube.

  By adopting such a configuration, even when the fluid A is water with a large amount of calcium precipitation, since the groove is not provided in the high temperature portion where calcium is likely to precipitate, the adhesion of calcium can be suppressed as much as possible. Good heat exchange can be realized.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the tube diameter of the second pipe excluding at least the low temperature part is set larger than the pipe diameter of the low temperature part.

  Thus, the pressure loss of the fluid B in a relatively high temperature range can be suppressed, and the accompanying decrease in heat exchange efficiency can be suppressed.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the first pipe is provided with an inlet and an outlet of the fluid A, and the second pipe is provided. The first pipe is provided with an inlet and an outlet for the fluid B, and the fluid A flowing through the first pipe and the flow of the fluid B flowing through the second pipe are opposed to each other. The inflow port and the outflow port in the second pipe are defined.

  Accordingly, the average temperature difference between the fluid A and the fluid B can be increased along with the counter flow of the fluid A and the fluid B, and as a result, the heat exchange amount can be increased.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the fluid A is water and the fluid B is carbon dioxide.

  Thus, when the heat exchanger is used as a heat exchanger for exchanging heat between water and a refrigerant, for example, for a heat pump type hot water heater, the carbon dioxide operates in a supercritical state, and a fluorocarbon refrigerant Since it operates in a state where the density is higher than the above, high heat pump efficiency can be obtained.

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

(Embodiment 1)
FIG. 1 is a side view of a heat exchanger according to Embodiment 1 of the present invention. FIG. 2 is a perspective view in which a part of the heat exchanger in Embodiment 1 is cut away. 3 is a cross-sectional view taken along the line AA of FIG. 2 showing the tube cross-sectional structure of the heat exchanger in the first embodiment. FIG. 4 is a perspective view of a main part showing the configuration of the inner tube in the first embodiment.

1 to 4, the heat exchanger 1 is of a double tube type, and an outer tube made of copper (first tube of the present invention) 3 through which water (fluid A of the present invention) 2 flows, and an outer tube. 3, which is made of copper as in the case of 3, mainly composed of two inner pipes (second pipe of the present invention) 5 through which the CO ₂ refrigerant (fluid B of the present invention) 4 flows. It is configured. The outer surface of the inner tube 3 is provided with a plurality of grooves 6 extending in the axial direction of the inner tube 3 at a predetermined depth, and a plurality of recesses 7 which are also positioned at predetermined intervals in the axial direction.

  The inner pipe 5 includes a refrigerant pipe a and a leak detection pipe b provided on the outer periphery of the refrigerant pipe a as shown in FIG. The refrigerant pipe a and the leak detection pipe b are closely integrated by expanding the refrigerant pipe a or contracting the leak detection pipe b.

  The inner tube 5 is spirally twisted with each other as shown in FIG. 2 and is contained in the outer tube 3 so that the center of the spiral is substantially coaxial with the axis of the outer tube 3. Therefore, the water 2 flows between the inner pipe 5 and the outer pipe 3. Moreover, the flow becomes a swirl flow along the spiral of the inner tube 5.

Furthermore, inflow ports 3a and 5a and outflow ports 3b and 5b are provided at both ends of the outer tube 3 and the inner tube 5, respectively. The inflow port 5a and the outflow port of the CO ₂ refrigerant 4 in the inner tube 5 are provided. 5b, the inlet 2a of the water 2 of the outer tube 3, and the outlet 3b are provided so as to face each other.

A plurality of grooves 6 and recesses 7 formed on the outer surface of the inner tube 5 are provided in a predetermined range (predetermined length) X from the outlet 5b of the CO ₂ refrigerant 4 to the inlet 5a side. However, the surface excluding the range X is formed without the groove 6.

  As an example of a specific configuration, as shown in FIG. 4, the inner pipe 5 employs two types of pipes, and a part corresponding to a predetermined range X (a range extending from a predetermined position to the inlet 3 a of the water 2). Uses a pipe 5c having a large number of grooves 6 and recesses 7 on the surface, and a pipe 5d that is simply piped to the other parts, and connects them by means such as brazing, and the inner pipe 5 is twisted together.

The inner diameter of the pipe 5d is set to be equal to or slightly larger than the outer diameter of the pipe 5c, and is continuous to the inlet 5a of the CO ₂ refrigerant 4.

  Here, in the following description, the predetermined range X will be referred to as “low temperature part X” for convenience of description, and a range other than the predetermined range X will be referred to as “high temperature part Y”.

  That is, when the water 2 flowing in the outer tube 3 contains calcium, precipitation of calcium hardly occurs when flowing at room temperature or cooled and at a low temperature, and tends to precipitate when heated to a high temperature.

In view of this, the heat exchanger 1 according to the first embodiment exchanges heat between the CO ₂ refrigerant 4 in a high temperature state and the water 2 in a normal temperature or a low temperature state. A range in the temperature range where calcium precipitation is relatively likely to occur, that is, a range close to the inflow port 5a side of the CO ₂ refrigerant 4 is defined as the high temperature portion Y, and the flow of the CO ₂ refrigerant 4 from the high temperature portion Y is defined. A range toward the outlet 5b side, that is, a temperature region in which calcium precipitation is relatively difficult to occur is defined as a low temperature portion X.

More specifically, for example, when the temperature of the hot water of the water 2 flowing through the outer pipe 3 is about 90 ° C., the temperature is low at the boundary where the temperature of the CO ₂ refrigerant 4 flowing through the inner pipe 5 is about 60 ° C. Part X and high temperature part Y are defined. This temperature value is unambiguous in the first embodiment, and the actual value varies depending on the heat load or the like. Therefore, it is necessary to determine the optimum range according to the form and capacity of the heat exchanger 1, and this can be dealt with as a design matter.

  The operation of the heat exchanger configured as described above will be described below.

Each inlet 3a, by CO ₂ refrigerant 4 and water 2 flows from 5a, the interior of the inner tube 5 CO ₂ refrigerant 4 to flow to the refrigerant of the heat pump, the inner tube 5 inside the outer tube 3 Water 2 flows between them. These flow direction, as described above the inlet 3a, 5a and the outlet 3b, the orientation of 5b, the flow to face, CO ₂ refrigerant 4 and water 2 is heat exchange through the wall of the inner tube 5.

Therefore, the temperature of the water 2 increases as it approaches the outlet 3b of the outer tube 3, and the temperature of the CO ₂ refrigerant 4 decreases as it approaches the outlet 5b.

In the heat exchange action, since the recesses 7 are provided on the surface of the inner tube 5 at predetermined intervals in the axial direction of the inner tube 5, the water 2 flowing on the recesses 7 causes the recesses 7 to be swirled. And the temperature boundary layer in the vicinity of the wall surface of the inner tube 5 is disturbed. Furthermore, the heat exchange area between the water 2 and the CO ₂ refrigerant 4 can be expanded by the plurality of grooves 6 provided on the outer surface of the inner tube 5, and more efficient heat exchange can be realized.

  The grooves 6 are preferably arranged so as to be in a direction opposite to the spiral angle of the inner tube 5 twisted in a spiral manner. That is, by twisting the inner pipe 5, the water 2 flows in the outer pipe 3 while turning spirally along the surface thereof, and at this time, a flow over the plurality of grooves 6 is generated. The temperature boundary layer can be further disturbed by the flow over the plurality of grooves 6, and more efficient heat exchange can be achieved.

  Further, since the two inner pipes 5 are spirally twisted with each other, the water 2 flowing around the inner pipe 5 becomes a swirling flow as described above, and has the effect of accelerating the temperature mixing. Furthermore, since the water 2 flows through the gap between the plurality of grooves 6 and the recesses 7 in the water stop region generated in the contact portion between the inner tube 5 and the inner tube 5 twisted in a spiral shape, the temperature boundary layer can be further disturbed, More efficient heat exchange can be realized.

  Furthermore, by providing a plurality of grooves 6 in the low temperature portion X and not in the high temperature portion Y, adhesion of the calcium component dissolved in the water 2 at the high temperature portion Y can be suppressed, and this calcium component adhesion Therefore, the reduction of the flow path area accompanying this can be suppressed, and long-term reliability can be ensured.

  Further, by providing the concave portion 7 in the low temperature portion X and not in the high temperature portion Y, the adhesion of the calcium component dissolved in the water 2 to the high temperature portion is suppressed similarly to the groove 6 described above. Can improve reliability.

Furthermore, since the diameter of the pipe 5d of the so-called high temperature part Y excluding at least the low temperature part X in the inner pipe 5 is set larger than the diameter of the pipe 5c of the low temperature part X, the CO ₂ refrigerant in a relatively high temperature range. 4 can be suppressed, and the accompanying decrease in heat exchange efficiency can be suppressed.

In addition, since the water 2 and the CO ₂ refrigerant 4 are opposed to each other, the temperature difference between the water 2 and the CO ₂ refrigerant 4 can be increased to increase the amount of heat exchange, and the capacity of the heat exchanger 1 is increased. be able to.

As described above, the heat exchanger 1 according to the first embodiment can effectively perform the heat exchange action between the CO ₂ refrigerant 4 flowing in the inner pipe 5 and the water 2 flowing in the outer pipe 3. Heat exchange performance can be improved without extending the tube length of the heat exchanger 1.

  Next, the structure which changed a part of heat exchanger based on the said structure is demonstrated.

  FIG. 5 is a perspective view of a main part showing a different configuration of the inner tube of the heat exchanger in the first embodiment.

  5 is different from FIG. 4 in that a concave portion 7a and a groove 6a are provided on the surface of the inner tube 5e used for the high temperature portion Y.

  With this configuration, the increase in the surface area of the inner tube 5e and the disturbing action of the water 2 flowing on the surface of the inner tube 5e are improved, and the heat exchange capability of the heat exchanger 1 can be increased.

  For the inner tube 5e provided in the high temperature portion Y, the number and depth of the grooves 6a are less than that of the low temperature portion X and shallower in order to suppress precipitation and adhesion of calcium contained in the water 2, and For the recesses 7a, consideration is given such that the mutual arrangement interval is set wider than that of the low temperature part X.

  Moreover, about the high temperature part Y, it can also be set as the structure which provides only any one of the groove | channel 6a and the recessed part 7a, About the shape, quantity, etc., in the range which can suppress precipitation and adhesion of calcium contained in the water 2 You only have to set it.

  In the first embodiment of the present invention, the number of the inner pipes 5 arranged in the outer pipe 3 is two. However, the number of the inner pipes 5 may be more than that and the same effect can be expected. .

  In the first embodiment, the recesses 7 and 7a are arranged at predetermined intervals in the axial direction of the tubes 5c and 5e constituting the inner tube 5, but are arranged in the circumferential direction in addition to the axial direction. Or a staggered arrangement, or a spiral arrangement, and the convex portion 7 can be expected to have the same effect regardless of the arrangement relationship.

  Furthermore, in Embodiment 1 of the present invention, the outer tube 3 and the inner tube 5 are made of copper, but at least one of them may be made of brass, stainless steel, corrosion-resistant iron, aluminum alloy, or the like as a material. Similar effects can be expected.

In Embodiment 1 of the present invention, the refrigerant flowing through the inner pipe 5 is the CO ₂ refrigerant 4, but it may be a hydrocarbon refrigerant, an HFC refrigerant (such as R410A), or an alternative refrigerant thereof.

As described above, the heat exchanger according to the present invention, without increasing the heat transfer area of the inner tube by increasing the tube length, one which can improve heat exchange performance of the heat exchanger, CO ₂ refrigerant Supercritical heat pump type water heaters using heat pumps, supercritical heat pump devices for heating heating brine, air conditioners for home use and commercial use, washing dryers equipped with a drying function using heat pumps, grain storage warehouses In addition to heat pump devices such as these, it can also be applied to heat exchange applications such as fuel cells.

Side view of heat exchanger in Embodiment 1 of the present invention The perspective view which excised part of the heat exchanger in Embodiment 1 Sectional drawing by the AA line of FIG. 2 which shows the pipe cross-section of the heat exchanger in Embodiment 1 The perspective view of the principal part which shows the structure of the inner tube | pipe in the same Embodiment 1. The perspective view of the principal part which shows the different structure of the inner tube | pipe of the heat exchanger in the same Embodiment 1. Top view of a conventional heat exchanger Sectional drawing by the BB line of FIG. 6 which shows the cross-section of the same heat exchanger

Explanation of symbols

1 Heat exchanger 2 Water (fluid A)
3 Outer pipe (first pipe)
3a Inlet 3b Outlet 4 CO ₂ refrigerant (fluid B)
5 Inner pipe (second pipe)
5a Inlet 5b Outlet 5c Pipe 5d Pipe 5e Pipe 6 Groove 7 Recess X Low-temperature part

Claims (6)

  A heat exchanger comprising: a first pipe through which fluid A flows; and a second pipe through which fluid B flows and a plurality of second pipes disposed in the first pipe, wherein the second pipe A plurality of recesses recessed at least in the axial direction on the outer surface of the second tube in the radial direction, and having a predetermined depth extending in the axial direction of the second tube on the outer surface of the second tube. A heat exchanger with many grooves.   The heat exchanger according to claim 1, wherein the plurality of second tubes are entangled with each other and twisted in a spiral shape.   3. The heat exchanger according to claim 1, wherein a low temperature part in which the temperature of the second pipe is relatively low is defined in the second pipe, and the groove is provided in the low temperature part of the second pipe. .   The heat exchanger according to claim 3, wherein a pipe diameter excluding at least the low temperature part in the second pipe is set larger than a pipe diameter of the low temperature part.   The first pipe is provided with an inlet and an outlet for the fluid A, the second pipe is provided with an inlet and an outlet for the fluid B, and the fluid A flowing through the first pipe The inflow port and the outflow port in the first tube and the second tube are defined so that the flow of the fluid B flowing through the second tube is an opposing flow. The described heat exchanger.   The heat exchanger according to any one of claims 1 to 5, wherein the fluid A is water and the fluid B is carbon dioxide.

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