JP2010071529A - Refrigerant heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerant heater improving heat transfer from an outer tube to an inner tube. <P>SOLUTION: The refrigerant heater 30 is equipped with: the inner tube 31 carrying a refrigerant; the outer tube 32 surrounding a periphery of the inner tube 31 and comprising a magnetic material; and an induction heating coil 33 surrounding a periphery of the outer tube 32 and carrying out induction heating of the outer tube 32. Area enlarging parts 44, 46 enlarging an area where an outer circumference face of the inner tube 31 and an inner circumference face of the outer tube 32 mutually contact are formed on the outer circumference face of the inner tube 31 and/or the inner circumference face of the outer tube 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerant heating device that heats a refrigerant flowing through a refrigerant pipe.

  Conventionally, there are various methods for heating the refrigerant in the refrigerant circuit, but an induction heater (hereinafter referred to as IH heater) is convenient in that the refrigerant can be rapidly heated using induction heating.

  Such an IH heater for heating a refrigerant can induce induction heating by exciting a pipe through which the refrigerant flows or a magnetic material inside and outside the pipe by an induction heating coil, thereby heating the refrigerant in the pipe. It is.

  Here, copper is usually adopted as the material of the piping constituting the refrigerant circuit in consideration of aspects such as thermal conductivity, workability, or material cost. However, it is preferable to employ a magnetic material such as stainless steel as the material of the pipe heated by the IH heater in order to efficiently perform electromagnetic induction heating.

Therefore, like the IH heater described in Patent Document 1, magnetic coating or powder is coated on the outer periphery of the copper tube so that induction heating can be efficiently performed even for the copper tube.
Japanese Patent Laid-Open No. 2001-174054

  Here, in order to further improve the efficiency of induction heating, it is conceivable to employ a stainless steel pipe as a pipe through which the refrigerant flows inside the IH heater. In this case, the stainless steel pipe heated by the IH heater and other refrigerant circuits are considered. Since the material is different from that of the copper pipe constituting the wire, it is necessary to braze different pipes, and there is a possibility that defects (such as cracks) occur in the manufacturing cost and the brazed part.

  It is also possible to insert a copper tube inside the stainless steel tube to make a double tube, but even if a copper tube having the same outer diameter is inserted into the inner diameter of the stainless steel tube, the stainless steel tube and the copper tube are good. There is a problem that it is difficult to obtain a proper contact state. For this reason, it is also difficult to improve the heat transfer from the stainless steel tube heated by induction to the copper tube.

  The subject of this invention is providing the refrigerant | coolant heating apparatus which can improve the heat transfer from an outer tube | pipe to an inner tube | pipe.

  The refrigerant heating device of the first invention includes an inner tube through which a refrigerant flows, an outer tube, and an induction heating coil. The outer tube surrounds the inner tube and is made of a magnetic material. The induction heating coil surrounds the periphery of the outer tube and induction-heats the outer tube. An area expansion portion is formed on the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube. The area expanding portion expands an area where the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube are in contact with each other.

  Here, since the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube is formed with an area expanding portion that expands the area where the outer peripheral surface of the inner tube and the inner peripheral surface of the outer tube are in contact with each other. The contact area between the two tubes is increased, and the heat transfer from the outer tube to the inner tube, which is heated by induction, and thus the heat transfer to the refrigerant is improved.

  The refrigerant heating device of the second invention is the refrigerant heating device of the first invention, wherein the area enlargement portion is unevenness formed on the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube.

  Here, since the area expanding portion is unevenness formed on the outer peripheral surface of the inner tube and / or the inner peripheral surface of the outer tube, the contact area of both the tubes increases, and the inner tube is changed from the outer tube that is induction-heated. The heat transfer to the refrigerant and thus the heat transfer to the refrigerant is improved.

  The refrigerant heating device of the third invention is the refrigerant heating device of the first invention or the second invention, and a groove or a ridge is formed on the inner peripheral surface of the outer tube.

  Here, since grooves or protrusions are formed on the inner peripheral surface of the outer pipe, the contact area between both pipes increases, and heat transfer from the outer pipe to the inner pipe, which is heated by induction, and thus to the refrigerant. The heat gets better. Moreover, compared with the case where a point-shaped convex part, a recessed part, etc. are formed, the direction of a groove | channel or a protrusion can ensure sufficient contact area.

  The refrigerant heating device of the fourth invention is the refrigerant heating device of the first invention or the second invention, and a groove or a protrusion is further formed on the outer peripheral surface of the inner tube.

  Here, since the grooves or protrusions are further formed on the outer peripheral surface of the inner pipe, the contact area between the two pipes increases, and heat transfer from the outer pipe to the inner pipe, which is heated by induction, and thus to the refrigerant. The heat gets better. Also, compared to the case of forming spot-like convex parts or concave parts, the groove and the ridge can secure a sufficient contact area, and the groove and ridge are formed on the outer peripheral surface of the inner tube. Is easier to process than forming on the inner peripheral surface side of the outer tube.

  The refrigerant heating device of the fifth invention is the refrigerant heating device of the third invention or the fourth invention, wherein the groove or the ridge extends in a spiral shape.

  Here, since the groove or the ridge extends spirally, the contact area further increases as compared with the linear groove or ridge.

  A refrigerant heating device according to a sixth invention is the refrigerant heating device according to any one of the first to fifth inventions, and the outer tube is made of stainless steel.

  Here, since the outer tube is made of stainless steel, induction heating can be performed efficiently, and since the outer tube is harder than the inner tube such as copper having good thermal conductivity, the area expansion portion such as the unevenness of the inner peripheral surface of the outer tube Easy to adhere to the inner tube surface.

  According to the first invention, the contact area between the inner tube and the outer tube is increased, and heat transfer from the outer tube to the inner tube, which is heated by induction, and thus heat transfer to the refrigerant is improved.

  According to the second aspect of the present invention, the contact area between the inner tube and the outer tube is increased, and heat transfer from the outer tube to the inner tube that is heated by induction is improved.

  According to the third aspect of the invention, the contact area between the inner tube and the outer tube is increased, and heat transfer from the outer tube that is induction-heated to the inner tube, and hence heat transfer to the refrigerant, is improved. Moreover, compared with the case where a point-shaped convex part, a recessed part, etc. are formed, the direction of a groove | channel or a protrusion can ensure sufficient contact area.

  According to the fourth aspect of the present invention, the contact area between the inner tube and the outer tube is increased, and heat transfer from the outer tube that is induction-heated to the inner tube, and hence heat transfer to the refrigerant, is improved. Moreover, compared with the case where a point-shaped convex part, a recessed part, etc. are formed, the direction of a groove | channel or a protrusion can ensure sufficient contact area. Also, forming grooves and protrusions on the outer peripheral surface of the inner tube is easier than processing on the inner peripheral surface side of the outer tube.

  According to the fifth aspect of the present invention, the contact area is further increased as compared with the linear grooves and protrusions, and the heat transfer performance of the heat transfer from the outer tube to the inner tube that is induction-heated, and further to the refrigerant, is further increased. improves.

  According to the sixth aspect of the invention, induction heating can be performed efficiently and harder than an inner tube made of copper or the like having good heat conductivity, so that the area enlarged portion such as the irregularities on the inner peripheral surface of the outer tube is easily adhered to the inner tube surface. .

  Next, an embodiment of the refrigerant heating device of the present invention will be described with reference to the drawings.

Embodiment
<Basic configuration>
In the air conditioner 1 including the refrigerant heating device 30 (hereinafter referred to as IH heater assembly 30) shown in FIG. 1, the outdoor unit 2 and the indoor unit 4 are connected to the liquid refrigerant communication pipe 6 and the gas refrigerant as shown in FIG. A refrigerant circuit 11 configured to be connected by a communication pipe 7 is provided. Each refrigerant pipe of the refrigerant circuit 11 is usually made of copper.

  As shown in FIGS. 1 and 2, the refrigerant circuit 11 includes, in the outdoor unit 2, a compressor 21, a four-way switching valve 22, an outdoor heat exchanger 23, an expansion valve 24 including an electronic expansion valve capable of adjusting the throttle, An IH heater assembly 30 and an accumulator 25 are provided. In addition, the refrigerant circuit 11 includes an indoor heat exchanger 26 and the like inside the indoor unit 4 as shown in FIG. In addition, the four-way selector valve 22 has shown the switching connection state in the case of performing heating operation in FIG.

  Here, the refrigerant flowing in the refrigerant circuit 11 is not particularly limited in the present invention, and is, for example, HFC (R410A or the like), carbon dioxide refrigerant, or the like.

  As shown in FIG. 1, the refrigerant circuit 11 includes a discharge pipe A, an indoor gas pipe B, an indoor liquid pipe C, an outdoor liquid pipe D, an outdoor gas pipe E, an accumulator pipe F, and a suction pipe G. ing.

  Hereinafter, the connection state of each refrigerant pipe will be described in the order of the flow path where the refrigerant discharged from the compressor 21 flows out and is sucked into the compressor 21 again.

  The discharge pipe A connects the discharge side of the compressor 21 and the four-way switching valve 22.

  The indoor side gas pipe B connects the four-way switching valve 22 and the gas side of the indoor heat exchanger 26.

  The indoor side liquid pipe C connects the liquid side of the indoor heat exchanger 26 and the expansion valve 24. Here, the indoor side liquid pipe C includes a liquid communication pipe 6 that connects the outdoor unit 2 and the indoor unit 4.

  The outdoor liquid pipe D connects the expansion valve 24 and the liquid side of the outdoor heat exchanger 23.

  The outdoor gas pipe E connects the gas side of the outdoor heat exchanger 23 and the four-way switching valve 22.

  The accumulator pipe F connects the four-way switching valve 22 and the accumulator 25.

  The suction pipe G connects the accumulator 25 and the suction side of the compressor 21.

  In this way, the refrigerant circuit 11 is configured, and heating operation can be performed by circulating the refrigerant in the above-described direction. The cooling operation can also be performed by switching the connection state of the four-way switching valve 22.

  In the middle of the accumulator tube F, an IH heater assembly 30 described later is connected by brazing.

<Configuration of IH heater assembly 30>
As shown in FIGS. 3 and 4, the IH heater assembly 30 is an IH heater composed of a double tube, and includes an inner tube 31, an outer tube 32, an induction heating coil 33, a bobbin 34, and a pair of lids. 35, a pair of nuts 36, a plurality of ferrite blocks 37, a ferrite holder 38, and a sheet metal cover 39.

  The inner pipe 31 is made of copper, which is the same material as the refrigerant pipe 5, and the refrigerant flows through the inner pipe 31.

  The outer tube 32 is made of stainless steel, which is a magnetic material, and is disposed around the inner tube 31. Specifically, by expanding the inner tube 31, the outer peripheral surface of the inner tube 31 and the inner peripheral surface of the outer tube are in close contact with each other.

  As shown in FIG. 8, a plurality of linear grooves 44 are formed on the inner peripheral surface 43 of the outer tube 32 at equal intervals along the inner peripheral surface 43 as an area expansion portion of the present invention. . On the other hand, on the outer peripheral surface 45 of the inner tube 31, linear protrusions 46 are formed as other area enlarged portions of the present invention, respectively, which fit into the grooves 44 of the outer tube 32.

  As will be described later, when the inner tube 31 is expanded, the protrusion 46 is pressed against the inner peripheral surface 43 of the outer tube 32 in which the groove 44 is formed in the inner peripheral surface 43 in advance. Formed on surface 45. Since the copper inner tube 31 is softer than the stainless outer tube 32, the protrusion 46 can be formed in close contact with the outer peripheral surface of the inner tube 31 easily and reliably.

  Thus, the area where the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 are in contact with each other by the groove 44 formed inside the outer tube 32 and the protrusion 46 formed outside the inner tube 31. Is expanding.

  The induction heating coil 33 surrounds the outer tube 32 and induction-heats the outer tube 32. The induction heating coil 33 is arranged so as to surround the outer periphery of the outer tube 32 in a state of being wound around a bobbin 34 which is a separate member from the outer tube 32.

  The bobbin 34 is a cylindrical member whose both ends are open, and the induction heating coil 33 is wound around the side peripheral surface thereof.

  The pair of lids 35 has an opening 35 a at the center and is fitted to the outer periphery of the outer tube 32. In addition, the pair of lids 35 is fixed from both the upper and lower sides by a C-shaped ferrite holder 38 to be described later while being attached to the bobbin 34.

  The pair of nuts 36 is a combination of the bobbin 34, the lid 35, the ferrite holder 38, and the nut 36 of the IH heater assembly 30 in advance by being screwed into male screw portions 32a formed on the outer periphery near both ends of the outer tube 32. Is fixed to the outer periphery of the outer tube 32.

  The plurality of ferrite blocks 37 are mounted side by side on a C-shaped ferrite holder 38 in order to reduce leakage magnetic flux to the outside of the sheet metal cover 39 of the IH heater assembly 30. The ferrite holder 38 is attached from the outside of the induction heating coil 33 from the four sides of the bobbin 34.

  As shown in FIGS. 2 and 4, the sheet metal cover 39 is a cover made of a thin metal plate and is screwed to the outside of the ferrite holder 38. The sheet metal cover 39 has a cylindrical shape or a polygonal shape so as to surround the cylindrical bobbin 34, and has an integrated shape or a shape divided into two or more.

  Thereby, since the inner pipe 31 is made of the same kind of copper as the other refrigerant pipes F, the inner pipe 31 and the refrigerant pipe F can be easily joined (manufactured easily). In addition, efficient induction heating is possible by the outer tube 32 made of a magnetic material such as stainless steel.

  Moreover, since the structure which supports the bobbin 34 with the induction heating coil 33 wound around the thick outer tube 32 is adopted, the overall strength of the IH heater assembly 30 is improved.

  As described above, the IH heater assembly 30 is provided in the middle of the portion of the accumulator pipe F that connects the four-way switching valve 22 and the accumulator 25, so that as shown in FIG. By the IH heater assembly 30 that receives the high-frequency alternating current from the high-frequency power source 60 via the intake air, the intake gas refrigerant that is directed from the four-way switching valve 22 to the accumulator 25 can be warmed, and the heating capacity can be improved.

  In addition, when the heating operation is started, the compressor 21 may not be sufficiently warmed. Here, the IH heater assembly 30 generates heat, so that the gas from the four-way switching valve 22 toward the accumulator 25 is generated. The refrigerant can be heated, and the lack of capacity at the start-up can be compensated.

  Further, when the four-way switching valve 22 is switched to the state for cooling operation and the defrost operation for removing the frost attached to the outdoor heat exchanger 23 is performed, the gas refrigerant heated through the IH heater assembly 30 is used. Can be further compressed by the compressor 21, so that the temperature of the hot gas discharged from the compressor 21 can be increased. Thereby, the time required to thaw frost by defrost operation can be shortened. Thereby, even if it is necessary to perform a defrost operation in a timely manner during the heating operation, the operation can be returned to the heating operation as soon as possible, and the user's comfort can be improved.

<Method for Manufacturing IH Heater Assembly 30>
When manufacturing the IH heater assembly 30 of the present embodiment, first, as shown in FIG. 5, the copper inner pipe 31 constituting a part of the refrigerant pipe of the refrigerant circuit 11 is made of a stainless steel outer part made of a magnetic material. It is inserted into the tube 32 (insertion step).

  And as FIG. 6 shows, the inner pipe 31 is expanded in the direction where the outer diameter expands by press-fitting the pipe expansion billet 41 which has an outer diameter a little larger than the inner diameter in the inner pipe 31. By this, it fits in the inside of the outer pipe | tube 32 (tube expansion process). At this time, when the inner tube 31 is expanded, the protrusion 46 is pressed on the outer peripheral surface 45 of the inner tube 31 by being pressed against the inner peripheral surface 43 of the outer tube 32 in which the groove 44 is formed in the inner peripheral surface 43 in advance. It is formed.

  Thereafter, as shown in FIG. 7, a combination of the bobbin 34, the lid 35, the ferrite holder 38 and the nut 36 of the IH heater assembly 30 in advance is inserted into the outer periphery of the outer tube 32 with the nut 36 loosened, After that, the nut 36 is tightened to the outer tube 32, and is pressed against the C-shaped ring 43 in the inner diameter direction, whereby the bobbin 34 and other main parts are mounted (bobbin mounting step). Thereby, the manufacture of the IH heater assembly 30 is completed.

<Features of the embodiment>
(1)
In the IH heater assembly 30 of the embodiment, a plurality of linear grooves 44 are formed along the inner peripheral surface 43 at equal intervals on the inner peripheral surface 43 of the outer tube 32 as an area expansion portion of the present invention. Yes. On the other hand, on the outer peripheral surface 45 of the inner tube 31, linear protrusions 46 are formed as other area enlarged portions of the present invention, respectively, which fit into the grooves 44 of the outer tube 32. Due to the grooves 44 and the protrusions 46, the contact area between the inner tube 31 and the outer tube 32 is expanded, and heat transfer from the outer tube 32 to the inner tube 31 that is induction-heated, and thus heat transfer to the refrigerant is improved.

  It is possible to achieve the same effect by reversing the arrangement of the groove 44 and the protrusion 46 and forming a protrusion on the inner peripheral surface of the outer tube 32 and a groove on the outer peripheral surface of the inner tube 31 ( The same applies below).

(2)
Further, in the IH heater assembly 30 of the embodiment, by expanding the inner tube 31, the groove 44 of the outer tube 32 can be brought into close contact with the outer peripheral surface 45 of the inner tube 31, and the protrusion 46 can be easily formed. is there. This is particularly effective when the outer tube 32 made of stainless steel is harder than the inner tube 31 made of copper. In addition, the groove 44 and the protrusion 46 can ensure a sufficient contact area as compared with the case of forming the dot-like convex portions or concave portions.

(3)
Further, in the IH heater assembly 30 of the embodiment, the outer tube 32 is made of stainless steel, so that induction heating can be performed more efficiently than other magnetic material tubes, such as iron tubes, In addition, it has advantages such as high strength and long life.

<Modification>
(A)
In the above embodiment, as shown in FIG. 8, the linear groove 44 and the protrusion 46 are formed on the contact surfaces of the inner tube 31 and the outer tube 32, respectively, but the present invention is limited to this. It is not a thing. In the present invention, the outer peripheral surface 45 of the inner tube 31 and / or the inner peripheral surface 43 of the outer tube 32 expands the area where the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 contact each other. If the area expansion portion is formed, the contact area between the inner tube 31 and the outer tube 32 is expanded, and heat transfer from the outer tube 32 to the inner tube 31 that is induction-heated, and thus heat transfer to the refrigerant is improved. .

(B)
Further, a groove or a ridge 46 extending in the axial direction of the inner tube 31 may be formed on the outer peripheral surface 45 of the inner tube 31. In this case, it is easier to form the grooves and the protrusions 46 on the outer peripheral surface 45 of the inner tube 31 than on the inner peripheral surface 43 side of the outer tube 32. Then, grooves or ridges 46 are formed in advance on the outer peripheral surface 45 of the inner tube 31, and the inner tube 31 is inserted into the outer tube 32 to expand the inner tube 43. It is also possible to easily form a ridge or groove corresponding to the groove or ridge 46 of the tube 31.

(C)
As yet another modification, a groove is formed in advance on the inner peripheral surface 43 of the outer tube 32, and a protrusion is formed on the outer peripheral surface 45 of the inner tube 31, and the inner tube 31 is expanded to form a groove and a protrusion. You may make it fit.

(D)
As still another modification of the present invention, for example, as shown in FIG. 9, the grooves 47 and the protrusions 48 may extend in a spiral shape. Also in this case, the contact area between the inner tube 31 and the outer tube 32 is expanded, and heat transfer from the outer tube 32 that is induction-heated to the inner tube 31 and thus heat transfer to the refrigerant is improved. Moreover, in the case of the spiral groove 47 and the ridge 48 shown in FIG. 9, the length is longer than that of the linear groove 44 and the ridge 46 shown in FIG. The contact area between the outer tube 32 and the outer tube 32 is increased, and the heat transfer performance is improved.

  Also in this case, when the inner tube 31 is expanded, the spiral protrusion 48 is pressed against the inner peripheral surface 43 of the outer tube 32 in which the spiral groove 47 is formed in the inner peripheral surface 43 in advance. It is formed on the outer peripheral surface 45 of the inner tube 31.

(E)
Further, in the present invention, the area expanding portion that expands the area where the outer peripheral surface 45 of the inner tube 31 and the inner peripheral surface 43 of the outer tube 32 contact each other is the direction in which the inner tube 31 and the outer tube 32 extend as described above. Is not limited to the grooves 44 and 47 and the ridges 46 and 48 formed along the groove, and may be any irregularities formed on the contact surface between the inner tube 31 and the outer tube 32, for example, as described above. In addition to regular grooves and ridges, there may be interspersed convex portions and concave portions.

  That is, in the modification shown in FIG. 10, a large number of recesses 49 are formed in advance on the inner peripheral surface 32 of the outer tube 32, and the inner tube 31 is expanded to expand the outer peripheral surface 45 of the inner tube 31. In this case as well, the contact area between the inner tube 31 and the outer tube 32 is increased, and heat transfer from the outer tube 32 to the inner tube 31 that is induction-heated, and hence to the refrigerant F, is performed. The heat gets better.

  Further, in another modification shown in FIG. 11, a large number of protrusions 51 are formed in advance on the inner peripheral surface 32 of the outer tube 32, and the inner tube 31 is expanded to expand the inner tube 31. A concave portion 52 is formed on the outer peripheral surface 45, and in this case also, the contact area between the inner tube 31 and the outer tube 32 is expanded, heat transfer from the outer tube 32 to the inner tube 31 that is induction-heated, and eventually to the refrigerant F. Better heat transfer.

  The present invention can be variously applied to the field of refrigerant heating devices.

The circuit diagram of the air conditioner to which the IH heater assembly concerning the embodiment of the present invention was attached. The expansion perspective view of the machine room part of the outdoor unit of FIG. FIG. 2 is a front view of the IH heater assembly of FIG. 1. FIG. 2 is a cross-sectional view of the IH heater assembly of FIG. 1. Cross-sectional explanatory drawing which shows the insertion process in the manufacturing method of the IH heater assembly of FIG. Cross-sectional explanatory drawing which shows the pipe expansion process in the manufacturing method of the IH heater assembly of FIG. Sectional explanatory drawing which shows the bobbin mounting process in the manufacturing method of the IH heater assembly of FIG. FIG. 2 is an enlarged perspective view showing linear grooves and ridges formed on a contact surface between an inner tube and an outer tube in FIG. 1. The perspective enlarged view which shows the helical groove | channel and protrusion which were formed in the contact surface of the inner tube and outer tube concerning the modification of this invention. Sectional drawing which shows the recessed part of the outer tube | pipe formed in the contact surface of the inner tube | pipe and outer tube | pipe concerning the other modification of this invention, and the convex part of an inner tube | pipe. Sectional drawing which shows the convex part of the outer tube | pipe formed in the contact surface of the inner tube | pipe and outer tube | pipe concerning the further another modification of this invention, and the recessed part of an inner tube | pipe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Air conditioner 2 Outdoor unit 4 Indoor unit 6 Liquid refrigerant communication piping 7 Gas refrigerant communication piping 11 Refrigerant circuit 21 Compressor 22 Four-way switching valve 23 Outdoor heat exchanger 24 Expansion valve 25 Accumulator 26 Indoor heat exchanger 30 IH heater assembly (Refrigerant heating device)
31 Inner tube 32 Outer tube 33 Induction heating coil 34 Bobbin 35 Lid 36 Nut 37 Ferrite block,
38 Ferrite holder 39 Sheet metal cover 41 Expanded billet 43 Inner peripheral surface 44 (outer tube 32) groove 44 (straight) groove 45 Outer surface 46 (inner tube 31) Projection 47 (spiral) groove 48 (spiral) ) Projection A Discharge pipe B Indoor gas pipe C Indoor liquid pipe D Outdoor liquid pipe E Outdoor gas pipe F Accumulation pipe G Suction pipe

Claims (6)

An inner pipe (31) through which a refrigerant flows;
Surrounding the inner pipe (31), and an outer pipe (32) made of a magnetic material;
An induction heating coil (33) surrounding the outer tube (32) and for induction heating the outer tube (32);
The outer peripheral surface of the inner tube (31) and / or the inner peripheral surface of the outer tube (32) are in contact with the outer peripheral surface of the inner tube (31) and / or the inner peripheral surface of the outer tube (32). Area expansion portions (44, 46, 47, 48, 49, 50, 51, 52) for expanding the area are formed,
Refrigerant heating device (30). The area enlarged portions (44, 46, 47, 48, 49, 50, 51, 52) are irregularities formed on the outer peripheral surface of the inner tube (31) and / or the inner peripheral surface of the outer tube (32). Is,
The refrigerant heating device (30) according to claim 1. Grooves (44, 47) or protrusions are formed on the inner peripheral surface of the outer tube (32).
The refrigerant heating device (30) according to claim 1 or 2. Grooves or protrusions (46, 48) are formed on the outer peripheral surface of the inner pipe (31).
The refrigerant heating device (30) according to claim 1 or 2. The groove (47) or the ridge (48) extends spirally,
The refrigerant heating device (30) according to claim 3 or 4. The outer tube (32) is made of stainless steel,
The refrigerant heating device (30) according to any one of claims 1 to 5.

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