Flat tube micro-channel heat exchanger

Abstract

The invention provides a flat tube micro-channel heat exchanger which is characterized in that a heat exchange tube is a flat tube, the flat tube comprises a first flat tube and a second flat tube, a shell comprises a first wall surface and a second wall surface, the first wall surface and the second wall surface are oppositely arranged, the length direction of the first flat tube extends from the first wall surface of the shell to the second wall surface, and the length direction of the second flat tube extends from the second wall surface of the shell to the first wall surface of the shell. A first gap is formed between the first flat tube and the second wall surface, the length direction of the second flat tube extends from the second wall surface of the shell to the first wall surface, a second gap is formed between the second flat tube and the first wall surface, and the first flat tube and the second flat tube are alternately arranged. According to the invention, even if the fluid passes through all the flat areas of the heat exchange tube under the condition of small flow, the heat exchange circulation area is increased, and the heat transfer is enhanced.

Description

Technical Field

[0001] The invention relates to a heat exchanger, belonging to the technical field of heat exchangers, in particular to the field of flat tube microchannel heat exchangers. 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 heavy weight, such as coil heat exchangers. With the development of manufacturing technology, shell and tube 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] There are many types of heat exchangers used in industrial production, and they need to be selected according to the actual situation during use. The plate and shell type has the advantages of wide application range, strong adaptability, simple structure, low cost, etc., and has great advantages in both quality and compactness. Flat tubes have been widely used in automotive air conditioning units and residential or commercial air conditioning heat exchangers in recent years. This type of flat tube has a large heat exchange area, so it can greatly improve the heat exchange effect.

[0005] A microchannel heat exchanger is a heat exchanger with a channel equivalent diameter of 10-1000μm. It consists of two headers, multiple flat tubes and fins. There are dozens of tiny channels in the flat tubes, and both ends of the flat tubes are connected to the circular headers. The headers are generally placed vertically, and horizontal partitions are set inside the headers to separate the heat exchanger flow channels into several processes.

[0006] 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. This flow causes part of the area outside the flat tube to not participate in heat exchange or not participate in heat exchange much due to the uneven distribution of the fluid in the shell side, resulting in heat short circuit in some areas. Therefore, the present invention designs a new type of heat exchanger to improve the structure of the traditional plate and shell heat exchanger to achieve the purpose of enhancing heat transfer. Summary of the invention

[0007] In order to achieve the above object, the technical solution of the present invention is as follows:

[0008] A flat tube microchannel heat exchanger, the shell and tube heat exchanger includes a tube side and a shell side, the tube side includes an inlet head, an outlet head, a tube sheet and a heat exchange tube, both ends of the heat exchange tube are fixedly installed on the tube sheet, the tube side fluid enters the flat tube from the inlet head and then flows out from the outlet head; the shell side includes a shell, the shell side fluid enters from the shell side inlet on the shell, and then flows out from the shell side outlet on the shell after heat exchange with the tube side fluid; it is characterized in that the heat exchange tube is a microchannel flat tube, the flat tube includes a first flat tube and a second flat tube, the shell includes a first wall surface and a second wall surface, the first wall surface and the second wall surface are arranged oppositely, wherein the length direction of the first flat tube starts from the first wall surface of the shell and extends to the second wall surface, and has a first gap with the second wall surface, the length direction of the second flat tube starts from the second wall surface of the shell and extends to the first wall surface, and has a second gap with the first wall surface, and the first flat tube and the second flat tube are alternately arranged in the flow direction of the shell side fluid.

[0009] As an improvement, the tube sheet is arranged horizontally, and the tube-side fluid in the heat exchange tube flows in the up-and-down direction.

[0010] As an improvement, the inlet head is located at the upper part, the outlet head is located at the lower part, and the inlet and outlet of the shell side are located at the left and right parts.

[0011] As an improvement, the length of the first gap and the second gap is 68-84% of the distance between the first wall and the second wall.

[0012] As an improvement, the inlet of the shell-side fluid is arranged on a side of the shell close to the first wall surface, and the first flat tube is close to the inlet of the shell-side fluid.

[0013] As an improvement, the outlet of the shell-side fluid is arranged on a side of the shell close to the second wall surface, and the second flat tube is close to the outlet of the shell-side fluid.

[0014] As an improvement, the tube-side fluid is liquid and the shell-side fluid is gas.

[0015] As an improvement, the tube-side fluid is water and the shell-side fluid is exhaust gas.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] In the present invention, the shell-side fluid flows along the length (height) of the flat tube, and the flow directions of the tube-side fluid and the shell-side fluid are parallel. Because the first and second flat tubes are arranged at intervals, a similar baffle effect is formed, so that the fluid flows along a tortuous path in the shell, allowing the fluid to pass through all areas of the flat tube, thereby improving the heat exchange effect of the heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the overall structure of the heat exchanger of the present invention;

[0019] Figure 2 yes Figure 1 Schematic diagram of the flat tube arrangement structure viewed from above in a transverse section;

[0020] Figure 3 It is a schematic diagram of the structure of the flat tube arrangement of the heat exchanger of the present invention observed from the flat surface side. DETAILED DESCRIPTION

[0021] In this article, unless otherwise specified, “ / ” represents division, and “×” and “*” represent multiplication.

[0022] 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.

[0023] 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.

[0024] Figure 1-3 A flat tube shell and tube heat exchanger is disclosed. Figure 2 yes Figure 1 Transverse section ( Figure 1 Horizontal section in Figure 1 The schematic diagram of the flat tube arrangement structure observed from above. The shell and tube heat exchanger includes a tube side and a shell side. The tube side includes an inlet head 1, an outlet head 2, a tube sheet 3 and a heat exchange tube 4. Both ends of the heat exchange tube 4 are fixedly mounted on the tube sheet 3. The tube side fluid enters the flat tube 4 from the inlet head 1 and then flows out from the outlet head 2. The shell side includes a shell 5. The shell side fluid enters from the shell side inlet 6 on the shell, and then flows out from the shell side outlet 7 on the shell after heat exchange with the tube side fluid. Figure 2-3As shown, the heat exchange tube is a flat tube, preferably a microchannel flat tube. The flat tube includes a first flat tube 41 and a second flat tube 42, and the shell includes a first wall 8 and a second wall 9, the first wall 8 and the second wall 9 are arranged opposite to each other, wherein the length direction of the first flat tube extends from the first wall 8 of the shell to the second wall 9, and has a first gap with the second wall, the length direction of the second flat tube extends from the second wall of the shell to the first wall, and has a second gap with the first wall, and the first flat tube and the second flat tube are arranged alternately. The flow direction of the fluid in the shell side is along the flat surface direction of the flat tube.

[0025] In the present invention, the shell-side fluid flows along the length (height) of the flat tube, and the flow directions of the tube-side fluid and the shell-side fluid are parallel. Because the first and second flat tubes are arranged at intervals, the fluid flows along a tortuous path in the shell, so that the fluid can pass through all areas of the flat tube, thereby improving the heat exchange effect of the heat exchanger.

[0026] The flat tube comprises a first plane and a second plane, wherein a fluid flow cavity is formed between the first plane and the second plane. The distance between the first plane and the second plane is 5-70 microns, preferably 20-40 microns.

[0027] As an improvement, the tube sheet is arranged horizontally, and the tube-side fluid in the heat exchange tube flows in the up-down direction. The heads 1 and 2 also adopt the up-down direction, and the tube-side fluid can flow in from the upper part and out from the lower part, or flow in from the lower part and out from the upper part.

[0028] As an improvement, the inlet head 1 is located at the upper part, the outlet head 2 is located at the lower part, and the inlet 6 and outlet 7 of the shell side are located at the left and right parts, so as to form a cross flow between the fluids.

[0029] As an improvement, the length of the first gap and the second gap is 68-84% of the distance between the first wall and the second wall. If the gap is too short, the flow resistance will be too large. The length will also affect the heat exchange efficiency of the heat pipe and reduce the heat exchange area. If the depth exceeds 84%, the flow resistance will increase greatly, resulting in increased costs.

[0030] As an improvement, the length of the first gap and the second gap is 75-80% of the distance between the first wall and the second wall. The heat exchange efficiency can be further increased by optimizing the above dimensions while meeting the resistance requirements.

[0031] As an improvement, the inlet of the shell-side fluid is arranged on the side of the shell close to the first wall, and the first flat tube is close to the inlet of the shell-side fluid. As an improvement, the outlet of the shell-side fluid is arranged on the side of the shell close to the second wall, and the second flat tube is close to the outlet of the shell-side fluid. Through the above-mentioned matching arrangement, the shell-side fluid can be guided to fully pass through the flat surface of the flat tube for heat exchange.

[0032] As an improvement, the tube-side fluid is liquid and the shell-side fluid is gas.

[0033] As an improvement, the tube-side fluid is water and the shell-side fluid is exhaust gas.

[0034] As an improvement, the tube sheet is arranged in a vertical direction, and the tube-side fluid in the heat exchange tube flows in a horizontal direction. The heads 1 and 2 also adopt a left-right direction, and the tube-side fluid can flow in from the left and out from the right, or flow in from the left and out from the right. The first wall 8 is located at the upper part, and the second wall 9 is located at the lower part. The inlet head and the outlet head are located on the left and right. The fluid in the shell side is gas. Along the flow direction of the fluid in the shell side, the length of the first gap gradually increases, and the length of the second gap gradually decreases.

[0035] During the research process, it was found that the heat exchange of the flat tube in the cross section in the direction of fluid flow was uneven. As the distance from the inlet increased, the gas density in the shell side 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 gap and the second gap changes along the flow direction of the gas, so that the gas in the shell side gradually decreases and moves toward the upper part as it flows, and stays in the middle and lower parts for more time, so that the heat exchange tubes around the shell and the lower part of the shell are strengthened to exchange heat, which changes the previous heat exchange mode, enhances the heat exchange efficiency at different positions, makes the heat exchange uniform on the whole, and further achieves the purpose of enhancing heat transfer.

[0036] As an improvement, along the flow direction of the fluid in the shell side, the first gap length gradually increases, and the second gap length gradually decreases. Through the above changes in amplitude, the overall heat exchange can be further uniform, further achieving the purpose of enhancing heat transfer.

[0037] As an improvement, the spacing between adjacent flat tubes increases continuously from the shell inlet to the shell outlet. Then, from the shell outlet to the shell outlet, the spacing between adjacent flat tubes decreases continuously. 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, the heat exchange area changes regularly by changing the spacing between the flat tubes. Therefore, the uneven heat exchange is compensated by the change in area, thereby further improving the heat exchange efficiency.

[0038] As an improvement, the distance between adjacent flat tubes increases from the shell inlet to the middle of the shell. Then, the distance between adjacent flat tubes decreases from the middle of the shell to the shell outlet. The above changes in the range can make the heat exchange per unit area of ​​the entire fluid movement more uniform, further improving the heat exchange efficiency.

[0039] The inlet end cap is provided with a tube-side fluid inlet 12, and the outlet end cap is provided with a tube-side fluid outlet 13. As an improvement, an inner fin is provided on the inner wall surface of the flat tube, and the inner fin protrudes outward from the inner wall surface of the flat tube. The inner fin is provided to increase the heat exchange area and strengthen the heat exchange in the tube.

[0040] As an improvement, the distribution density of the inner fins in different flat tubes is different, and the distribution density of the inner fins in the flat tubes is greater as the distance between the flat tubes and the inlet 12 is closer. By such an arrangement, the closer to the inlet 12, the greater the resistance to fluid flow due to the arrangement of the inner fins, so that the fluid flows into the heat exchange tube with small flow resistance, and the fluid flows into the heat exchange tube at a position farther from the inlet, so that the fluid is evenly distributed.

[0041] As an improvement, the distribution density of the inner fins in the flat tube increases with the distance from the inlet 12. It is found through experiments that the increase in the distribution density can make the fluid distribution more uniform.

[0042] As an improvement, the distribution density of the fins in the heat exchange tube closest to the inlet 12 is 1.8-2.0 times, preferably 1.9 times, the distribution density of the fins in the heat exchange tube farthest from the inlet 12 .

[0043] 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 flat tube microchannel heat exchanger, the shell and tube heat exchanger comprises a tube side and a shell side, the tube side comprises an inlet head, an outlet head, 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 flat tube from the inlet head and then flows out from the outlet head; the shell side comprises a shell, the shell side fluid enters from the shell side inlet on the shell, then exchanges heat with the tube side fluid and then flows out from the shell side outlet on the shell; characterized in that, The heat exchange tube is a microchannel flat tube, which includes a first flat tube and a second flat tube. The shell includes a first wall and a second wall. The first wall and the second wall are arranged opposite to each other, wherein the length direction of the first flat tube extends from the first wall of the shell to the second wall and has a first gap with the second wall. The length direction of the second flat tube extends from the second wall of the shell to the first wall and has a second gap with the first wall. The first flat tube and the second flat tube are alternately arranged in the flow direction of the shell-side fluid.

2. The heat exchanger according to claim 1, characterized in that The tube sheet is arranged horizontally, and the tube-side fluid in the heat exchange tube flows in the up-and-down direction.

3. The heat exchanger according to claim 1, characterized in that The inlet head is located at the upper part, the outlet head is located at the lower part, and the inlet and outlet of the shell side are located at the left and right parts.

4. The heat exchanger according to claim 1, characterized in that The length of the first gap and the second gap is 68-84% of the distance between the first wall and the second wall.

5. The heat exchanger according to claim 1, characterized in that The inlet of the shell-side fluid is arranged on a side of the shell close to the first wall surface, and the first flat tube is close to the inlet of the shell-side fluid.

6. The heat exchanger according to claim 1, characterized in that The outlet of the shell-side fluid is arranged on a side of the shell body close to the second wall surface, and the second flat tube is close to the outlet of the shell-side fluid.

7. The heat exchanger according to claim 1, characterized in that: The tube-side fluid is liquid and the shell-side fluid is gas.

8. The heat exchanger according to claim 7, characterized in that The tube-side fluid is water and the shell-side fluid is exhaust gas.

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