A plate-fin heat exchanger

Abstract

The present invention discloses a plate-fin heat exchanger, which relates to the technical field of heat exchangers. It includes an outer shell body. Liquid inlets and outlets are respectively arranged on both sides of the outer shell body. A support bottom plate is arranged on the bottom surface of the outer shell body. A circulation mechanism is arranged at the center of the outer shell body. The circulation mechanism is composed of a plurality of heat conduction components stacked up and down. A set of heat conduction components consists of two ventilation components and a liquid flow component. Two side sealing plates are arranged between the two ventilation components. The ventilation component includes: two spaced sealing plates, an outer fin is arranged between the two spaced sealing plates, and a short sealing strip is arranged on each side of the outer fin. The liquid flow component is arranged between the two ventilation components. The liquid flow component includes: a plurality of lower heat exchange tubes and upper heat exchange tubes. The lower heat exchange tubes are arranged on the upper surface of the ventilation component located below, and the upper heat exchange tubes are arranged on the bottom surface of the ventilation component located above. When in use, by setting the circulation mechanism, the uniformity and stability of the heat exchange of the equipment are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and particularly to a plate-fin heat exchanger. Background Art

[0002] As an efficient and compact heat exchange device, the plate-fin heat exchanger has been widely used in industrial production. Its structural feature is that by alternately stacking a series of thin metal fins and partition plates, a complex channel system is formed, enabling hot and cold fluids to efficiently exchange heat in these channels. The extended surface area of the fins greatly increases the contact area between the fluid and the heat exchange surface, thus significantly improving the heat exchange efficiency.

[0003] In the existing plate-fin heat exchanger technology, there are still some deficiencies. Traditional heat exchangers often adopt a single fluid channel design, and the flow path of the fluid in the heat exchanger is relatively fixed, resulting in a limited contact area between the fluid and the heat exchange tube wall, and it is difficult to further improve the heat exchange efficiency. In addition, due to the uneven residence time of the fluid in the heat exchanger, some fluids have too long a residence time in the heat exchange tube, which is prone to excessive heat exchange, while some fluids may not achieve the expected heat exchange effect due to too short a residence time, thus affecting the overall heat exchange uniformity and stability. Moreover, existing heat exchangers often lack an effective reflux mechanism when dealing with fluids with unqualified temperatures. Once the fluid fails to reach the predetermined temperature standard after the initial heat exchange, these fluids are usually directly discharged, resulting in waste of energy. At the same time, due to the lack of a flexible switching mechanism, the flow direction and path of the fluid during the heat exchange process are often not adjustable, which limits the adaptability and flexibility of the heat exchanger under different working conditions and causes inconvenience in use. Summary of the Invention

[0004] The purpose of the present invention is to provide a plate-fin heat exchanger to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A plate-fin heat exchanger, comprising:

[0006] An outer housing, on both sides of which are respectively provided with a liquid inlet and a liquid outlet, a support bottom plate is arranged on the bottom surface of the outer housing, and a circulation mechanism is arranged at the center of the outer housing;

[0007] The circulation mechanism is composed of a plurality of heat-conducting components stacked up and down. A set of heat-conducting components consists of two ventilation components and a liquid-flowing component. Two side seal plates are arranged between the two ventilation components. The ventilation component includes: two spaced-apart seal plates, with external fins arranged between the two spaced-apart seal plates, and a short seal strip is arranged on each side of the external fins. The liquid-flowing component is arranged between the two ventilation components. The liquid-flowing component includes: a plurality of lower heat-exchanging tubes and upper heat-exchanging tubes. The lower heat-exchanging tubes are arranged on the upper surface of the ventilation component located below, and the upper heat-exchanging tubes are arranged on the bottom surface of the ventilation component located above. The upper heat-exchanging tubes and the lower heat-exchanging tubes are connected by connecting liquid tubes. The liquid storage capacity inside the upper heat-exchanging tubes and the lower heat-exchanging tubes closer to the liquid outlet side is lower.

[0008] Further, an external liquid temperature detector is arranged on the side surface of the upper heat-exchanging tube closest to the liquid outlet side. One end of the upper heat-exchanging tube is also provided with a liquid-transferring box. A small motor is arranged on the side surface of the liquid-transferring box, and a liquid-transferring frame body is arranged inside the liquid-transferring box.

[0009] Further, liquid-flowing openings are formed on both side surfaces and the bottom surface of the liquid-transferring frame body. The three liquid-flowing openings communicate with each other. The end of the output shaft of the small motor is connected to one end of the liquid-transferring frame body. A transfer box is arranged on the bottom surface of the liquid-transferring box, and the transfer box communicates with the inside of the liquid-transferring box.

[0010] Further, the liquid-flowing component further includes a reflux component. The reflux component includes: a plurality of valve boxes, and the plurality of valve boxes are all arranged on the upper surface of the ventilation component located below. A liquid return pipe is arranged between every two valve boxes. One end of the liquid return pipe is connected to the bottom surface of the transfer box, and a connection port matching the liquid return pipe is formed on the bottom surface of the transfer box.

[0011] Further, two inclined slope plates are also arranged on the upper surface of the ventilation component located below. A reflux liquid outlet pipe is arranged on the upper surface of the inclined slope plates. An outlet pipe is arranged on the side surface of the valve box, and the other end of the outlet pipe is connected to the reflux liquid outlet pipe. One end of the reflux liquid outlet pipe is communicated with the liquid outlet.

[0012] Further, a liquid pipe plug is arranged at one end of the outlet pipe. A movable liquid discharge pipe is arranged inside the outlet pipe, and a plurality of leakage openings are formed on the surface of the movable liquid discharge pipe.

[0013] Further, side connecting pieces that match each other are arranged on the surfaces of the liquid pipe plug and the outlet pipe. A connecting spring is arranged between two corresponding side connecting pieces. Liquid outlet side ports are arranged on both side surfaces of the valve box.

[0014] Furthermore, an internal liquid temperature detector is provided on the inner side surface of the valve box body. A liquid passing opening is further formed on the surface of the liquid outlet side port. An installation notch is provided at the center of the liquid outlet side port, and a control motor is arranged inside the installation notch. The end of the output shaft of the control motor is provided with a rotating cover plate.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. During use, by providing a heat conduction component, the connection effect of a plurality of stacked heat exchange tubes (lower heat exchange tube and upper heat exchange tube) and the connecting liquid pipe forms a continuous fluid channel, increasing the contact area between the fluid and the heat exchange tube wall. Also, the fluid can pass through the heat exchange tube multiple times during the flow process, thereby fully absorbing or releasing heat, significantly improving the heat exchange efficiency. The volume of the heat exchange tubes in the heat conduction component gradually decreases, and the characteristic that the liquid storage capacity inside the heat exchange tubes closer to the liquid outlet side is lower makes the residence time of the fluid in the heat exchange tubes longer at first during the flow process, enabling the liquid to better receive the heat exchange effect. As the pipe volume decreases, the flow rate gradually increases, which helps to reduce the residence time of the fluid that has undergone preliminary heat exchange and whose temperature has approached the standard temperature in the pipe, reducing energy loss and minimizing the situation where the degree of fluid heat exchange exceeds the standard, improving the uniformity and stability of heat exchange;

[0017] 2. During use, by providing a reflux component, the external liquid temperature detector monitors the temperature of the fluid in real time, and collects the fluid with unqualified temperature into the transfer box for secondary heat exchange, enabling the fluid with unqualified temperature to be re-introduced into the heat exchange process for secondary heat exchange, thereby improving the energy utilization rate. The valve box body and the liquid return pipe in the reflux component enable the fluid to flexibly switch between multiple heat exchange stages. When the fluid reaches the predetermined temperature in one valve box body, the internal liquid temperature detector drives the control motor to rotate the rotating cover plate to cover the liquid passing opening, preventing the fluid from entering the next valve box body, avoiding unnecessary heat exchange processes, and saving energy and time. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the overall structural schematic diagram of the present invention;

[0019] Figure 2 is the structural schematic diagram of the circulation mechanism of the present invention;

[0020] Figure 3 is the structural schematic diagram of the heat conduction component of the present invention;

[0021] Figure 4 is the structural schematic diagram of the liquid flow component of the present invention;

[0022] Figure 5Schematic diagram of the internal structure of the infusion pipeline of the present invention;

[0023] Figure 6 Schematic diagram of the connection structure between the upper heat exchange tube and the lower heat exchange tube of the present invention;

[0024] Figure 7 Schematic diagram of the reflux assembly structure of the present invention;

[0025] Figure 8 Schematic diagram of the liquid transfer frame structure of the present invention.

[0026] In the figure: 1, outer housing; 2, liquid inlet; 3, liquid outlet; 4, outer fins; 5, side sealing plate; 6, support bottom plate; 7, spacer sealing plate; 8, short seal strip; 9, liquid separation sealing plate; 10, installation groove; 11, reflux outlet pipe; 12, connecting liquid pipe; 13, lower heat exchange tube; 14, inclined slope plate; 15, upper heat exchange tube; 16, external liquid temperature detector; 17, liquid transfer box; 18, small motor; 19, internal liquid temperature detector; 20, liquid outlet pipeline; 21, liquid pipe plug; 22, side connecting piece; 23, connecting spring; 24, movable drain pipe; 25, liquid outlet side port; 26, installation notch; 27, control motor; 28, rotating cover plate; 29, liquid passing opening; 30, transfer box; 31, liquid transfer frame; 32, liquid flow opening; 33, valve box body; 34, liquid return pipe. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0028] Embodiment 1: Please refer to Figures 1 - 8, a plate-fin heat exchanger, comprising: a housing 1, with a liquid inlet 2 and a liquid outlet 3 respectively opened on both sides of the housing 1, a support bottom plate 6 provided on the bottom surface of the housing 1, and a circulation mechanism provided at the center of the housing 1. The circulation mechanism is composed of a plurality of heat conduction components stacked up and down. A set of heat conduction components consists of two ventilation components and a liquid flow component. Two side sealing plates 5 and two liquid separation sealing plates 9 are arranged between the two ventilation components. The liquid flow component is located between the two side sealing plates 5 and the two liquid separation sealing plates 9. The ventilation component includes: two spaced sealing plates 7, with an external fin 4 arranged between the two spaced sealing plates 7, and a short sealing strip 8 respectively arranged on both sides of the external fin 4. The liquid flow component is arranged between the two ventilation components. The liquid flow component includes: a plurality of lower heat exchange tubes 13 and upper heat exchange tubes 15. The lower heat exchange tubes 13 are arranged on the upper surface of the ventilation component located below, and the upper heat exchange tubes 15 are arranged on the bottom surface of the ventilation component located above. The upper heat exchange tubes 15 and the lower heat exchange tubes 13 are connected by connecting liquid tubes 12. The liquid storage capacity inside the upper heat exchange tubes 15 and the lower heat exchange tubes 13 is lower on the side closer to the liquid outlet 3. An external liquid temperature detector 16 is provided on the side surface of the upper heat exchange tube 15 closest to the liquid outlet 3. One end of the upper heat exchange tube 15 is also provided with a liquid transfer box 17. A small motor 18 is provided on the side surface of the liquid transfer box 17. A liquid transfer frame 31 is arranged inside the liquid transfer box 17. Liquid flow openings 32 are opened on both side surfaces and the bottom surface of the liquid transfer frame 31. The three liquid flow openings 32 are communicated with each other. The end of the output shaft of the small motor 18 is connected to one end of the liquid transfer frame 31. A transfer box 30 is provided on the bottom surface of the liquid transfer box 17. The transfer box 30 is communicated with the inside of the liquid transfer box 17;

[0029] During use, the staff first let the fluid to be heated or cooled enter the outer housing 1 from the liquid inlet 2. When the liquid enters, it will enter the interior of the lower heat exchange tube 13 and flow inside it. When the fluid flows in the lower heat exchange tube 13, it transfers heat to the spaced baffles 7 and the outer fins 4 in contact with it through the tube wall. Due to its extended surface area, the outer fins 4 greatly improve the heat exchange efficiency with the surrounding air. At the same time, the upper heat exchange tube 15 under the ventilation component located above also conducts the same heat exchange. The lower heat exchange tube 13 and the upper heat exchange tube 15 are connected by a connecting liquid pipe 12. When the liquid flows, it gradually flows in the lower heat exchange tube 13 and the upper heat exchange tube 15 along the connecting liquid pipe 12. When the fluid flows between multiple lower heat exchange tubes 13 and upper heat exchange tubes 15, it continuously absorbs or releases heat, causing the temperature of the fluid to gradually change as it flows through the heat conduction component. Moreover, because the shapes of the upper heat exchange tube 15 and the lower heat exchange tube 13 closer to the liquid outlet 3 side are smaller and the internal liquid storage capacity is also lower, during the flow of the liquid, when passing through the first-entered upper heat exchange tube 15 and lower heat exchange tube 13, due to their larger internal liquid storage capacity, the liquid will stay inside for a longer time when passing through and can be more effectively affected by the heat exchange effect of the upper and lower ventilation components. As the liquid flows, when the liquid flows to the upper heat exchange tube 15 and the lower heat exchange tube 13 close to the liquid outlet 3 side, because the internal liquid storage capacity becomes smaller, under the condition of constant liquid pressure, the passing speed of the liquid inside the upper heat exchange tube 15 and the lower heat exchange tube 13 becomes faster, and finally the liquid is discharged from the liquid outlet 3. When the liquid passes through the upper heat exchange tube 15 closest to the liquid outlet 3 side, the liquid will be detected by the external liquid temperature detector 16 to determine whether the temperature of the liquid reaches the expected temperature. When the temperature is insufficient, the liquid is introduced into the reflux component for secondary heat exchange.

[0030] The liquid flow component further includes a reflux component, and the reflux component includes: a plurality of valve boxes 33, and the plurality of valve boxes 33 are all arranged on the upper surface of the ventilation component located below. A liquid return pipe 34 is arranged between every two valve boxes 33. One end of the liquid return pipe 34 is connected to the bottom surface of the transfer box 30, and a connection port matching the liquid return pipe 34 is opened on the bottom surface of the transfer box 30. Two inclined plates 14 are further arranged on the upper surface of the ventilation component located below. An installation groove 10 for installing the inclined plate 14 is opened on the upper surface of the spacer plate 7. A return liquid outlet pipe 11 is arranged on the upper surface of the inclined plate 14. A liquid outlet pipe 20 is arranged on the side surface of the valve box 33, and the other end of the liquid outlet pipe 20 is connected to the return liquid outlet pipe 11. One end of the return liquid outlet pipe 11 is communicated with the liquid outlet 3. A liquid pipe plug 21 is arranged at one end of the liquid outlet pipe 20. An active drain pipe 24 is arranged inside the liquid outlet pipe 20, and a plurality of leakage ports are opened on the surface of the active drain pipe 24. Side connection pieces 22 that cooperate with each other are arranged on the surfaces of the liquid pipe plug 21 and the liquid outlet pipe 20, and a connection spring 23 is arranged between two corresponding side connection pieces 22. Liquid outlet side ports 25 are arranged on both side surfaces of the valve box 33. An internal liquid temperature detector 19 is arranged on the inner side surface of the valve box 33. A liquid passing opening 29 is further opened on the surface of the liquid outlet side port 25. An installation notch 26 is arranged at the center of the liquid outlet side port 25, and a control motor 27 is arranged inside the installation notch 26. A rotating cover plate 28 is arranged at the end of the output shaft of the control motor 27;

[0031] After the fluid that has undergone heat exchange through the lower heat exchange pipe 13 and the upper heat exchange pipe 15 enters the transfer box 17, if the temperature reaches the standard, it directly enters the liquid outlet 3 and is discharged from the inside of the device. When the liquid is detected by the external liquid temperature detector 16 as not reaching the standard temperature, a signal is sent through the external liquid temperature detector 16 to drive the small motor 18 to rotate, driving the transfer frame 31 to rotate by ninety degrees, so that the liquid is collected into the transfer box 30. The transfer box 30 is connected to the liquid return pipe 34 through the connection port opened on its bottom surface. A plurality of valve boxes 33 are arranged in the middle section of the liquid return pipe 34. When the liquid sequentially enters the plurality of valve boxes 33, secondary heat exchange is performed between the liquid inside the valve boxes 33 and the ventilation component below. And whenever the liquid enters a valve box 33, the internal liquid temperature detector 19 inside it will detect it. When the temperature reaches the standard, the control motor 27 at the outlet end of the valve box 33 where the current liquid stays is driven to rotate by the internal liquid temperature detector 19, so that the rotating cover plate 28 covers the liquid passing opening 29, preventing the liquid from entering the next valve box 33. And when the liquid gradually accumulates inside a valve box 33 and enters the liquid outlet pipe 20, the liquid pipe plug 21 moves forward under the action of hydraulic pressure, exposing the active drain pipe 24 and the leakage ports. The liquid inside the valve box 33 enters the return liquid outlet pipe 11 from the liquid outlet side port 25 and is discharged from the liquid outlet 3 through the return liquid outlet pipe 11.

[0032] The working principle of the present invention is as follows:

[0033] During use, the staff first allows the fluid to be heated or cooled to enter the outer casing 1 from the liquid inlet 2. When the liquid enters, it will enter the interior of the lower heat exchange tube 13 and flow therein. When the fluid flows in the lower heat exchange tube 13, heat is transferred through the tube wall to the spaced baffles 7 and the outer fins 4 in contact therewith. Due to its expanded surface area, the outer fins 4 greatly improve the heat exchange efficiency with the surrounding air. At the same time, the upper heat exchange tube 15 below the ventilation component located above also undergoes the same heat exchange. The lower heat exchange tube 13 and the upper heat exchange tube 15 are connected by a connecting liquid pipe 12. When the liquid flows, it gradually flows in the lower heat exchange tube 13 and the upper heat exchange tube 15 along the connecting liquid pipe 12. When the fluid flows between multiple lower heat exchange tubes 13 and upper heat exchange tubes 15, it continuously absorbs or releases heat, causing the temperature of the fluid to gradually change during its flow in the heat conduction assembly. Moreover, because the shapes of the upper heat exchange tube 15 and the lower heat exchange tube 13 closer to the liquid outlet 3 are smaller and the internal liquid storage capacity is also lower, during the flow of the liquid, when passing through the first-entered upper heat exchange tube 15 and lower heat exchange tube 13, due to their larger internal liquid storage capacity, the liquid will stay inside for a longer time when passing through and can be more effectively affected by the heat exchange effect of the upper and lower ventilation components. As the liquid flows, when the liquid flows to the upper heat exchange tube 15 and the lower heat exchange tube 13 close to the liquid outlet 3, because the internal liquid storage capacity becomes smaller, under the condition of constant liquid pressure, the passing speed of the liquid inside the upper heat exchange tube 15 and the lower heat exchange tube 13 becomes faster, and finally the liquid is discharged from the liquid outlet 3. When the liquid passes through the upper heat exchange tube 15 closest to the liquid outlet 3, the liquid will be detected by the external liquid temperature detector 16 to determine whether the temperature of the liquid reaches the expected temperature. When the temperature is insufficient, the liquid is introduced into the reflux assembly for secondary heat exchange;

[0034] After the fluid that has undergone heat exchange through the lower heat exchange tube 13 and the upper heat exchange tube 15 enters the liquid transfer box 17, if the temperature meets the standard, it directly enters the liquid outlet 3 and is discharged from the interior of the device. When the liquid is detected by the external liquid temperature detector 16 as not reaching the standard temperature, a signal is sent through the external liquid temperature detector 16 to drive the small motor 18 to rotate, driving the liquid transfer frame 31 to rotate by 90 degrees, so that the liquid is collected in the transfer box 30. The transfer box 30 is connected to the liquid return pipe 34 through a connection port opened on its bottom surface. A plurality of valve boxes 33 are provided in the middle section of the liquid return pipe 34. When the liquid sequentially enters the plurality of valve boxes 33, secondary heat exchange is carried out between the liquid inside the valve boxes 33 and the liquid through the ventilation components below. And whenever the liquid enters a valve box 33, the internal liquid temperature detector 19 inside it will detect it. When the temperature meets the standard, the control motor 27 at the outlet end of the valve box 33 where the current liquid stays is driven to rotate by the internal liquid temperature detector 19, so that the rotating cover plate 28 covers the liquid passing opening 29, preventing the liquid from entering the next valve box 33. And when the liquid gradually accumulates inside a valve box 33 and enters the liquid outlet pipe 20, the liquid pipe plug 21 moves forward under the action of hydraulic pressure, exposing the movable liquid discharge pipe 24 and the leakage opening. The liquid inside the valve box 33 enters the return liquid outlet pipe 11 from the leakage opening and is discharged from the liquid outlet 3 through the return liquid outlet pipe 11.

[0035] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A plate-fin heat exchanger, characterized in that: include: An outer shell (1), wherein two sides of the outer shell (1) are respectively provided with a liquid inlet (2) and a liquid outlet (3), a bottom surface of the outer shell (1) is provided with a supporting bottom plate (6), and a circulation mechanism is provided at the center of the outer shell (1); The circulation mechanism comprises a plurality of heat-conducting components stacked up and down, a group of heat-conducting components comprises two ventilation components and a liquid flow component, two side sealing plates (5) are arranged between the two ventilation components, the ventilation components comprise: two spacing sealing plates (7), an outer fin (4) is arranged between the two spacing sealing plates (7), a short sealing strip (8) is arranged on both sides of the outer fin (4), the liquid flow component is arranged between the two ventilation components, the liquid flow component comprises: a plurality of lower heat exchange tubes (13) and upper heat exchange tubes (15), the lower heat exchange tubes (13) are arranged on the upper surface of the ventilation component located below, the upper heat exchange tubes (15) are arranged on the bottom surface of the ventilation component located above, the upper heat exchange tubes (15) and the lower heat exchange tubes (13) are connected through a connecting liquid tube (12), and the liquid storage capacity inside the upper heat exchange tubes (15) and the lower heat exchange tubes (13) closer to the liquid outlet (3) is lower.

2. A plate-fin heat exchanger according to claim 1, characterized in that: An external liquid temperature detector (16) is provided on the side surface of the upper heat exchange tube (15) closest to the liquid outlet (3), and a liquid transfer box (17) is also provided at one end of the upper heat exchange tube (15). A small motor (18) is provided on the side surface of the liquid transfer box (17), and a liquid transfer frame (31) is provided inside the liquid transfer box (17).

3. A plate-fin heat exchanger according to claim 2, characterized in that: The two side surfaces and the bottom surface of the liquid transfer frame (31) are provided with liquid flow openings (32), and the three liquid flow openings (32) are interconnected. The output shaft end of the small motor (18) is connected to one end of the liquid transfer frame (31). The bottom surface of the liquid transfer box (17) is provided with a transfer box (30), and the transfer box (30) is connected to the inside of the liquid transfer box (17).

4. The plate-fin heat exchanger according to claim 1, characterized in that: The liquid flow assembly also includes a reflux assembly, which includes: a plurality of valve boxes (33), the plurality of valve boxes (33) are arranged on the upper surface of the ventilation component located below, a liquid reflux pipe (34) is arranged between every two of the valve boxes (33), one end of the liquid reflux pipe (34) is connected to the bottom surface of the transfer box (30), and the bottom surface of the transfer box (30) is provided with a connection port that matches the liquid reflux pipe (34).

5. A plate-fin heat exchanger according to claim 4, characterized in that: Two inclined ramps (14) are also provided on the upper surface of the ventilation component located below, a reflux liquid outlet pipe (11) is provided on the upper surface of the inclined ramp (14), a liquid outlet pipe (20) is provided on the side surface of the valve box (33), the other end of the liquid outlet pipe (20) is connected to the reflux liquid outlet pipe (11), and one end of the reflux liquid outlet pipe (11) is connected to the liquid outlet (3).

6. A plate-fin heat exchanger according to claim 5, characterized in that: A liquid pipe plugging cover (21) is provided at one end of the liquid outlet pipe (20), a movable liquid discharge pipe (24) is provided inside the liquid outlet pipe (20), and a plurality of leakage openings are provided on the surface of the movable liquid discharge pipe (24).

7. A plate-fin heat exchanger according to claim 6, characterized in that: The surfaces of the liquid pipe plugging cover (21) and the liquid outlet pipe (20) are both provided with side connecting pieces (22) that cooperate with each other, a connecting spring (23) is provided between two corresponding side connecting pieces (22), and liquid outlet side ports (25) are provided on both side surfaces of the valve box (33).

8. A plate-fin heat exchanger according to claim 7, characterized in that: An internal liquid temperature detector (19) is disposed on the inner side surface of the valve housing (33); a liquid-passing opening (29) is also provided on the surface of the liquid outlet side port (25); a mounting notch (26) is disposed at the center of the liquid outlet side port (25); a control motor (27) is disposed inside the mounting notch (26); and a rotating cover plate (28) is disposed at the end of the output shaft of the control motor (27).

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