JPH04194592A - Double piped heat exchanger - Google Patents

Abstract

PURPOSE:To improve more a heat exchanging performance, enable a compact and light weight heat exchanger to be attained by a method wherein fins of an outer pipe are abutted against an outer surface of an inner pipe and a clearance between the outer pipe and the inner pipe is partitioned by the fins. CONSTITUTION:A plurality of fins 22 disposed at an inner surface of an outer pipe 20 are arranged in a circumferential direction in a predetermined spaced- apart relation. A plurality of projections 28 are disposed on an outer circumferential surface of the inner pipe 24 in a circumferential direction in a predetermined spaced-apart relation. The inner pipe 24 is inserted into the outer pipe 20, an extremity end surface of each of the fins 22 is abutted against an outer surface between the projections 28 and integrally fixed to the outer pipe 20. A plurality of independent refrigerant passages 30 are formed between the inner pipe 24 and the outer pipe 20. Since the projections 28 are present on the outer surface of the inner pipe 24, an area of the inner pipe 24 contacting with refrigerant flowing outside the inner pipe is increase and then a heat exchanging operation between fluid flowing in the inner holes 26 of the inner pipe 24 and refrigerant flowing in a plurality of refrigerant passages 30 is efficiently carried out.

Description

Detailed Description of the Invention (Technical Field) The present invention is comprised of an inner tube and an outer tube, and provides a method for connecting a fluid that is made to flow through the inner tube and a fluid that is made to flow between the outer tube and the inner tube. This invention relates to a double-tube heat exchanger that performs heat exchange.

(Background technology) - Various types of heat exchangers have been used in a wide range of cooling and heating fields. As a heat exchanger, a double-tube heat exchanger consisting of an inner tube and an outer tube is known.

For example, the heat exchanger shown in FIGS. 3(a) and 3(b) is a double-tube heat exchanger.

As is clear from FIG. 4, which shows the cross section of the double-pipe part, the heat exchanger 2 consists of an outer pipe 4 made of a predetermined metal and an inner pipe 6 inserted inside the outer pipe 4. It has a double tube structure, and here, the double tube is wound a plurality of times in an oval shape.

A plurality of fins 12 having a predetermined height are provided on the inner circumferential surface side of the outer tube 4 at predetermined intervals in the circumferential direction, and extend in the axial direction. for,
A cylindrical inner tube 6 having an inner hole 16 is fitted and
The tips of the fins 12 are brought into close contact with the outer peripheral surface of the inner tube 6, forming an integral structure. As a result, a gap of a predetermined size, that is, the height of the fins 12, is formed between the inner tube 6 and the outer tube 4, and the gap is partitioned by a plurality of fins 12.
A plurality of 14 independent refrigerant passages are formed using 2 as partition walls.

By the way, in the double-tube heat exchanger 2 having such a configuration, a plurality of communicating paths 14 are connected through one of the heat transfer medium (refrigerant) inflow/outflow ports 10 provided at the joint 8 A predetermined refrigerant is injected into the inner tube 6 to cool or heat the fluid (mainly water) flowing through the inner hole 16 of the inner tube 6. At this time, generally speaking, the larger the ratio of the inner and outer surface areas of the inner tube 6, the better the heat exchange performance of the fluid in contact with the inner and outer surfaces of the inner tube 6. Since the ratio of the inner and outer areas of the inner tube 6 is adjusted by the wall thickness of the cylindrical inner tube 6, there is a limit to the heat exchange performance.

(Problems to be solved) The present invention has been made against this background, and the problems to be solved are as follows:
It is an object of the present invention to provide a double-tube heat exchanger that can further improve heat exchange performance and can be made compact and lightweight.

(Solution Means) In order to solve this problem, the present invention provides an outer tube provided with a plurality of fins of a predetermined height extending in the tube axis direction on the inner surface, and an outer tube that is inserted and fixed into the outer tube. It consists of an inner tube having a plurality of grooves or protrusions on its outer surface extending in the tube axis direction, and the fins of the outer tube come into contact with the outer surface of the inner tube to create a gap between the outer tube and the inner tube. The gist thereof is a double-tube heat exchanger characterized in that gaps are partitioned by the fins.

(Specific configuration and operation) The present invention will be explained in more detail below with reference to the drawings.

In short, in the double pipe heat exchanger according to the present invention,
An example of the cross-sectional structure of the double pipe is shown in Figure 1(a).
As shown in b), an outer tube 20 integrally provided with a plurality of fins 22 having a predetermined height on its inner surface;
An inner tube 24 located therein and having an inner bore 26
It is composed of.

More specifically, the plurality of fins 22 provided on the inner surface of the outer tube 20 are provided so as to extend in the axial direction at predetermined intervals in the circumferential direction over the entire inner circumferential surface of the outer tube 20. Furthermore, on the outer circumferential surface of the inner tube 24, a plurality of protrusions 28 are provided at predetermined intervals in the circumferential direction and extend in the tube axis direction. And, such an inner tube 24 is
It is inserted into the outer tube 20 which has a plurality of fins 22 on the inner surface, and is integrally fixed to the outer tube 20 by being in contact with the tip surface of the fins 22 or the outer surface between the protrusions 28. There is. Therefore, in the gap formed between the inner tube 24 and the outer tube 20 by the height dimension of the fins 22 of the outer tube 20, there are a plurality of independent refrigerants (heat transfer media) partitioned by the fins 22. ) A passage 30 is formed.

Therefore, in such a double tube structure, the presence of the protrusions 28 on the outer surface of the inner tube 24 reduces the outer area of the inner tube 24, that is, the heat transfer medium (refrigerant) flowing on the outside of the inner tube 24. ) is significantly increased compared to a smooth tube,
Since the ratio of the inner and outer areas of the inner tube 24 can be increased,
Thereby, the fluid that is allowed to flow inside and outside of the inner tube 24, that is, the fluid that flows through the inner hole 26 of the inner tube 24, and
4 and the refrigerant flowing in the plurality of independent refrigerant passages 30 formed between the outer tube 20 and the refrigerant can be performed extremely efficiently.

Note that the plurality of refrigerant passages 30 extending in the tube axis direction, which are formed by being partitioned in the tube diameter direction by the gaps between the inner and outer tubes or the fins 22, are connected to each other by communicating with each other. In order to prevent the medium flowing inside the passage from becoming biased and the heat transfer performance decreasing, it is necessary to provide the fins 22 with such a degree that there is no free flow of fluid between them. It is tightly (pressure-welded) to the outer surface so that there is no gap.

By the way, the inner tube 24 of the double tube heat exchanger according to the present invention.
The material of the outer tube 20 may be selected as appropriate depending on the purpose of use of the heat exchanger.For example, the material of the outer tube 20 may be selected from the same material using copper.
While copper is used for the inner tube 24, titanium, stainless steel,
Metals such as cupronickel can also be used, and depending on the material selected, the inner tube,
The wall thickness of the outer tube will be selected accordingly.

In addition, the height, pitch, etc. of the protrusion 28 are as follows:
It is preferable that the height of the fins 22 provided inside the outer tube 20 is determined appropriately depending on the material of the inner tube 24, the refrigerant flowing through the refrigerant passage 3o, etc. It is desirable that the height and pitch be appropriately determined depending on the purpose and the type of refrigerant. ,
According to the present invention, a heat exchanger made of double pipes having such a structure is shown in FIG. 3(a).

It can be constructed in various forms, such as a form wound multiple times in an oval shape as shown in (b), a form wound in a circle or bent in a U-shape, a form formed into a straight rod shape, etc. Also, usually, there are
As shown in FIG. 3, a predetermined refrigerant inflow or outflow port 1
0 or more connecting portions 8 are each integrally disposed, and a predetermined refrigerant is allowed to flow through the plurality of communication passages 18 through the inflow/outflow ports 10.

In addition, when using the double-tube heat exchanger as described above, in the same way as in the past, the inside of the inner hole 26 is passed through the openings at both ends of the inner tube 24 connected to a normal circulating water supply device.
A predetermined fluid such as water is allowed to circulate, and the fluid flowing through the inner hole 26 of the inner pipe 24 is allowed to circulate through the inlet/outlet port 10 of the connection part 8 connected to the refrigerant supply device. A predetermined refrigerant is allowed to flow and circulate within the plurality of refrigerant passages 30 in a direction opposite to the flow direction.

In this way, heat exchange is performed between the fluid flowing through the inner tube 24 and the refrigerant flowing through the refrigerant passage 30.

Incidentally, when manufacturing a double-tube heat exchanger having the above structure, first, the outer tube 20 made of metal such as copper is formed into a desired shape using a tube reducer in the same manner as in the past. The inner tube 24 is formed into a cylindrical tube having a predetermined thickness and having a predetermined number of protrusions 28 on its outer peripheral surface by drawing a tube made of a predetermined metal.

The outer tube 20 is thus formed into a desired shape.
With the inner tube 24 inserted inside the inner tube 24, a drawing process is performed to insert the tip of the fin 22 of the outer tube 20 into the inner tube 2.
, 4, and fix the inner tube 24 within the outer tube 20 to form an integral double tube. As a result, a plurality of fluid-tightly isolated refrigerant passages 30 are formed between the inner tube 24 and the outer tube 20 in the tube axis direction by the plurality of fins 22 functioning as partition walls. By using such a double tube and molding it into the desired shape as described above, the desired double tube heat exchanger can be obtained.

Note that the double-tube heat exchanger according to the present invention is not limited to the one using the inner tube having a plurality of protrusions 28 on the outer surface as described above; Figure 2 (a)
, (b), it is also possible to provide a plurality of grooves 36 extending in the tube axis direction at a predetermined depth on the outer surface of the inner tube 32 having an inner hole 34. Note that if you look at this from a different perspective, you can view the portion between the two grooves 36 and 36 as a protrusion. Such a groove 36
However, it is preferable that the depth, pitch, etc. be appropriately selected depending on the material of the inner tube 32 and the refrigerant. and,
On the outer surface portion of the inner tube 32 provided with such a groove 36,
The fins 22 of the outer tube 2o are brought into fluid-tight contact to form a plurality of independent refrigerant passages 38 without communicating with each other.

(Examples) Below, typical examples of the present invention will be shown to further clarify the present invention.
Furthermore, it is to be understood that various changes, modifications, improvements, etc. can be made based on the knowledge of those skilled in the art without limiting the same to the above-mentioned specific description.

Example 1 First, a double pipe structure as shown in Figs. 1 and 2 was adopted, and the inner and outer pipes were both made of copper and had the dimensions shown in Table 1 below. Prepare double tubes, each with a double tube heat exchanger (as shown in Fig. 3).
NCLI, Nα2) was produced.

In addition, in the Nαl heat exchanger, 24 protrusions (28) formed on the outer surface of the inner tube are provided at predetermined intervals along the circumferential direction of the inner tube. In the heat exchanger, 90 grooves (36) are provided on the outer surface of the inner tube at uniform intervals in the circumferential direction.

Each of these heat exchangers is then operated as an evaporator that cools water, which is circulated at a constant flow rate inside the inner tube, using a refrigerant flowing between the inner tube and the outer tube, in accordance with the usual method. The evaporative heat transfer performance was investigated and shown in Figure 5.
It is shown as a graph of the relationship between the amount of refrigerant circulation and the heat transfer rate.

Note that Freon 22 was used as the refrigerant.

For comparison, a heat exchanger (Nα3) using an inner tube made of a smooth tube shown in FIG.
Evaporative heat transfer performance tests were conducted and the results are also shown.

As is clear from the results in Table 1 and above, in the heat exchanger (Nα1, Nα2) consisting of a double pipe in which a predetermined number of protrusions or grooves are provided on the outer peripheral surface of the inner pipe according to the present invention The ratio of the inner and outer areas of the inner tube to the inner tube is extremely high compared to that of the smooth tube (Nα3), and as is clear from the graph in Figure 5, the evaporative heat transfer performance (cooling capacity) of the Nnl and Nα2 heat exchangers is extremely high. It can be seen that there has been a significant improvement.

Example 2 A double tube heat exchanger (Nα1-N
α3) is used as a condenser to heat the water circulating inside its inner tube, and Freon R22 is used as the refrigerant.
In addition, the amount of circulating water flowing through the inner pipe is 1000 to 2000.
! ! /h, the condensation heat transfer performance of each heat exchanger was investigated.

The results are shown in FIG.

As is clear from these results, the heat exchangers (Nα1, Nα2) according to the present invention are superior to the conventional heat exchangers (Nα2).
It can be seen that the condensing heat transfer performance (heating ability) is significantly improved compared to α3).

(Effects of the Invention) As is clear from the above description, the double-tube heat exchanger according to the present invention has a plurality of grooves or protrusions extending in the tube axis direction on the outer surface of the inner tube. As a result, the ratio of the inner and outer areas of the inner tube can be made significantly higher than the ratio of the inner and outer areas of the conventional inner tube made of a smooth tube. The heat exchange performance with the circulating fluid can be greatly improved, and both cooling performance and heating performance can be effectively improved.

In addition, by increasing the ratio of the inner and outer areas of the inner tube by providing grooves or ridges on the outer surface of the inner tube, the heat exchanger itself can be made more compact and lighter. You get it.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are an explanatory cross-sectional view and an enlarged sectional view of part A of a double-tube portion showing an example of a double-tube heat exchanger according to the present invention, respectively, and FIG. (a) and (b) respectively show other examples of the present invention.
), and FIGS. 3(a) and ('b) are
FIG. 4 is a plan view and a front view showing a conventional double-tube heat exchanger, respectively, and FIG. 4 is an explanatory cross-sectional view taken along IV-iV in FIG. 3. Moreover, FIG. 5 is a graph showing the relationship between the amount of refrigerant circulation and the heat transfer rate obtained in Example 1, and FIG. 6 is a graph showing the relationship between the amount of circulating water and the heat transfer rate obtained in Example 2. It is a graph showing a relationship. 2: Double tube heat exchanger 2o: Outer tube 22: Fin 24.32 Inner tube 26.3
4: Inner hole 28/projection 30. 38: Refrigerant passage 36: Ganto Mizoyama Sumitomo Light Metal Industries Ltd. L1 diagram (b) Product 2 diagram (a) (b) Figure 3 Figure 4 Figure 5 Figure 2 Female fruit circulation amount (kg//Lr)

Claims (1)

[Claims] An outer tube is provided with a plurality of fins of a predetermined height extending in the tube axis direction on the inner surface, and an inner tube is provided with a plurality of grooves or protrusions on the outer surface that extend in the tube axis direction and are inserted and fixed into the outer tube. A double pipe type, characterized in that the fins of the outer pipe are in contact with the outer surface of the inner pipe, and a gap between the outer pipe and the inner pipe is partitioned by the fins. Heat exchanger.