A plate heat exchanger for central heating and central heating system thereof

Abstract

The present invention provides a plate heat exchanger for centralized heating, wherein the heat exchange tube is a plate structure, the plate structure includes a long side and a short side, an inner partition is arranged inside the plate structure, the inner partition connects the two long sides of the plate structure, and divides the inner cavity of the plate structure into a first inner cavity and a second inner cavity, a partition wall is arranged inside the first head and the second head, and the first head is divided into a first cavity and a second cavity, and the second head is divided into a first cavity and a second cavity, wherein the first cavity of the first head is connected to the first cavity of the plate structure, and the first cavity of the plate structure is connected to the first cavity of the second head, wherein the second cavity of the first head is connected to the second cavity of the plate structure, and the second cavity of the plate structure is connected to the second cavity of the second head. The present invention divides the heat exchange tube into two parts, and the two parts of fluid flow countercurrently to each other, so that the heat exchange in the overall flow direction of the heat exchange tube is uniform, thereby enhancing heat transfer.

Description

Technical Field

[0001] The invention relates to a heat exchanger, belonging to the technical field of heat exchangers, in particular to a plate heat exchanger for centralized heating. Background Art

[0002] Heat exchangers are widely used in industrial production, for example, they play an important role in various industrial sectors such as chemical industry, power, metallurgy, construction, machinery manufacturing, food, medicine and aerospace. Therefore, it is necessary for the industry to optimize the design of heat exchangers to improve the heat exchange efficiency. For the automotive industry, optimizing the design of automobile engine exhaust gas recirculation coolers, improving the heat exchange efficiency to reduce the emission of nitrogen oxides, and making the exhaust gas emissions meet the requirements of the increasingly stringent exhaust gas emission standards are also urgent issues to be solved.

[0003] Due to the limitations of manufacturing process and technical level, early heat exchangers could only adopt simple structures, small heat transfer area, large volume, and bulky, such as coil heat exchangers. With the development of manufacturing technology, plate heat exchangers have a larger heat transfer area per unit volume and better heat transfer effect. They have long been a typical heat exchanger in industrial production. Plate heat exchangers appeared in the 1920s and were used in the food industry. Heat exchangers made of plates instead of tubes have compact structures and good heat transfer effects. After the 1980s, a large number of enhanced heat transfer components were introduced to the market, and the manufacturing process of heat exchangers such as plate and shell heat exchangers was further improved, which promoted the vigorous development and widespread application of compact heat exchangers.

[0004] In the plate and shell heat exchanger of the prior art, the fluid in the shell side all passes through the flat surface of the flat tube horizontally, so it flows vertically with the fluid in the flat tube. The above heat exchange method has insufficient heat exchange capacity compared with the countercurrent heat exchange method. Therefore, in order to enhance heat transfer, for the tube side, a partition is generally used to achieve U-shaped flow of the tube side fluid. For example, Chinese patent publication number CN101040163A discloses such a structure. For example, a U-shaped tube structure can also be adopted, or a partition can be set in the tube side head to achieve multi-tube flow of the tube side fluid to achieve enhanced heat transfer.

[0005] At that time, the above structures all had the tube-side fluid go directly from the tube-side inlet to the tube-side outlet. During the fluid flow process, the heat exchange capacity of the cold fluid gradually decreased, and the degree of decrease became larger and larger. Although there was a certain improvement in the enhanced heat transfer, there was still a difference in the heat exchange capacity in the flow direction of the shell-side fluid and the tube-side fluid as a whole, resulting in uneven heat exchange along the flow direction of the tube-side fluid and the shell-side fluid, resulting in uneven heat exchange of the heat exchange tube as a whole along the flow direction of the fluid in the tube, resulting in a decrease in heat exchange efficiency. Therefore, the present invention designs a new type of heat exchanger to improve the structure of the traditional plate heat exchanger to achieve the purpose of enhanced heat transfer. Summary of the invention

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A plate heat exchanger for centralized heating, the plate heat exchanger comprising a tube side and a shell side, the tube side comprising a first end cap, a second end cap, a tube sheet and a heat exchange tube, both ends of the heat exchange tube are fixedly mounted on the tube sheet, the tube side fluid enters the heat exchange tube from the inlet end cap, and then flows out from the outlet end cap; characterized in that the heat exchange tube is a plate structure, the plate structure comprises a long side and a short side, an inner partition is arranged in the plate structure, the inner partition connects the two long sides of the plate structure, and divides the inner cavity of the plate structure into a first inner cavity and a second inner cavity, the first end cap and the second end cap are provided in the inner cavity of the plate structure. A partition wall is arranged at the part to divide the first end cap into a first cavity and a second cavity, and the second end cap is divided into a first cavity and a second cavity, wherein the first cavity of the first end cap is connected to the first inner cavity of the plate structure, and the first inner cavity of the plate structure is connected to the first cavity of the second end cap, wherein the second cavity of the first end cap is connected to the second inner cavity of the plate structure, and the second inner cavity of the plate structure is connected to the second cavity of the second end cap; the first cavity and the second cavity of the first end cap are respectively provided with a first inlet and a first outlet of the tube-side fluid, and the first cavity and the second cavity of the second end cap are respectively provided with a second outlet and a second outlet of the tube-side fluid.

[0008] As an improvement, a shell-side fluid inlet and outlet are provided on the shell side, and a line connecting the shell-side fluid inlet and outlet forms an angle of 30-150° with the flow direction in the first inner cavity of the plate structure.

[0009] As an improvement, the line connecting the shell-side fluid inlet and outlet is a line connecting the center points of the openings of the shell-side fluid inlet and outlet on the shell.

[0010] As an improvement, the line connecting the shell-side fluid inlet and outlet forms an angle of 90° with the flow direction in the first inner cavity of the plate structure.

[0011] As an improvement, the heat exchanger is a horizontal plate heat exchanger, the long side of the plate structure is arranged along the vertical direction, and the inner partition and the partition wall are arranged in the horizontal direction.

[0012] As an improvement, the first inner cavity is located above the second inner cavity, and the first cavities of the first head and the second head are located above the second cavity.

[0013] As an improvement, the heat exchanger is a vertical plate heat exchanger, the long side of the plate structure is arranged in the horizontal direction, and the inner partition and the partition wall are arranged in the vertical direction.

[0014] As an improvement, the first inner cavity is located at the seat of the second inner cavity, and the first cavity of the first head and the second head is located at the left part of the second cavity.

[0015] As an improvement, the inner partition divides the inner cavity of the plate structure into equal parts.

[0016] As an improvement, the plate structure is a flat tube.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] The present invention divides the plate-type heat exchange tube into two parts, the two side heads are also divided into two parts, and the tube-side fluid is divided into two parts, one part enters from the first head and flows out from the second head, and the other part enters from the second head and flows out from the first head. The two parts of the fluid are separated from each other and form a countercurrent structure. Because the upper and lower tube-side fluids flow in opposite directions, the upper part has a strong heat exchange capacity and the lower part has a weak heat exchange capacity, and similarly, the upper part has a weak heat exchange capacity and the lower part has a strong heat exchange capacity. In this way, the average heat exchange amount per unit length of the heat exchange tube along the length direction is basically the same, and the heat exchange capacity is basically uniform, and there will be no uneven local heat exchange capacity in the length direction, thereby achieving a heat exchange effect similar to countercurrent and realizing the purpose of enhanced heat transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the overall structure of the heat exchanger of the present invention;

[0020] Figure 2 It is a schematic diagram of the cross-sectional structure of the heat exchanger of the present invention;

[0021] Figure 3 It is a schematic diagram of the cross-sectional structure of the plate structure of the present invention;

[0022] Figure 4 It is a schematic diagram of the arrangement structure of fins in a flat tube of a heat exchanger of the present invention. DETAILED DESCRIPTION

[0023] In this article, unless otherwise specified, “ / ” represents division, and “×” and “*” represent multiplication.

[0024] In the description of the present invention, the terms "left" and "right" are used based on the position or orientation relationship shown in the drawings, and do not indicate or imply the specific installation and operating orientation that the described device or element must have, and therefore cannot be understood as a limitation of the present invention.

[0025] The technical solutions in the embodiments of the present invention will be supplemented below with reference to the accompanying drawings in the embodiments of the present invention.

[0026] Figure 1-3 A plate heat exchanger is disclosed. It is preferably used in a centralized heating system. The plate heat exchanger includes a tube side and a shell side, and the shell side includes a shell 2. The tube side includes a first head 3, a second head 4, a tube sheet 5 and a heat exchange tube 1. Both ends of the heat exchange tube 1 are fixedly mounted on the tube sheet 5. The tube side fluid enters the heat exchange tube 1 from the inlet head and then flows out from the outlet head.

[0027] As an improvement, the heat exchange tube 1 is a plate structure 1, which includes a long side 11 and a short side 12. An inner partition 13 is arranged in the plate structure, and the inner partition 13 connects the two long sides 11 of the plate structure to divide the inner cavity of the plate structure into a first inner cavity 14 and a second inner cavity 15. The first head 3 and the second head 4 are respectively provided with partition walls 31 and 41, which divide the first head 3 into a first cavity 32 and a second cavity 33, and divide the second head 4 into a first cavity 42 and a second cavity 43, wherein the first cavity 32 of the first head 3 is connected to the first cavity 14 of the plate structure, and the first cavity 14 of the plate structure is connected to the first cavity 42 of the second head, wherein the second cavity 33 of the first head is connected to the second cavity 15 of the plate structure, and the second cavity 15 of the plate structure is connected to the second cavity 43 of the second head; the first cavity 34 and the first outlet 45 of the tube-side fluid are respectively provided in the first cavity and the second cavity of the second head, and the second outlet 44 and the second outlet 35 of the tube-side fluid are respectively provided in the first cavity and the second cavity of the second head.

[0028] The present invention divides the plate-type heat exchange tube into two parts, the two side heads are also divided into two parts, and the tube-side fluid is divided into two parts, one part enters from the first head and flows out from the second head, and the other part enters from the second head and flows out from the first head. The two parts of the fluid are separated from each other and form a countercurrent structure. Because the upper and lower tube-side fluids flow in opposite directions, the upper part has a strong heat exchange capacity and the lower part has a weak heat exchange capacity, and similarly, the upper part has a weak heat exchange capacity and the lower part has a strong heat exchange capacity. In this way, the average heat exchange amount per unit length of the heat exchange tube along the length direction is basically the same, and the heat exchange capacity is basically uniform, and there will be no uneven local heat exchange capacity in the length direction, thereby achieving a heat exchange effect similar to countercurrent and realizing the purpose of enhanced heat transfer.

[0029] The tube-side and shell-side fluids of the present invention can achieve the technical effect of countercurrent flow regardless of whether they are cocurrent or countercurrent, and thus can satisfy a variety of different flow directions as a whole, and have a wide range of applications.

[0030] As an improvement, a shell-side fluid inlet 6 and an outlet 7 are provided on the shell side, and the connecting line of the shell-side fluid inlet and outlet forms an angle of 30-150° with the flow direction in the first inner cavity of the plate structure. Because the present invention is a cross flow, not a pure countercurrent flow, the plate structure heat exchange tube is divided into two parts, so that a technical effect close to countercurrent heat exchange can be achieved.

[0031] As an improvement, the line connecting the shell-side fluid inlet and outlet is a line connecting the center points of the openings of the shell-side fluid inlet and outlet on the shell.

[0032] As an improvement, the line connecting the shell-side fluid inlet and outlet forms a 90° angle with the flow direction in the first inner cavity of the plate structure. The advantages of the above arrangement can be better reflected through vertical flow, achieving the technical effect of countercurrent heat exchange regardless of the flow.

[0033] As an improvement, the heat exchanger is a horizontal plate heat exchanger, the long side of the plate structure is arranged along the vertical direction, and the inner partition and the partition wall are arranged in the horizontal direction. The above arrangement can realize the flow of the horizontal heat exchanger.

[0034] As an improvement, the first inner cavity is located above the second inner cavity, and the first cavities of the first and second heads are located above the second cavity. Through the above arrangement, the horizontal heat exchanger can further improve the heat exchange effect.

[0035] As an improvement, the heat exchanger is a vertical plate heat exchanger, the long side of the plate structure is arranged in the horizontal direction, and the inner partition and the partition wall are arranged in the vertical direction. The above arrangement can realize the flow of the vertical heat exchanger.

[0036] As an improvement, the first inner cavity is located at the left part of the second inner cavity, and the first cavity of the first head and the second head is located at the left part of the second cavity.

[0037] As an improvement, the inner partition evenly divides the inner cavity of the plate structure. The partition wall evenly divides the first end cap and the second end cap. By evenly distributing the chamber volume, heat transfer can be further enhanced.

[0038] As an improvement, the plate structure is a flat tube.

[0039] The plate structures are multiple and arranged in parallel, and the shell-side fluid flows between the plate structures. Figure 3 shown.

[0040] The shell-side fluid passes through the shell-side inlet and is then distributed to the gaps between adjacent plate structures to exchange heat with the heat exchange surface where the long sides of the plate structures are located. Preferably, the short sides of the plate structures are connected to the inner wall of the shell of the shell side to prevent the fluid from flowing away from the inner wall side of the shell, causing a short circuit of the fluid.

[0041] Preferably, the cross section of the shell is rectangular to match the arrangement of the plate structure.

[0042] As an improvement, Figure 3 As shown, the shell side inlet is connected to the inlet header 21, which is mounted on the shell, and an inlet through hole 22 is provided on the shell. Preferably, the through hole is provided between adjacent plate structures, and preferably the through hole is a strip through hole, extending along the gap between the plate structures. The shell side outlet is connected to the outlet header 23, which is mounted on the shell, and an outlet through hole 24 is provided on the shell. Preferably, the outlet through hole is provided between adjacent plate structures, and preferably the outlet through hole is a strip through hole, extending along the gap between the plate structures. The fluid enters the inlet header through the shell side inlet, and then enters the gap between the plate structures in the shell through the through hole. Then it enters the outlet header, and finally flows out from the outlet to complete the heat exchange.

[0043] As an improvement, the tube-side fluid is gas and the shell-side fluid is gas.

[0044] As an improvement, the shell side fluid is exhaust gas, and waste heat is achieved through the exhaust gas.

[0045] As an improvement, see Figure 1 The fluids in the first inner cavity and the second inner cavity of the heat exchange tube are provided by a fluid source 8. The fluid source 8 provides two fluid paths, one path entering the first inner cavity and the other path entering the second inner cavity. After heat exchange in the first inner cavity and the second inner cavity, the fluids are combined and enter the fluid source 8.

[0046] As an improvement, Figure 4 As shown, the first inner cavity 14 and / or the second inner cavity 15 in the plate structure are provided with fins 16, the first fins extend from the long side 11 of the plate structure toward the inner partition 13, and the second fins extend from the inner partition toward the long side, and the two types of fins are alternately arranged, so that the fluid in the plate structure forms a curved flow direction. Short circuit of fluid flow can be avoided, and the fins are provided to increase the heat exchange area, further achieving the technical effect of enhancing heat transfer.

[0047] As an improvement, the first inner cavity in the horizontal heat exchanger is located at the upper part. The long side of the plate structure is arranged in the horizontal direction, and the inner partition and the partition wall are arranged in the horizontal direction. The fluid in the tube side is gas, and along the flow direction of the gas in the first inner cavity, the extension length of the first fin gradually increases, and the extension length of the second fin gradually decreases.

[0048] During the research process, it was found that the heat exchange in the cross section of the first cavity in the direction of fluid flow was uneven. As the distance from the inlet increased, the gas density in the tube was small, so the gas flowed upward, which significantly increased the gas in the upper part. Therefore, it was necessary to design a heat exchange structure for improvement. In the present invention, the length of the first fin and the second fin changes along the flow direction of the gas, so that the gas in the first inner cavity gradually decreases and moves toward the upper part as it flows, and is retained in the middle and lower parts for more time, so that the center and lower part of the first inner cavity are strengthened in heat exchange, which changes the previous heat exchange method, enhances the heat exchange efficiency at different positions, makes the heat exchange uniform as a whole, and further achieves the purpose of enhanced heat transfer.

[0049] As an improvement, along the flow direction of the gas in the first inner cavity, the length of the first fin increases gradually, and the length of the second fin decreases gradually. Through the above changes in amplitude, the overall heat exchange can be further uniform, further achieving the purpose of enhancing heat transfer.

[0050] As an improvement, along the flow direction of the fluid in the first inner cavity, from the inlet 17 of the first inner cavity to the middle position of the first inner cavity ( Figure 4 The distance between adjacent fins increases from the middle position of the long side of the heat exchange tube to the first inner cavity outlet 18. Then, from the middle position of the heat exchange tube to the first inner cavity outlet 18, the distance between adjacent fins decreases. Because the heat exchange between the cold and hot fluids is relatively uniformly arranged in the flow direction during the heat exchange process, the overall heat exchange effect is the best. However, it was found in experiments and simulations that the heat exchange in the middle is significantly greater than the heat exchange at the inlet and outlet. Therefore, by changing the spacing between the fin tubes, the increased internal heat exchange area also changes regularly. Therefore, the uneven heat exchange is compensated by the change in area, thereby further improving the heat exchange efficiency.

[0051] As an improvement, from the entrance of the first inner cavity to the middle position of the heat exchange tube, the spacing between adjacent fins increases continuously. Then, from the middle position of the heat exchange tube to the exit of the first inner cavity, the spacing between adjacent fins decreases continuously. The above-mentioned change in amplitude can make the heat exchange per unit area of ​​the entire fluid movement more uniform, further improving the heat exchange efficiency.

[0052] A centralized heating system, the system includes a boiler, the hot water heated in the boiler enters the plate heat exchanger of the heat exchange station, exchanges heat with the cold source in the plate heat exchanger, and then returns to the boiler; the cold source is heated and enters the user for heating; the plate heat exchanger is the plate heat exchanger described above.

[0053] Although the specific embodiments of the present invention are described above, it should be understood by those skilled in the art that these are only examples, and the protection scope of the present invention is defined by the appended claims. Those skilled in the art may make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but these changes and modifications all fall within the protection scope of the present invention.

Claims

1. A plate heat exchanger for centralized heating, the plate heat exchanger comprising a tube side and a shell side, the tube side comprising a first end cap, a second end cap, a tube sheet and a heat exchange tube, and both ends of the heat exchange tube are fixedly mounted on the tube sheet; It is characterized in that The heat exchange tube is a plate structure with an inner cavity in the middle, the cross-section of the inner cavity of the plate structure includes a long side and a short side, an inner partition is arranged in the plate structure, the inner partition connects the two long sides of the plate structure, and divides the inner cavity of the plate structure into a first inner cavity and a second inner cavity, the first head and the second head are provided with a partition wall inside, the first head is divided into a first cavity and a second cavity, and the second head is divided into a first cavity and a second cavity, wherein the first cavity of the first head is connected to the first inner cavity of the plate structure, and the first inner cavity of the plate structure is connected to the first cavity of the second head, wherein the second cavity of the first head is connected to the second inner cavity of the plate structure, and the second inner cavity of the plate structure is connected to the second cavity of the second head; the first cavity of the first head and the first cavity of the second head are respectively provided with a first inlet and a first outlet of the tube-side fluid, the second cavity of the first head and the second cavity of the second head are respectively provided with a second outlet and a second inlet of the tube-side fluid, the first inlet, the first inner cavity and the first outlet are fluidly connected, and the second inlet, the second inner cavity and the second outlet are fluidly connected.

2. The heat exchanger according to claim 1, It is characterized in that The shell side is provided with a shell side fluid inlet and an outlet, and a connecting line of the shell side fluid inlet and outlet forms an angle of 30-150° with the flow direction in the first inner cavity of the plate structure.

3. The heat exchanger according to claim 2, It is characterized in that The line connecting the shell-side fluid inlet and outlet is the line connecting the center points of the openings of the shell-side fluid inlet and outlet on the shell.

4. The heat exchanger according to claim 2, It is characterized in that The connecting line of the shell-side fluid inlet and outlet forms an angle of 90° with the flow direction in the first inner cavity of the plate structure.

5. The heat exchanger according to claim 1, It is characterized in that The heat exchanger is a horizontal plate heat exchanger, the long side of the plate structure is arranged along the vertical direction, and the inner partition plate and the partition wall are arranged in the horizontal direction.

6. The heat exchanger according to claim 5, It is characterized in that The first inner cavity is located at the upper part of the second inner cavity, and the first cavities of the first head and the second head are located at the upper part of the second cavity.

7. The heat exchanger according to claim 1, It is characterized in that The plate structure is a flat tube.

8. A centralized heating system, the system comprising a boiler, the hot water heated in the boiler enters a plate heat exchanger of a heat exchange station, exchanges heat with a cold source in the plate heat exchanger, and then returns to the boiler; the cold source is heated and enters the user for heating; the plate heat exchanger is the plate heat exchanger of any one of claims 1-7.

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