A heat exchanger

Abstract

The present invention discloses a heat exchanger, which comprises a plurality of heat exchange plates and rectangular corrugated fins that are alternately stacked and tightly connected; the heat exchange plates are composed of an upper plate and a lower plate, and a heat exchange plate inlet, a general heat exchange area, more than two levels of enhanced heat exchange areas and a heat exchange plate outlet are arranged on the lower surface of the upper plate and the upper surface of the lower plate along the working medium flow direction, and a plurality of discontinuous airfoil ribs are arranged in each heat exchange area. The density of the airfoil ribs in the first-level enhanced heat exchange area is increased compared with that of the airfoil ribs in the general heat exchange area; the density of the airfoil ribs in the subsequent-level enhanced heat exchange area is increased compared with that of the airfoil ribs in the previous-level enhanced heat exchange area. The heat exchange plates of the present invention are provided with multiple heat exchange areas, and according to the deterioration degree of heat transfer, different arrangement forms of airfoil ribs are set in each heat exchange area, and correspondingly, the rectangular corrugated fins are provided with a non-uniform pitch fin structure, so as to gradually increase the heat exchange area and flow disturbance of the heat exchange plates and the fins from line to surface along the working medium flow direction, and realize the improvement of the overall heat exchange performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of heat exchangers, and particularly relates to a heat exchanger with variable cross-section micro-channels. Background Art

[0002] Heat exchangers are heat transfer devices frequently used in the fields of energy, machinery, chemical industry, medicine, food, etc. However, the heat exchangers in the prior art have the technical problems of low heat transfer efficiency and poor heat transfer effect. Especially when the temperature difference between the two working fluids exchanging heat in the heat exchanger gradually decreases as the heat exchange progresses, it will further lead to the deterioration of the heat transfer effect. Therefore, a new heat exchanger is needed to improve the heat transfer effect of the heat exchanger. Summary of the Invention

[0003] The present invention provides a heat exchanger with variable cross-section micro-channels, such as a plate-fin air-cooled heat exchanger. In view of the situation that in the cross-flow heat exchange process discovered by the inventor during the research and development of heat exchangers, the temperature difference between the hot-side working fluid and the cold side decreases along the flow direction and the heat transfer capacity decays due to the change of the physical properties of the working fluid, an improvement is made based on the structure of the plate-fin heat exchanger. It is applicable to directly cooling high-temperature and high-pressure variable-property working fluids, especially the cooling of carbon dioxide working fluids. Its structure is simple and compact, with high heat transfer capacity, material saving and easy manufacturing.

[0004] The present invention provides a heat exchanger, which comprises:

[0005] A plurality of heat exchange plates (1);

[0006] A plurality of rectangular corrugated fins (2),

[0007] The heat exchange plates (1) and the rectangular corrugated fins (2) are alternately stacked and tightly connected;

[0008] The heat exchange plate (1) is composed of an upper plate (1') and a lower plate (1"). Along the flow direction of the first working fluid, the lower surface of the upper plate (1') and the upper surface of the lower plate (1") are sequentially provided with a heat exchange plate inlet (3) with the same structure, a general heat exchange area (4), more than two levels of enhanced heat exchange areas, and a heat exchange plate outlet (3'). Each heat exchange area in the general heat exchange area (4) and the enhanced heat exchange area is provided with a plurality of discontinuous airfoil ribs; the first working fluid sequentially enters the general heat exchange area (4) and each level of enhanced heat exchange area from the heat exchange plate inlet (3), exchanges heat with the second working fluid through the rectangular corrugated fins (2) in the heat exchange area, and finally flows out from the heat exchange plate outlet (3'); the second working fluid flows in the rectangular corrugated fins (2) and forms cross-flow heat exchange with the first working fluid in the heat exchange plate (1);

[0009] The density of the airfoil ribs in the first-level enhanced heat exchange area is increased compared with that of the airfoil ribs in the general heat exchange area (4); the density of the airfoil ribs in the subsequent-level enhanced heat exchange area is increased compared with that of the airfoil ribs in the previous-level enhanced heat exchange area;

[0010] Along the first working fluid flow direction, the spacing between the two fin surfaces of the fin units of the rectangular wavy fins (2) corresponding to the general heat exchange zone (4) and the enhanced heat exchange zones with two or more levels decreases linearly or non-linearly.

[0011] Among them, the first working fluid is the hot-side working fluid or the cold-side working fluid. Correspondingly, the second working fluid is the cold-side working fluid or the hot-side working fluid. The first working fluid and the second working fluid can be the same kind of working fluid but at different temperatures.

[0012] Preferably, for the heat exchanger described above, the enhanced heat exchange zones include the first-level enhanced heat exchange zone (5) and the second-level enhanced heat exchange zone (6).

[0013] Preferably, for the heat exchanger described above, the shape of the airfoil ribs in the first-level enhanced heat exchange zone (5) remains unchanged compared with the airfoil ribs in the general heat exchange zone (4). The spacing between the airfoil ribs in the first-level enhanced heat exchange zone (5) along the first working fluid flow direction is smaller than the spacing between the last set of airfoil ribs in the general heat exchange zone (4) along the first working fluid flow direction. Such a setting ensures that the density of the airfoil ribs in the first-level enhanced heat exchange zone (5) is increased compared with the density of the airfoil ribs in the general heat exchange zone (4).

[0014] Preferably, for the heat exchanger described above, the spacing between the airfoil ribs in the first-level enhanced heat exchange zone (5) along the first working fluid flow direction decreases linearly or non-linearly; the spacing between the airfoil ribs in the first-level enhanced heat exchange zone (5) along the direction perpendicular to the first working fluid flow direction remains unchanged.

[0015] Preferably, for the heat exchanger described above, the maximum inscribed circle diameter of the airfoil ribs in the first-level enhanced heat exchange zone (5) decreases linearly or non-linearly along the first working fluid flow direction.

[0016] Preferably, for the heat exchanger described above, the percentage by which the maximum inscribed circle diameter of the airfoil ribs in the first-level enhanced heat exchange zone (5) decreases along the first working fluid flow direction is less than the percentage by which the spacing between the airfoil ribs in the first-level enhanced heat exchange zone (5) along the first working fluid flow direction decreases.

[0017] The effects achieved by the above technical features are that, without reducing the flow channel cross-section and ensuring that the flow resistance remains unchanged, the number of airfoil ribs per unit length is increased in the first-level enhanced heat exchange zone (5), the heat exchange area and local flow disturbance are increased, and preliminary heat transfer enhancement in the heat transfer deterioration area is achieved.

[0018] Preferably, in the heat exchanger, compared with the airfoil ribs in the first-stage enhanced heat transfer zone (5), the shape of the airfoil ribs in the second-stage enhanced heat transfer zone (6) remains unchanged; the spacing between the airfoil ribs in the second-stage enhanced heat transfer zone (6) along the first working fluid flow direction and the spacing along the direction perpendicular to the first working fluid flow direction are smaller than the spacing between the last set of airfoil ribs in the first-stage enhanced heat transfer zone (5) along the first working fluid flow direction and the spacing along the direction perpendicular to the first working fluid flow direction. Such a setting ensures that the density of the airfoil ribs in the second-stage enhanced heat transfer zone (6) is higher than that of the airfoil ribs in the first-stage enhanced heat transfer zone (5).

[0019] Preferably, in the heat exchanger, the maximum inscribed circle diameter of the airfoil ribs inside the second-stage enhanced heat transfer zone (6) decreases linearly or non-linearly along the first working fluid flow direction.

[0020] Preferably, in the heat exchanger, the spacing between the airfoil ribs inside the second-stage enhanced heat transfer zone (6) along the first working fluid flow direction decreases linearly or non-linearly.

[0021] Preferably, in the heat exchanger, the spacing between the airfoil ribs inside the second-stage enhanced heat transfer zone (6) along the direction perpendicular to the first working fluid flow direction decreases linearly or non-linearly.

[0022] Preferably, in the heat exchanger, the length of the airfoil ribs themselves inside the second-stage enhanced heat transfer zone (6) decreases linearly or non-linearly along the first working fluid flow direction.

[0023] Preferably, in the heat exchanger, the percentage decrease in the maximum inscribed circle diameter of the airfoil ribs and the length of the airfoil ribs themselves inside the second-stage enhanced heat transfer zone (6) along the first working fluid flow direction is less than the percentage decrease in the spacing between the airfoil ribs inside the second-stage enhanced heat transfer zone (6) along the direction perpendicular to the first working fluid flow direction.

[0024] The effects achieved by the above technical features are as follows: without significantly increasing the flow resistance, the number of airfoil ribs per unit area is further increased in the subsequent heat transfer zone, the heat transfer area and flow disturbance are increased, heat transfer is further enhanced in the area where heat transfer deteriorates the most, the maximum inscribed circle radius of the airfoil ribs gradually becomes smaller along the flow direction in this heat transfer zone (6), the windward surface of the fin of the airfoil rib is further reduced to achieve sharpening, and the increase in resistance caused by the reduction of the flow channel cross-section is slowed down.

[0025] Preferably, in the heat exchanger, the heat transfer plate (1) and the rectangular corrugated fins (2) are connected by diffusion welding, and the upper plate (1') and the lower plate (1") of the heat transfer plate (1) are connected by diffusion welding.

[0026] Preferably, in the heat exchanger, the discontinuous airfoil ribs are manufactured by photochemical etching.

[0027] Due to the adoption of the above technical solutions, the present invention has the following advantages and positive effects compared with the prior art:

[0028] In the application and research and development of plate-fin heat exchangers, the inventors found that for the hot-side working fluid, especially temperature-sensitive variable-property working fluids, when exchanging heat with the cold-side working fluid in the heat exchanger, the temperature gradually decreases along the flow direction, the temperature difference with the cold-side working fluid also decreases, and usually the density gradually increases, so the flow velocity also decreases, and the corresponding Reynolds number decreases. The boundary layer thickness of the hot-side working fluid on the wall gradually increases, resulting in a gradual decrease in the local heat transfer coefficient and ultimately a phenomenon of gradually deteriorating heat transfer capacity. To mitigate this phenomenon, the present invention has made the following targeted designs:

[0029] First, the present invention sets multiple heat exchange zones (preferably, for example, a general heat exchange zone (4), a first-level enhanced heat exchange zone (5), and a second-level enhanced heat exchange zone (6)) on the heat exchange plate. According to the degree of deterioration of heat transfer, different airfoil rib arrangement forms are set in each heat exchange zone. Correspondingly, a non-uniform pitch fin structure is set on the cold-side working fluid side. Along the flow direction of the hot-side working fluid, from line to surface, the heat transfer area and flow disturbance of the heat exchange plate and fins are gradually increased. At the same time, the maximum inscribed circle diameter of the airfoil rib is gradually adjusted to adjust the windward area of the airfoil rib, so as to improve the overall heat transfer performance without significantly increasing the flow resistance.

[0030] Second, the present invention sets different airfoil rib arrangement forms in each heat exchange zone. Specifically, the pitch of the airfoil ribs and the windward cross-section of the airfoil ribs along the flow direction of the working fluid are gradually reduced first. The windward cross-section of the airfoil ribs is achieved by reducing the maximum inscribed circle diameter along the flow direction. The reduction amplitude of the windward cross-section of the airfoil ribs is less than the reduction amplitude of the pitch of the airfoil ribs. While increasing the number of airfoil ribs per unit length, the flow channel cross-section is not reduced. The effect is to increase the heat transfer area and the disturbance of the heat transfer boundary layer, while not increasing the resistance loss.

[0031] Third, further, in the area where heat transfer deterioration is most serious, the pitch of the airfoil ribs along the flow direction and the perpendicular flow direction of the hot-side working fluid are both reduced. The windward cross-section of the airfoil fin is further sharpened and the length of the airfoil fin along the flow direction is reduced. The number of airfoil ribs per unit area of the heat exchange plate is gradually increased, the heat transfer area per unit area of the heat exchange plate and the flow disturbance are increased, and the wall boundary layer is further destroyed, ultimately improving the overall heat transfer performance of the heat exchanger without significantly increasing the flow resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a cross-sectional view of the plate-fin heat exchanger according to an embodiment of the present invention;

[0033] Figure 2 is an internal structure diagram of the heat exchange plate and fins in the plate-fin heat exchanger according to an embodiment of the present invention;

[0034] Figure 3Structural diagram of the wing-shaped rib in the plate-fin heat exchanger according to an embodiment of the present invention. Specific embodiments

[0035] The present invention discloses a heat exchanger with variable cross-section microchannels, for example, a plate-fin air-cooled heat exchanger. Specifically, it may include several heat exchange plates on the hot side and several rectangular corrugated fins on the cold side. The several heat exchange plates and rectangular corrugated fins are alternately stacked and tightly connected by diffusion welding; the heat exchange plate is composed of an upper plate and a lower plate. Along the flow direction of the hot-side working medium, the lower surface of the upper plate and the upper surface of the lower plate are sequentially provided with a heat exchange plate inlet, a general heat exchange area, a first-level enhanced heat exchange area, a second-level enhanced heat exchange area, and a heat exchange plate outlet with the same structure. In each area, several discontinuous airfoil ribs are processed by photochemical etching. The present invention sets multiple enhanced heat exchange areas in the heat exchange plate. According to the degree of heat transfer deterioration, different airfoil rib arrangement forms are set in each partition. Correspondingly, a non-uniform pitch fin structure is set on the air side. Along the flow direction of the hot-side working medium, from line to surface, the heat exchange area and flow disturbance of the heat exchange plate and fins are gradually increased, and at the same time, the windward area of the airfoil rib is gradually adjusted to improve the overall heat exchange performance without significantly increasing the flow resistance.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. The same reference numerals in the drawings represent the same elements. Obviously, the embodiments described herein are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0037] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for the purpose of distinction and description, and should not be construed as indicating or implying relative importance.

[0038] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0039] The following further elaborates in detail on an automatically filled thermal expansion pipeline insulation device proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. According to the following description and the claims, the advantages and features of the present invention will be clearer.

[0040] Embodiment

[0041] Please refer to Figures 1 - 3 , this embodiment provides a plate-fin air-cooled heat exchanger with variable cross-section microchannels, including:

[0042] Several heat exchange plates (1) on the hot side and several rectangular corrugated fins (2) on the cold side. The heat exchange plates (1) and the rectangular corrugated fins (2) are alternately stacked and connected by diffusion welding. Air is used as the cooling medium (or cold-side working fluid) in the rectangular corrugated fins (2) of this heat exchanger. The hot-side working fluid can be, for example, carbon dioxide working fluid.

[0043] Among them, the heat exchange plate (1) is composed of an upper plate (1’) and a lower plate (1”). Along the flow direction of the hot-side working fluid, the lower surface of the upper plate (1’) and the upper surface of the lower plate (1”) are sequentially and mirror-image arranged with a heat exchange plate inlet (3), a general heat exchange area (4), a first-level enhanced heat exchange area (5), a second-level enhanced heat exchange area (6), and a heat exchange plate outlet (3’). Each heat exchange area is processed with several discontinuous airfoil ribs by photochemical etching.

[0044] Among them, please refer to Figure 2 as shown, the spacing of the airfoil ribs along the flow direction in each heat exchange area is marked as L2, the spacing of the airfoil ribs along the direction perpendicular to the working fluid flow in each heat exchange area is marked as L1, and the length of the airfoil ribs along the flow direction is marked as L3. Specifically, in each heat exchange area,

[0045] Compared with the airfoil ribs (4’) in the general heat exchange area (4), the shape of the airfoil ribs (5’) in the first-level enhanced heat exchange area (5) remains unchanged;

[0046] The first-level enhanced heat exchange area (5) has the following change characteristics compared with the general heat exchange area (4): The spacing of the airfoil ribs (5’) in the first-level enhanced heat exchange area (5) along the flow direction of the hot-side working fluid is smaller than the spacing of the last set of airfoil ribs (4’) at the tail end of the general heat exchange area (4) along the flow direction; the spacing of the airfoil ribs (5’) inside the first-level enhanced heat exchange area (5) along the flow direction of the hot-side working fluid linearly decreases, and the spacing of the airfoil ribs (5’) in the first-level enhanced heat exchange area (5) along the direction perpendicular to the hot-side working fluid flow remains unchanged;

[0047] The maximum inscribed circle diameter (5”) of the airfoil ribs (5’) in the first-level enhanced heat transfer zone (5) is smaller than that of the airfoil ribs (4’) in the general heat transfer zone (4); the maximum inscribed circle diameter (5”) of the airfoil ribs (5’) inside the first-level enhanced heat transfer zone (5) decreases linearly, and the percentage decrease in the maximum inscribed circle diameter (5”) is 1 / 3 of the percentage decrease in the spacing of the airfoil ribs (5’) in the first-level enhanced heat transfer zone (5) along the flow direction of the hot-side working fluid. The effect achieved by this technical feature is that, without reducing the flow channel cross-section and ensuring that the flow resistance remains unchanged, the number of airfoil ribs per unit length of the heat exchange plate (1) is increased, the heat exchange area and local flow disturbance are increased, and preliminary heat transfer enhancement in the heat transfer deterioration area is achieved.

[0048] Compared with the airfoil ribs (5’) in the first-level enhanced heat transfer zone (5), the shape of the airfoil ribs (6’) in the second-level enhanced heat transfer zone (6) remains unchanged.

[0049] The second-level enhanced heat transfer zone (6) has the following changes compared with the first-level enhanced heat transfer zone (5): the spacing L2 along the flow direction of the hot-side working fluid and the spacing L1 perpendicular to the flow direction of the hot-side working fluid of the airfoil ribs (6’) in the second-level enhanced heat transfer zone (6) are both smaller than those of the last set of airfoil ribs (5’) at the end of the first-level enhanced heat transfer zone (5) along the flow direction of the hot-side working fluid and the spacing L1 perpendicular to the flow direction of the hot-side working fluid; the spacing L2 along the flow direction of the hot-side working fluid and the spacing L1 perpendicular to the flow direction of the hot-side working fluid of the airfoil ribs (6’) inside the second-level enhanced heat transfer zone (6) both decrease linearly;

[0050] Please refer to Figure 2 and Figure 3 , the diameter of the maximum inscribed circle (6”) and the length L3 along the flow direction of the airfoil ribs (6’) in the second-level enhanced heat transfer zone (6) are respectively smaller than those of the maximum inscribed circle (5”) and the length L3 along the flow direction of the airfoil ribs (5’) in the first-level enhanced heat transfer zone; the diameter of the maximum inscribed circle (6”) and the length L3 along the flow direction of the airfoil ribs (6’) inside the second-level enhanced heat transfer zone (6) decrease linearly; the percentage decrease in the diameter of the maximum inscribed circle (6”) and the length L3 along the flow direction of the airfoil ribs (6’) is 3 / 5 of the percentage decrease in the spacing L1 perpendicular to the flow direction of the hot-side working fluid of the airfoil ribs (6’) in the second-level enhanced heat transfer zone (6). The effect achieved by the above technical features is that, without significantly increasing the flow resistance, the number of airfoil ribs (6’) per unit area of the heat exchange plate (1) is further increased, the heat exchange area and flow disturbance are increased, heat transfer is further enhanced in the area with the worst heat transfer, and the maximum inscribed circle radius of the airfoil ribs gradually becomes smaller to further reduce the windward surface (6”’) of the fin to achieve sharpening and slow down the increase in resistance caused by the reduction of the flow channel cross-section.

[0051] The airfoil ribs (4', 5', 6') on the above-mentioned general heat exchange area (4), the first-stage enhanced heat exchange area (5), and the second-stage enhanced heat exchange area (6) form a variable cross-section microchannel.

[0052] Please refer to Figure 2 As shown, along the hot-side flow direction, the distance L4 ( Figure 2 shown in ) between two opposite fin surfaces of the fin units of the rectangular wavy fins (2) in different regions corresponding to the general heat exchange area (4), the first-stage enhanced heat exchange area (5), and the second-stage enhanced heat exchange area (6) decreases linearly. The effect is to increase the heat exchange area on the cold side (air side) and enhance the heat exchange capacity between the hot-side working fluid and air in the most deteriorated region of the hot-side heat exchange.

[0053] The design concept of the plate-fin air-cooled heat exchanger in this embodiment is also applicable to other types of heat exchangers.

[0054] The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, provided that these changes fall within the scope of the claims of the present invention and their equivalent technologies, they still fall within the protection scope of the present invention.

[0055] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A heat exchanger, characterized in that: include: Several heat exchange plates (1) on the hot side; Several rectangular corrugated fins (2) on the cold side, The heat exchange plates (1) and the rectangular corrugated fins (2) are alternately stacked and tightly connected; The heat exchange plate (1) is composed of an upper plate (1') and a lower plate (1''); along the flow direction of the first working medium, a heat exchange plate inlet (3), a general heat exchange area (4), a two-stage enhanced heat exchange area, and a heat exchange plate outlet (3') of the same structure are sequentially arranged on the lower surface of the upper plate (1') and the upper surface of the lower plate (1''); each heat exchange area in the general heat exchange area (4) and the enhanced heat exchange area is provided with a plurality of discontinuous wing-shaped ribs; the first working medium enters the general heat exchange area (4) and each stage enhanced heat exchange area in sequence from the heat exchange plate inlet (3), exchanges heat with the second working medium through the rectangular corrugated fins (2) in the heat exchange area, and finally flows out from the heat exchange plate outlet (3'); the second working medium flows in the rectangular corrugated fins (2), and forms a cross-flow heat exchange with the first working medium in the heat exchange plate (1); The airfoil ribs of the first stage enhanced heat exchange zone have a higher density than the airfoil ribs of the general heat exchange zone (4); the airfoil ribs of the latter stage enhanced heat exchange zone have a higher density than the airfoil ribs of the former stage enhanced heat exchange zone; Along the flow direction of the first working medium, the distance between the two fin surfaces of the fin unit of the rectangular corrugated fin (2) corresponding to the general heat exchange zone (4) and the two-stage enhanced heat exchange zone decreases linearly or nonlinearly; The enhanced heat exchange zone includes a first-level enhanced heat exchange zone (5) and a second-level enhanced heat exchange zone (6); The shape of the airfoil ribs of the first-stage enhanced heat exchange zone (5) remains unchanged compared to the airfoil ribs of the general heat exchange zone (4), and the spacing between the airfoil ribs of the first-stage enhanced heat exchange zone (5) along the first working medium flow direction is reduced compared to the spacing between the last group of airfoil ribs at the tail end of the general heat exchange zone (4) along the first working medium flow direction; Compared with the general heat exchange zone (4), the distance between the airfoil ribs inside the first-stage enhanced heat exchange zone (5) along the direction perpendicular to the flow of the first working medium remains unchanged; The maximum inscribed circle diameter of the airfoil ribs in the first-level enhanced heat exchange zone (5) is smaller than the maximum inscribed circle diameter of the airfoil ribs in the general heat exchange zone (4); The spacing between the wing-shaped ribs of the II-stage enhanced heat exchange zone (6) along the first working medium flow direction and the spacing perpendicular to the first working medium flow direction are reduced compared with the spacing between the last group of wing-shaped ribs at the tail end of the I-stage enhanced heat exchange zone (5) along the first working medium flow direction and the spacing perpendicular to the first working medium flow direction; the diameter of the maximum inscribed circle (6") and the length along the flow direction of the wing-shaped rib (6') of the II-stage enhanced heat exchange zone (6) are reduced compared with the diameter of the maximum inscribed circle (5") and the length along the flow direction of the wing-shaped rib (5') in the I-stage enhanced heat exchange zone.

2. The heat exchanger according to claim 1, characterized in that The spacing between the airfoil ribs inside the first-stage enhanced heat exchange zone (5) decreases linearly or nonlinearly along the flow direction of the first working medium.

3. The heat exchanger according to claim 1, wherein The maximum inscribed circle diameter of the airfoil rib inside the first-stage enhanced heat exchange zone (5) decreases linearly or nonlinearly along the flow direction of the first working medium.

4. The heat exchanger according to claim 3, characterized in that The percentage by which the maximum inscribed circle diameter of the airfoil ribs inside the first-stage enhanced heat exchange zone (5) decreases along the first working medium flow direction is less than the percentage by which the spacing between the airfoil ribs inside the first-stage enhanced heat exchange zone (5) decreases along the first working medium flow direction.

5. The heat exchanger according to claim 1, wherein Compared with the airfoil ribs in the first-stage enhanced heat exchange zone (5), the shape of the airfoil ribs in the second-stage enhanced heat exchange zone (6) remains unchanged.

6. The heat exchanger according to claim 5, characterized in that The maximum inscribed circle diameter of the airfoil rib inside the second-stage enhanced heat exchange zone (6) decreases linearly or nonlinearly along the flow direction of the first working medium.

7. The heat exchanger according to claim 5, characterized in that The spacing between the airfoil ribs inside the second-stage enhanced heat exchange zone (6) along the flow direction of the first working medium decreases linearly or nonlinearly.

8. The heat exchanger according to claim 5, wherein The spacing between the airfoil ribs inside the second-stage enhanced heat exchange zone (6) decreases linearly or nonlinearly along the direction perpendicular to the flow of the first working medium.

9. The heat exchanger according to claim 5 or 6, characterized in that: The length of the airfoil ribs inside the second-stage enhanced heat exchange zone (6) decreases linearly or nonlinearly along the flow direction of the first working medium.

10. The heat exchanger according to claim 9, characterized in that The percentages of reduction of the maximum inscribed circle diameter of the airfoil rib inside the second-stage enhanced heat exchange zone (6) and the length of the airfoil rib itself along the flow direction of the first working medium are both smaller than the percentage of reduction of the spacing of the airfoil rib inside the second-stage enhanced heat exchange zone (6) along the direction perpendicular to the flow direction of the first working medium.

11. The heat exchanger according to claim 1, wherein The heat exchange plate (1) and the rectangular corrugated fins (2) are connected by diffusion welding, and the upper plate (1') and the lower plate (1'') of the heat exchange plate (1) are connected by diffusion welding.

12. The heat exchanger according to claim 1, wherein The discontinuous airfoil rib is manufactured by photochemical etching.

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