A design method for tower solar collector

Abstract

The present invention discloses a design method for a tower solar collector, which divides each tube panel of the collector into blocks, and at the same time comprehensively considers convective heat transfer to establish a partitioned thermal physical model of the absorber tube panel, and obtains the heat balance equation of each block; it adopts iteration and parallel calculation to solve the accurate solution that meets the actual working conditions, which is used to optimize the thermal efficiency value of the collector. The algorithm adopted by the present invention achieves a balance between accuracy and computational efficiency in a large-scale system. During the design and operation of the collector, a wide range of energy flow distribution can be processed, and the overall trend of heat transfer and the global temperature field distribution of the absorber as a whole can be quickly obtained, which significantly improves the calculation speed and efficiency, and solves the problem that the efficiency and accuracy of the traditional algorithm cannot be taken into account in the calculation. It provides a new solution for the design of complex solar thermal systems.

Description

Technical Field

[0001] The invention belongs to the technical field of solar thermal utilization, and in particular relates to a design method for a tower type solar thermal collector. Background Art

[0002] The collector is the most important equipment in the tower solar thermal utilization system. It absorbs the energy of sunlight focused on its surface and efficiently converts it into heat energy, realizing the function of light-heat coupling, and transfers the heat energy to subsequent energy storage devices or generators through heat transfer media (such as molten salt, air or water vapor).

[0003] As the core equipment of the CSP system, the collector has harsh working conditions and is subjected to extremely high working temperatures and complex stress environments. In addition, since the solar collector must be frequently started and stopped during operation, it is easily damaged under high temperatures and alternating stresses. In addition, its investment cost is high and the temperature and pressure control requirements are strict. Once a failure occurs, the power generation efficiency of the entire power station will be greatly reduced or even shut down. Therefore, the design calculation of the collector has a decisive influence on the overall performance and economy of the CSP station.

[0004] Traditional collector design calculation methods ignore many key factors such as uneven energy flow distribution, cosine loss and circumferential temperature differences, resulting in increased calculation errors and difficulty in meeting the design requirements of modern high-efficiency solar thermal power generation systems. In addition, traditional methods also have obvious limitations when dealing with complex geometric shapes, dynamic working conditions and accurate heat loss distribution, and thus perform poorly in optimizing the design of large collectors, predicting local temperature distribution and evaluating the safety of key parts. It is difficult to meet the precise design and operation requirements of large solar thermal systems. Therefore, more advanced algorithms are urgently needed to make up for these defects in actual engineering applications.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a design method for a tower solar collector. Through an efficient and accurate design calculation method, the design process of the collector is optimized, the design thermal efficiency of the collector is improved, and the long-term safe and reliable operation of the equipment is ensured.

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

[0008] In a first aspect, the present invention provides a design method for a tower solar thermal collector, the design method comprising:

[0009] The collector tube panels are divided into blocks, and the convective heat transfer is comprehensively considered to establish a partitioned thermal physical model of the absorber tube panel to obtain the heat balance equation of each block;

[0010] Iterative and parallel calculation methods are used to obtain an accurate solution that meets the actual working conditions and is used to optimize the thermal efficiency of the collector.

[0011] Furthermore, the heat balance equation for each block is as follows,

[0012] q i -q fluid,i =q rad,sky,i +q rad,ground,i +q conv,i ;

[0013] in,

[0014] q i ——The solar radiation energy received by the surface of the i-th block;

[0015] q fluid,i ——Heat absorbed by the flow of working medium;

[0016] q rad,sky,i ——Radiation loss to the sky from the ith block;

[0017] q rad,ground,i ——Radiation loss from the ith block to the earth;

[0018] q conv,i ——Convective heat transfer loss of the ith block.

[0019] Furthermore, the solar radiation energy received by the surface of the i-th block is calculated using the following formula:

[0020] q i =G i ·A i α;

[0021] in,

[0022] G i ——The solar radiation energy flux density incident on the i-th block;

[0023] A i ——the surface area of ​​the ith block;

[0024] α – thermal diffusion coefficient of air.

[0025] Furthermore, the heat absorbed by the working medium flow is calculated using the following formula,

[0026]

[0027] in,

[0028] U i ——The comprehensive heat transfer coefficient of the ith block;

[0029] T s,i ——Surface temperature of the ith block;

[0030] T in,i ——the inlet temperature of the working medium of the ith block;

[0031] T out,i ——The outlet temperature of the working medium of the ith block;

[0032] The heat absorbed by the working medium flow can also be calculated using the following formula:

[0033]

[0034] in,

[0035] ——Mass flow rate of medium flowing through the block;

[0036] c p ——Specific heat capacity of the working medium.

[0037] The following equilibrium equation is obtained:

[0038]

[0039] The equilibrium equation is solved by iteration for each block in the heat absorption screen. The initial medium outlet temperature is Substitute into the equilibrium equation to calculate the new medium outlet temperature

[0040]

[0041] The new outlet temperature is calculated And the new outlet temperature As the initial medium outlet temperature, iterative calculation is performed until and The difference is less than 10 -4 , the iteration ends, and the new medium temperature As the medium inlet temperature of the next block in the medium flow direction, and repeat the calculation until the surface temperature and medium inlet and outlet temperatures of all blocks are determined;

[0042] Solve the heat balance equation for each block and accumulate the total heat dissipation loss of the collector and the medium outlet temperature.

[0043] Furthermore, the radiation loss of the ith block to the sky is calculated using the following formula:

[0044]

[0045] in,

[0046] ε——emissivity of collector surface;

[0047] σ——Sterfan-Boltzmann constant;

[0048] A i ——The area of ​​the ith block;

[0049] T s,i ——Surface temperature of the ith block;

[0050] T sky ——effective radiation temperature of the sky;

[0051] cosθ sky,i ——The cosine angle factor between the surface normal of the ith block and the direction to the sky;

[0052] The effective radiation temperature of the sky is calculated using the following formula,

[0053]

[0054] in,

[0055] T amb - ambient temperature;

[0056] e——Atmospheric water vapor pressure.

[0057] Furthermore, the radiation loss of the ith block to the earth is calculated using the following formula:

[0058]

[0059] in,

[0060] T ground ——Effective radiation temperature of the earth;

[0061] cos θ ground,i ——The cosine angle factor between the surface normal of the ith block and the earth. Furthermore, the comprehensive heat transfer coefficient U of the heat absorption screen is calculated using the following formula:

[0062]

[0063] in,

[0064] h salt ——Heat transfer coefficient of working medium side in the tube;

[0065] h ext ——Heat transfer coefficient outside the collector;

[0066] R f ——fouling thermal resistance;

[0067] A in——Inner surface area of ​​heat absorption tube;

[0068] A out ——Surface area of ​​heat absorption tube;

[0069] d w ——The wall thickness of the heat absorption tube;

[0070] D m ——Equivalent diameter of heat absorption tube;

[0071] L——length of heat absorption tube;

[0072] k w ——Thermal conductivity of heat absorption tube.

[0073] Furthermore, the heat transfer coefficient of the outer side of the collector is calculated using the following formula:

[0074]

[0075] in,

[0076] G r ——The ratio of buoyancy to viscosity;

[0077] T eff - effective radiation temperature of the environment;

[0078] C, n - constants related to flow characteristics and geometry;

[0079] v – kinematic viscosity of air;

[0080] α——thermal diffusion coefficient of air;

[0081] K air ——thermal conductivity of air;

[0082] The heat transfer coefficient on the working medium side of the tube is calculated using the following formula:

[0083]

[0084] in,

[0085] Re——Reynolds number, used to judge the flow state of the fluid;

[0086] Pr is the Prandtl number, which represents the ratio of momentum diffusivity to thermal diffusivity.

[0087] k salt ——thermal conductivity of the medium;

[0088] d o ——Inner diameter of heat absorption tube.

[0089] Furthermore, the design method also includes:

[0090] Calculate and obtain the inner wall temperature and the inner film temperature of the heat absorption tube;

[0091] Conduct risk point analysis based on calculation results to optimize the layout design of the mirror field and guide the safe operation of the collector;

[0092] The inner wall temperature of the heat absorbing tube is calculated using the following formula:

[0093]

[0094] The inner film temperature of the heat absorbing tube is calculated using the following formula:

[0095]

[0096] in,

[0097] h salt,i ——heat transfer coefficient on the medium side;

[0098] T fluid,i ——Average temperature of the medium in the pipe.

[0099] After adopting the above technical solution, the design method of the tower solar collector provided by the present invention has the following beneficial effects compared with the prior art:

[0100] 1. The algorithm used in this invention achieves a balance between accuracy and computational efficiency in large-scale systems. During the design and operation of the collector, it can process a wide range of energy flow distribution, quickly obtain the overall trend of heat transfer and the global temperature field distribution of the absorber, significantly improve the calculation speed and efficiency, and solve the problem that traditional algorithms cannot balance efficiency and accuracy in calculations. It provides a new solution for the design of complex solar thermal systems.

[0101] 2. The present invention proposes a method for the "light-heat" coupling design and calculation of the heat absorber. This method improves the design accuracy of the core equipment heat absorber by constructing a thermodynamic model and establishing a mathematical model partition block for iterative solution. The design method has been verified by engineering and has high accuracy.

[0102] 3. The present invention effectively improves the conversion efficiency of the collector. The method can accurately calculate the radiation loss and convection loss of the collector tube, thereby optimizing the design efficiency of the absorber. The thermodynamic calculation results of the optimized collector are used to guide the optimization layout of the mirror field, which reduces the investment in power station equipment and improves the light-to-heat conversion efficiency of the entire plant.

[0103] 4. The present invention can provide a basis for the structural optimization of the heat absorber. The design method can clearly identify the high film temperature area and high stress concentration area of ​​the collector, avoiding possible thermal runaway or material damage, thereby providing a data basis for the structural optimization of the heat absorber.

[0104] 5. The present invention can provide reliable support for the safe operation of the power station. Through this method, the high-temperature state of the collector in operation can be predicted, thereby providing effective support and basis for the long-term safe operation of the absorber, and can effectively avoid the risk of pipe blockage and pipe explosion, thereby improving the safety of the operation of the solar thermal power station. DETAILED DESCRIPTION

[0105] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0106] [Example 1]

[0107] This embodiment provides a design method for a tower solar collector, divides each tube panel of the collector into blocks, and establishes a partitioned thermal physical model of the heat absorption tube panel by comprehensively considering convective heat transfer, obtains the heat balance equation of each block, and uses iterative and parallel calculation methods to solve the precise solution that meets the actual working conditions, so as to optimize the thermal efficiency value of the collector.

[0108] Further, the design method comprises the following steps:

[0109] 1. Calculation of the total flow of the working medium flowing through the collector and the medium flow in the absorber tube. The flow through the collector can be calculated based on the power plant output and the working medium inlet and outlet parameters; then, based on the total amount flowing through the collector and the number of absorber tubes, the medium flow in the absorber tube can be calculated by analyzing the collector's pipeline layout and fluid mechanics characteristics.

[0110] 2. Analyze and process the theoretical energy flux density distribution diagram of the entire collector surface obtained by using ray tracing numerical simulation technology, divide the energy incident on the collector surface after reflection from the mirror field into modules and process the data to obtain the input energy of each module.

[0111] 3. Each tube panel of the collector is divided into blocks according to the height direction and the circumferential direction, and a zoned thermal physical model of the heat absorbing tube panel is established.

[0112] 4. Based on the cosine relationship between the normal direction of each block of the collector tube panel and the radiation angle of the earth and the sky, and taking into account the convective heat transfer, the heat dissipation model of the collector tube panel is established.

[0113] 5. Calculation of the heat transfer coefficient of the medium in the collector. Determine the overall heat transfer coefficient of the medium in the collector based on the flow analysis of the medium in the tube.

[0114] 6. Establish mathematical models of the collector as a whole and each block of the heat absorption screen, use iterative and parallel calculation methods to solve the accurate solution that meets the actual working conditions, and optimize the thermal efficiency value of the collector.

[0115] Specifically, the heat balance equation for each block is as follows:

[0116] q i -q fluid，i =q rad，sky，i +q rad,ground，i +q conv，i ;

[0117] in,

[0118] q i ——The solar radiation energy received by the surface of the i-th block;

[0119] q fluid，i ——Heat absorbed by the flow of working medium;

[0120] q rad，sky，i ——Radiation loss to the sky from the ith block;

[0121] q rad，ground，i ——Radiation loss from the ith block to the earth;

[0122] q conv，i ——Convective heat transfer loss of the ith block.

[0123] Furthermore, the solar radiation energy received by the surface of the i-th block is calculated using the following formula:

[0124] q i =G i ·A i α;

[0125] in,

[0126] G i ——The solar radiation energy flux density incident on the i-th block (W / m 2 );

[0127] A i ——the surface area of ​​the ith block;

[0128] α – thermal diffusion coefficient of air.

[0129] Furthermore, the heat absorbed by the working medium flow is calculated using the following formula,

[0130]

[0131] in,

[0132] U i ——The comprehensive heat transfer coefficient of the ith block;

[0133] T s,i ——Surface temperature of the ith block;

[0134] T in,i ——the inlet temperature of the working medium of the ith block;

[0135] T out,i ——The outlet temperature of the working medium in the i-th block.

[0136] Furthermore, the heat absorbed by the working medium flow can also be calculated using the following formula:

[0137]

[0138] in,

[0139] ——Mass flow rate of medium flowing through the block (kg / s);

[0140] c p ——Specific heat capacity of the working medium.

[0141] The following equilibrium equation is obtained:

[0142]

[0143] Furthermore, the equilibrium equations are solved by iterative method for each block in the heat absorption screen, assuming that the initial medium outlet temperature is Substitute the working medium energy balance equation into the calculation, and the new medium outlet temperature after updating is as follows

[0144]

[0145] Calculate the new outlet temperature if and The difference is less than 10 -4 , then the iteration ends and the new medium temperature The medium inlet temperature of the next block in the medium flow direction is taken as the medium inlet temperature, and the calculation is repeated until the surface temperature and medium inlet and outlet temperatures of all blocks are determined. The heat balance equation of each block is solved by numerical method, and the total heat dissipation loss of the collector and the medium outlet temperature are accumulated.

[0146] Furthermore, the angle between the surface normal of each block on the side of the collector and the radiation direction is θ sky , the radiation loss of the ith block to the sky is calculated using the following formula,

[0147]

[0148] in,

[0149] ε——emissivity of collector surface;

[0150] σ——Sterfan-Boltzmann constant;

[0151] A i ——The area of ​​the ith block;

[0152] T s,i ——Surface temperature of the ith block;

[0153] T sky ——effective radiation temperature of the sky;

[0154] cosθ sky,i ——The cosine angle factor between the surface normal of the ith block and the direction to the sky.

[0155] Furthermore, the effective radiation temperature of the sky is calculated using the following formula,

[0156]

[0157] in,

[0158] T amb - ambient temperature;

[0159] e——Atmospheric water vapor pressure (Pa).

[0160] Furthermore, the angle between the surface normal of each block on the side of the collector and the radiation direction is θ ground , the radiation loss of the ith block to the earth is calculated using the following formula:

[0161]

[0162] in,

[0163] T ground ——Effective radiation temperature of the earth;

[0164] cosθ ground,i ——The cosine angle factor between the surface normal of the ith block and the earth.

[0165] Furthermore, the cosine angle factor between the block surface normal of the block and the earth can be calculated using the following formula:

[0166]

[0167] in,

[0168] R——collector radius;

[0169] H——total height of the collector;

[0170] h i ——The height of the ith block.

[0171] Furthermore, the comprehensive heat transfer coefficient U of the heat absorption screen is calculated using the following formula:

[0172]

[0173] in,

[0174] h salt ——Heat transfer coefficient of working medium side in the tube;

[0175] h ext ——Heat transfer coefficient outside the collector;

[0176] R f ——fouling thermal resistance;

[0177] A in ——Inner surface area of ​​heat absorption tube;

[0178] A out ——Surface area of ​​heat absorption tube;

[0179] d w ——The wall thickness of the heat absorption tube (m);

[0180] D m ——Equivalent diameter of heat absorption tube;

[0181] L——length of heat absorption tube;

[0182] k w ——Thermal conductivity of heat absorption tube (W / mK).

[0183] Furthermore, the heat transfer coefficient of the outer side of the collector is calculated using the following formula:

[0184]

[0185] in,

[0186] G r ——The ratio of buoyancy to viscosity;

[0187] T eff ——effective radiation temperature of the environment (K);

[0188] C, n - constants related to flow characteristics and geometry;

[0189] ν——kinematic viscosity of air;

[0190] α——thermal diffusion coefficient of air;

[0191] K air ——Thermal conductivity of air.

[0192] Furthermore, the heat transfer coefficient of the working medium side in the tube is calculated using the following formula:

[0193]

[0194] in,

[0195] Re——Reynolds number, used to judge the flow state of the fluid;

[0196] Pr is the Prandtl number, which represents the ratio of momentum diffusivity to thermal diffusivity.

[0197] k salt ——thermal conductivity of the medium;

[0198] d o ——Inner diameter of heat absorption tube.

[0199] [Example 2]

[0200] This embodiment provides a design method for a tower solar thermal collector. Based on the above embodiment, the design method further includes:

[0201] Calculate and obtain the inner wall temperature and the inner film temperature of the heat absorption tube;

[0202] Danger point analysis is performed based on the calculation results to optimize the layout design of the mirror field and guide the safe operation of the collector.

[0203] The inner wall temperature of the heat absorbing tube is calculated using the following formula:

[0204]

[0205] The inner film temperature of the heat absorbing tube is calculated using the following formula:

[0206]

[0207] in,

[0208] h salt,i ——heat transfer coefficient on the medium side;

[0209] T fluid,i ——Average temperature of the medium in the pipe.

[0210] In a preferred embodiment, a first threshold and a second threshold are set for the inner wall temperature of the heat absorber tube and the inner film temperature of the heat absorber tube, respectively. The area where the inner wall temperature of the heat absorber tube exceeds the first threshold or the inner film temperature of the heat absorber tube exceeds the second threshold is a high film temperature area and a high stress concentration area of ​​the collector. Special high temperature resistant materials or special structures can be used to design the above areas to avoid thermal runaway or material damage. At the same time, the high temperature state prediction of the collector in operation can also be realized, thereby providing effective support and basis for the long-term safe operation of the heat absorber.

[0211] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0212] The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes by using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation scheme in the above embodiment can also be further combined or replaced. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of the solution of the present invention.

[0213] It should be noted that the embodiments of the present invention can be implemented by hardware, software, or a combination of software and hardware. The hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated design hardware. It can be understood by a person of ordinary skill in the art that the above-mentioned devices and methods can be implemented using computer executable instructions and / or contained in a processor control code, such as a carrier medium such as a disk, CD or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. Such code is provided on the carrier medium. The device and its modules of the present invention can be implemented by hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips, transistors, etc., or programmable hardware devices such as field programmable gate arrays, programmable logic devices, etc., can also be implemented by software executed by various types of processors, and can also be implemented by a combination of the above-mentioned hardware circuits and software, such as firmware.

Claims

1. A design method for a tower solar collector, characterized in that: The design method comprises: Each tube panel of the collector is divided into blocks, and a partitioned thermal physical model of the absorber tube panel is established by convective heat transfer to obtain the heat balance equation of each block; Iterative and parallel calculation methods are used to obtain accurate solutions that meet actual working conditions and are used to optimize the thermal efficiency of the collector; The heat balance equation for each block is as follows, q i -q fluid，i =q rad,sky，i +q rad,ground,i +q conv，i ; in, q i ——The solar radiation energy received by the surface of the i-th block; q fluid,i ——Heat absorbed by the flow of working medium; q rad,sky,i ——Radiation loss to the sky from the ith block; q rad，ground,i ——Radiation loss from the ith block to the earth; q conv，i ——Convection heat loss of the ith block; The heat absorbed by the working medium flow is calculated using the following formula: in, U i ——The comprehensive heat transfer coefficient of the ith block; T s，i ——Surface temperature of the ith block; T in，i ——the inlet temperature of the working medium of the ith block; T out,i ——The outlet temperature of the working medium of the ith block; The heat absorbed by the working medium flow can also be calculated using the following formula: in, ——Mass flow rate of medium flowing through the block; c p ——Specific heat capacity of the working medium; The following equilibrium equation is obtained: The equilibrium equation is solved by iteration for each block in the heat absorption screen. The initial medium outlet temperature is Substitute into the equilibrium equation to calculate the new medium outlet temperature The new outlet temperature is calculated And the new outlet temperature As the initial medium outlet temperature, iterative calculation is performed until and The difference is less than 10 -4 , the iteration ends, and the new medium temperature As the medium inlet temperature of the next block in the medium flow direction, and repeat the calculation until the surface temperature and medium inlet and outlet temperatures of all blocks are determined; Solve the heat balance equation for each block and accumulate the total heat dissipation loss of the collector and the medium outlet temperature.

2. The design method of a tower solar collector according to claim 1, characterized in that: The solar radiation energy received by the surface of the i-th block is calculated using the following formula: q i =G i ·A i ·a; in, G i ——The solar radiation energy flux density incident on the i-th block; A i ——the surface area of ​​the ith block; α – thermal diffusion coefficient of air.

3. The design method of a tower solar collector according to claim 1, characterized in that: The radiation loss of the ith block to the sky is calculated using the following formula: in, ε——emissivity of collector surface; σ——Sterfan-Boltzmann constant; A i ——The area of ​​the ith block; T s，i ——Surface temperature of the ith block; T sky ——effective radiation temperature of the sky; cosθ sky，i ——The cosine angle factor between the surface normal of the ith block and the direction to the sky; The effective radiation temperature of the sky is calculated using the following formula, in, T amb - ambient temperature; e——Atmospheric water vapor pressure.

4. The design method of a tower solar collector according to claim 1, characterized in that: The radiation loss from the i-th block to the earth is calculated using the following formula: in, T ground ——Effective radiation temperature of the earth; cosθ ground，i ——The cosine angle factor between the surface normal of the ith block and the earth.

5. The design method of a tower solar collector according to claim 1, characterized in that: The comprehensive heat transfer coefficient U of the heat absorption screen is calculated using the following formula: in, h salt ——Heat transfer coefficient of working medium side in the tube; h ext ——Heat transfer coefficient outside the collector; R f ——fouling thermal resistance; A in ——Inner surface area of ​​heat absorption tube; A out ——Surface area of ​​heat absorption tube; d w ——The wall thickness of the heat absorption tube; D m ——Equivalent diameter of heat absorption tube; L——length of heat absorption tube; k w ——Thermal conductivity of heat absorption tube.

6. The design method of a tower solar thermal collector according to claim 5, characterized in that: The heat transfer coefficient of the outer side of the collector is calculated using the following formula: in, G r ——The ratio of buoyancy to viscosity; T eff - effective radiation temperature of the environment; C, n - constants related to flow characteristics and geometry; v – kinematic viscosity of air; α——thermal diffusion coefficient of air; K air ——thermal conductivity of air; The heat transfer coefficient on the working medium side of the tube is calculated using the following formula: in, Re——Reynolds number, used to judge the flow state of the fluid; Pr is the Prandtl number, which represents the ratio of momentum diffusivity to thermal diffusivity. k salt ——thermal conductivity of the medium; d o ——Inner diameter of heat absorption tube.

7. The design method of a tower solar collector according to any one of claims 1 to 6, characterized in that: The design method further comprises: Calculate and obtain the inner wall temperature and the inner film temperature of the heat absorption tube; Conduct risk point analysis based on calculation results to optimize the layout design of the mirror field and guide the safe operation of the collector; The inner wall temperature of the heat absorbing tube is calculated using the following formula: The inner film temperature of the heat absorbing tube is calculated using the following formula: in, h salt，i ——heat transfer coefficient on the medium side; T fluid，i ——Average temperature of the medium in the pipe.

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