A bending channel type high-efficiency heat exchange structure

Abstract

The present invention discloses a bending channel type high-efficiency heat exchange structure. Based on the formation principle of Karman vortices, the fluid channel is designed into a multi-channel bending channel structure. Each bending forms two heat exchange mode planes: the AB plane is in the front of the fluid flow direction, and the movement direction of the fluid is forcibly changed and it is subjected to a frontal impact, so that the fluid on the surface of the AB plane is continuously replaced by new fluid and driven away, which extremely enhances the heat exchange effect; the BC plane forms Karman vortices, and through the Karman vortices, the high-temperature fluid at the center of the fluid channel moves regularly towards the heat exchange wall surface and exchanges heat with the heat exchange wall surface, thereby further improving the heat exchange efficiency. The heat exchange structure of the present invention is different from turbulent flow. Turbulent flow emphasizes forming turbulent flow on the surface of the heat exchange surface to enhance the heat exchange effect, while the present invention designs the fluid channel into a multi-channel bending structure and improves the heat exchange effect through the dual actions of strengthening fluid impact and Karman vortex mixing flow, and the heat exchange efficiency can be more than 95%.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and particularly to a bent-channel type high-efficiency heat exchange structure designed based on the principle of Karman vortex formation, which can greatly improve the heat exchange efficiency of a wall-type heat exchanger. Background Art

[0002] A heat exchanger is an energy-saving device that realizes heat transfer between materials among two or more fluids at different temperatures, and is widely used in fields such as petroleum, chemical industry, metallurgy, electric power, ships, central heating, refrigeration and air conditioning, machinery, food, and pharmaceuticals.

[0003] Heat exchangers suitable for different media, different working conditions, different temperatures, and different pressures have different structural forms. According to different heat transfer principles, heat exchangers can be specifically divided into the following categories: wall-type heat exchangers, regenerative heat exchangers, fluid-connected indirect heat exchangers, direct-contact heat exchangers, and compound heat exchangers, etc. Among them, wall-type heat exchangers are the most widely used heat exchangers. In a wall-type heat exchanger, two fluids at different temperatures flow in spaces separated by a wall surface, and heat exchange occurs between the two fluids through heat conduction of the wall surface and convection of the fluid on the wall surface. Specifically, there are also shell-and-tube type, sleeve type, and other types of heat exchangers. In the prior art, in a conventional wall-type heat exchanger, when a high-temperature fluid flows parallel to the wall surface, the heat exchange efficiency with the wall surface is very low, especially the fluid far from the wall surface basically does not participate in heat exchange. Please refer to the appendix Figure 1 , when a fluid quickly passes through a parallel fluid channel, a laminar flow structure is formed. There is a temperature gradient between the high-temperature fluid H or low-temperature fluid C at the center and the fluid close to the heat exchange side wall W. The fluids f and i at the center of the channel can only transfer heat through convection with the fluids d and g close to the heat exchange side wall W. As is well known, the thermal conductivity of the fluid is very poor, and the efficiency of convective heat transfer is very low, resulting in a very low contribution of the fluids f and i at the center to the heat exchange efficiency. In order to enhance heat exchange, people have tried to make the heat exchange wall surface into a rough surface (such as designing a fin structure, etc.) to increase the turbulent flow effect to enhance the heat exchange effect between the high-temperature fluid and the wall surface. This has led to a more complex structure of the heat exchanger, an increase in processing costs, and at the same time, since the degree of participation of the fluid at the center in heat exchange has been increased limitedly, the improvement of the overall heat exchange efficiency is also very limited. Summary of the Invention

[0004] Based on the above technical problems, the object of the present invention is to provide a bent-channel type high-efficiency heat exchange structure, which designs the fluid channel as a multi-channel bent structure, so that the fluid impacts the bent wall surface during the forward movement and forms regular Karman vortices, and strengthens heat exchange by enhancing fluid impact and the form of Karman vortices, greatly improving the heat exchange efficiency.

[0005] In view of the above problems, a technical solution adopted by the present invention is to provide a bending channel type high-efficiency heat exchange structure, and the heat exchange structure has: a fluid channel, the fluid channel includes a fluid channel for cold fluid and a fluid channel for hot fluid separated by a heat exchange wall surface, the cold fluid and the hot fluid flow reversely in the corresponding fluid channels, and heat exchange is carried out through the heat exchange wall surface, and it is characterized in that: multiple bending obstacles are arranged along the flow direction of the fluid, and each of the bending obstacles is formed with: a first heat exchange plane and a second heat exchange plane: the first heat exchange plane is in the front of the fluid flow direction, and the movement direction of the fluid is forcibly changed and it is subjected to a frontal impact; the second heat exchange plane is arranged on the back of the first heat exchange plane along the forward direction of the fluid, and a Karman vortex is formed on the surface of the second heat exchange plane, and through the Karman vortex, the high-temperature fluid at the center of the fluid channel moves regularly towards the heat exchange wall surface and exchanges heat with the heat exchange wall surface.

[0006] Further, the fluid channel is composed of a first bending plate, a second bending plate and a third bending plate arranged in parallel, and the surface of the second bending plate forms the heat exchange wall surface; a fluid channel for the cold fluid is formed between the first bending plate and the second bending plate, a fluid channel for the hot fluid is formed between the third bending plate and the second bending plate, and multiple bending structures are uniformly arranged on the first bending plate, the second bending plate and the third bending plate along the flow direction of the fluid, and the bending structure includes: a first plane for the fluid to impact forward and a second plane arranged opposite to the first plane, the first plane forms the first heat exchange plane, and the second plane forms the second heat exchange plane.

[0007] Further, the bending angle α between the first heat exchange plane and the second heat exchange plane is set to: 45°≤α≤135°.

[0008] Further, the value range of the Reynolds number Re1 of the cold fluid is set to: 5<Re1<150, and the value range of the Reynolds number Re2 of the hot fluid is set to: 5<Re2<150.

[0009] Further, the value range of the width d of the fluid channel is set to: (L / 2)·sin(α / 2)≤d≤L·sin(α / 2), where L is the length of the bending side of each bending structure.

[0010] Further, the first bending plate, the second bending plate and the third bending plate are all made of metal plates, and the thickness a of the metal plates is set to: 0.1mm≤a≤100mm.

[0011] Further, the value range of the bending obstacle n of the fluid channel is: n≥3.

[0012] The beneficial effects of the present invention are as follows: The fluid channel is designed as a multi-channel bent channel structure, and a first heat exchange plane and a second heat exchange plane are formed at each bending point, and two heat exchange modes are formed by the fluid at the first heat exchange plane and the second heat exchange plane; when the fluid passes through the bending point, the cold and hot fluids respectively collide head-on with the two sides of the first heat exchange plane, and the static fluid on both sides of the first heat exchange plane is continuously impacted and replaced, improving the heat exchange efficiency; while at the second heat exchange plane, the fluid will form continuous Karman vortices, so that the high-temperature or low-temperature fluid at the center of the fluid channel impacts the second heat exchange plane through the Karman vortices, driving away the static fluid on its surface and making the high-temperature fluid at the center of the fluid channel move regularly towards the heat exchange wall surface and exchange heat with the heat exchange wall surface, so as to achieve the purpose of improving the heat exchange effect and avoiding the phenomenon that the fluid at the center has a low contribution to the heat exchange efficiency and a too high temperature in the conventional wall-type heat exchanger with a convection structure. The heat exchange structure of the present invention is different from the turbulent flow structure. Turbulent flow emphasizes the formation of turbulent flow on the surface of the heat exchange surface to enhance the heat exchange effect. The present invention is to set bending obstacles during the forward movement of the fluid to strengthen the impact of the fluid and form Karman vortices. Through the dual effects of strengthening the fluid impact and forming Karman vortices, the heat exchange efficiency of the cold and hot fluids is greatly improved. After passing through several bending obstacles, the temperature of the high-temperature fluid drops significantly, and the outlet temperature of the high-temperature fluid can even be made consistent with the outlet temperature of the low-temperature fluid, achieving heat exchange to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is the working principle diagram of a traditional laminar flow structure heat exchanger in the prior art;

[0014] Figure 2 is the formation principle diagram of Karman vortices;

[0015] Figure 3 is the working principle diagram of the embodiment of the present invention;

[0016] Figure 4 is the structural principle diagram of the embodiment of the present invention;

[0017] Description of the reference numerals:

[0018] O Obstacle

[0019] K Karman vortex

[0020] F Fluid

[0021] P1 Hot fluid channel

[0022] P2 Cold fluid channel

[0023] C Cold fluid

[0024] H Hot fluid

[0025] 1 First bending plate

[0026] 2 Second bending plate

[0027] 3 Third bending plate

[0028] K1 Fin

[0029] W Heat exchange wall surface Detailed implementation manners

[0030] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention. The implementation manner of the present invention is a bending channel heat exchange structure designed based on the formation principle of Karman vortices, and is used to enhance the heat exchange effect between high-temperature fluid and low-temperature fluid.

[0031] Please refer to Figure 2 , the formation principle of Karman vortices is as follows: If an obstacle O is set in the middle of a pipeline, when fluid F passes through, continuous vortices, that is, Karman vortices K, will be formed behind the obstacle O. The biggest feature of Karman vortices K is that they can mix the fluid in the pipeline.

[0032] Based on the above principle, the applicant designed the heat exchange structure of the present invention. Please refer to Figure 3 , the heat exchange structure of the implementation manner of the present invention at least has: the first bending plate 1, the second bending plate 2, and the third bending plate 3 with a parallel structure. A hot fluid channel P1 is formed between the first bending plate 1 and the second bending plate 2, and a cold fluid channel P2 is formed between the second bending plate 2 and the third bending plate 3. The surface of the second bending plate 2 forms the heat exchange wall surface of the cold and hot fluids. The hot fluid H and the cold fluid C flow reversely in their respective fluid channels, and heat exchange is realized through the second bending plate 2; multiple bending structures are arranged on the first bending plate 1, the second bending plate 2, and the third bending plate 3 along the fluid flow direction, so that the hot fluid channel P1 and the cold fluid channel P2 form a multi-channel bending channel structure. Each bending structure has: an AB surface impacted by the fluid frontally and a BC surface opposite to the AB surface. Two heat exchange modes are formed by the cold and hot fluids on the AB surface and the BC surface respectively; during the movement of the hot fluid H and the cold fluid C, they collide head-on on the AB surface of the bending structure. The cold fluid C and the hot fluid H directly impact the two side surfaces of the AB surface respectively. The static fluid at the two side surfaces of the AB surface is continuously impacted and replaced, and the heat exchange efficiency is improved through the strong impact of the fluid. This is the first heat exchange mode; while on the BC surface of the bending structure, Karman vortices K will be formed, so that the high-temperature or low-temperature fluid at the center of the bending channel impacts the BC surface through the movement of the above Karman vortices K, driving away the static fluid on the surface of the BC surface to achieve the purpose of improving the heat exchange effect. This is the second heat exchange mode.

[0033] In practical applications, each bending plate is usually made of a metal plate, and the heat transfer efficiency of the metal plate is relatively high. The bottleneck restricting the heat transfer speed during the heat exchange process between cold and hot fluids often lies in: how to transfer the temperature at the center of the fluid to the surface of the heat exchange wall. If it is a traditional laminar flow partition heat exchange structure as shown in the appendix Figure 1 When the fluid channels are formed by parallel tube walls and the fluid passes through the fluid channels quickly in parallel, a temperature gradient is formed between the high-temperature or low-temperature fluid at the center and the fluid close to the heat exchange wall W. The fluid at the fluid channels f and i can only transfer heat through convection to the fluid at d and g. However, the thermal conductivity of the fluid is very poor, and the efficiency of convective heat transfer is very low, resulting in poor heat exchange effect of this heat exchange structure. In the present invention, the applicant innovatively designs the fluid channels into a multi-channel bending channel structure, and uses the bending structure to strengthen the fluid impact and form a Karman vortex. The strong impact movement of the fluid effectively disperses the stationary fluid stagnating on the surface of the heat exchange wall, thereby improving the heat transfer efficiency. The formation of the Karman vortex also makes the high-temperature fluid at the center of the flow channel move relative to the low-temperature fluid near the heat exchange wall, thus solving the problem of transferring the temperature at the center of the fluid channel to the heat exchange wall, strengthening the participation degree of the fluid at the center in heat exchange, and further improving the heat transfer efficiency. The test data of the applicant shows that after the cold and hot fluids pass through several bending obstacles, the temperature of the hot fluid drops significantly. Furthermore, by increasing the length of the fluid channel and the number of bending structures, the bending channel heat exchange structure of the present invention can make the outlet temperatures of the cold and hot fluids reach the same, achieving the maximum heat exchange.

[0034] Please refer to Figure 4 , in order to achieve the technical effects of the present invention, the present invention further makes specific limitations on the bending angle α, bending side length L, width d of the fluid channel, and number n of bends. Among them, the relationship between the width d of the fluid channel (hot fluid channel P1 or cold fluid channel P2), the bending side length L of the bending structure, and the bending angle α (i.e., the included angle between the AB surface and the BC surface) is limited by the following formula: d1 ≤ d ≤ d2, where d1 = (L / 2)·sin(α / 2), d2 = L·sin(α / 2), 45° ≤ α ≤ 135°; and in order to achieve the heat exchange effect, the number n of the bending structures ≥ 3.

[0035] Next, multiple embodiments and comparative examples are used to investigate the improvement effect of the bending heat exchange structure of the present invention on the heat transfer efficiency.

[0036] For the heat exchange structure principle of Comparative Example 1 of the present invention, please refer to the appendix Figure 1, the cold fluid C and the hot fluid H flow in parallel and reverse directions in their respective flow channels, forming a laminar flow heat exchange structure with a partition wall. Heat exchange is achieved through the heat exchange wall surface W; its fluid channel is composed of heat exchange plates with a smooth surface.

[0037] The heat exchange structure of Comparative Example 2 of the present invention is based on Comparative Example 1. By setting roughness on the surface of the heat exchange plate, the turbulent flow is strengthened, thereby improving the heat exchange efficiency.

[0038] In the examples and comparative examples, the total length s of the fluid channel, the width d of the fluid channel, the material and thickness of the tube wall of the fluid channel are all set to be the same; the heat exchange effects of each heat exchange structure are investigated by changing the flow velocity of the fluid medium and the specific parameters of the bending structure.

[0039] Table 1 Comparison of heat exchange effects between the heat exchange structure of the present invention and the conventional heat exchange structure

[0040]

[0041]

[0042] As can be seen from Table 1, compared with the conventional partition wall heat exchange structure in the prior art, the heat exchange structure of the present invention can greatly improve the heat exchange effect under the same fluid channel size and medium conditions. At the same time, the structure and processing technology of the present invention are relatively simple, with low cost, and have good industrial promotion and application value.

[0043] The above are only the embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of the present invention.

Claims

1. An efficient heat exchange structure with a bent channel, the heat exchange structure having: a fluid channel, the fluid channel including: The fluid channels for the cold fluid and the hot fluid are separated by a heat exchange wall surface. The cold fluid and the hot fluid flow in opposite directions in their respective fluid channels and exchange heat through the heat exchange wall surface. It is characterized in that: multiple bending obstacles are provided in the fluid channels along the fluid flow direction, and each of the bending obstacles forms: a first heat exchange plane and a second heat exchange plane. The first heat exchange plane is in the front of the fluid flow direction, and the movement direction of the fluid is forcibly changed and it is subjected to a frontal impact. The second heat exchange plane is arranged on the back of the first heat exchange plane along the forward direction of the fluid. A Karman vortex is formed on the surface of the second heat exchange plane, and through the Karman vortex, the high-temperature fluid at the center of the fluid channel regularly moves towards the heat exchange wall surface and exchanges heat with the heat exchange wall surface. The fluid channel is composed of a first bending plate, a second bending plate and a third bending plate arranged in parallel. The surface of the second bending plate forms the heat exchange wall surface. The fluid channel for the cold fluid is formed between the first bending plate and the second bending plate, and the fluid channel for the hot fluid is formed between the third bending plate and the second bending plate. The first bending plate, the second bending plate and the third bending plate are all provided with multiple bending structures evenly along the fluid flow direction. The bending structure includes: a first plane for the frontal impact of the fluid and a second plane arranged opposite to the first plane. The first plane forms the first heat exchange plane, and the second plane forms the second heat exchange plane. The bending angle α between the first heat exchange plane and the second heat exchange plane is set to: 45°≤α≤135°.

2. The high-efficiency heat exchange structure of a bent channel type according to claim 1, characterized in that, The value range of the Reynolds number Re1 of the cold fluid is set to: 5<Re1<150, and the value range of the Reynolds number Re2 of the hot fluid is set to: 5<Re2<150.

3. The highly efficient heat exchange structure of a bent channel type according to claim 1, characterized in that, The value range of the width d of the fluid channel is set to: (L / 2)·sin(α / 2)≤d≤L·sin(α / 2), where L is the length of the bending side of each bending structure.

4. The high-efficiency heat exchange structure of a bending channel type according to claim 1, wherein, The first bending plate, the second bending plate and the third bending plate are all made of metal plates, and the thickness a of the metal plates is set to: 0.1mm≤a≤100mm.

5. The high-efficiency heat exchange structure with a bent channel according to claim 1, characterized in that, The value range of the number n of the bending obstacles of the fluid channel is: n≥3.

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