A novel fin and a heat exchanger including the fin

Abstract

The present invention provides a fish-scale bionic fin, which is arranged on the inner wall of a heat exchanger and extends from the inner wall towards the outer wall. The fish-scale bionic fin includes a first curved wall and a second curved wall connected to each other. The length of the first curved wall is greater than that of the second curved wall, and the bending radius of the first curved wall is smaller than that of the second curved wall. The first curved wall is located upstream of the fluid flow, and the second curved wall is located downstream of the fluid flow. The present invention designs a novel fin structure. By setting the dimensions of the first curved wall and the second curved wall and the change of the bending radius, it is possible to increase the heat transfer area while maintaining the same resistance, improve the heat transfer effect, and save the distribution area of the fins and the cost.

Description

Technical Field

[0001] The present invention relates to a heat transfer enhancement structure, and particularly to a fish-scale bionic fin. Background Art

[0002] A heat exchanger is a commonly used component in refrigeration systems and air conditioning systems. According to its functions, it can be divided into condensers, evaporators, and so on. To improve the heat transfer performance of the heat exchanger, among other things, the heat exchanger is usually provided with fins. A finned tube is a heat transfer element. In order to improve the heat transfer efficiency, fins are usually added to the surface of the heat transfer tube to increase the outer surface area (or inner surface area) of the heat transfer tube, thereby achieving the purpose of improving the heat transfer efficiency. Such a heat transfer tube.

[0003] Adding fins in the flow channel helps to increase the heat transfer area and can enhance the perturbation of the flow field. Enhancing heat transfer by adding fins has been widely applied in heat exchangers. However, this design cannot solely consider the heat dissipation effect. It is also necessary to avoid as much as possible the situation where the pressure drop increases sharply after adding fins while the heat dissipation improvement effect is minimal. Considering that the temperature of the refrigerant inlet is relatively lower, therefore, the fins should be reasonably designed at the center and the periphery. Moreover, the current fin designs all adopt conventional designs, and it is necessary to consider improving heat transfer enhancement from the fin design.

[0004] Moreover, air-cooled plate-shell heat exchangers generally adopt a flat plate structure or the structure of a conventional shell-and-tube heat exchanger, so further improvement is also required.

[0005] In view of the above problems, the present invention provides a new fish-scale bionic fin and its heat exchanger, which are improved by optimizing the fin structure, thereby solving the problem of insufficient heat transfer capacity of the finned tube. Summary of the Invention

[0006] The present invention provides a new fish-scale bionic fin with a circular ring structure and its heat exchanger, which are improved to solve the above-mentioned technical problems.

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

[0008] A fish-scale bionic fin is provided on the heat transfer inner wall and extends from the inner wall to the outer wall. The fish-scale bionic fin includes a first curved wall and a second curved wall connected to each other. The length of the first curved wall is greater than that of the second curved wall, and the bending radius of the first curved wall is less than that of the second curved wall; the first curved wall is located upstream of the fluid flow, and the second curved wall is located downstream of the fluid flow.

[0009] Preferably, the heat transfer inner wall is an annular inner wall.

[0010] Preferably, the flow channel inside the ring is provided with a circumferential central fin located at the center of the flow channel and two rows of side fins located on both sides of the central fin. The height of the central fin is the same as that of the side fins, and the thickness of the central fin is 1.5 - 2.5 times that of the side fins.

[0011] Preferably, the thickness of the central fin is 2 times that of the side fins.

[0012] Preferably, the fish-scale bionic fin is inclined with respect to the axis of the inner wall, that is, the included angle is less than 90°, that is, it is inclined with respect to the fluid flow direction. When the fluid in the annular flow channel flows from the upper part to the lower part, the included angle between the fish-scale bionic fin and the axis of the inner wall becomes smaller and smaller.

[0013] A shell-and-tube heat exchanger, the heat exchanger includes a shell and an internal flow channel. The shell is provided with a fluid inlet and a fluid outlet. The shell includes an inner wall and an outer wall. The inner wall is circular, and the outer wall is octagonal or circular. The center of the inner wall and the center of the outer wall are the same point; an internal flow channel is formed between the inner wall and the outer wall. Multiple annular dividing members are arranged in the internal flow channel, so that the internal flow channel is divided into multiple annular flow channels axially. The inlets and outlets of the annular flow channels are respectively arranged at opposite ends, so that the annular flow channels are of a U-shaped structure and are formed by the parallel connection of two side flow channels; openings are provided on the annular dividing members, so that adjacent two annular flow channels form a series structure through the openings; fish-fin-shaped bionic fins are arranged in the annular flow channels. When viewed axially, the protruding directions of the fish-scale bionic fins in adjacent flow channels are opposite.

[0014] Optionally, the fluid inlet and the fluid outlet are arranged at the top of the shell.

[0015] Optionally, the fish-scale bionic fins are arranged on the inner wall and extend from the inner wall towards the outer wall.

[0016] Optionally, the fish-scale bionic fin includes a first curved wall and a second curved wall connected to each other. The length of the first curved wall is greater than that of the second curved wall, and the bending radius of the first curved wall is smaller than that of the second curved wall.

[0017] Optionally, a circumferential central fin located at the center of the flow channel and two rows of side fins distributed on both sides of the central fin are arranged in the annular flow channel. The height of the central fin is the same as that of the side fins, and the width of the central fin is 1.5 - 2.5 times that of the side fins.

[0018] Optionally, the central fins and the side fins are arranged in a staggered manner.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1) The present invention designs a novel fin structure. By setting the dimensions of the first bending wall and the second bending wall and the change of the bending radius, it is possible to increase the heat transfer area while maintaining the same resistance, improve the heat transfer effect, and save the distribution area of the fins, thus saving costs.

[0021] 2) The present invention designs a shell-and-tube heat exchanger with a novel annular shell, which integrates a U-shaped parallel flow channel and a fish fin-shaped bionic fin. Compared with the traditional spiral and S-shaped series flow channels, the U-shaped parallel flow channel can reduce the pressure drop and has better temperature uniformity performance.

[0022] 3) The fish fin-shaped bionic fins are arranged in a staggered manner in the flow channel to enhance the flow around and increase the effective heat transfer area. The relatively gentle side of the fish fin-shaped bionic fin is opposite to the flow direction of the working medium, and it has a better flow-around effect and a larger heat dissipation area compared with ordinary rectangular fins. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a cross-sectional view of the housing flow channel of the present invention.

[0024] Figure 2 is a schematic diagram of the fluid channel of the present invention.

[0025] Figure 3 is a schematic diagram of the fish fin-shaped bionic fin in a single flow channel of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The following will make a detailed description of the specific embodiments of the present invention with reference to the drawings.

[0027] In this article, if not otherwise specified, for formulas, " / " represents division, and "×", "*" represent multiplication.

[0028] The left and right sides of the present application are observed from the fluid inlet 2-3 direction to the fluid outlet 2-4 direction. Taking the plane where the connecting line between the fluid inlet 2-3 and the center of the inner wall 1-1 extends along the axis of the inner wall as the center, the left and right sides of the plane are the left side and the right side respectively.

[0029] A fish scale bionic fin, as Figure 1 shown, the fish scale bionic fin is arranged on the inner wall and extends from the inner wall to the outer wall.

[0030] As Figure 3As shown, the fish scale bionic fin includes a first curved wall and a second curved wall connected to each other, wherein the length of the first curved wall is greater than the length of the second curved wall, and the bending radius of the first curved wall is less than the bending radius of the second curved wall. The first curved wall is located upstream of the fluid flow, and the second curved wall is located downstream of the fluid flow. The bending radius and length of the second curved wall arranged downstream are smaller than the first curved wall, and the fluid preferentially contacts the first curved wall when flowing in the U-shaped flow channel. Because the slope of the first curved wall is relatively gentle and the contact surface with the fluid is large, the fluid can fully contact and exchange heat with the bionic fin under relatively small resistance. The second curved wall increases the heat exchange area, and the heat exchange area of the second curved wall of the same length increases, because the flow resistance located downstream is basically not increased, so by setting the size of the first curved wall and the second curved wall and the change of the bending radius, the heat exchange area can be increased while maintaining the same resistance, the heat exchange effect is improved, and the distribution area of the fin is saved, saving costs.

[0031] A choice such as Figure 2-3 As shown, the annular flow channel is provided with a circle of circumferential center fins located at the center of the flow channel and two circles of side fins located at the center fins. The height of the center fins is the same as the height of the side fins. The thickness of the center fins is 1.5-2.5 times the thickness of the side fins, preferably twice. During the heat dissipation process, the thicker center fins can fully conduct heat, and the thinner side fins can reserve sufficient channels for the fluid while ensuring heat conduction, so as not to cause excessive resistance. The above-mentioned ratio of the thickness of the center fins to the thickness of the side fins is also the best relationship obtained through experiments and numerical simulations, which achieves the best heat exchange effect while ensuring resistance.

[0032] like Figure 2 As shown, the fish scale bionic fin is perpendicular to the axis of the inner wall and parallel to the direction of fluid flow. As an improvement, the fish scale bionic fin is inclined to the axis of the inner wall, that is, the angle is less than 90°, that is, it is inclined to the direction of fluid flow. When the fluid in the annular flow channel flows from the top to the bottom, the angle between the fish scale bionic fin and the axis of the inner wall becomes smaller and smaller, that is, the angle of inclination with the direction of fluid flow becomes larger and larger, that is, the inclination of the fish scale bionic fin to the fluid flow becomes larger and larger. The main reason is that the cold fluid flows faster and faster due to gravity, so it is inevitable to slow down its flow speed so that it can reach a uniform flow. Therefore, the change of the inclination angle can make the fluid flow as uniform as possible, thereby improving the heat exchange effect.

[0033] As an improvement, when the fluid in the annular flow channel flows from the top to the bottom, the angle between the fish scale bionic fin and the axis of the inner wall becomes smaller and smaller, that is, the angle between the fish scale bionic fin and the flow direction of the fluid becomes larger and larger. Because with the acceleration of gravity, the flow rate will increase. Such a setting can further improve the heat exchange effect.

[0034] As an improvement, the distribution density of the fish-scale bionic fins in the annular flow channel where the fluid flows from the upper part to the lower part is greater than that in the annular flow channel where the fluid flows from the lower part to the upper part. That is, when the inlet of the annular flow channel is located in the upper part (the top), the inlet of the adjacent annular flow channel is located in the lower part (the bottom), and the distribution density of the fish-scale bionic fins with the inlet of the annular flow channel located in the upper part is greater than that with the inlet located in the lower part. Because when flowing downward from the upper part, it benefits from the gravity and has a small flow resistance, while when flowing upward from the lower part, the flow resistance is large. Therefore, by setting the fin density, the uniform flow and balanced pressure are achieved through the change of flow resistance, thereby promoting heat transfer.

[0035] Figure 1-3 A shell-and-tube heat exchanger is shown. As Figure 1 shown, the heat exchanger includes a shell 1 and an internal flow channel 2. A fluid inlet 2-3 and a fluid outlet 2-4 are provided on the shell 1. The shell 1 includes an inner wall 1-1 and an outer wall 1-2. The inner wall is a circular structure, and the outer wall is a polygon, preferably an octagon with more than eight sides. As a preference, the center of the circle is the center of the polygon; or the outer wall is circular, and the inner circular wall and the outer circular wall have the same center; an internal flow channel 2 is formed between the inner wall and the outer wall. As Figure 2 shown, a plurality of annular dividing members 2-1 are arranged in the internal flow channel, so that the internal flow channel is axially divided into a plurality of annular flow channels 2-2. The fluid inlets 2-3 and fluid outlets 2-4 of the annular flow channels are respectively arranged at opposite ends, so that the annular flow channel is of a U-shaped structure, and each annular flow channel is formed by the parallel connection of two side flow channels (the left side flow channel 2-5 and the right side flow channel 2-6); openings 2-7 are provided on the annular dividing members, so that adjacent two annular flow channels form a series structure through the openings, and fish-fin-shaped bionic fins 2-8 are distributed in the annular flow channels.

[0036] The present invention designs a shell-and-tube heat exchanger with a new annular shell, integrating the U-shaped parallel flow channel and the fish-fin-shaped bionic fins. Compared with the traditional spiral and S-shaped series flow channels, the U-shaped parallel flow channel can reduce the pressure drop by more than 60%, and at the same time has better temperature uniformity performance. The fish-fin-shaped bionic fins are staggered in the flow channel, enhancing the flow around, increasing the effective heat transfer area by 21%, and increasing the convective heat transfer coefficient by 26%.

[0037] The annular flow channel is provided with fish-fin-shaped bionic fins. When viewed axially, the protruding directions of the fish-scale-shaped bionic fins in adjacent flow channels are opposite. Through this design, it can make the fluid continuously receive the same flow disturbance effect when flowing in the U-shaped flow channel, reducing the increment of flow resistance.

[0038] As an option, the heat exchanger is arranged in the up-down direction. As a preference, as Figure 2As shown, the fluid inlet 2-3 and the fluid outlet 2-4 are arranged at the top end of the housing. By arranging in this way, the fluid can flow in the flow channel by means of gravity, and the fluid can be in full contact with the wall surface.

[0039] As an improvement, the opening 2-7 is arranged at the upper part or the lower part of the internal flow channel. By arranging it at the upper part or the lower part, the fluid can flow from the top end to the bottom end or from the bottom to the top end, so that the fluid can flow in the flow channel by means of gravity and the fluid can be in full contact with the wall surface; or flow against gravity, so that the fluid can fully exchange heat during the flow.

[0040] As an option, the central fins and the edge fins are arranged in a staggered distribution.

[0041] As an improvement, the heat exchanger of the present invention is applied as a radiator. The inner ring formed by the inner wall is the heat source, and the heat source dissipates heat outward through the internal flow channel. The cold fluid in the internal flow channel is air or water.

[0042] Preferably, an observation hole is arranged on the outer wall, as Figure 1 shown, for observing the fluid flow condition inside.

[0043] As an improvement, the heat exchanger of the present invention is applied to the heat dissipation of the motor. The inner ring formed by the inner wall is provided with the motor.

[0044] The existing motor heat dissipation systems are mainly divided into air-cooled and water-cooled systems. The air-cooled heat dissipation system does not require too complex auxiliary facilities, but cannot meet the heat dissipation requirements of high-power density motors. The liquid-cooled heat dissipation system mostly relies on liquids with superior physical property parameters than gases, such as water, oil, etc. With the help of auxiliary settings, very good cooling effects can be produced. The traditional liquid-cooling method usually arranges an evaporator or a flow channel outside the machine shell. The coolant is far from the heat source, and the heat dissipation effect is poor for the rotor and the stator. There is also a method of inserting cooling pipes into the stator, such as inserting cooling pipes into the stator slots and the stator yoke. Although this cooling method shortens the distance from the heat source, the cooling pipes in the slots occupy a large amount of space, are not applicable to motors with a multi-slot structure of the stator, have a complex structure, and a high assembly difficulty. There is also a method of directly contacting the coolant with the internal heat source of the motor. Although this cooling method has a good effect, it has high requirements for sealing, has many cooling device components, a complex cooling structure, a high cost, and the cooling medium can only be oil.

[0045] The heat exchanger of the present application is used for motor heat dissipation. The bottom of the casing is directly attached to the stator through a heat-conducting material. The heat generated by the stator is conducted from the bottom of the casing to the inner wall surface of its flow channel and the fin-shaped bionic fins. At the same time, the fluid working medium flows in from the inlet at the top of the casing, and then is shunted under the action of gravity, flowing downward through the right flow channel and the left flow channel respectively and converging at the bottom, entering the next annular flow channel through the bottom opening channel. Under the action of pressure, the fluid is shunted upward again and converges at the top, and then enters the next annular flow channel through the top opening channel again. This repeated flow finally flows out from the outlet at the top of the casing. During the flow process, the working medium conducts convective heat transfer with the bottom of the flow channel and the fin-shaped bionic fins distributed in the flow channel, taking away the heat of the heating components such as the stator attached to the bottom of the casing.

[0046] As Figure 1 shown, the two-phase heat dissipation casing includes an outer casing 1 and an inner flow channel 2. A fluid inlet 2-3 and a fluid outlet 2-4 are provided on the outer casing 1. As Figure 2 shown, the inner flow channel 2-2 is a U-shaped structure, which is formed by the parallel connection of a left flow channel 2-5 and a right flow channel 2-6. The inner flow channel is provided with fin-shaped bionic fins 2-8, and the protruding directions of the fin-shaped bionic fins in adjacent flow channels are opposite.

[0047] As Figure 2 shown, the fluid inlet 2-3 and the fluid outlet 2-4 of the inner flow channel are arranged at the top end of the heat dissipation casing. By setting like this, the fluid can flow in the flow channel by means of gravity and make the fluid fully contact with the wall surface.

[0048] The flow channel structure is as Figure 2 shown. It is divided into multiple annular flow channels 2-2 by an annular dividing member 2-1. Each annular flow channel is formed by the parallel connection of a left flow channel 2-5 and a right flow channel 2-6. Preferably, the width (the length along the axial direction of the inner wall surface) of each flow channel is 12 mm to 13 mm, and the height (the height along the radial direction of the inner wall surface) is 5 mm to 6 mm. The ratio of the two is required to be between 2 and 3 to ensure that the fluid has sufficient contact area with the inner wall side of the flow channel. The thickness of the annular dividing member is 3.5 mm to 4.5 mm, and each annular dividing member is provided with an opening. The circumferential span of each opening is 29° to 31°, so that the velocity change of the fluid converging and re-shunting in the parallel flow channels is small, meeting the best requirements of flow resistance and heat transfer.

[0049] As Figure 3As shown in the figure, each annular flow channel is distributed with fin-shaped bionic fins, and the middle fins and the side fins are arranged staggeredly at intervals of 2.5° to 3.5° along the circumferential direction; the middle fin is located in the center of the flow channel, with a thickness of 1.5 to 1.8 mm, and the side fins are symmetrically distributed on both sides of the middle plane of the flow channel. Axially, the center distance between the two side fins is 5 mm to 6 mm, and the thickness of each is 0.7 to 0.9 mm. The circumferential span of each fin is 14.5° to 15.5°, and the protruding height of the fin top is 3.2 mm to 3.4 mm; the curvature radius of the first bending wall of the fin is 14 mm to 17 mm, and the corresponding arc length is 9 mm to 11 mm. The curvature radius of the second bending wall is 26 mm to 29 mm, and the corresponding arc length is 4 mm to 6 mm. The above optimal dimensions are the preferred dimensions obtained through a large number of numerical simulations and experimental studies, and can meet the best heat transfer requirements with a flow resistance of (600 - 700 pa).

[0050] It is found in experiments and numerical simulations that the protruding height H of the fin top, the spacing of the fins, and the circumferential span of the fins cannot be too large or too small, otherwise the heat transfer effect will be poor or the resistance will be too large. Based on a large number of numerical simulations and experiments, the following optimizations are carried out to ensure the best heat transfer effect under the condition of a small increase in flow resistance:

[0051] As Figure 3 , assuming that the protruding height of the fin top is H, the axial spacing of the side fins is S, and the circumferential span angle of the fins is A, the following requirements are met: sinA = a - b * ln(H / S), where a and b are parameters, satisfying 0.1880 < a < 0.1890, 0.135 < b < 01.40, A is 14.5° to 15.5°, H is 3.2 mm to 3.4 mm, and S is 5 mm to 6 mm.

[0052] Preferably, a = 0.1884 and b = 0.138.

[0053] Through the above optimization design, the best heat transfer effect is achieved when the flow resistance is 600 - 700 Pa.

[0054] As Figure 2 shown, the fluid working medium flows in from the fluid inlet 2 - 3 at the top of the casing, and then is divided under the action of gravity, flows downward through the left flow channel 2 - 5 and the right flow channel 2 - 6 respectively, and then converges at the bottom, enters the next annular flow channel through the bottom opening channel, is divided upward again under the action of pressure and converges at the top, and then enters the next annular flow channel through the top opening channel again, repeating the flow in this way, and finally flows out from the fluid outlet 2 - 4 at the top of the casing. During the flow process, the working medium exchanges convective heat with the bottom of the flow channel and the fin-shaped bionic fins distributed in the flow channel, taking away the heat of the stator and other heating components attached to the bottom of the casing.

[0055] Although the present invention has been disclosed above in preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A fish-scale bionic finned annular tube-shell heat exchanger, the heat exchanger comprising a shell and an internal flow channel, a fluid inlet and a fluid outlet being provided on the shell, the shell comprising an inner wall and an outer wall, the inner wall being circular, the outer wall being polygonal or circular, and the center of the inner wall and the center of the outer wall being the same point; an internal flow channel is formed between the inner wall and the outer wall, and a plurality of annular partition members are arranged in the internal flow channel, so that the internal flow channel is axially divided into a plurality of annular flow channels, the inlets and outlets of the annular flow channels are respectively arranged at opposite ends, so that the annular flow channels are of a U-shaped structure, and each annular flow channel is formed by the parallel connection of two side flow channels; openings are provided on the annular partition members, so that adjacent two annular flow channels form a series structure through the openings; fish fin bionic fins are arranged in the annular flow channels; the fish-scale bionic fins are arranged on the heat exchange inner wall and extend from the inner wall towards the outer wall, and the fish-scale bionic fins comprise a first bent wall and a second bent wall which are connected to each other, wherein the length of the first bent wall is greater than the length of the second bent wall, and the bending radius of the first bent wall is less than the bending radius of the second bent wall; the first bent wall is located upstream of the fluid flow, and the second bent wall is located downstream of the fluid flow.

2. The fish-scale bionic finned annular tube-sheet heat exchanger according to claim 1, wherein A circumferential center fin located at the center of the flow channel and two circumferential edge fins located on both sides of the center fin are arranged in the annular flow channel, the height of the center fin is the same as the height of the edge fins, and the thickness of the center fin is 1.5-2.5 times the thickness of the edge fins.

3. The fish-scale bionic finned annular tube-shell heat exchanger according to claim 2, wherein The thickness of the center fin is 2 times the thickness of the edge fins.

4. The fish-scale bionic finned annular tube shell heat exchanger according to claim 1, wherein The fish-scale bionic fins are inclined with respect to the fluid flow direction, and when the fluid in the annular flow channel flows from top to bottom, the included angle with the fluid flow direction becomes larger and larger, that is, the inclination degree of the fish-scale bionic fins with respect to the fluid flow direction becomes larger and larger.

Images