EP4257906A1

EP4257906A1 - Spiral heat exchanger and manufacturing method therefor

Info

Publication number: EP4257906A1
Application number: EP21899991.0A
Authority: EP
Inventors: Feng Gao; Zaixiang LIU; Yanfeng Chen; Yuanfeng CAI; Bing Wang; Zhengyan NIU
Original assignee: Shanghai Xingye Material Technology Co Ltd
Current assignee: Shanghai Xingye Material Technology Co Ltd
Priority date: 2020-12-02
Filing date: 2021-11-30
Publication date: 2023-10-11
Also published as: CN112179182B; US20240011713A1; JP2023551878A; WO2022116960A1; KR20230116867A; CN112179182A

Abstract

The present invention application relates to a spiral heat exchanger and a manufacturing method therefor. The spiral heat exchanger comprises: a mandrel (1) having an axis extending in the direction of left and right; and a heat-conducting thin strip (2) spirally wound around the periphery of the mandrel (1) for at least three laps. The heat-conducting thin strip (2) of any two adjacent laps are spaced apart by a certain distance; baffle ribs (3) extending in the direction of left and right are supported between the heat-conducting thin strip (2) of any two adjacent laps; the baffle ribs (3) are arranged in sequence along a radial direction of the mandrel (1), so as to form a plurality of hot fluid flow channels (4) and a plurality of cold fluid flow channels (5) which are arranged alternately along the radial direction of the mandrel (1); each cold fluid outlet (5b)is provided with a first blocking bar (6) for blocking a portion of the cold fluid outlet (5b); each of the fluid outlet (4b) is provided with a second blocking bar (7) for blocking a portion of the hot fluid outlet (4b); the first blocking bars (6) are arranged in sequence along a first radial direction (R1), and the second blocking bars (7) are arranged in sequence along a second radial direction (R2). The spiral heat exchanger is compact and ingenious in structure and with a small flow resistance, has a large heat exchange area and high heat exchange efficiency, and is quite suitable situations both for gas-gas heat exchange and gas-liquid heat exchange.

Description

FIELD OF THE INVENTION

The present invention application relates to the field of heat exchange, and specifically to a spiral heat exchanger and manufacture method therefor.

BACKGROUND

A heat exchanger refers to the equipment that transfers the heat of the heat fluid to the cold fluid. The heat exchanger has an important application in life and industrial production. Due to the pursuit of a larger heat exchange area, the traditional heat exchanger generally covers a large area, so it has disadvantages such as higher requirements for installation space and inconvenient maintenance. Therefore, on the premise of ensuring sufficient heat exchange area, how to reduce the volume of the heat exchanger is an urgent problem to be solved in the industry.
The Chinese utility model patent with authorized notice number CN201520085162.X exposes a new type of spiral plate reaction heat exchanger which includes a first sheet, a second sheet, a middle partition and an outer cylinder. The first and second plates are spaced apart to form a double spiral cylinder. The middle partition is connected to the ends of the first and second plates near the center of the helix respectively, and separates the double spiral cylinder into two spaces without interference each other. One of the spaces is a hot fluid channel (the hot medium enters the chamber) for running the hot fluid, the other space is a cold fluid channel (the cold medium enters the chamber) for running the cold fluid. The hot and cold fluid channels are arranged into an interval distribution. Hot fluid channel and cold fluid channel are located near the center of the helix with a hot fluid inlet and a cold fluid outlet, respectively, and the hot fluid channel and the cold fluid channel are provided with hot fluid outlet and cold fluid inlet, respectively. When undergoing a heat exchange, the surface areas of both the first and second plates are the heat transfer area of the hot and cold fluid which ensure the sufficient heat transfer area with the setting of a double-helical cylinder, and can effectively reduce the volume of the heat exchanger. However, the spiral plate reaction heat exchanger in the patent document as described above has the following disadvantages.

1. The flow resistance is relatively large. A hot fluid and a cold fluid are moved in the spiral coil direction in a hot fluid channel and a cold fluid channel, respectively. In the movement process, the motion directions of the fluids change all the time, and a large interaction force will be generated between the thin plate and the heat exchange fluid, so that the flow resistance of the cold and the hot fluid in the fluid channels is large, which is not suitable for the heat exchange of the gaseous fluid.
2. The maintenance frequency is high. Although the fluid channel of the hot fluid is a spiral coil shape, its essence is still a space, that is, the hot fluid is transported in a single fluid channel, and the fluid channel and the fluid transport for the hot fluid and the cold fluid are the same. In hot fluid flow channel, for example, the problem of a single channel is that if hot fluid flow a position blockage, it will affects the hot fluid in the whole hot fluid channel. Serious will directly cause the heat fluid cannot be transported, so that the heat exchanger cannot work normally, that is, as long as there is a position of the hot fluid channel blocked, the staff will need to maintain the heat exchanger, maintenance frequency is high.

The present invention application comes from this.

SUMMARY

The technical problems to be solved in this application are: in view of the above problems, a spiral heat exchanger and its manufacturing method with compact structure, small flow resistance, a large heat transfer area and high heat transfer efficiency is proposed, which is very suitable for gas-gas heat exchange and gas-liquid heat exchange.
The technical solution of this application is as follows.
In the first aspect of the present invention application, there is provided a spiral heat exchanger, which comprises:

a mandrel with an axis left-right extending, and
a heat conduction thin tape having a spiral shape wound around the periphery of the mandrel for at least three circles;
any adjacent two circle players of the heat conduction thin tape are separated by a certain distance, and baffle ribs extending in the direction of left and right are configured to support between any adjacent two circles of the heat conduction thin tape, each of the baffle ribs is sequentially arranged in a radial direction of the mandrel, thereby forming a plurality of hot fluid flow channels and a plurality of cold fluid flow channels which are arranged alternately along the radial direction of the mandrel, each of the hot fluid flow channels has a hot fluid inlet located on its left end and a hot fluid outlet located on its right end, each of the cold fluid flow channels has a cold fluid outlet located on its left end and a cold fluid inlet on its right end;
first block bars are disposed at each of the cold fluid outlets for partially blocking thereof, second block bars are disposed at each of the hot fluid outlets for partially blocking thereof, each of the first block bars is sequentially disposed along a first radial direction of the mandrel, each of the second block bars is sequentially disposed along a second radial direction of the mandrel.

In an optional design, third block bars are disposed at each of the cold fluid outlets for partially blocking thereof, each of the third block bars is sequentially arranged along a third radial direction of the mandrel, the third radial direction and the first radial direction are arranged at a non-zero clip angle.
In an optional design, fourth block bars are disposed at each of the hot fluid outlets for partially blocking thereof, each of the fourth block bars is sequentially arranged along a fourth radial direction of the mandrel, the fourth radial direction and the second radial direction are arranged at a non-zero clip angle.
In an optional design, fifth block bars are disposed at each of the cold fluid outlets for partially blocking thereof, each of the fifth block bars is sequentially arranged along a fifth radial direction of the mandrel; the fifth radial direction is arranged at a non-zero clip angle with the first radial direction and the third radial direction, respectively.
In an optional design, sixth block bars are disposed at each of the cold fluid inlets for partially blocking thereof, seventh block bars are disposed at each of the hot fluid inlets for partially blocking thereof, each of the sixth block bars are sequentially arranged along a sixth radial direction of the mandrel, each of the seventh block bars are sequentially arranged along a seventh radial direction of the mandrel; the sixth radial direction is arranged at a non-zero clip angle with the second radial direction and the fourth radial direction, respectively; the seventh radial direction is arranged at a non-zero clip angle with the third radial direction, the first radial direction and the fifth radial direction, respectively.
In an optional design, eighth block bars are disposed at each of the cold fluid inlets for partially blocking thereof, ninth block bars are disposed at each of the hot fluid inlets for partially blocking thereof, each of the eighth block bars is sequentially arranged alone an eighth radial direction of the mandrel, each of the ninth block bars is sequentially arranged along a ninth radial direction of the mandrel; the eighth radial direction is arranged at a non-zero clip angle with the sixth radial direction, the second radial direction and the fourth radial direction, respectively; the ninth radial direction, and the seventh radial direction, the third radial direction, the first radial direction and the fifth radial direction are respectively arranged at a non-zero clip angle.
In an optional design, tenth block bars are disposed at each of the hot fluid outlets for partially blocking thereof, each of the tenth block bars is sequentially arranged along a tenth radial direction of the mandrel; the tenth radial direction is arranged at a non-zero clip angle with the eighth radial direction, the sixth radial direction, the fourth radial direction and the second radial direction, respectively.
In an optional design, the sixth radial direction and the first radial direction are arranged at a non-zero clip angle, the seventh radial direction and the second radial direction are arranged at a non-zero clip angle;

a region of each cold fluid outlets out of the seventh radial direction is fully blocked by the first block bars, a region of each hot fluid outlets out of the sixth radial direction is fully blocked by the second block bars;
a region of each cold fluid inlets out of the second radial direction is fully blocked by the sixth block bars, and a region of each hot fluid inlets out of the first radial direction is fully blocked by the seventh block bars.

In an optional design, both the first block bars and the second block bars are an arc block bar;

in the radial direction of the mandrel from inside to outside, the length of each first block bar increases sequentially, the length of each second block bar increases sequentially, and make each first block bar fan distribution, each second block bar fan distribution;
both the sixth block bar and the seventh block bar are an arc block bar;
in the radial direction of the mandrel from inside to outside, the length of each sixth block bar increases sequentially, the length of each seventh block bar increases sequentially, and make each sixth block bar fan distribution, each seventh block bar fan distribution.

In the second aspect of the present invention application, there is provided a manufacturing method of the spiral heat exchanger as described in the first aspect of the present invention application, which comprises:
winding a heat conduction thin tape around the periphery of a mandrel to have a spiral shape; coating an adhesive on the left and right of the heat conduction thin tape for forming first block bars and second block bars on the corresponding position with a certain length at a certain interval, in the process of the winding the heat conduction thin tape, meanwhile, coating an adhesive on a surface of the heat conduction thin tape for forming the baffle ribs at a certain interval.
In the third aspect of the present invention application, there is provided a spiral heat exchanger, which comprises:

a mandrel having an axis extending in left-right direction, and
a heat conduction thin tape having a spiral shape wound around the periphery of the mandrel for at least three circles;
any adjacent two circles of the heat conduction thin tape are separated by a certain distance, and baffle ribs are configured to support between any adjacent two circles of the heat conduction thin tape, each of the baffle ribs is sequentially arranged along a radial direction of mandrel, thereby forming a plurality of hot fluid flow channels and a plurality of cold fluid flow channels arranged alternately along a radial direction of the mandrel, each of the hot fluid flow channels has a hot fluid inlet located on the left end and a hot fluid outlet located on the right end, each of the cold fluid flow channels has a cold fluid outlet located on the left end and a cold fluid inlet located on the right end;
sixth block bars are disposed at each of the cold fluid inlets for partially blocking thereof, seventh block bars are disposed at each of the hot fluid inlets for partially blocking thereof, each of the sixth block bars is sequentially arranged along a sixth radial direction of the mandrel, each of the seventh block bars is sequentially arranged along a seventh radial direction of the mandrel.

In an optional design, eighth block bars are disposed at each of the cold fluid inlets for partially blocking thereof, ninth block bars are disposed at each of the hot fluid inlets for partially blocking thereof, each of the eighth block bars is sequentially arranged along a eighth radial direction of the mandrel, each of the ninth block bars is sequentially arranged along a ninth radial direction of the mandrel, the eighth radial direction and the sixth radial direction are arranged at a non-zero clip angle, the ninth radial direction and the seventh radial direction are arranged at a non-zero clip angle.
In an optional design, the sixth block bars and the seventh block bars are arc block bars.
In a radial direction of the mandrel from inside to outside, the lengths of the sixth block bars increase sequentially, the lengths of the seventh block bars increase sequentially, and so that the sixth block bars are fan-distributed, the seventh block bars are fan-distributed.
In an optional design, each of the sixth block bars has a radiant 180° , each of the seventh block bars has a radian ≥180°.
Beneficial effects of the present invention application are as follows.

1. According to the spiral heat exchanger of the first and third aspects of the present invention application, each hot fluid flow channels and cold fluid flow channels are axial extension rather than spiral extension, when working, cold and hot fluids flow along the axial direction of the heat exchanger in the hot channel, and the flow resistance of the heat transfer fluid is small, which is very suitable for gas-gas exchange and gas-liquid exchange.
2. According to the spiral heat exchanger of the first aspect of the present invention application, the spiral heat conduction thin tape is coiled around the mandrel periphery and sets baffle ribs between the heat conduction thin tape of adjacent circle layers, and sets the corresponding positions on both sides of the heat conduction thin tape in the width direction, thus, multiple staggered hot fluid flow channels and cold fluid flow channels are formed, and the inlet of hot fluid flow channels and cold fluid flow channels are concentrated in different positions of the heat exchanger, which greatly facilitates the introduction of cold and hot fluid to the flow channel of the heat exchanger.
3. According to the spiral heat exchanger of the third aspect of the present invention application, coiling the heat conduction thin tape helix around the mandrel periphery, and set the baffle ribs between the heat conduction thin tape of the adjacent circle layer, also set the bars on both sides of heat conduction thin tape in the width direction, thus forming multiple staggered arranged hot fluid flow channels and cold fluid flow channels. The outlets of each hot fluid flow channels and cold fluid flow channels are concentrated at different positions of the heat exchanger, greatly facilitates the cold or hot fluid is derived from each channel of the heat exchanger.
4. The spiral heat exchanger according to the first and third aspects of the present invention application is made by heat conduction thin tape around the mandrel. The left and right extended baffle ribs are supported between the heat conduction thin tape of any adjacent two circle layer. Multiple baffle ribs separate the space formed between two adjacent circle layers into multiple hot fluid flow channels and cold fluid flow channels independent of each other. Each hot fluid flow channels independent of each other has its own hot fluid inlet and hot fluid outlet, and each cold fluid flow channels independent of each other has its own cold fluid inlet and cold fluid outlet. When one of these hot fluid flow channels or cold fluid flow channels is blocked, only the fluid channel cannot be delivered, does not affect fluid heat exchange in other fluid channels, only when multiple fluid channels are become simultaneously, the maintenance will be needed. Thus, the maintenance frequency of the heat exchanger is reduced.
5. The first radial direction, the sixth radial direction, the third radial direction, the eighth radial direction, the fifth radial direction in couples are arranged at a non-zero clip angle, the second radial direction, the seventh radial direction, the fourth radial direction, the ninth radial direction, the tenth radial direction in couples are arranged at a non-zero clip angle, increasing the cold and hot fluid flow stroke of the hot fluid in this heat exchanger, then improve the heat transfer efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to clearly illustrate the technical solution of the embodiments of the invention, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the invention and thus are not limitative of the invention.

Fig. 1 is an overall schematic diagram of the first spiral heat exchanger in an embodiment of the present invention application.
Fig. 2 is an overall schematic representation of the first spiral heat exchanger in an embodiment of the present invention application in the other view.
Fig. 3 is a schematic representation of the internal structure of the first spiral heat exchanger in an embodiment of the present invention application, where mandrel is removed and the stamping bulge is hidden.
Fig. 4 is a schematic diagram of the internal structure of the first spiral heat exchanger in an embodiment of the present invention application in another view, where mandrel is removed and the stamping bulge is hidden.
Fig. 5 is a schematic diagram of the internal section structure of the first spiral heat exchanger in an embodiment of the present invention application, where mandrel is removed and the stamping bulge and bar are hidden.
Fig. 6 is an internal structural axis view of the second spiral heat exchanger in an embodiment of the present invention application, where mandrel is removed.
Fig. 7 is an internal structural axis view of the second spiral heat exchanger in an embodiment of the present invention application in another view angle, where the mandrel is moved out.
Fig. 8 is an internal structural axis view of the third spiral heat exchanger in an embodiment of the present invention application, where mandrel is removed.
Fig. 9 is an axis view of the internal structure of third spiral heat exchanger in an embodiment of the present invention application in another view, where mandrel is moved out.
Fig. 10 is a schematic representation of the structure of heat conduction thin tape after unfolded first spiral heat exchanger in an embodiment of the present invention application.
Fig. 11 is a local structural view of Fig. 10.
Fig. 12 is a schematic representation of the local structure of the heat conduction thin tape of the first spiral heat exchanger in an embodiment of the present invention application.
Fig. 13 is a schematic representation of the axial profile of the first spiral heat exchanger in an embodiment of the present invention application.
Fig. 14 is a stereoscopic schematic of the left end cap in first spiral heat exchanger in an embodiment of the present invention application.
Fig. 15 is a stereoscopic schematic of the right-end lid in the first spiral heat exchanger in an embodiment of the present invention application.
Fig. 16 is a stereoscopic schematic of the left end lid in the first spiral heat exchanger in an embodiment of the present invention application.
Fig. 17 is a stereoscopic schematic of the right end lid in the first spiral heat exchanger in an embodiment of the present invention application.

explanation of the reference symbols:

1-mandrel, 2-heat conduct thin tape, 3-baffle ribs, 4-hot fluid flow channels, 5-cold fluid flow channels, 6-first block bars, 7-second block bars, 8-third block bars, 9-fourth block bars, 10-fifth block bars, 11-sixth block bars, 12-seventh block bars, 13-eighth block bars, 14-ninth block bars, 15-tenth block bars, 16-left end cover, 17-right end cover, 18-shell;
R1-first radial direction, R2-second radial direction, R3-third radial direction, R4-fourth radial direction, R5-fifth radial direction, R6-sixth radial direction, R7-seventh radial direction, R8-eighth radial direction, R9-ninth radial direction, R10-tenth radial direction;
2a-hold table, 4a-hot fluid inlet, 4b-hot fluid outlet, 5a-cold fluid inlet, 5b-cold fluid outlet, 16a-hot fluid lead hole, 16b-cold fluid flow tank, 16c-cold fluid lead joint, 17a-hot fluid lead hole, 17b-cold fluid buffer tank, 17c-cold fluid into the joint.

DETAILED DESCRIPTION

In order to clearly illustrate the technical solution of the embodiments of the invention, the drawings of the embodiments will be briefly described in the following; it is obvious that the described drawings are only related to some embodiments of the invention and thus are not limitative of the invention.
Unless otherwise defined, all the technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The terms "first," "second," etc., which are used in the description and the claims of the present application for invention, are not intended to indicate any sequence, amount or importance, but distinguish various components. Also, the terms such as "a," "an," etc., are not intended to limit the amount, but indicate the existence of at least one. The terms "comprise," "comprising," "include," "including," etc., are intended to specify that the elements or the objects stated before these terms encompass the elements or the objects and equivalents thereof listed after these terms, but do not preclude the other elements or objects. The phrases "connect", "connected", etc., are not intended to define a physical connection or mechanical connection, but may include an electrical connection, directly or indirectly. "On," "under," "right," "left" and the like are only used to indicate relative position relationship, and when the position of the object which is described is changed, the relative position relationship may be changed accordingly.
Now, embodiments of the present invention application will be described with reference to the drawings.
The spiral heat exchanger of this embodiment mainly includes a mandrel 1 and a heat conduction thin tape 2, where the heat conduction thin tape 2 is coiled around the periphery of the mandrel 1, and the coil number of heat conduction thin tape 2 is 10 circles. In order to more conveniently describe the specific structure of the spiral heat exchanger, the length direction of mandrel 1 is now defined as the left and right direction, that is, the axis of mandrel 1 extends in left-right direction (extending from left to right).
In this embodiment, the heat conduction thin tape 2 of any two adjacent circle layers are separated by a certain distance to form a spiral void. Moreover, the left and right extended baffle ribs 3 are configured to support between any adjacent two circle layers of the heat conduction thin tape, thereby these baffle ribs 3 are used to separate the large helical voids into nine small class round voids(circular spaces). Further, the aforementioned baffle ribs 3 are arranged along a radial direction of mandrel 1 so that the aforementioned nine circular voids are arranged along the radial direction of the mandrel 1. In this embodiment, in the radial direction of the mandrel 1 from inside to outside, the circular spaces of the first, third, fifth, seventh and ninth layers are hot fluid flow channels 4 for the hot fluid, and the even circular spaces of the second, fourth, sixth and eighth layers are cold fluid flow channels 5 for the cold fluid. Hot fluid flow channels 4 and cold fluid flow channels 5 are sequentially arranged alternately along the radial direction of the mandrel 1. Each of the hot fluid flow channels 4 has a hot fluid inlet 4a located on the left and a hot fluid outlet4 b located on the right, and each of the cold fluid flow channels 5 has a cold fluid outlet 5b located on the left and a cold fluid inlet 5a on the right. In practical application, the hot fluid flows from left to right in each hot fluid flow channels 4, and the cold fluid flows from right to left in each cold fluid flow channels 5, both convective heat exchange.
Since the hot fluid inlet 4a of each hot fluid flow channels 4 and the cold fluid outlet 5b of each cold fluid flow channels 5 are on the same side of the heat exchanger (left side), and alternately closely arranged with each other, the cold fluid inlet 5a of each cold fluid flow channels 5 is on the same side as the hot fluid outlets 4b of each hot fluid flow channels 4 (right side), and alternately closely arranged. If the heat fluid and cold fluid are directly fed to the heat exchanger from the left and right side respectively, part of the heat fluid into the cold fluid flow channels 5 and some cold fluid into the hot fluid flow channels 4 will occur. Based on this, the present embodiment adopts the following optimization design to more conveniently introduce the hot fluid and the cold fluid into each hot fluid flow channels 4 and each cold fluid flow channels 5, respectively, to avoid the hot and cold fluid crosstalk.
Referring to Fig. 3, Fig. 4, Fig. 6 to Fig. 9, first block bars 6 are disposed at each cold fluid outlets 5b to block part of the hot fluid inlet (i.e. first block bars does not block all the cold fluid outlets, block only part of the cold fluid outlet). Second block bars 7 are disposed at each hot fluid outlets 4b to block part of the hot fluid outlet. Moreover, each first block bars 6 are sequentially arranged along the first radial direction R1 of the mandrel 1, and each second block bars 7 are sequentially arranged along the second radial direction R2 of the mandrel 1.
It is not difficult to see that after adopting the above design, at least part of the hot fluid inlet 4a of each hot fluid flow channels 4 is centrally arranged - on the above first radial direction R1 for convenient description, and the centralized arrangement area becomes the first region. Moreover, in the first region, the cold fluid outlet 5b of each cold fluid flow channels 5 is blocked by first block bars 6. Therefore, in practical application, only need to send the hot fluid to the first region, it can flow into each hot fluid flow channels 4, without string into the cold fluid flow channels 5.
At least a part of the cold fluid inlet 5a of each cold fluid flow channels 5 is centrally arranged in the second region of the above second radial direction R2. Moreover, in the second region, the hot fluid outlet 4b of each hot fluid flow channels 4 is blocked by second block bars 7. Therefore, in practical application, only need to send the cold fluid to the aforementioned second region, it can flow into each cold fluid flow channels 5, but not into cold fluid flow channels 5.
If, in practical application, all the hot fluid and cold fluid are only fed into the heat exchanger from the first region and the second region respectively, then it is best to increase the area of the first region and the second region, otherwise the inflow area of the hot fluid is small, which is not conducive to the improvement of heat transfer efficiency. However, due to the influence of various factors, the area of the first and second regions usually cannot be set very large. In this case, the inflow area of the cold and hot fluid can be increased by increasing the number of integrated areas shown in Figs. 6 and 7, thus increasing the heat transfer efficiency.
In Figs. 6 and 7, each cold fluid outlets 5b mentioned above also has third block bars 8 to block part of the cold fluid outlet, each third block bars 8 are sequentially arranged along a third radial direction R3 of the mandrel 1, and each hot fluid outlets 4b of third radial direction R3 and first radial direction R1 are arranged at a non-zero clip angle. Each hot fluid outlets 4b have fourth block bars 9 partially blocking the hot fluid outlets 4b, each fourth block bars 9 are sequentially arranged along a fourth radial direction R4 of the mandrel 1, and the fourth radial direction R4 and the second radial direction R2 are arranged at a non-zero clip angle.
It is not difficult to understand that after adopting the scheme of Figs. 6 and 7, the heat exchanger has at least two hot fluid integration areas on the left and two cold fluid integration areas on the right, which improves the inflow area of the cold and hot fluid by increasing the number of cold and hot fluid integration areas, and then improves the heat transfer efficiency.
Of course, we can also set up even more amounts of cold, hot fluid integration area, for example, Figs. 3 and 4, each cold fluid outlets 5b also has fifth block bars 10 to partially blocks it, each fifth block bars 10 are sequentially arranged along the fifth radial direction R5 of the mandrel 1, and the fifth radial direction R5 is arranged at a non-zero clip angle with the aforementioned first radial direction R1 and the third radial direction R3. Therefore, there are three staggered hot fluid integration areas on the left side of the heat exchanger, and two staggered cold fluid areas are formed on the right side of the heat exchanger.
The above solution solves how to bring the cold and heat fluid into the heat exchanger, without considering how to draw the heat fluid independently of each other, which does not affect the use of the heat exchanger in some specific environments. However, in other environments, we hope that the cold fluid derived from the heat exchanger should not be mixed with hot fluid, and that the hot fluid derived from the heat exchanger should not be mixed with cold fluid. Thus, we can do the following further optimization of the heat exchanger.
In the first embodiment shown in Figs. 3 and 4, the second embodiment shown in Figs. 6 and 7, the third embodiment shown in Figs. 8 and 9, the sixth block bars 11 blocking the cold fluid inlet at each cold fluid inlets 5a, and each hot fluid inlets 4a has the seventh block bars 12 blocking the hot fluid inlet. Each sixth block bars11 is sequentially arranged along a sixth radial direction R6 of mandrel 1, and each seventh block bars 12 are along a seventh radial direction R7 of mandrel 1. Moreover, the sixth radial direction R6 is arranged at a non-zero clip angle with the aforementioned second radial direction R2 and the fourth radial direction R4 respectively, and the seventh radial direction R7 is arranged at a non-zero clip angle with the third radial direction R3, the first radial direction R1 and the fifth radial direction R5 respectively.
After adopting the above design, at least part of the hot fluid outlet 4b of each hot fluid flow channels 4 is arranged - on the above sixth radial direction R6 for convenient description, and the centralized arrangement area becomes the sixth region. Moreover, at the location of the sixth region, the cold fluid inlet 5a of each cold fluid flow channels 5 is blocked by the sixth block bars 11. Therefore, in practical application, a large hot fluid draw out hole can be provided in the aforementioned sixth region to draw out the heat fluid without incorporating cold fluid.
At least part of the cold fluid outlet 5b of each cold fluid flow channels 5 is arranged - on the above seventh radial direction R7 for convenient description, and the centralized arrangement area becomes the seventh area. Moreover, in the seventh area, the hot fluid inlet 4a of each hot fluid flow channels 4 is blocked by the seventh block bars 12. Therefore, in practical application, a large cold fluid draw out hole can be provided in the aforementioned seventh region to concentrate the heat-exchanged cold fluid from the place without incorporating the hot fluid.
Similarly, if in practical application, all the hot and cold fluids only lead from the sixth and seventh regions respectively, then it is best to improve the area of the sixth and seventh regions, otherwise, the outflow area of the hot fluid is small, which is not conducive to the improvement of heat transfer efficiency. However, due to the influence of various factors, the area of the sixth and seventh areas usually cannot be set very large. In this case, the outflow area of the cold and hot fluid can be increased by increasing the number of the areas in the sets of cold and hot fluid, thus improving the heat transfer efficiency.
In Figs. 6 and 7, each above cold fluid inlets 5a also have an eighth block bars 13 to blocking part of the cold fluid inlet. Each eighth block bars 13 are sequentially arranged along an eighth radial direction R8 of the mandrel 1, and the eighth radial direction R8 is arranged at a non-zero clip angle with the aforementioned sixth radial direction R6, the second radial direction R2 and the fourth radial direction R4. Each hot fluid inlets 4a also have ninth block bars 14 for partially blocking the hot fluid inlet, each ninth block bars14 are sequentially arranged along the ninth radial direction R9 of the mandrel 1, and the ninth radial direction R9 is arranged at a non-zero clip angle with the aforementioned seventh radial direction R7, the third radial direction R3, the first radial direction R1 and the fifth radial direction R5.
It is not difficult to understand that after adopting the scheme of Figs. 6 and 7, the heat exchanger has at least two cold fluid outlet areas on the left and two hot fluid outlet areas on the right, which increases the number of outlet areas of cold and hot fluid, and then improves the heat transfer efficiency.
Of course, we can also adopt the setting scheme shown in Figs. 3 and 4 for more amounts of cold and fluid collection regions. In the first embodiment shown in Figs. 3 and 4, each cold fluid inlets 5a are also provided with tenth block bars15 to partially block it, Each tenth block bars 15 are sequentially arranged along a tenth radial direction R10 of the mandrel1, and the tenth radial direction R10 is arranged at a non-zero clip angle with the aforementioned eighth radial direction R8, the sixth radial direction R6, the fourth radial direction R4 and the second radial direction R2. Thus, three staggered hot fluid regions are formed on the right side of the heat exchanger, and two staggered cold fluid regions are formed on the left side of the heat exchanger.
In the first embodiment shown in Figs. 3 and 4, in the first radial direction R1, the sixth radial direction R6, the third radial direction R3, the eighth radial direction R8, the fifth radial direction R5, between two pairs, are arranged at a non-zero clip angle, and the second radial direction R2, the seventh radial direction R7, the fourth radial direction R4, the ninth radial direction R9, the tenth radial direction R10, between two pairs, are arranged at a non-zero clip angle. Thus, this can lift flow stroke of the cold and hot fluid in this heat exchanger, then improve the heat transfer efficiency.
As mentioned above, in addition to increasing the numbers of cold and hot fluid, and the inflow and outflow area of hot fluid, and then improving the heat transfer efficiency, the heat transfer efficiency of the heat exchanger may also be increased by increasing the area of the first, the second, the sixth and the seventh regions the second area, the sixth heat region and the seventh heat exchanger regions, such as the embodiment shown in Figs. 8 and 9.
In Figs. 8 and 9, the area of each cold fluid outlets 5b out of the seventh radial direction R7 is completely blocked by the first block bars 6 to obtain a sufficiently large hot fluid influx area. All regions of each hot fluid outlets 4b out of the sixth radial direction R6 were blocked by the second block bars 7 to obtain a sufficiently large cold fluid sink area. All regions of each cold fluid inlets 5a outside the second radial direction R2 were blocked by the sixth block bars 11 to obtain a sufficiently large hot fluid set region. All regions of each hot fluid inlets 4a out of the first radial directionr1 were blocked by the seventh block bars 12 to obtain a sufficiently large cold fluid set region.
In the first embodiment shown in Figs. 3 and 4, the above various blocks, in other words, all of the first block bars 6, the second block bars 7, the third block bars 8, the fourth block bars 9, the fifth block bars 10, the sixth block bars 11, the seventh block bars 12, the eighth block bars 13, the ninth block bars 14 and the tenth block bars 17 are arc block bars. Moreover, in the radial direction of mandrel 1, the length of each first block bars 6 increases sequentially, the lengths of each second block bars 7 increase sequentially, the lengths of each third block bars 8 increase sequentially, and the lengths of each fourth block bars 8 increase sequentially. In turn, each first block bars 6 have a scalloped distribution, each second block bars 7 show a scalloped distribution, each third block bars 8 show a scalloped distribution, each fourth block bars 9 show a scalloped distribution, each fifth block bars 10 show a scalloped distribution, each sixth block bars 11 show a scalloped distribution, each seventh block bars 12 show a scalloped distribution, each eighth block bars13 show a scalloped distribution, each ninth block bars16 show a scalloped distribution, each tenth block bars17 show a scalloped distribution. By the above fan-shaped distribution, the inlet and the outlet of each cold and hot fluid flow channels are arranged in the corresponding multiple fan areas, which is conducive to the concentrated introduction of the cold and hot fluids.
In the first embodiment shown in Figs. 3 and 4, mentioned above baffle ribs 3 and each block bars all of the first block bars 6, the second block bars 7, the third block bars 8, the fourth block bars 9, the fifth block bars 10, the sixth block bars 11, the seventh block bars 12, the eighth block bars 13, the ninth block bars 14, the tenth block bars 17 are adhesive adhered with the heat conduction thin tape 2. When manufacturing, with the mandrel1 as the support center, coil the heat conduction thin tape 2 around the periphery of the mandrel 1, and during the winding of the heat conduction thin tape 2, with a certain interval in the length of the left and right sides of the heat conduction thin tape 2, coating an adhesive on the left and right of the heat conduction thin tape for forming first block bars and second block bars on the corresponding position with a certain length, in the process of the winding the heat conduction thin tape, meanwhile, coating an adhesive on a surface of the heat conduction thin tape for forming the baffle ribs at a certain interval. After the winding is completed, part of the adhesive can be removed to form the inlet and outlet for the cold and hot fluid.
It is not difficult to understand that the above barriers can not only block the inlet and outlet of the flow channels, so that the inlet and outlet of each cold fluid flow channels and hot fluid flow channels are concentrated in different positions, but also support the heat conduction thin tape 2 of different circles, so that the heat conduction thin tape 2 of each circle can form the flow channels at a certain distance.
Because there is only a block structure on the left and the right side of the heat conduction thin tape 2 in the width direction, the support strength of the block for different circles layer heat conduction thin tape 2 is limited. If the width of the heat conduction thin tape 2 is large, the heat conduction thin tape 2 of adjacent circles layer will easily be close to each other, leading to the blockage of the fluid flow channel. Based on this, in the present embodiment, a plurality of supports 2a are configured to support between any adjacent two layers of the heat conduction thin tape 2, and supports the heat conduction thin tape 2 of the adjacent layer, so as to ensure the structural stability of the cold and hot fluid flow channels.
In the first embodiment shown in Figs. 3 and 4, the above heat conduction thin tape 2 is a metal thin strip, and the support platform 2a is a stamping bump formed to stamp on the metal thin strip. When manufacturing, the stamping bump can be made as the support platform 2a on the heat conduction thin tape 2 in advance, and then wrap the heat conduction thin tape 2 with the stamping bump on the outside of the mandrel 1. In the process of winding heat conduction thin tape 2, multiple intervals of stamping bumps can be flushed on the section to be rolled in heat conduction thin tape 2. That is, punching the stamping bumps at one side and winding heat conduction thin tape 2 at the same time.
In the first embodiment shown in Figs. 3 and 4, each stamping bump is formed on the outer side - of heat conduction thin tape 2, i.e., the side departing from mandrel 1.
Of course, it is also possible to set the stamping bumps on both the inner and outer sides of the heat conduction thin tape 2.
In another embodiment of the present invention application, the above support platform 2a may be a welded bump. The shapes of the stamping bulges and bulges can be hemispherical or cylindrical.
In the first embodiment shown in Figs. 3 and 4, the above heat conduction thin tape 2 is an aluminum foil with a thickness of less than one mm. The distance between the adjacent circle layers of the heat conduction thin tape 2 is 2~10mm, that is, the thicknesses of the hot fluid flow channels 4 and the cold fluid flow channels 5 in the radial direction of the mandrel 1 are 2~10mm. The thin heat conduction thin tape and the thin fluid flow channel improve the heat transfer area and heat transfer efficiency of the hot and hot fluid.
When the thermal fluid flow in hot fluid flow channels, in the radial direction of the mandrel, the thermal fluid at the contact position with heat conduction thin tape is lower than the thermal fluid not in contact with heat conduction thin tape, and the heat of the hot fluid not in contact with heat conduction thin tape cannot be effectively released; stamping bulge is located in the path of the hot fluid flow, hot fluid (and cold fluid) in the position of stamping bulge will produce turbulence, making the hot flow in the flow process in the radial direction mixing, thus increasing the hot fluid temperature at the contact position with heat conduction thin tape up, increasing the temperature difference with the other side of heat conduction thin tape cold fluid, accelerating the heat exchange, and then improving the heat exchange rate. At the same time, the stamping bulge increases the contact area between heat conduction thin tape and the fluid, so that the hot and cold fluids on both sides of the heat conduction thin tape can exchange heat better, and thus improves the heat exchange rate.
In this embodiment, the heat conduction thin tape 2 is coiled around the periphery of mandrel 1 in a spiral shape, that is, the heat conduction thin tape 2 is a circular spiral shape, which is easier to manufacture. In some other embodiments of the present invention application, the heat conduction thin tape 2 is of a non-circular helical shape, or the heat conduction thin tape 2 may also be coiled around the periphery of mandrel 1 in a non-circular helix. Generally speaking, the aforementioned non-circular spiral is preferably an oval spiral. The heat exchanger of this shape is flat, more beautiful, and can be arranged in a flat space to make full use of the flat space to maximize the heat transfer performance of the heat exchanger.
In the first embodiment shown in Figs. 3 and 4, a left end cover 16 and a right end cover 17 are provided to set on the mandrel 1. The left end cover 16 and the right end cover 17 are fixed with the mandrel 1 by bolt and nut, and the left end cover 16 is disposed against the left side of the heat conduction thin tape 2 and the right end cover 17 against the right side of the heat conduction thin tape 2. Two hot fluid concentration lead holes 16a are provided in the left end cover 16, and two hot fluid concentration lead holes 17a are provided in the right end cover 17.
Since each first block bars 6 are arranged in close proximity to each fifth block bars 10 in the present embodiment, there is only a very narrow baffle ribs 3 between them. Therefore, the first one of the two hot fluid concentration introduction holes 16a is simultaneously arranged at the position of each of the first block bars 6 and the fifth block bars 10. The second thermal fluid concentration introduction hole 16a from the first thermal fluid concentration may flow simultaneously to each hot fluid inlets 4a in a first radial direction R1 and a fifth radial direction R5. The second thermal fluid concentration introduction hole 16a is arranged only at the third block bars 8, and the thermal fluid from the second thermal fluid concentration introducing hole 16a flows only to the hot fluid inlet 4a in the third radial direction R3.
The first one of the two hot fluid concentration holes 17a is arranged at the position of each sixth block bars 11, and the thermal fluid from each hot fluid outlets 4b at a position in the sixth radial direction R6 is derived from the first hot fluid concentration hole 17a. The second hot fluid concentration hole 17a is arranged at the position of the eighth block bars 13 and the hot fluid emerging from each hot fluid outlets 4b at a position in the eighth radial direction R6 is derived from the second hot fluid concentration hole 17a.
Of course, we can also open the cold fluid concentration drawing hole at a position of the seventh block bars 12 and the cold fluid concentration drawing hole at a position of each seventh block bars 12 in the second block bars 2, respectively, to make the cold fluid introduce and draw from right to left along the axis of the mandrel 1, but this design is not adopted in this embodiment. As shown in Figs. 16 and 17, the left end cover 16 of this embodiment includes two cold fluid collecting tray 16b from the right end facing the left recess, respectively, and the cold fluid lead joint 16 c communicating with the two cold fluid flow sinks 16b. The right end cover 17 of this embodiment includes two cold fluid buffer grooves 17b facing from the left end of the right end cover, and a cold fluid introduction joint 17 c communicating with the two cold fluid buffer grooves 17b. One of the cold fluid buffer grooves 17b is located at both second block bars 7 and tenth block bars15, and the other at fourth block bars 9.
In practical application, the cold fluid inlet joint 17c and the cold fluid outlet joint 16c can be connected to the supply end and return end of the external cold fluid circulation unit (usually circulating water), respectively, to the axial side of the coil and the heat conduction thin tape 2, prompting the air (hot fluid) to flow in each hot fluid flow channels. The cold fluid flows from the cold fluid inlet joint 17c into the cold fluid collecting tray 16b, from the cold fluid flow channel 16b into the cold fluid inlets 5a of each cold fluid flow channels 5, after heat exchange in cold fluid flow channels 5 with the thermal fluid (air) in hot fluid flow channels, from each cold fluid outlets 5b into the cold fluid sink groove 16b, then flows from the cold fluid collecting tray 16b to the cold fluid outlet joint 16c, return to the external cold fluid circulation unit.
The mandrel 1 of this embodiment is a hollow tube, in which a cold or hot fluid can be fed into the central through hole to enhance the heat transfer capacity of the heat exchanger.
For ease of illustration, the spiral winding section in this embodiment is approximately circular, but in practice, a heat conduction thin tape of an oval or a rectangle with rounded corners is also included in the claimed range.
In order to fully heat exchange between cold fluid and hot fluid, the axial length can be increased by series or parallel with multiple sets of heat exchanger, so as to increase the heat transfer time and make the heat transfer between cold fluid and hot fluid more sufficient.
What are described above is related to the illustrative embodiments of the disclosure only and not limitative to the scope of the disclosure; the scopes of the disclosure are defined by the accompanying claims.

Claims

A spiral heat exchanger, characterized in that, comprising:
a mandrel (1) having an axis extending in left- right direction, and

a heat conduction thin tape (2) having a spiral shape wound around the periphery of the mandrel for at least three circles;

any adjacent circles of the heat conduction thin tape (2) are separated by a certain distance, and baffle ribs (3) extending in left-right direction are configured to support between any adjacent two circles of the heat conduction thin tape, each of the baffle ribs (3) is sequentially arranged along a radial direction of the mandrel (1), thereby forming a plurality of hot fluid flow channels (4) and a plurality of cold fluid flow channels (5) arranged alternately along the radial direction of the mandrel (1), each of the hot fluid flow channels (4) has a hot fluid inlet (4a) located at its left end and a hot fluid outlet (4b) located at its right end, each of the cold fluid flow channels (5) has a cold fluid outlet (5b) located at its left end and a cold fluid inlet (5a) located at its right end;

first block bars (6) are disposed at each of the cold fluid outlet (5b) for partially blocking thereof, second block bars (7) are disposed at each of the hot fluid outlet (4b) for partially blocking thereof, each of the first block bars (6) is sequentially arranged along a first radial direction (R1) of the mandrel (1), each of the second block bars (7) is sequentially arranged along a second radial direction (R2) of the mandrel (1).
The spiral heat exchanger according to claim 1, characterized in that, third block bars (8) are disposed at each cold fluid outlet (5b) for partially blocking thereof, each of the third block bars (8) is sequentially arranged along a third radial direction (R3) of the mandrel (1), the third radial direction (R3) and the first radial direction (R1) are arranged at a non-zero clip angle.
The spiral heat exchanger according to claim 2, characterized in that, fourth block bars (9) are disposed at each of the hot fluid outlets (4b) for partially blocking thereof, each of the fourth block bars (9) is sequentially arranged along a fourth radial direction (R4) of the mandrel (1), the fourth radial direction (R4) and the second radial direction (R2) are arranged at a non-zero clip angle.
The spiral heat exchanger according to claim 3, characterized in that, fifth block bars (10) are disposed at each of the cold fluid outlets (5b) for partially blocking thereof, each of the fifth block bars (10) is sequentially arranged along a fifth radial direction (R5) of the mandrel (1), the fifth radial direction (R5) is arranged at a non-zero clip angle with the first radial direction (R1) and the third radial direction (R3), respectively.
The spiral heat exchanger according to claim 4, characterized in that, sixth block bars (11) are disposed at each of the cold fluid inlet (5a) for partially blocking thereof, seventh block bars (12) are disposed at each of the hot fluid inlets (4a) for partially blocking thereof, each of the sixth block bars (11) is sequentially arranged along a sixth radial direction (R6) of the mandrel (1), each of the seventh block bars (12) is sequentially arranged along a seventh radial direction (R7) of the mandrel (1), the sixth radial direction (R6) is arranged at a non-zero clip angle with the second radial direction (R2) and the fourth radial direction (4), respectively, the seventh radial direction (R7) is arranged at a non-zero clip angle with the third radial direction (R3), the first radial direction (R1) and the fifth radial direction (R5), respectively.
The spiral heat exchanger according to claim 5, characterized in that, eighth block bars (13) are disposed at each of the cold fluid inlets (5a) for partially blocking thereof, ninth block bars (14) are disposed at each of the hot fluid inlets (4a) for partially blocking thereof, each of the eighth block bars (13) is sequentially arranged along a eighth radial direction (R8) of the mandrel (1), each of the ninth block bars (14) is sequentially arranged along a ninth radial direction (R9) of the mandrel (1), the eighth radial direction (R8) is arranged with the sixth radial direction (R6), the second radial direction (R2) and the fourth radial direction (4), respectively, the ninth radial direction (R9) is arranged at a non-zero clip angle with the seventh radial direction (R7), the third radial direction (R3), the first radial direction (R1) and the fifth radial direction (R5), respectively.
The spiral heat exchanger according to claim 6, characterized in that, tenth block bars (15) are disposed at each of the hot fluid outlets (4b) for partially blocking thereof, each of the tenth block bars (15) is sequentially arranged along a tenth radial direction (R10) of the mandrel (1), the tenth radial direction (R10) is arranged at a non-zero clip angle with the eighth radial direction (R8), the sixth radial direction (R6), the fourth radial direction (R4) and the second radial direction (R2).
The spiral heat exchanger according to claim 5, characterized in that,
the sixth radial direction (R6) and the first radial direction (R1) are arranged at a non-zero clip angle, the seventh radial direction (R7) and the second radial direction (R2) are arranged at a non-zero clip angle;
a region of each cold fluid outlets (5b) out of the seventh radial direction (R7) is fully blocked by the first block bars (6), a region of each hot fluid outlets (4b) out of the sixth radial direction (R6) is fully blocked by the second block bars (7);

a region of each cold fluid inlets (5a) out of the second radial direction (R2) is fully blocked by the sixth block bars (11), a region of each hot fluid inlets (4a) out of the first radial direction (R1) is fully blocked by the seventh block bars (12).
The spiral heat exchanger according to claim 1, characterized in that,
both the first block bars (6) and the second block bars (7) are an arc block bars;

in a radial direction of the mandrel (1) from inside to outside, the length of each of the first block bars (6) increases sequentially, the length of each of the second block bars (7) increases sequentially, and so that the first block bars (6) are fan-distributed, the second block bars (7) are fan-distributed.
The spiral heat exchanger according to claim 5, characterized in that,
both the sixth block bars (11) and the seventh block bars (12) are an arc block bar;

in a radial direction of the mandrel (1) from inside to outside, the length of the sixth block bars (11) increases sequentially, the length of the seventh block bars (12) increases sequentially, and so that the sixth block bars (11) are fan-distributed, the seventh block bars (12) are fan-distributed.
A manufacturing method for the spiral heat exchanger as claimed in any of claims 1 to 10, characterized in that, comprising:
winding a heat conduction thin tape (2) around the periphery of a mandrel (1) to have a spiral shape; coating an adhesive on the left and right of the heat conduction thin tape (2) for forming first block bars (6) and second block bars (7) on the corresponding position with a certain length at a certain interval, in the process of the winding the heat conduction thin tape (2); meanwhile, coating an adhesive on a surface of the heat conduction thin tape (2) for forming the baffle ribs (3) at a certain interval.
A spiral heat exchanger, characterized in that, comprising:
a mandrel (1) having an axis extending in left-right direction, and

a heat conduction thin tape (2) having a spiral shape wound around the periphery of the mandrel for at least three circles;

any adjacent two circles of the heat conduction thin tape (2) are separated by a certain distance, and baffle ribs (3) extending in left-right direction are configured to support between any adjacent two circles of the heat conduction thin tape, each of the baffle ribs (3) is sequentially arranged along a radial direction of the mandrel (1), thereby forming a plurality of hot fluid flow channels (4) and a plurality of cold fluid flow channels (5) arranged alternately along a radial direction of the mandrel (1), each of the hot fluid flow channels (4) has a hot fluid inlet (4a) located on its left end and a hot fluid outlet (4b) located on its right end, each of the cold fluid flow channels (5) has a cold fluid outlet (5b) located on its left end and a cold fluid inlet (5a) located on its right end;

a sixth block bars (11) are disposed at each of the cold fluid inlets (5a) for partially blocking thereof, a seventh block bars (12) is disposed at each of the hot fluid inlets (4a) for partially blocking thereof, each of the sixth block bars (11) is sequentially arranged along a sixth radial direction (R6) of the mandrel (1), each of the seventh block bars (12) is sequentially arranged along a seventh radial direction (R7) of the mandrel (1).
The spiral heat exchanger according to claim 12, characterized in that, eighth block bars (13) are disposed at each of the cold fluid inlets (5a) for partially blocking thereof, ninth block bars (14) are disposed at each of the hot fluid inlets (4a) for partially blocking thereof, each of the eighth block bars (13) is sequentially arranged along an eighth radial direction (R8) of the mandrel (1), each of the ninth block bars (14) is sequentially arranged along a ninth radial direction (R9) of the mandrel (1), the eighth radial direction (R8) and the sixth radial direction (R6) are arranged at a non-zero clip angle, the ninth radial direction (R9) and the seventh radial direction (R7) are arranged at a non-zero clip angle.
The spiral heat exchanger according to claim 12, characterized in that,
both the sixth block bars (11) and the seventh block bars (12) are arc block bars;

in a radial direction of the mandrel (1) from inside to outside, the length of each of the sixth block bars (11) increases sequentially, the length of each of the seventh block bars (12) increases sequentially, and so that the sixth block bars (11) are fan-distributed, the seventh block bars (12) are fan-distributed.
The spiral heat exchanger according to claim 14, characterized in that, each of the sixth block bars (11) has a radian≥180°, each of the seventh block bars (12) has a redian≥180°.