C-shaped parallel pipe design method based on non-uniform heat flux density

Abstract

The invention belongs to the field of application of tower type solar heat absorber parallel pipes, and particularly relates to a design method of C-shaped parallel pipes based on non-uniform heat flux density, which comprises the following steps: collecting the average heat flux density of the heated side of the outer wall of each pipe; collecting the mass flow of each pipe and the heat absorption capacity of the outer wall of the pipe; the ratio of the heat absorption capacity of each pipe to the heat absorption capacity of the standard pipe is obtained; the ratio is subjected to arithmetic square root opening to obtain a new ratio; calculating a preliminary ideal value of the inner diameter of each pipe; providing a flow coefficient correction coefficient based on the initial mass flow distribution of each pipe; a final ideal inner diameter is obtained by combining a flow correction coefficient; and combining the calculated ideal inner diameter with the eccentric pipe to form a novel parallel pipe structure. The heat-flow matching principle is used as guidance, the core is that flow distribution of the parallel pipes is changed through reducing, so that the redistributed flow is matched with the non-uniform heat flow density outside the pipes, the temperature of fluid at an outlet is uniform, and the advantage that the temperature of the outer walls of the pipes can be greatly reduced is combined with the eccentric pipes.

Description

Technical Field

[0001] The invention belongs to the application field of tower solar thermal absorber parallel pipes, and in particular relates to a design method of C-type parallel pipes based on non-uniform heat flux density. Background Art

[0002] Carbon dioxide is widely present in nature and the raw materials are easily available. It has the characteristics of being pollution-free and having stable chemical properties. CO2 has a low critical point parameter (7.38MPa, 35°C). When heated and pressurized to a supercritical state as a heat transfer fluid, it has the advantages of good fluidity, high heat transfer efficiency, and low compression power. These characteristics make supercritical carbon dioxide (S-CO2) suitable for thermal cycles and are expected to be used in nuclear power generation, solar power generation, and coal-fired power generation. Solar power generation is mainly divided into solar thermal power generation and photovoltaic power generation. The tower solar power generation technology combined with the S-CO2 Brayton cycle is one of the most promising methods for the third generation of concentrated solar thermal power generation (CSP).

[0003] Tower solar thermal absorbers are mainly divided into two types: external type and cavity type. The cavity type absorber has a compact structure and relatively small heat loss, but it is usually under highly non-uniform solar energy flow, which leads to local overheating of the outer wall of the absorber tube, large temperature gradient, and uneven outlet temperature of each tube, which brings huge hidden dangers to the safe operation of the system. The absorber is composed of a series of parallel tubes composed of branch pipes. The parallel tube flow layout is mainly divided into C type, I type, Z type and N type. The C type flow layout is characterized by more uniform flow distribution than other layouts, so it is widely used. However, under the traditional structure, there are still problems of overheating and thermal deviation of outlet fluid temperature. At present, the solution to the above problems is mainly to enhance the heat transfer capacity of the fluid. There are relatively few research results on the design and optimization of parallel tube structures, and there are no relevant patents and papers. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention proposes a design method for C-type parallel tubes under non-uniform heat flux density, which can reduce the maximum temperature of the outer wall of the parallel tubes of the tower solar absorber and make the outlet fluid temperature uniform under highly non-uniform heat flux density, thereby improving the safety of the absorber operation.

[0005] In order to achieve the above effects, the technical solution adopted by the present invention is as follows:

[0006] A design method for C-type parallel pipes under non-uniform heat flux density includes the following steps:

[0007] Step (1): collecting the average heat flux density on the heated side of the outer wall of each tube;

[0008] Step (2): collecting the mass flow rate of each tube and the heat absorbed by the outer wall of the tube;

[0009] Step (3): obtaining the ratio of the heat absorption of each tube to the heat absorption of the standard tube;

[0010] Step (4): Take the square root of the ratio to obtain a new ratio;

[0011] Step (5): Calculate the initial ideal value of the inner diameter of each tube;

[0012] Step (6): Propose a flow coefficient correction factor based on the initial mass flow distribution of each tube;

[0013] Step (7): combining the flow correction coefficient to obtain the final ideal inner diameter;

[0014] Step (8): Combine the calculated ideal inner diameter with the eccentric tube to form a new parallel tube structure.

[0015] Furthermore, in step (1), a parallel tube group includes ten branch tubes and two main tubes. The absorber includes multiple parallel tube groups, and the average heat flux density of the outer wall of each branch tube in a parallel tube group is for the sunny side of the 10 branch tubes, where each branch tube only collects the heat flux density average of half of the outer wall area of ​​the tube, and the other half is the insulation side; the heat flux density symbol is denoted by q wo , unit is kW / m 2 .

[0016] Furthermore, in step (2), the heat absorbed by the outer wall of each branch pipe is the product of the average heat flux density of the branch pipe and the surface area of ​​one side of the branch pipe, symbolized by Q n (n=1,2,3,......,10), unit is kW, Q n =A·q wo,n (n=1,2,3,......,10), A is half of the outer wall area of ​​a tube; the mass flow distribution is the mass flow of the total mass flow of the main tube inlet in the parallel tube group flowing into each branch after being divided, recorded as G m,n (n=1,2,3,........,10), unit is kg / s.

[0017] Furthermore, in step (3), let α1:α2:.....:α 10 =Q1:Q2:......:Q 10 , because the heat absorption of each tube is centrally symmetrically distributed, the standard tube is selected as No. 3 or No. 8 tube, and α 3,8 =1, Among them, α1 to α 10 It is a variable ratio with no specific meaning.

[0018] Furthermore, in step (4), the new ratio is denoted as β n(n=1,2,3,......,10), since the mass flow rate is proportional to the square of the radius, let α n It is the relative ratio of the heat absorbed by the outer wall of each branch pipe Q1 to Qn, where n is 1 to 10, representing the sequence number of each branch pipe. The ratio ranges from greater than 0 to less than 2.

[0019] Furthermore, in step (5), the initial inner diameter of each branch pipe is denoted as D i,n (n=1,2,3,......,10), the initial ideal value of the inner diameter is D i,n ﹡ (n=1,2,3,......,10),D i,n ﹡ =D i,n ×β n .

[0020] Furthermore, in step (6), since the U-shaped parallel pipe has the problem of uneven mass flow distribution, it is necessary to adjust D i,n ﹡ After correction, the average mass flow rate of each tube is obtained from step (3): The flow correction factor is

[0021] Furthermore, in step (7), the final ideal inner diameters of the 10 branch pipes are d i,n (n=1,2,3,......,10),

[0022] Furthermore, in step (8), based on the traditional structure, the inner and outer diameters of the branch pipe are kept unchanged, and the eccentricity E is changed. c , forming an eccentric structure. On the basis of the eccentric tube, the new inner diameters of the 10 branch pipes calculated by the diameter reduction scheme in step (7) are used to maintain the eccentricity E c unchanged, according to the formula The size of the eccentricity e is calculated, and a new parallel pipe structure is constructed according to the calculated new eccentricity and new inner diameter.

[0023] The advantages of this application are:

[0024] 1. This application provides a design method based on C-type parallel pipes under non-uniform heat flux density, which can improve the safety of heat absorber operation. Under non-uniform heat flux density, the heat gradient and thermal deviation of the heat absorber are large, the flow distribution is not uniform, and problems such as large heat loss and over-temperature pipe burst are prone to occur, which brings a series of hidden dangers to the safe operation of the heat absorber. If the parallel pipes of the core components of the heat absorber can be structurally optimized, the safety of operation can be improved.

[0025] 2. This application is guided by the "heat-flow" matching principle. The core lies in changing the flow distribution of the parallel pipes by changing the diameter, so that the redistributed flow matches the non-uniform heat flux density outside the pipe, thereby achieving uniform outlet fluid temperature. Secondly, the eccentric pipe can greatly reduce the temperature of the outer wall of the pipe. The new structure has the advantages of both.

[0026] 3. The new parallel pipe structure can reduce heat loss and reduce the heat transfer temperature difference when the fluid converges. The reduction of the circumferential and axial temperature difference of the parallel branch pipes can reduce the thermal stress of the metal pipe wall, and also has a certain preventive effect on metal fatigue, fracture, creep and other problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention provides a flow chart for the new structural design of C-type parallel pipes.

[0028] Figure 2 This is a typical C-type parallel tube structure diagram.

[0029] Figure 3 It is a schematic diagram comparing the traditional structure and the new structure of the parallel pipe branch cross section of the present invention.

[0030] Figure 4 It is a schematic diagram of the cross section of parallel pipe branches under the new structure. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] In the description of the present application, it should be noted that the terms "upper", "vertical", "inner", "outer", etc. indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the product of the application is usually placed when in use, or the orientation or position relationship commonly understood by those skilled in the art. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0036] Example 1

[0037] like Figure 1 As shown, a design method for C-type parallel pipes under non-uniform heat flux density includes the following steps:

[0038] Step (1): collecting the average heat flux density on the heated side of the outer wall of each tube;

[0039] Step (2): collecting the mass flow rate of each tube and the heat absorbed by the outer wall of the tube;

[0040] Step (3): obtaining the ratio of the heat absorption of each tube to the heat absorption of the standard tube;

[0041] Step (4): Take the square root of the ratio to obtain a new ratio;

[0042] Step (5): Calculate the initial ideal value of the inner diameter of each tube;

[0043] Step (6): Propose a flow coefficient correction factor based on the initial mass flow distribution of each tube;

[0044] Step (7): combining the flow correction coefficient to obtain the final ideal inner diameter;

[0045] Step (8): Combine the calculated ideal inner diameter with the eccentric tube to form a new parallel tube structure.

[0046] The present application provides a design method based on C-type parallel pipes under non-uniform heat flux density, which can improve the safety of heat absorber operation. Under non-uniform heat flux density, the heat absorber has large thermal gradient and thermal deviation, and the flow distribution is not uniform, which is prone to large heat loss, over-temperature pipe burst and other problems, which bring a series of hidden dangers to the safe operation of the heat absorber. If the parallel pipes of the core components of the heat absorber can be structurally optimized, the safety of operation can be improved. The present application is guided by the "heat-flow" matching principle. The core is to change the flow distribution of the parallel pipes by changing the diameter, so that the redistributed flow matches the non-uniform heat flux density outside the pipe, and the outlet fluid temperature is uniform. Secondly, the eccentric pipe can greatly reduce the temperature of the outer wall of the pipe. The new structure has the advantages of both. The new structure of the parallel pipe can reduce heat loss and reduce the heat transfer temperature difference when the fluid converges. The reduction of the circumferential and axial temperature differences of the parallel branches can reduce the thermal stress of the metal pipe wall, and also has a certain preventive effect on metal fatigue, fracture, creep and other problems.

[0047] Example 2

[0048] like Figure 1 As shown, a design method for C-type parallel pipes under non-uniform heat flux density includes the following steps:

[0049] Step (1): collecting the average heat flux density on the heated side of the outer wall of each tube;

[0050] Step (2): collecting the mass flow rate of each tube and the heat absorbed by the outer wall of the tube;

[0051] Step (3): obtaining the ratio of the heat absorption of each tube to the heat absorption of the standard tube;

[0052] Step (4): Take the square root of the ratio to obtain a new ratio;

[0053] Step (5): Calculate the initial ideal value of the inner diameter of each tube;

[0054] Step (6): Propose a flow coefficient correction factor based on the initial mass flow distribution of each tube;

[0055] Step (7): combining the flow correction coefficient to obtain the final ideal inner diameter;

[0056] Step (8): Combine the calculated ideal inner diameter with the eccentric tube to form a new parallel tube structure.

[0057] In step (1), a parallel tube group includes ten branch tubes and two main tubes. The two main tubes include a shunt main tube and a converging main tube. The shunt main tube is located below each branch tube. After the heat-absorbing fluid enters the shunt main tube, it is shunted to each branch tube and finally converges into the converging main tube above. The main tube plays the role of "support", "shunt" and "convergence". The heat absorber includes multiple parallel tube groups. The average heat flux density of the outer wall of each branch tube (numbered 1, 2, 3, ..., 10 from left to right) in a parallel tube group is for the sunny side of the 10 branch tubes, where each branch tube only collects the heat flux density average of half of the outer wall area, and the other half is the adiabatic side; the heat flux density symbol is denoted by q wo , unit is kW / m 2 .

[0058] In step (2), the heat absorbed by the outer wall of each branch pipe is the product of the average heat flux density of the branch pipe and the surface area of ​​one side of the branch pipe, symbolized by Q n (n=1,2,3,......,10), unit is kW, Q n =A·q wo,n (n=1,2,3,......,10), A is half of the outer wall area of ​​a tube; the mass flow distribution is the mass flow of the total mass flow of the main tube inlet in the parallel tube group flowing into each branch after being divided, recorded as G m,n (n=1,2,3,........,10), unit is kg / s.

[0059] In step (3), let α1:α2:...:α 10 =Q1:Q2:......:Q 10 , because the heat absorption of each tube is centrally symmetrically distributed, the standard tube is selected as No. 3 or No. 8 tube, and α 3,8 =1, Among them, α1 to α 10 It is a variable ratio with no specific meaning.

[0060] In step (4), the new ratio is denoted as β n (n=1,2,3,......,10), since the mass flow rate is proportional to the square of the radius, let α n It is the relative ratio of the heat absorbed by the outer wall of each branch pipe from Q1 to Qn, where n is 1 to 10, representing the serial number of each branch pipe. The ratio ranges from greater than 0 to less than 2. It has no specific meaning and is just a variable ratio.

[0061] In step (5), the initial inner diameter of each branch is denoted as D i,n (n=1,2,3,......,10), the initial ideal value of the inner diameter is D i,n﹡ (n=1,2,3,......,10),D i,n ﹡ =D i,n ×β n .

[0062] In step (6), because the U-shaped parallel pipe has the problem of uneven mass flow distribution, it is necessary to adjust D i,n ﹡ After correction, the average mass flow rate of each tube is obtained from step (3): The flow correction factor is

[0063] In step (7), the final ideal inner diameters of the 10 branch pipes are d i,n (n=1,2,3,......,10),

[0064]

[0065] In step (8), if Figure 3 As shown, based on the traditional structure, the inner and outer diameters of the branch pipe are kept unchanged and the eccentricity E is changed. c , forming an eccentric structure. On the basis of the eccentric tube, the new inner diameters of the 10 branch pipes calculated by the diameter reduction scheme in step (7) are used to maintain the eccentricity E c unchanged, according to the formula The size of the eccentricity e is calculated, and a new parallel pipe structure is constructed according to the calculated new eccentricity and new inner diameter.

[0066] Example 3

[0067] The present invention provides a design method for C-type parallel pipes under non-uniform heat flux density, comprising the following steps:

[0068] Step (1): collecting the average heat flux density on the heated side of the outer wall of each tube;

[0069] Step (2): collecting the mass flow rate of each tube and the heat absorbed by the outer wall of the tube;

[0070] Step (3): obtaining the ratio of the heat absorption of each tube to the heat absorption of the standard tube;

[0071] Step (4): Take the square root of the ratio to obtain a new ratio;

[0072] Step (5): Calculate the initial ideal value of the inner diameter of each tube;

[0073] Step (6): Propose a flow coefficient correction factor based on the initial mass flow distribution of each tube;

[0074] Step (7): combining the flow correction coefficient to obtain the final ideal inner diameter;

[0075] Step (8): Combine the calculated ideal inner diameter with the eccentric tube to form a new parallel tube structure.

[0076] The present invention provides a design method for C-type parallel tubes under non-uniform heat flux density, which can reduce the maximum temperature of the outer wall of the parallel tubes of a tower solar thermal absorber under highly non-uniform heat flux density and make the outlet fluid temperature uniform, thereby improving the safety of the operation of the absorber.

[0077] In step (1), the average heat flux density of the outer wall of each tube is the sun-facing side of the 10 branch tubes, where each branch tube only collects the average heat flux density of half of the outer wall area of ​​the tube, and the other half is the insulation side. The heat flux density symbol is denoted by q wo , unit is kW / m 2 .

[0078] The 10 branch pipes have the same structure and the heating area of ​​each pipe is the same, so the average heat flux density is only related to the external heat flux radiation conditions. wo The value range is 100~500kW / m 2 .

[0079] In step (2), the heat absorbed by the outer wall of each branch pipe is the product of the average heat flux density of the branch pipe and the surface area of ​​one side of the branch pipe, symbolized by Q n (n=1,2,3,......,10), unit is kW, Q n =A·q wo,n (n=1,2,3,......,10), A is half of the outer wall area of ​​a tube. The mass flow distribution is the mass flow of the total mass flow of the main tube inlet flowing into each branch after the flow is divided, recorded as G m,n (n=1,2,3,........,10), unit is kg / s. G m,n The value range is 3~7kg / s.

[0080] In step (3), let α1:α2:...:α 10 =Q1:Q2:......:Q 10 , because the heat absorption of each tube is centrally symmetrically distributed, the standard tube is selected as No. 3 or No. 8 tube, and α 3,8 =1,

[0081] In step (4), the new ratio is denoted as β n (n=1,2,3,......,10), since the mass flow rate is proportional to the square of the radius, let

[0082] In step (6), because the C-type parallel pipe has the problem of uneven mass flow distribution, it is necessary to i,n ﹡ After correction, the average mass flow rate of each tube is obtained from step (3): The flow correction factor is

[0083] In step (7), the final ideal inner diameters of the 10 branch pipes are d i,n (n=1,2,3,......,10),

[0084]

[0085] In step (8), based on the traditional structure, the ideal values ​​of the inner diameters of the 10 branch pipes given in step (7) are applied, and then combined with the eccentric structure to form a new parallel pipe structure. The eccentricity of the eccentric pipe is expressed by E c express, Where R is the outer radius, r is the inner radius, and e is the eccentricity, i.e., the distance between the inner and outer centers. R is a fixed constant, and r is d calculated in step (7). i Half of E. c The value range of is 0.1~0.4. After the eccentricity is determined, the eccentricity can be calculated by combining the difference of (Rr). Finally, the new variable diameter structure of the 10 branch pipes is obtained.

[0086] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0087] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0088] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0089] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0090] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A design method for C-type parallel pipes under non-uniform heat flux density, characterized in that: The steps include: Step (1): collecting the average heat flux density on the heated side of the outer wall of each tube; Step (2): collecting the mass flow rate of each tube and the heat absorbed by the outer wall of the tube; Step (3): obtaining the ratio of the heat absorption of each tube to the heat absorption of the standard tube; Step (4): Take the square root of the ratio to obtain a new ratio; Step (5): Calculate the initial ideal value of the inner diameter of each tube; Step (6): Propose a flow coefficient correction factor based on the initial mass flow distribution of each tube; Step (7): combining the flow correction coefficient to obtain the final ideal inner diameter; Step (8): Combine the calculated ideal inner diameter with the eccentric tube to form a new parallel tube structure.

2. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 1, characterized in that: In the step (1), a parallel tube group includes ten branch tubes and two main tubes, and the heat absorber includes multiple parallel tube groups. The average heat flux density of the outer wall of each branch tube in a parallel tube group is for the sunny side of the 10 branch tubes, wherein each branch tube only collects the heat flux density average of half of the outer wall area of ​​the tube, and the other half is the insulation side; the heat flux density symbol is denoted by q wo , unit is kW / m 2 .

3. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 2 is characterized in that: In step (2), the amount of heat absorbed by the outer wall of each branch pipe is the product of the average heat flux density of the branch pipe and the surface area of ​​one side of the branch pipe, symbolized by Q n (n=1,2,3,......,10), unit is kW, Q n =A·q wo,n (n=1,2,3,......,10), A is half of the outer wall area of ​​a tube; The mass flow distribution is the mass flow of the total mass flow of the main pipe inlet in the parallel pipe group flowing into each branch pipe after being divided, which is recorded as G m,n (n=1,2,3,........,10), unit is kg / s.

4. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 3 is characterized in that: In step (3), let α1:α2:...:α 10 =Q1:Q2:......:Q 10 , because the heat absorption of each tube is centrally symmetrically distributed, the standard tube is selected as No. 3 or No. 8 tube, and α 3,8 =1, Among them, α1 to α 10 It is a variable ratio with no specific meaning.

5. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 4 is characterized in that: In step (4), the new ratio is denoted as β n (n=1,2,3,......,10), since the mass flow rate is proportional to the square of the radius, let α n It is the relative ratio of the heat absorbed by the outer wall of each branch pipe Q1 to Qn, where n is 1 to 10, representing the sequence number of each branch pipe. The ratio ranges from greater than 0 to less than 2.

6. The design method of C-type parallel pipes under non-uniform heat flux according to claim 5, characterized in that: In step (5), the initial inner diameter of each branch pipe is denoted as D i,n (n=1,2,3,......,10), the initial ideal value of the inner diameter is D i,n ﹡ (n=1,2,3,......,10),D i,n ﹡ =D i,n ×β n .

7. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 6, characterized in that: In the step (6), D i,n ﹡ After correction, the average mass flow rate of each tube is obtained from step (3): The flow correction factor is 8. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 7, characterized in that: In step (7), the final ideal inner diameters of the 10 branch pipes are d i,n (n=1,2,3,......,10), 9. The design method of C-type parallel pipes based on non-uniform heat flux according to claim 8, characterized in that: In step (8), the inner and outer diameters of the branch pipe are kept unchanged, and the eccentricity E is changed. c , forming an eccentric structure. On the basis of the eccentric tube, the new inner diameters of the 10 branch pipes calculated by the diameter reduction scheme in step (7) are used to maintain the eccentricity E c unchanged, according to the formula The size of the eccentricity e is calculated, and a new parallel pipe structure is constructed according to the calculated new eccentricity and new inner diameter.

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