CN104964585A - Heat exchanger, alternating flow system and machining method of heat exchanger - Google Patents

Abstract

The invention relates to a heat exchanger, an alternating flow system and a processing method for the heat exchanger, aiming at solving the problem of how to reduce the processing complexity or difficulty of the heat exchanger while improving the heat exchange performance. The heat exchanger includes a sleeve and several tube bundle units sleeved in the sleeve for gas circulation; each tube bundle unit includes an outer tube and at least two inner tubes sleeved in the outer tube , each of the inner tubes is arranged in contact with the outer tube. The invention increases the contact area between the air flow and the tube bundle unit by adding inner tubes, thereby improving the heat exchange performance. Moreover, the present invention replaces the fins in the prior art by sheathing the inner tube inside the outer tube, which saves the complicated processing process of the wire cutting technology or the difficult process of the stretching forming technology, and not only has low processing complexity, but also has low difficulty. ,easy to accomplish.

Description

Heat exchanger, alternating flow system and processing method for heat exchanger

technical field

The invention relates to the field of alternating flow heat exchange, in particular to a heat exchanger, a processing method of the heat exchanger and an alternating flow system.

Background technique

Alternating flow systems, such as Stirling engines and refrigerators, thermoacoustic engines and refrigerators, pulse tube refrigerators, etc., are widely used in various energy conversion processes. The heat exchanger is one of the core components of the alternating flow system, and the heat exchange effect of the heat exchanger determines the energy conversion efficiency of the alternating flow system.

Fig. 1 is a water cooler structure in a traditional alternating flow system, the water cooler includes a shell 1 and copper fins 2 arranged in the shell 1, a water flow channel 3 is formed between the copper fins 2 and the shell 1, and the copper fins Inside is the airflow channel. A small amount of fins 21 are also arranged on the side of the copper fins 2 facing the water flow channel 3 to enhance heat exchange between the copper fins and water. The distribution density of copper fins is relatively large, which increases the heat transfer area. When exchanging heat, the heat of the airflow needs to be transferred to the cooling water through the copper fins, so the heat of the airflow needs to pass through a long distance to be transferred to the cooling water, resulting in a large temperature difference between the top and the root of the copper fins. affect the heat transfer performance. As the power of the alternating flow system increases, the radial height of the copper fins needs to increase, so that the temperature difference between the top and root of the copper fins will be greater.

Figure 2 shows the structure of a shell-and-tube heat exchanger, which includes a sleeve 4 and several circular tubes 61 arranged in the sleeve, the air flow flows in the circular tubes 61, and the cooling water flows through the circular tubes. Flow in the sleeve 4 outside 61. A water inlet or outlet 41 is opened on the sleeve 4, and end caps 5 are connected to both ends of the sleeve. Because the cooling water is in contact with each circular tube, the temperature of the outer wall of each circular tube is relatively close, and the gas in different circular tubes will not have a large temperature difference. But the heat exchanger of this structure also has disadvantages. Because the heat transfer area on the airflow side of this structure is basically equal to the heat transfer area on the cooling water side, but the heat transfer coefficient of the gas is more than an order of magnitude smaller than that of the cooling water, so the heat transfer of the heat exchanger with this structure Performance is not ideal. For this reason, the circular tube can be processed into the structure shown in Figure 3, which can increase the heat exchange area on the gas side. However, if the wire cutting technology is used, the processing process is very cumbersome and the cost is relatively high. If stretch forming technology is used, since the distance between the fins in the circular tube is very small, the process is difficult and the processing is difficult.

Contents of the invention

The technical problem to be solved by the invention is how to reduce the processing complexity or difficulty of the heat exchanger while improving the heat exchange performance.

In order to solve the above technical problems, the present invention proposes a heat exchanger. The heat exchanger includes a sleeve and several tube bundle units sleeved in the sleeve, the inside of the tube bundle unit is for the circulation of the first flow medium, and the sleeve outside the tube bundle unit is for the circulation of the second flow medium ; Each tube bundle unit includes an outer tube and at least two inner tubes sleeved in the outer tube, and the outer wall of each inner tube is in contact with the inner wall of the outer tube.

Further, the outer wall of each inner tube is in surface contact with the inner wall of the outer tube.

Further, the outer wall of each inner tube is in contact with the inner wall of the outer tube.

Furthermore, the outer wall of each inner tube is connected to the inner wall of the outer tube in a plane.

The present invention also provides an alternating flow system, including any one of the above heat exchangers.

The present invention also provides a processing method of a heat exchanger, the method comprising:

fitting at least two inner tubes inside an outer tube;

The outer tube is squeezed so that the inner wall of the outer tube is in contact with the outer wall of each of the inner tubes.

Further, the outer tube is pressed with a force greater than a preset force, so that the inner wall of the outer tube forms surface contact with the outer wall of each inner tube.

Further, the method also includes:

The outer wall of the inner tube is welded to the inner wall of the outer tube.

Further, the welding the outer wall of the inner tube to the inner wall of the outer tube includes:

coating the outer wall of the inner tube with solder prior to fitting the inner tube inside the outer tube;

After the outer tube is brought into contact with each of the inner tubes by pressing the outer tube, the tube bundle unit is heated until the solder is melted.

The invention increases the contact area between the air flow and the tube bundle unit by adding inner tubes, thereby improving the heat exchange performance. Moreover, the fins in the prior art are replaced by the method of sheathing the inner tube in the outer tube, which saves the complicated processing process of the wire cutting technology or the difficult process of the stretching forming technology, and not only has low processing complexity, but also is less difficult and easy. accomplish.

Description of drawings

The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the accompanying drawings:

Fig. 1 shows a schematic structural view of a water cooler in a traditional alternating flow system;

Figure 2 shows a schematic structural view of a shell-and-tube heat exchanger;

Fig. 3 shows the improved cross-sectional view of the circular tube in Fig. 2 in the prior art;

Fig. 4 shows the structural representation of a kind of heat exchanger of the present invention;

Fig. 5 shows an exploded schematic diagram of a heat exchanger of the present invention;

Fig. 6 shows a cross-sectional view of a tube bundle unit in a heat exchanger of the present invention;

Fig. 7 shows a cross-sectional view of a tube bundle unit in a heat exchanger of the present invention before extrusion.

Detailed ways

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In order to understand the above-mentioned purpose, features and advantages of the present invention more clearly, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described here. Therefore, the protection scope of the present invention is not limited by the specific details disclosed below. EXAMPLE LIMITATIONS.

The present invention provides a heat exchanger, as shown in Figures 4, 5, and 6, the heat exchanger includes a sleeve 4 and several tube bundle units 62 sleeved in the sleeve 4 for gas circulation; each The tube bundle unit 62 includes an outer tube 622 and at least two inner tubes 621 sheathed in the outer tube, and each of the inner tubes is arranged in contact with the outer tube. The first flow medium circulates in the tube bundle unit 62 , and the second flow medium circulates in the sleeve outside the tube bundle unit. The first flow medium and the second flow medium may be water, air, or the like.

Generally, the first flow medium is hot air, and the second flow medium is cooling water, and the following content takes this case as an example for description.

Since the heat exchanger of the present invention adopts a structure in which several tube bundle units are arranged in the casing, similar to the structure of the shell-and-tube heat exchanger shown in Figure 2, since the cooling water is in contact with the outer tube of each tube bundle unit, each tube bundle The temperature of the outer wall of the outer tube in the unit is relatively close, and the gas in different tube bundle units will not have a large temperature difference, thus avoiding the problem of poor heat transfer performance caused by the large temperature difference.

Moreover, since at least two inner tubes are arranged in the outer tube of each tube bundle unit, and each inner tube is arranged in contact with the outer tube, the airflow flowing through the inner tube in the tube bundle unit or the gap between the inner tubes will The heat is transferred to the cooling water outside the tube bundle unit through the outer tube, or the heat is transferred to the inner tube, and the inner tube transfers the heat to the cooling water through the outer tube. The invention increases the contact area between the air flow and the tube bundle unit by adding inner tubes, thereby improving the heat exchange performance.

Although the function of the inner tube in the present invention is similar to that of the fins in Figure 3, the present invention replaces the fins in the prior art by sheathing the inner tube in the outer tube, which saves the complicated wire cutting technology. The high difficulty process of processing or stretch forming technology is not only low in processing complexity, but also small in difficulty and easy to implement.

Because the tube bundle unit of the present invention is easy to process, the diameter of the tube bundle unit can be made very small, which is also impossible for the round tube in Figure 3, because the diameter of the round tube is limited by the difficulty of fin processing. Since the diameter of the tube bundle unit can be made very small, it can meet various heat exchange requirements.

The tube bundle unit shown in Figures 4, 5, and 6 is provided with four inner tubes, of course, the number of inner tubes can be freely selected during specific implementation.

Since the number of inner tubes in each outer tube can be adjusted, and the diameter and wall thickness of each inner tube can also be adjusted according to needs, the flow area ratio of the entire heat exchanger can be freely adjusted within a wide range. This is impossible for the shell-and-tube heat exchanger shown in Figure 2 and Figure 3. Since there is no inner tube or fin in the circular tube in Figure 2, the flow area ratio is limited by factors such as tube wall thickness and tube spacing. , the adjustable range is very small. However, the diameter of the circular tube in Figure 3 is relatively small, the processing of the fins is very difficult, and the adjustable range of the spacing and thickness of the fins is very small, so the flow area of the heat exchanger formed by the circular tube in Figure 3 The ratio adjustable range is also very small.

The hydraulic diameter required by the heat exchangers in Figures 2 and 3 is mainly affected by the operating frequency of the system. The hydraulic diameter of the finned heat exchanger in Figure 3 is equal to 2 times the fin spacing, and the adjustability is small. Moreover, the smaller the hydraulic diameter and the smaller the fin pitch, the more difficult it is to process. However, the diameter of the inner pipe in the present invention can be large or small, even as small as 0.1mm, so the hydraulic diameter of the present invention can be very small to meet various heat exchange requirements.

As an improvement to the above technical solution, the outer wall of each inner tube is in surface contact with the inner wall of the outer tube. Since the contact area of the surface contact is larger than that of the line contact, the surface contact can increase the amount of heat conduction per unit time between the inner tube and the outer tube.

In another improvement to the above technical solution, the outer wall of each inner tube is in contact with the inner wall of the outer tube. In this improved scheme, the inner tube and the outer tube are not only in contact but also connected, which improves the stability of the tube bundle unit and prolongs the service life of the heat exchanger. As a further improvement to this improvement solution, the outer wall of each inner tube is connected to the inner wall of the outer tube by surface. On the basis of improving the stability of the tube bundle unit, the heat conduction amount per unit time between the inner tube and the outer tube is increased.

In addition, as shown in FIG. 4 , the side wall of the sleeve 4 of the heat exchanger is also provided with an inlet or outlet 41 of cooling water. The two ends of the sleeve are respectively sealed with the end cover 5 . The space can be connected by welding, and the tube bundle unit communicates with the air inlet or outlet on the end cover.

The present invention also provides an alternating flow system, which includes the above-mentioned heat exchanger. The alternating flow system has the same advantages as the heat exchanger, which will not be repeated here.

The present invention also provides a method for processing the above-mentioned heat exchanger. Of course, the above-mentioned heat exchanger can also be processed by other methods.

The method includes:

nesting at least two inner tubes within said outer tube;

Squeezing the outer tube brings the outer tube into contact with each of the inner tubes.

Fig. 7 shows the state of the tube bundle unit before extrusion, by extruding the outer tube, the outer tube and the inner tube are deformed and come into contact.

It can be seen from the above processing method that the processing process is simple, and the processing cost and difficulty are relatively low.

During specific implementation, by squeezing the outer tube, not only the outer tube can be brought into contact with each inner tube, but also adjacent inner tubes can be brought into contact.

In order to form a good thermal conductivity between the outer tube and the inner tube and increase the stability of the tube bundle unit, the processing method may further include: welding the outer tube and the inner tube.

The specific welding method is:

coating the outer wall of the inner tube with solder before fitting the inner tube on the outer tube;

After the outer tube is brought into contact with each of the inner tubes by pressing the outer tube, the tube bundle unit is heated until the solder is melted.

In order to increase the heat conduction speed between the outer tube and the inner tube, it can be realized by increasing the heat conduction area. Therefore, during the extrusion process, the outer tube is extruded with a force greater than a predetermined force, so that surface contact or surface connection is formed between the outer tube and the inner tube.

To sum up, the heat exchanger and the alternating flow system provided by the present invention not only improve the heat exchange performance, but also have a simple structure. It can be seen from its simple structure that the processing process is less difficult and easy to realize. The processing method provided by the invention has simple process and low processing cost and difficulty.

Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention. within the bounds of the requirements.

Claims (9)

1. a heat exchanger, is characterized in that, comprises sleeve and is set in several tube bundle unit in described sleeve, and the inside of described tube bundle unit, for first-class moving medium circulation, supplies the circulation of second moving medium in the sleeve of described tube bundle unit outside; Tube bundle unit described in each comprises an outer tube and is set in pipe at least two in described outer tube, and the outer wall of each described interior pipe contacts with the inwall of described outer tube.

2. heat exchanger according to claim 1, is characterized in that, for face contacts between the outer wall of each described interior pipe and the inwall of described outer tube.

3. heat exchanger according to claim 1, is characterized in that, connects between the outer wall of each described interior pipe and the inwall of described outer tube for contacting.

4. heat exchanger according to claim 3, is characterized in that, for face is connected between the outer wall of each described interior pipe and the inwall of described outer tube.

5. an Oscillating flow system, is characterized in that, comprises the arbitrary described heat exchanger of claim 1-4.

6. a processing method for heat exchanger, is characterized in that, comprising:

At least two interior pipe boxes are contained in the inside of an outer tube;

Extrude described outer tube, the inwall of described outer tube is contacted with the outer wall of each described interior pipe.

7. processing method according to claim 6, is characterized in that, extrudes described outer tube with the active force being greater than default active force, and forming surface between the inwall of described outer tube and the outer wall of each described interior pipe is contacted.

8. processing method according to claim 6, is characterized in that, also comprises:

The outer wall of described interior pipe is welded with the inwall of described outer tube.

9. processing method according to claim 8, is characterized in that, the described outer wall by described interior pipe welds with the inwall of described outer tube, comprising:

Before the inside interior pipe box being contained in outer tube, coated with solder on the outer wall of described interior pipe;

Being made by the described outer tube of extruding after described outer tube contacts with each described interior pipe, to be heated to described solder fusing to described tube bundle unit.