CN105008839A - Double-layer tube heat exchanger and refrigeration cycle device - Google Patents

Abstract

The invention provides a double-layer tube heat exchanger capable of improving heat exchange performance under the condition that two-phase flow flows in a second flow path. A double-tube heat exchanger (1) is provided with a heat transfer area enlarging tube (11) having irregularities with respect to a radial direction, and the inner surface of a part of the heat transfer area enlarging tube, which is in close contact with the inner surface of an outer tube (3), of the inner surface of the heat transfer area enlarging tube (11), and the part of the inner surface of the outer tube, which defines a second flow path (23) together with the outer surface of the heat transfer area enlarging tube, are set to a non-grooved range which is a non-grooved surface. On the other hand, a groove candidate range is provided which is composed of a portion excluding the groove range from a portion defining the second flow path together with the outer surface of the inner tube in the inner surface of the heat transfer area enlarging tube, a portion defining the second flow path together with the inner surface of the outer tube in the outer surface of the heat transfer area enlarging tube, and a portion defining the second flow path together with the inner surface of the heat transfer area enlarging tube in the outer surface of the inner tube (5), and a groove extending in the flow direction is formed in a part or the whole of the groove candidate range.

Description

Double-layer tube heat exchanger and refrigeration cycle device

technical field

The present invention relates to a double-tube heat exchanger in which two flow paths are formed by combining round tubes having different diameters, and a refrigeration cycle device using the double-tube heat exchanger.

Background technique

In a double-tube heat exchanger, a circular tube with a small diameter (hereinafter referred to as the inner tube) is inserted into a circular tube with a large diameter (hereinafter referred to as the outer tube), and the inside of the inner tube is used as the first flow path, and the outside of the inner tube is In addition, the inner portion of the outer tube serves as a second flow path, and heat exchange is performed between the first fluid in the first flow path and the second fluid in the second flow path.

In addition, in this double-tube heat exchanger, there is a structure disclosed in Patent Document 1, for example, as a study to improve heat transfer performance. That is, Patent Document 1 proposes a method of inserting a multi-lobed cross section into an annular second flow path located between the outside of the cylindrical inner tube and the inside of the cylindrical outer tube. The heat transfer area expansion tube improves the heat transfer performance through the expansion effect of the heat transfer area.

prior art literature

patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2012-063067

Contents of the invention

The problem to be solved by the invention

In the above-mentioned Patent Document 1, only a study on enlarging the heat transfer area is disclosed. Here, the present inventors paid attention to appropriate heat transfer when exchanging heat with the two-phase refrigerant.

The present invention has been made in view of this situation, and an object of the present invention is to provide a double-tube heat exchanger and the like capable of improving heat exchange performance when a two-phase flow flows in a second flow path.

means to solve the problem

In order to achieve the above object, the double-tube heat exchanger of the present invention includes: an outer tube; an inner tube inserted into the inner side of the outer tube to form an annular region with the outer tube a first flow path is formed on the inner side; and a heat transfer area expanding tube having concavities and convexities with respect to the radial direction, arranged inside the outer tube and outside the inner tube, in the annular region forming a second flow path; the inner surface of the part of the heat transfer area expanding tube that is in close contact with the inner surface of the outer tube among the inner surfaces of the heat transfer area expanding tube and the part of the inner surface of the outer tube The part defining the second flow path together with the outer surface of the heat transfer area expanding tube is set as a non-grooving range, the non-grooving range is a surface without grooves, and the groove-forming candidate range is composed of the following parts, namely Out of the inner surface of the heat transfer area enlarged tube, the portion defining the second flow path together with the outer surface of the inner tube removes the portion in which the grooves are not formed, the heat transfer A part of the outer surface of the area-enlarging tube that defines the second flow path together with the inner surface of the outer tube, and a part of the outer surface of the inner tube together with the inner surface of the heat transfer area expanding tube In the portion defining the second flow path, grooves extending in the flow direction are formed in at least a part or the entire range of the groove formation candidates.

The effect of the invention

According to the present invention, heat exchange performance can be improved when a two-phase flow flows in the second flow path.

Description of drawings

Fig. 1 is a diagram showing the internal structure of a double tube heat exchanger according to Embodiment 1 of the present invention in a direction perpendicular to the tube axis.

Fig. 2 is a cross-sectional view of the double-tube heat exchanger taken along line II-II in Fig. 1 .

Fig. 3 is an enlarged view showing a second flow path in Fig. 2 .

FIG. 4 is a diagram showing the outer tube, the heat transfer area expansion tube, and the inner tube separated from each other for the purpose of explaining the part of FIG. 3 .

Fig. 5 is a diagram showing Example 1 of a refrigeration cycle apparatus using a double-tube heat exchanger.

Fig. 6 is a diagram showing Example 2 of a refrigeration cycle apparatus using a double-tube heat exchanger.

Fig. 7 is a diagram showing Example 3 of a refrigeration cycle apparatus using a double-tube heat exchanger.

Fig. 8 is a diagram showing Example 4 of a refrigeration cycle apparatus using a double-tube heat exchanger.

FIG. 9 is a diagram of the same form as FIG. 3 related to Embodiment 2. FIG.

FIG. 10 is a diagram of the same format as FIG. 3 related to Embodiment 3. FIG.

Detailed ways

Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same reference numerals denote the same or corresponding parts.

Embodiment 1

Fig. 1 is a diagram showing the internal structure of a double tube heat exchanger according to Embodiment 1 of the present invention in a direction perpendicular to the tube axis. Fig. 2 is a cross-sectional view of the double-tube heat exchanger taken along line II-II in Fig. 1 . In addition, priority is given to ensuring the clarity of the drawing, and the illustration of the later-described heat transfer area expansion tube is omitted in FIG. 1 . The double-tube heat exchanger 1 has a double-tube structure in which an inner tube 5 which is a relatively small-diameter circular tube is concentrically inserted inside an outer tube 3 which is a relatively large-diameter circular tube. The inner space of the inner tube 5 functions as the first flow path 7 . On the other hand, a heat transfer area expansion tube 11 is accommodated outside the inner tube 5 and inside the outer tube 3 , that is, the annular region 9 .

The heat transfer area expansion tube 11 has a plurality of convex portions 13 and a plurality of concave portions 15 as opposing concavo-convex portions with respect to the radial direction. As shown in the cross section of FIG. 2 , a plurality of protrusions 13 are radially provided to protrude toward the radially outer side of the heat transfer area expanding tube 11 . In addition, the plurality of protrusions 13 are arranged at substantially equal intervals in the circumferential direction. On the other hand, the plurality of concave portions 15 are respectively located between the corresponding pair of convex portions 13 in the circumferential direction. These recesses 15 are also located at substantially equal intervals in the circumferential direction. Therefore, the plurality of protrusions 13 and the plurality of recesses 15 are alternately located in the circumferential direction when viewed from the heat transfer area expansion tube 11 as a whole.

In the present invention, various forms of the convex shape of the convex portion and the concave shape of the concave portion seen in the cross section of FIG. shown. The heat transfer area expansion tube 11 includes a plurality of outer close-contact portions 17 , a plurality of inner close-contact portions 19 , and a plurality of continuous portions 21 . As shown in FIG. 2 , the outer surface 17a of the outer contact portion 17 of the heat transfer area expansion tube 11 is in close contact with the inner surface 3b of the outer tube 3 , especially in this example, the outer surface 17a is in surface contact with the inner surface 3b. That is, the outer surface 17 a of the outer close contact portion 17 of the heat transfer area expansion tube 11 has substantially the same curvature as that of the inner surface 3 b of the outer tube 3 . Similarly, the inner surface 19b of the inner side contact portion 19 of the heat transfer area expansion tube 11 is in close contact with the outer surface 5a of the inner tube 5, and especially in this example, the inner surface 19b is in surface contact with the outer surface 5a. That is, the inner surface 19 b of the inner side contact portion 19 of the heat transfer area expansion tube 11 has substantially the same curvature as that of the outer surface 5 a of the inner tube 5 . In addition, the same bending state can be obtained in the individual state of the outer tube 3, the inner tube 5, and the heat transfer area expansion tube 11, and can also be obtained from the center side or radial direction of the double-tube heat exchanger 1. Obtained after the assembly process with a certain force applied to the outside is completed.

The continuous portions 21 are respectively located between the adjacent outer close contact portions 17 and inner close contact portions 19 . In the present embodiment, the plurality of outer close contact portions 17 are located at equal intervals in the circumferential direction, and the plurality of inner close contact portions 19 are also located at equal intervals in the circumferential direction. Looking at the entire heat transfer area expansion tube 11 , in the circumferential direction, the sequential arrangement of the outer close contact portion 17 , the continuous portion 21 , the inner close contact portion 19 , and the continuous portion 21 is repeated. In addition, there is no clear boundary between the convex portion 13 and the concave portion 15. The convex portion 13 is composed of the outer close portion 17 and the part of the continuous portion 21 that is close to the radial direction outside, and the concave portion 15 is formed by the radial direction of the inner close portion 19 and the continuous portion 21. The inner part is composed.

The inner side of the convex portion 13 and the outer side of the concave portion 15 in the above-mentioned annular region 9 function as the second flow path 23 . That is, the second flow path 23 is defined in the annular region 9 by the heat transfer area expansion tube 11 .

More specifically, the second flow path 23 includes two types of parts. The first type of part consists of the inner surface 17b of the outer side contact part 17, the inner surface 21b of the corresponding pair of continuous parts 21, and the outer surface of the inner tube 5. 5a delineated. In addition, the portion of the second form is defined by the outer surface 19 a of the inner side contact portion 19 , the outer surface 21 a of the corresponding pair of continuous portions 21 , and the inner surface 3 b of the outer tube 3 . The sections of the first form alternate with the sections of the second form in the circumferential direction.

In such a structure, the first fluid flows through the first flow path 7 , and the second fluid flows through the second flow path 23 . The temperature of the first fluid and the second fluid are different, and heat exchange is performed between the first fluid and the second fluid through the heat conduction of the inner tube 5 and the heat transfer area expansion tube 11 .

Generally, there is a relationship shown in formula (1) among the exchange heat Q, the heat transfer area A, the heat transfer rate K, and the temperature difference dT between the first fluid and the second fluid.

[number 1]

Q＝A·K·dT (1)

In addition, the heat transfer rate K can be represented by formula (2).

[number 2]

$\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; \&pi;L</span>}}{<span\; class="notranslate">\; \{</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; /</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; \&CenterDot;</span>\mathrm{<span\; class="notranslate">\; ln</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; io</span>}}<span\; class="notranslate">\; /</span>{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; i</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; R</span>}<span\; class="notranslate">\; \}</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

In addition, the meaning of each symbol is as follows. α1: heat transfer rate of fluid 1, d1: hydraulic diameter of flow path 1, α2: heat transfer rate of fluid 2, d2: hydraulic diameter of flow path 2, λ: thermal conductivity of inner pipe, dio: outer diameter of inner pipe Diameter, doi: inner diameter of inner tube, R: thermal resistance.

The above-mentioned heat transfer area expanding tube 11 functions as a heat sink by being in contact with the inner tube 5 , so that the heat transfer area can be enlarged, and the heat exchange amount between the first fluid and the second fluid can be increased.

Here, the flow state of the refrigerant when the gas-liquid two-phase flow flows in the second flow path 23 will be described with reference to FIGS. 3 and 4 . Fig. 3 is a view in the same form as Fig. 2, and is an enlarged view showing the second flow path. Fig. 4 is a part related to Fig. 3, and the outer tube, the heat transfer area expansion tube, and the inner tube are separated from each other for explanation. Represented figure. Here, in general, in the two-phase flow, the liquid refrigerant with a high heat transfer rate is in close contact with the tube wall, and the gas refrigerant with a low heat transfer rate flows in a portion away from the tube wall. That is, the liquid refrigerant concentrates on the wall surfaces indicated by reference numerals 3 b , 5 a , 17 b , 19 a , 21 a , and 21 b shown in FIG. 3 .

Therefore, in the present invention, the non-groove-forming range and the groove-forming candidate range are set as follows. The present Embodiment 1 is an example of a case where grooves are formed over the entire groove formation candidate range.

The details of the non-groove-formed range and the groove-formed candidate range will be described. Specifically, among the inner surfaces of the heat transfer area expansion tube 11, the inner surface of the part of the heat transfer area expansion tube 11 that is in close contact with the inner surface 3b of the outer tube 3 (the inner surface 17b of the outer close contact portion 17) does not form grooves. scope. In addition, the portion of the inner surface 3b of the outer tube 3 that defines the second flow path 23 together with the outer surface of the heat transfer area expansion tube 11 is also a range where no grooves are formed. No grooves 25 to be described later are formed in these non-groove-formed ranges.

In addition, the groove-forming candidate range is composed of the portion in which the above-mentioned non-groove-forming range is removed from the portion defining the second flow path 23 together with the outer surface 5a of the inner pipe 5 among the inner surfaces of the heat transfer area expansion tube 11 The portion (the inner surface 21b of the continuous portion 21) obtained from (the inner surface 17b of the outer close contact portion 17), and the outer surface of the heat transfer area expansion tube 11 together with the inner surface 3b of the outer tube 3 define the second flow path. 23 (the outer surface 21a of the continuous portion 21 and the outer surface 19a of the inner side contact portion 19), and the outer surface 5a of the inner tube 5 together with the inner surface of the heat transfer area expansion tube 11 define the second flow path 23 part.

In Embodiment 1, as described above, no groove is formed in the non-groove formation range, and grooves are formed in the entire groove formation candidate range, more specifically as follows. The groove 25 is formed at the portion of the outer surface 5a of the inner tube 5 defining the second flow path 23 together with the outer close contact portion 17 and the pair of continuous portions 21, and the inner close contact portion 19 of the heat transfer area expansion tube 11. The outer surface 19a, and the outer surface 21a and the inner surface 21b of the continuous portion 21 . In addition, the inner surface 17b of the outer close portion 17 and the portion of the inner surface 3b of the outer tube 3 defining the second flow path 23 together with the inner close portion 19 and the pair of continuous portions 21 are groove-free surfaces. In addition, although the present invention is not particularly limited, in Embodiment 1, the outer surface 17a of the outer close contact portion 17 of the heat transfer area expansion tube 11 and the portion of the inner surface 3b of the outer tube 3 that is in close contact with the outer surface 17a The groove-free surface is used, and the inner surface 19b of the inner side contact portion 19 and the portion of the outer surface 5a of the inner tube 5 that is in close contact with the inner surface 19b are made into a groove-free surface.

In order for the refrigerant to flow smoothly in the flow direction, the grooves 25 are formed to extend along the flow direction. In addition, the grooves in FIGS. 3 and 4 are schematically drawn, and in FIG. 2 , it is preferable to omit illustration of the grooves to ensure clarity of the drawing.

In addition, it is conceivable to form the heat transfer area expansion tube 11 by press forming or drawing, so the groove 25 is simultaneously formed during press forming and drawing in order to simplify the process. In addition, by inserting the heat transfer area expansion tube 11 formed with the groove 25 into the annular region 9 between the outer tube 3 and the inner tube 5 and shrinking the outer tube 3 or expanding the inner tube 5, the heat transfer area is expanded. The tube 11 is supported by the outer tube 3 and the inner tube 5 .

Alternatively, as a method of more reliably bringing the inner tube 5 and the outer tube 3 into close contact with the heat transfer area expansion tube 11 , a form in which each contact surface is joined by brazing is also suitable. Specifically, after the heat transfer area expansion tube 11 is installed on the outer tube 3 and the inner tube 5, a brazing material may be applied to the contact surface, and the brazing material may be melted by brazing in a furnace, etc., and the contact surface may be heated. Brazing. In addition, when it is difficult to coat the brazing material after installing the heat transfer area expansion tube 11 on the inner tube 5 and the outer tube 3, it is also possible to use the cladding material coated with the brazing material in advance for heat transfer. The area expansion tube 11 is brazed.

According to the double-tube heat exchanger 1 constituted as described above, the following excellent advantages can be obtained. The predetermined portion of the outer surface 5a of the inner tube 5 and the outer surface 19a of the inner close contact portion 19 are very close to the first flow path 7 even in the portion defining the second flow path 23, which is the most effective heat transfer surface. highest part. In addition, the continuous part 21 is located between the part of the above-mentioned first form and the part of the second form of the second flow path 23. The portion of the first type and the portion of the second type (internal relationship of the second flow path 23 ) are effective heat transfer surfaces when exchanging heat between the second fluids. Therefore, by forming the grooves 25 as described above, the liquid refrigerant can be positively collected on the predetermined portion close to the outer surface 5 a of the inner tube 5 of the first flow path 7 and on the outer surface of the inner side contact portion 19 that is in close contact with the inner tube 5 . 19a and the inner and outer surfaces of the continuum 21. In addition, at the same time, by presetting the predetermined portion of the inner surface 3b of the outer tube 3 that is far away from the first flow path 7 and having low effectiveness as a heat transfer surface, and the inner surface 17b of the outer close contact portion 17 as a surface without grooves, relatively , compared with the prescribed portion of the outer surface 5a and the outer surface 19a, the liquid refrigerant is less likely to gather, and as a reverse effect, the auxiliary liquid refrigerant gathers at the prescribed portion of the outer surface 5a, the outer surface 19a, and the inner surface and the inner surface of the continuous portion 21. The outer surface. That is, a large amount of liquid refrigerant having a high heat transfer rate is also supplied to the predetermined portion of the inner surface 3b of the outer tube 3 and the inner surface 17b of the outer close contact portion 17, which are less effective as heat transfer surfaces, thereby suppressing the liquid refrigerant accordingly. The amount of supply to the predetermined portion of the outer surface 5a, the outer surface 19a, and the inner surface and the outer surface of the continuous portion 21, which are highly effective heat transfer surfaces, decreases. Thus, according to the present embodiment, even when a gas-liquid two-phase flow flows in the second flow path, heat exchange performance can be improved by effectively utilizing the heat transfer surface.

In addition, in Embodiment 1, the outer surface 17a of the outer close contact portion 17 of the heat transfer area expansion tube 11 and the portion of the inner surface 3b of the outer tube 3 that is in close contact with the outer surface 17a are surfaces without grooves. The inner surface 19b of the inner side contact portion 19 and the part of the outer surface 5a of the inner tube 5 that is in close contact with the inner surface 19b are non-grooved surfaces, so that the inner tube 5 and the outer tube 3 can be in close contact with the heat transfer area expansion tube 11. Not only that, but especially because the inner tube 5 and the heat transfer area expansion tube 11 have high adhesion, the efficiency of heat conduction by the heat transfer area expansion tube 11 can be improved, and the heat transfer area expansion tube can be efficiently used. 11 exists.

Hereinafter, an embodiment of a refrigeration cycle apparatus to which the above-mentioned double-tube heat exchanger 1 is applied will be described with reference to FIGS. 5 to 8 .

As Embodiment 1 of the refrigeration cycle device, the refrigeration cycle device 101 shown in FIG. 5 has a compressor 103, a condenser 105, an expansion valve 107, an evaporator 109, and the above-mentioned double-tube heat exchanger 1 as the main components of the circuit. . In the double-tube heat exchanger 1, the high-pressure liquid refrigerant (second fluid) from the outlet of the condenser 105 (before the inlet of the expansion valve 107) and the outlet of the evaporator 109 (before the inlet of the compressor 103) ) for heat exchange between the low-pressure gas refrigerant (first fluid). In this way, by using the double-tube heat exchanger 1, the inlet temperature of the condenser 105 rises, so that the capacity during heating can be improved and the COP (the value obtained by dividing the capacity by the input) can be improved, or the return of the liquid refrigerant can be prevented. to the compressor.

Hereinafter, as Embodiment 2 of the refrigeration cycle apparatus, the refrigeration cycle apparatus 201 shown in FIG. Type heat exchanger 1 is used as the main component of the circuit. The compressor 103, the condenser 105, the first expansion valve 207a, and the evaporator 109 constitute a basic refrigeration cycle as in the case of Embodiment 1. The refrigeration cycle device 201 is also provided with a bypass passage 211, the bypass passage 211 is connected between the outlet of the condenser 105 and the inlet of the first expansion valve 207a at the first connection point 213a, and is connected to the inlet of the first expansion valve 207a at the second connection point 213b. Between the outlet of the evaporator 109 and the inlet of the compressor 103 . The second expansion valve 207b is provided in the bypass passage 211 .

In the double-tube heat exchanger 1, between the high-pressure liquid refrigerant (first fluid) from the outlet of the condenser 105 (before reaching the first connection point 213a) and the outlet of the second expansion valve 207b from the bypass passage 211 Heat exchange is performed between the compressed gas-liquid two-phase refrigerant (second fluid). The intermediate-pressure gas refrigerant having undergone heat exchange in the double-tube heat exchanger 1 is sucked into the compressor 103 . In this way, by using the double-pipe heat exchanger, the amount of refrigerant circulating downstream of the first expansion valve 207a can be reduced, so that the pressure loss can be reduced and the COP can be improved.

Hereinafter, as Embodiment 3 of the refrigeration cycle apparatus, the refrigeration cycle apparatus 301 shown in FIG. Type heat exchanger 1 is used as the main component of the circuit. The compressor 303, the condenser 105, the first expansion valve 207a, and the evaporator 109 are the same as those in Embodiment 1, and constitute a basic refrigeration cycle.

In the double-tube heat exchanger 1, between the high-pressure liquid refrigerant (first fluid) from the outlet of the condenser 105 (before reaching the first connection point 213a) and the outlet of the second expansion valve 207b from the bypass passage 211 Heat exchange is performed between the compressed gas-liquid two-phase refrigerant (second fluid). Then, the intermediate-pressure gas refrigerant that has been heat-exchanged in the double-tube heat exchanger 1 is bypassed to the middle of the compression section of the compressor 303 . Thus, by using the double-tube heat exchanger, the amount of refrigerant circulation downstream of the first expansion valve 207a can be reduced, and the compression process can be performed in multiple stages, so that the input to the compressor can be reduced and the COP can be improved.

Furthermore, the refrigeration cycle device 401 shown in FIG. 8 uses the double-tube heat exchanger 1 as the condenser itself of the basic refrigeration cycle. The refrigeration cycle device 401 is to make the refrigerant (second fluid) of the condenser under the normal condition of the refrigeration cycle circuit in the double-tube heat exchanger 1 and the fluids such as water and brine delivered by the pump 415 (the first fluid). Fluid) is an example of a device that exchanges heat to provide hot water.

Embodiment 2

Embodiment 2 of the present invention will be described below. FIG. 9 is a diagram related to the second embodiment in the same form as FIG. 3 . This second embodiment is the same as the above-mentioned first embodiment except for the parts described below, and can also be implemented by configuring the refrigeration cycle apparatus shown in FIGS. 5 to 8 in the same way.

The double-pipe heat exchanger 51 is an example in which the grooves 25 extending in the flow direction are formed in at least a part of the groove formation candidate ranges. That is, in the second embodiment, only the above-mentioned predetermined portion of the outer surface 5a of the inner tube 5, the outer surface 19a of the inner side contact portion 19, and the inner surface and the outer surface of the continuous portion 21 that form the groove candidate range, as shown in FIG. Grooves 25 are formed on the inner and outer surfaces of the continuation portion 21 shown at 9 . In this second embodiment, as in the first embodiment, the liquid refrigerant can be efficiently collected on the inner and outer surfaces of the continuous portion 21 that is highly effective as a heat transfer surface, and even in the second flow path In the case of a gas-liquid two-phase flow, the heat exchange performance can also be improved by effectively utilizing the heat transfer surface.

Embodiment 3

Embodiment 3 of the present invention will be described below. FIG. 10 is a diagram of the same form as FIG. 3 related to Embodiment 3. FIG. This third embodiment is the same as the above-mentioned first embodiment except for the parts described below, and can also be implemented by configuring the refrigeration cycle apparatus shown in FIGS. 5 to 8 in the same way.

The double pipe heat exchanger 61 is also an example in which the grooves 25 extending in the flow direction are formed in at least a part of the groove formation candidate range. In Embodiment 3, only the predetermined portion of the outer surface 5a of the inner pipe 5, the outer surface 19a of the inner side contact portion 19, and the inner and outer surfaces of the continuous portion 21, as shown in FIG. The groove 25 is formed in the predetermined portion of the outer surface 5a of the inner tube 5 and the outer surface 19a of the inner close contact portion 19 as shown. Also in the third embodiment, as in the first embodiment, when the gas-liquid two-phase flow flows in the second flow path, the heat exchange performance can be improved by effectively using the heat transfer surface.

As mentioned above, the content of this invention was concretely demonstrated with reference to preferable embodiment, However, Of course, those skilled in the art can adopt various modification forms based on the basic technical idea and instruction|indication of this invention.

For example, in the first embodiment described above, the groove 25 can also be formed on the outer surface 17 a of the outer close contact portion 17 of the heat transfer area expansion tube 11 . With such a change, the grooves 25 are provided as a unified process on the entire outer surface of the heat transfer area expansion tube 11, and the manufacturing can be simplified by the uniformity of the process. In addition, even if such a change is made, the outer surface 17a of the outer side close contact portion 17 of the heat transfer area expansion tube 11 that is in close contact with the outer tube 3 is less important as a heat transfer surface. From the viewpoint of utilizing the heat transfer surface, It also does not reduce the effectiveness of the present invention. That is, the ease of production can be improved while properly maintaining the effective utilization of the heat transfer surface in the present invention.

Explanation of reference signs

1, 51, 61 double-layer tube heat exchanger, 3 outer tubes, 5 inner tubes, 7 first flow path, 9 annular area, 11 heat transfer area expansion tube, 23 second flow path, 25 grooves, 101, 201 , 301, 401 refrigeration cycle device.

Claims (7)

1. a double-tube type heat exchanger, is characterized in that, possesses:

Outer tube;

Interior pipe, described interior pipe is inserted into the inner side of described outer tube, between this outer tube, form annular section, and forms first flow path in inner side; And

Heat transfer area enlarged tube, it is concavo-convex that described heat transfer area enlarged tube has relative to radial direction, is configured in the inner side of described outer tube and the outside of described interior pipe, forms the second stream at described annular section,

The part of with the outer surface of described heat transfer area enlarged tube together with delimiting described second stream of inner surface in the inner surface of described outer tube of the part of this heat transfer area enlarged tube of touching with the inner surface of described outer tube in the inner surface of described heat transfer area enlarged tube is set to respectively and does not form groove scope, this does not form groove scope is without groove face

Form groove candidate scope to form by with lower part, namely from not forming groove scope described in delimiting together with the outer surface of described interior pipe in the part of described second stream the inner surface of described heat transfer area enlarged tube eliminates and the part of delimiting described second stream together with the inner surface of described heat transfer area enlarged tube in the outer surface of the part of delimiting described second stream together with the inner surface of described outer tube in the outer surface of the part obtained, described heat transfer area enlarged tube and described interior pipe

At least partially or whole described formation groove candidate scope be formed along flow direction extend groove.

2. double-tube type heat exchanger according to claim 1, is characterized in that,

The part of touching with the outer surface of described interior pipe in the part of touching with the inner surface of described heat transfer area enlarged tube in the outer surface of the part of touching with the inner surface of described outer tube in the outer surface of the part of touching with the outer surface of described heat transfer area enlarged tube in the inner surface of described outer tube, described heat transfer area enlarged tube, described interior pipe and the inner surface of described heat transfer area enlarged tube is without groove face respectively.

3. double-tube type heat exchanger according to claim 1 and 2, is characterized in that,

After described heat transfer area enlarged tube defines described groove, this heat transfer area enlarged tube is inserted the described annular section between described outer tube and described interior pipe, the draw is carried out to described outer tube or expander is carried out to described interior pipe, thus this heat transfer area enlarged tube is by this outer tube and this interior piping support.

4. double-tube type heat exchanger according to any one of claim 1 to 3, is characterized in that,

Soldering is carried out to described interior pipe and described outer tube and described heat transfer area enlarged tube.

5. double-tube type heat exchanger according to claim 4, is characterized in that,

Described heat transfer area enlarged tube is the clad material of brazing material at surface application.

6. a refrigerating circulatory device, is characterized in that,

There is the double-tube type heat exchanger any one of claim 1 to 5,

In described double-tube type heat exchanger, cold-producing medium carries out heat exchange each other.

7. a refrigerating circulatory device, is characterized in that,

There is the double-tube type heat exchanger any one of claim 1 to 5,

Heat exchange is carried out between cold-producing medium and water or refrigerating medium in described double-tube type heat exchanger.