CN116202235A

Movatterモバイル変換

Info

Publication number: CN116202235A
Application number: CN202310208648.7A
Authority: CN
Inventors: 王坤; 张翔; 张展鹏; 闵春华; 饶中浩
Original assignee: Hebei University of Technology
Current assignee: Hebei University of Technology
Priority date: 2023-03-07
Filing date: 2023-03-07
Publication date: 2023-06-02

Abstract

The invention discloses a circumferentially arrayed radial bending coiled pipe solar heat absorber, which consists of a plurality of flow loops in a parallel mode; the single flow loop is arc-shaped, and a plurality of flow loops are spliced into a cylindrical heat absorber along the circumferential direction; each flow loop comprises N heat absorption tube rows and N-1 connecting tubes; the heat absorption tube rows are sequentially connected end to end through connecting pipelines to form a serial connection type communication structure; the initial end of the first heat absorption tube row of each flow loop is a flow loop inlet, and the tail end of the last heat absorption tube row is a flow loop outlet; each heat absorbing tube row comprises an upper header, a manifold, a lower header, a serpentine tube, an upper header and a lower header. The serpentine pipe can strengthen the disturbance of fluid, strengthen the turbulence degree of the fluid, destroy a thermal boundary layer, form a larger temperature gradient, and further achieve a more excellent heat exchange effect, thereby improving the average temperature of an outlet of the heat absorption pipe and enhancing the integral heat absorption efficiency of the heat absorber.

Description

Translated fromChinese

一种圆周阵列式径向弯曲蛇形管太阳能吸热器A Circumferential Array Radial Bending Serpentine Tube Solar Heat Absorber

技术领域technical field

本发明属于太阳能热发电领域，具体是一种圆周阵列式径向弯曲蛇形管太阳能吸热器。The invention belongs to the field of solar thermal power generation, in particular to a circular array type radial curved serpentine tube solar heat absorber.

背景技术Background technique

吸热器是太阳能热发电系统中实现光热转换的核心部件，其安全高效运行对于整个太阳能系统的可靠性和经济性是至关重要的。太阳光通过定日镜场聚集到吸热器外侧，形成高密度非均匀的太阳能流。太阳能流经吸热器吸收传递给吸热器内部循环流动的吸热介质，自此完成了光热转换过程。The receiver is the core component of solar thermal power generation system to realize light-to-heat conversion, and its safe and efficient operation is crucial to the reliability and economy of the entire solar system. The sunlight is concentrated to the outside of the heat sink through the heliostat field, forming a high-density non-uniform solar flow. The solar energy flows through the heat absorber to absorb and transfer to the heat absorbing medium circulating inside the heat absorber, and since then the light-to-heat conversion process has been completed.

传统管式太阳能吸热器是应用最为广泛的吸热器形式之一，其以直圆管作为基本换热单元。其工作过程面临着高密度、非均匀的能流环境以及内部流体换热不均匀不充分的问题。以上问题会使造成了吸热管内存在较大温度梯度或温度峰值，这是吸热器发生应力集中或应力失效的主要原因之一。强化吸热管换热，降低吸热器内的温度峰值或温度梯度，是缓解吸热器应力失效的有效手段之一。The traditional tubular solar heat absorber is one of the most widely used forms of heat absorber, which uses a straight circular tube as the basic heat exchange unit. Its working process faces the problems of high density, non-uniform energy flow environment and uneven and insufficient internal fluid heat transfer. The above problems will cause a large temperature gradient or temperature peak in the heat absorber, which is one of the main reasons for the stress concentration or stress failure of the heat absorber. Enhancing the heat transfer of the heat absorber tube and reducing the temperature peak or temperature gradient in the heat absorber is one of the effective means to alleviate the stress failure of the heat absorber.

常见的强化吸热管换热的手段有：添加内部翅片和轧制槽道、改变流道形状等。其中，添加内部翅片和轧制槽道的方式可以使管道内部形成突出，以达到破坏流动边界层并达到强化对流换热效果的目的。但是添加内部翅片或轧制槽道会增大管道的制造难度，且不便于清洗。相比之下，改变流道形状制作难度较小，还可以增加吸热管换热面积、增强流体扰动。常见改变流道形状的方式有螺旋扭转扁管、螺旋盘管以及蛇形管。螺旋扭转扁管虽然增加了换热面积及流体扰动，但相较于传统直圆管结构更加复杂、制造成本更高，并且其仅在高普朗特数和低雷诺数情况下表现出良好的换热性能。专利CN211451416U基于螺旋盘管设计了一种太阳能塔式螺旋吸热器，该吸热器以螺旋盘管作为吸热单元，利用螺旋盘管的曲率作用强化管内工质的换热性能，以达到提高吸热器换热效果的目的。然而，较大的曲率半径对强化流体换热的作用有限，且螺旋盘管结构限制较大，适用于小型吸热器，难以胜任大型吸热器的构建。相对的，蛇形管结构灵活，更能够满足塔式电站对于大型吸热器的需求。The common means of enhancing the heat transfer of the heat absorbing tube are: adding internal fins and rolling channels, changing the shape of the flow channel, etc. Among them, adding internal fins and rolling channels can make the inside of the pipe protrude, so as to achieve the purpose of destroying the flow boundary layer and enhancing the effect of convective heat transfer. But adding internal fins or rolled channels makes the pipe more difficult to manufacture and less convenient to clean. In contrast, changing the shape of the flow channel is less difficult to manufacture, and it can also increase the heat exchange area of the heat absorbing tube and enhance fluid disturbance. Common ways to change the shape of the flow channel are helically twisted flat tubes, spiral coiled tubes, and serpentine tubes. Although the helically twisted flat tube increases the heat transfer area and fluid turbulence, it is more complicated in structure and higher in manufacturing cost than the traditional straight tube, and it only shows good performance in the case of high Prandtl number and low Reynolds number. heat transfer performance. Patent CN211451416U designs a solar tower spiral heat absorber based on the spiral coil. The heat absorber uses the spiral coil as the heat absorption unit, and uses the curvature of the spiral coil to enhance the heat transfer performance of the working fluid in the tube to achieve improved The purpose of the heat exchange effect of the heat sink. However, a large radius of curvature has limited effect on enhancing fluid heat transfer, and the structure of the spiral coil is relatively limited, which is suitable for small heat sinks, but it is difficult to be suitable for the construction of large heat sinks. In contrast, the flexible structure of the serpentine tube can better meet the needs of tower power plants for large heat sinks.

因此，需要设计一种以蛇形管作为基本吸热单元的新型太阳能吸热器，以相对较低的制造要求及相对简单的结构达到强化流体换热的目的。Therefore, it is necessary to design a new type of solar heat absorber with a serpentine tube as the basic heat absorbing unit, so as to achieve the purpose of enhancing fluid heat exchange with a relatively low manufacturing requirement and a relatively simple structure.

发明内容Contents of the invention

针对现有技术的不足，本发明拟解决的技术问题是，提供一种圆周阵列式径向弯曲蛇形管太阳能吸热器。Aiming at the deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a circular array type radial curved serpentine tube solar heat absorber.

本发明解决所述技术问题的技术方案是，提供一种圆周阵列式径向弯曲蛇形管太阳能吸热器，其特征在于，该吸热器由若干个流动回路以并联方式组成；单个流动回路呈圆弧状，将若干个流动回路沿周向拼接成圆柱状吸热器；The technical solution of the present invention to solve the above-mentioned technical problem is to provide a circular array type radially curved serpentine tube solar heat absorber, which is characterized in that the heat absorber is composed of several flow circuits connected in parallel; a single flow circuit In the shape of an arc, several flow circuits are spliced into a cylindrical heat absorber along the circumferential direction;

每个流动回路均包括N个吸热管排和N-1个连接管道；吸热管排之间通过连接管道依次首尾相接，形成串联式连通结构；每个流动回路的第一个吸热管排的始端为流动回路入口，最后一个吸热管排的末端为流动回路出口；Each flow circuit includes N heat-absorbing tube rows and N-1 connecting pipes; the heat-absorbing pipe rows are connected end-to-end through connecting pipes in turn to form a series connection structure; the first heat-absorbing tube of each flow circuit The beginning of the pipe row is the inlet of the flow circuit, and the end of the last heat-absorbing pipe row is the outlet of the flow circuit;

每个吸热管排均包括上端集箱、歧管、下端集箱、蛇形管、上端汇管和下端汇管；Each heat absorbing pipe row includes an upper header, a manifold, a lower header, a serpentine pipe, an upper header and a lower header;

上端集箱的一端设置有上端汇管，另一端通过K条歧管与K条蛇形管的一端连接；K条蛇形管的另一端通过K条歧管与下端集箱的一端连接；下端集箱的另一端设置有下端汇管；上端汇管和下端汇管均与连接管道连通；蛇形管沿吸热器的周向均布于上端集箱和下端集箱之间，形成圆弧状结构；每个蛇形管的波峰和波谷均指向吸热器的旋转轴。One end of the upper header is provided with an upper header, and the other end is connected to one end of K serpentine pipes through K manifolds; the other end of K serpentine pipes is connected to one end of the lower header through K manifolds; the lower end The other end of the header is provided with a lower header; the upper header and the lower header are connected to the connecting pipe; the serpentine pipes are evenly distributed between the upper header and the lower header along the circumferential direction of the heat absorber, forming an arc-shaped structure ; The crests and troughs of each serpentine are directed towards the axis of rotation of the heat sink.

与现有技术相比，本发明有益效果在于：Compared with the prior art, the present invention has the beneficial effects of:

(1)本发明设计了一种全新的圆周阵列布置的沿吸热器径向弯曲的正弦蛇形吸热管(简称蛇形管)作为吸热单元的太阳能管式吸热器。蛇形管中心线是正弦曲线，由于正弦管道中循环存在波峰和波谷两种波形结构，当流体通过蛇形管时会受到波形结构的影响，产生二次流动，进而增强流体的扰动，加强流体湍流程度，破坏热边界层，形成较大的温度梯度，进而达到更加优秀的换热效果，从而提高吸热管出口平均温度，增强吸热器整体的吸热效率。(1) The present invention designs a new type of solar tube heat absorber with sinusoidal serpentine heat absorbing tubes (serpentine tubes for short) bent along the radial direction of the heat absorber arranged in a new circumferential array as the heat absorbing unit. The center line of the serpentine pipe is a sinusoidal curve. Since there are two wave structures in the sinusoidal pipe, wave peaks and troughs, when the fluid passes through the serpentine pipe, it will be affected by the wave structure, resulting in secondary flow, thereby enhancing the disturbance of the fluid and strengthening the flow of the fluid. The degree of turbulence destroys the thermal boundary layer and forms a larger temperature gradient, thereby achieving a better heat transfer effect, thereby increasing the average temperature at the outlet of the heat absorbing tube and enhancing the overall heat absorption efficiency of the heat absorber.

(2)本发明蛇形管的位置不在同一个平面，而是圆周排列，吸热管排串联形成流动回路，流动回路并联组成一个完整的圆柱吸热器结构，对于同一太阳能吸热塔，圆弧形吸热管排结构相较于平面布置可以产生更大的周向换热面积，使较为集中的太阳能流分布更加均匀。(2) The positions of the serpentine tubes of the present invention are not on the same plane, but are arranged in a circle. The heat-absorbing tubes are connected in series to form a flow circuit, and the flow circuits are connected in parallel to form a complete cylindrical heat absorber structure. For the same solar heat absorption tower, the circle Compared with the planar arrangement, the arc-shaped heat-absorbing tube row structure can generate a larger circumferential heat exchange area, so that the concentrated solar energy flow can be distributed more evenly.

(3)本发明的每个蛇形管的波峰和波谷均指向吸热器的旋转轴(即蛇形管中心线与吸热器的旋转轴处于同一竖直面)，这种布置可以使蛇形管吸热器比传统直管吸热器在高度方向产生更大的换热面积。(3) The crests and troughs of each serpentine tube of the present invention are all directed to the rotation axis of the heat absorber (that is, the center line of the serpentine tube is in the same vertical plane as the rotation axis of the heat absorber), and this arrangement can make the snake The shaped tube absorber produces a larger heat exchange area in the height direction than the traditional straight tube absorber.

(4)本发明的吸热器可以根据实际工程工况合理选择结构参数、吸热管排数量、单个吸热管排所包含的蛇形管数量，在尽量强化传热的同时合理的控制整体吸热器的结构，且相较于传统的直管式吸热器，并无显著困难的加工工艺。(4) The heat absorber of the present invention can reasonably select structural parameters, the number of heat-absorbing pipe rows, and the number of serpentine pipes contained in a single heat-absorbing pipe row according to actual engineering conditions, and reasonably control the overall heat transfer while strengthening heat transfer as much as possible. The structure of the heat absorber, and compared with the traditional straight tube heat absorber, there is no significant difficult processing technology.

(5)以本发明吸热器应用于以超临界CO₂为传热工质的换热中，保证了传热工质的流动阻力和压力损失，显著的提升了换热效果。(5) Applying the heat absorber of the present invention to heat exchange using supercritical CO₂ as the heat transfer working medium ensures the flow resistance and pressure loss of the heat transfer working medium, and significantly improves the heat exchange effect.

附图说明Description of drawings

图1为本发明的吸热器的整体结构立体示意图；Fig. 1 is the three-dimensional schematic view of the overall structure of the heat absorber of the present invention;

图2为本发明的吸热管排的主视示意图；Fig. 2 is the schematic front view of the heat absorbing pipe row of the present invention;

图3为本发明的图2中的管排沿D-D方向的断面图；Fig. 3 is the sectional view of the pipe row in Fig. 2 of the present invention along the D-D direction;

图4为本发明的蛇形管的左视示意图；Fig. 4 is the schematic diagram of the left view of the serpentine tube of the present invention;

图5为本发明的图4中的蛇形管沿A-A、B-B和C-C方向的断面图；Fig. 5 is the sectional view of the serpentine pipe in Fig. 4 of the present invention along A-A, B-B and C-C direction;

图6为本发明实施例2的蛇形管和直管在相同边界条件下的出口截面的平均温度随外部热流密度变化的点线图；Fig. 6 is the point-line diagram of the average temperature of the outlet section of the serpentine tube and the straight tube of theembodiment 2 of the present invention under the same boundary conditions as the external heat flux changes;

图7为本发明实施例2的蛇形管和直管在相同边界条件下出口截面的最高温度和最低温度随外部热流密度变化的点线图；Fig. 7 is the dot-line diagram of the highest temperature and the lowest temperature of the outlet section of the serpentine pipe and the straight pipe of theembodiment 2 of the present invention under the same boundary conditions as the external heat flux changes;

图8为本发明实施例2的蛇形管和直管在相同边界条件下出口截面温差随外部热流密度变化的点线图。Fig. 8 is a dot-line diagram of the temperature difference at the outlet section of the serpentine tube and the straight tube of Example 2 of the present invention under the same boundary conditions as a function of the external heat flux.

图中，吸热管排1、连接管道2、流动回路入口3、流动回路出口4；上端集箱11、歧管12、下端集箱13、蛇形管14、上端汇管15、下端汇管16；蛇形管中心线21。In the figure, heat absorbing pipe row 1, connectingpipe 2, flow circuit inlet 3, flow circuit outlet 4;upper header 11,manifold 12,lower header 13,serpentine pipe 14,upper header 15,lower header 16; thecentral line 21 of the serpentine tube.

具体实施方式Detailed ways

下面给出本发明的具体实施例。具体实施例仅用于进一步详细说明本发明，不限制本发明权利要求的保护范围。Specific examples of the present invention are given below. The specific embodiments are only used to further describe the present invention in detail, and do not limit the protection scope of the claims of the present invention.

本发明提供了一种圆周阵列式径向弯曲蛇形管太阳能吸热器(简称吸热器)，其特征在于，该吸热器由若干个流动回路以并联方式组成；单个流动回路呈圆弧状，将若干个流动回路沿周向拼接成圆柱状，形成吸热器；工作时，以吸热器的旋转轴为中心轴进行旋转；The invention provides a circular array type radial curved serpentine tube solar heat absorber (referred to as the heat absorber), which is characterized in that the heat absorber is composed of several flow circuits connected in parallel; a single flow circuit is in the form of a circular arc shape, splicing several flow circuits into a cylindrical shape along the circumferential direction to form a heat absorber; when working, it rotates with the rotation axis of the heat absorber as the central axis;

每个流动回路均包括N个吸热管排1和N-1个连接管道2；吸热管排1之间通过连接管道2依次首尾相接，形成串联式连通结构；每个流动回路的第一个吸热管排1的始端为流动回路入口3，最后一个吸热管排1的末端为流动回路出口4；吸热管排1的数量N根据传热流体出口温度的设计需要确定，本实施例中传热流体的出口温度(即流动回路出口4处的温度)为400～800℃；Each flow circuit includes N heat-absorbing pipe rows 1 and N-1 connectingpipes 2; the heat-absorbing pipe rows 1 are connected end-to-end through connectingpipes 2 to form a series connection structure; the first flow circuit of each flow circuit The beginning of a heat absorption pipe row 1 is the flow circuit inlet 3, and the end of the last heat absorption pipe row 1 is the flow circuit outlet 4; the number N of heat absorption pipe rows 1 is determined according to the design requirements of the outlet temperature of the heat transfer fluid. The outlet temperature of the heat transfer fluid in the embodiment (ie the temperature at the outlet 4 of the flow circuit) is 400-800°C;

每个吸热管排1均包括上端集箱11、歧管12、下端集箱13、蛇形管14、上端汇管15和下端汇管16；Each heat absorbing pipe row 1 includes anupper header 11, amanifold 12, alower header 13, aserpentine pipe 14, anupper header 15 and alower header 16;

上端集箱11的一端设置有上端汇管15，另一端通过K条歧管12与K条蛇形管14的一端连接；K条蛇形管14的另一端通过K条歧管12与下端集箱13的一端连接；下端集箱13的另一端设置有下端汇管16；上端汇管15和下端汇管16均与连接管道2连通，作为传热工质在吸热管排1的出入口；蛇形管14沿吸热器的周向均布于上端集箱11和下端集箱13之间，形成圆弧；每个蛇形管14的波峰和波谷均指向吸热器的旋转轴(即蛇形管中心线21与吸热器的旋转轴处于同一竖直面)，便于减小相邻蛇形管之间的空隙，减小吸热器透光率。One end of theupper header 11 is provided with anupper header 15, and the other end is connected to one end ofK serpentine pipes 14 throughK manifolds 12; the other end ofK serpentine pipes 14 is connected to the lower header throughK manifolds 12 One end of thebox 13 is connected; the other end of thelower header 13 is provided with alower header 16; both theupper header 15 and thelower header 16 are connected with the connectingpipe 2, and serve as the inlet and outlet of the heat-absorbing pipe row 1 for the heat transfer working medium; Theserpentine tubes 14 are evenly distributed between theupper header 11 and thelower header 13 along the circumferential direction of the heat absorber, forming an arc; the crests and troughs of eachserpentine tube 14 point to the rotation axis of the heat absorber (i.e.serpentine Tube centerline 21 is in the same vertical plane as the axis of rotation of the heat absorber), which is convenient for reducing the gap between adjacent serpentine tubes and reducing the light transmittance of the heat absorber.

优选地，每个流动回路的出口温度、吸热管表面最高温度、吸热器最大热应力、蠕变疲劳特性均满足电厂或吸热器的设计工况。Preferably, the outlet temperature of each flow circuit, the maximum surface temperature of the heat absorbing pipe, the maximum thermal stress of the heat absorber, and the creep fatigue characteristics all meet the design conditions of the power plant or the heat absorber.

优选地，每个吸热管排1所包含的蛇形管14的数量相同。Preferably, each heat absorbing tube row 1 contains the same number ofserpentine tubes 14 .

优选地，上端集箱11和下端集箱13用于汇总和分配吸热管排1中的传热工质，即混合同一吸热管排1中的各个蛇形管14汇入的传热工质以及向吸热管排1的各个蛇形管14中分配混合后的传热工质。Preferably, theupper header 11 and thelower header 13 are used to collect and distribute the heat transfer fluid in the heat absorption pipe row 1, that is, to mix the heat transfer fluids that are brought into by eachserpentine tube 14 in the same heat absorption pipe row 1. and distribute the mixed heat transfer working fluid to eachserpentine tube 14 of the heat absorbing tube row 1.

优选地，歧管12为弯曲圆管，相邻歧管12交错排列在上端集箱11或下端集箱13的两侧，便于减少相邻歧管12之间的间距，使歧管12在上端集箱11和下端集箱13上的布置更加紧凑。为了防止蛇形管14在受热膨胀时对上端集箱11和下端集箱13的约束过于集中，使用歧管12作为缓冲段用来缓解蛇形管内的应力。Preferably, themanifold 12 is a curved circular tube, and theadjacent manifolds 12 are staggered on both sides of theupper header 11 or thelower header 13, so as to reduce the distance betweenadjacent manifolds 12, so that themanifold 12 is at the upper end The arrangement on theheader 11 and thelower header 13 is more compact. In order to prevent theserpentine tube 14 from being too concentrated on theupper header 11 and thelower header 13 when heated and expanded, themanifold 12 is used as a buffer section to relieve the stress in the serpentine tube.

优选地，每个吸热管排1均分别沿各自的水平中垂面(即图2中的对称面一)和竖直中垂面(即图2中的对称面二)对称设计，对称结构便于研究一部分结构进而计算出整体的性能，保证吸热管排中管道的参数便于研究和实际控制，并且所有吸热管排1的外形均相同，不需要区分不同位置的吸热管排，降低吸热器的组装难度。Preferably, each heat-absorbing pipe row 1 is symmetrically designed along its respective horizontal mid-vertical plane (ie, symmetry plane 1 in FIG. 2 ) and vertical mid-vertical plane (ie,symmetry plane 2 in FIG. 2 ), and the symmetrical structure It is convenient to study a part of the structure and then calculate the overall performance, to ensure that the parameters of the pipes in the heat-absorbing pipe row are convenient for research and actual control, and all the heat-absorbing pipe rows 1 have the same shape, and there is no need to distinguish the heat-absorbing pipe rows in different positions, reducing the Difficulty in assembling the heat sink.

优选地，两个流动回路之间，两个流动回路入口3相邻(即流动回路入口3与流动回路入口3相邻)，两个流动回路出口4相邻(即流动回路出口4与流动回路出口4相邻)。Preferably, between the two flow circuits, the two flow circuit inlets 3 are adjacent (that is, the flow circuit inlet 3 is adjacent to the flow circuit inlet 3), and the two flow circuit outlets 4 are adjacent (that is, the flow circuit outlet 4 is adjacent to the flow circuit exit 4 adjacent).

优选地，由图4和图5可以看出，沿蛇形管中心线21上任意一点的切线方向做截面(即法向截面)均得到内圆半径为r、外圆半径为R的完全相同的圆环。蛇形管是圆环形截面管道且处处的截面均相同。Preferably, as can be seen from Fig. 4 and Fig. 5, a cross-section (i.e. a normal cross-section) along the tangent direction of any point on thecenterline 21 of the serpentine tube can be obtained with exactly the same inner radius r and outer radius R. ring. The serpentine tube is a circular cross-section pipe and the cross-section is the same everywhere.

优选地，蛇形管中心线21的曲线函数为正弦曲线，正弦曲线周期为T；每根蛇形管14两端之间的直线距离为正弦曲线周期T的偶数倍，便于吸热器加工制造和安装。Preferably, the curve function of thecenterline 21 of the serpentine tube is a sinusoidal curve, and the period of the sinusoidal curve is T; the straight-line distance between the two ends of eachserpentine tube 14 is an even multiple of the period T of the sinusoidal curve, which is convenient for processing and manufacturing the heat sink. and install.

优选地，传热工质采用超临界CO₂。Preferably, the heat transfer working fluid is supercritical CO₂ .

优选地，为了减小吸热器内部的热损失，需要在吸热器的内侧添加有保温隔热层。Preferably, in order to reduce heat loss inside the heat absorber, a thermal insulation layer needs to be added inside the heat absorber.

优选地，在运行过程中，为了避免蛇形管14吸热膨胀后相互接触，蛇形管14之间保留有间距，间距之间填充耐高温导热材料。Preferably, during operation, in order to prevent theserpentine tubes 14 from contacting each other after absorbing heat and expanding, spaces are reserved between theserpentine tubes 14, and the gaps are filled with high-temperature-resistant heat-conducting materials.

本发明的工作原理和工作流程是：Principle of work and work flow of the present invention are:

经过初步处理的传热工质超临界CO₂以一定的质量流量从流动回路入口3进入吸热器，通过流动回路始端的吸热管排1中的上端集箱11和下端集箱13中的一个进行分流后，再进入每个蛇形管14；太阳能以辐射能形式照射在蛇形管14的表面，并转化为热能，之后通过热传导传递给管内的超临界CO₂；超临界CO₂流动至蛇形管14的末端，经由歧管12进入此吸热管排1的上端集箱11和下端集箱13中的另一个进行充分混合，再经由连接管道2进入下一吸热管排1继续吸热，最终从流动回路出口4流出；蛇形管14的弯曲结构会使超临界CO₂在流动过程中湍流程度增强，破坏传热工质的热边界层，进而增大管壁附近传热工质的温度梯度，从而达到更好的换热效果，增强吸热器整体的集热效率。The preliminarily treated heat transfer working medium supercritical_CO2 enters the heat absorber from the inlet 3 of the flow circuit at a certain mass flow rate, and passes through theupper header 11 and thelower header 13 in the heat absorption pipe row 1 at the beginning of the flow loop. After one is divided, it enters eachserpentine tube 14; solar energy irradiates the surface of theserpentine tube 14 in the form of radiation energy, and converts it into heat energy, which is then transferred to the supercritical CO₂ in the tube by heat conduction; the supercritical CO₂ flows To the end of theserpentine pipe 14, the other one of theupper header 11 and thelower header 13 of this heat absorption pipe row 1 is entered through the manifold 12 to fully mix, and then enter the next heat absorption pipe row 1 through the connectingpipe 2 Continue to absorb heat, and finally flow out from the outlet 4 of the flow circuit; the curved structure of the serpentine tube₁₄ will increase the degree of turbulence of the supercritical CO in the flow process, destroy the thermal boundary layer of the heat transfer working medium, and then increase the heat transfer rate near the tube wall. The temperature gradient of the thermal working medium can achieve better heat transfer effect and enhance the overall heat collection efficiency of the heat absorber.

实施例1Example 1

本实施例中，吸热器由2个相同规格的流动回路构成，使得每个流动回路的流动回路入口3和流动回路出口4的距离最远，便于传热工质充分吸收热量转化为传热工质的内能，从而使传热工质达到更高的出口温度；In this embodiment, the heat absorber is composed of two flow circuits of the same specification, so that the distance between the flow circuit inlet 3 and the flow circuit outlet 4 of each flow circuit is the farthest, which is convenient for the heat transfer medium to fully absorb heat and convert it into heat transfer The internal energy of the working fluid, so that the heat transfer working fluid can reach a higher outlet temperature;

每个流动回路均包括12个吸热管排1和11个连接管道2；每个吸热管排1包含32根蛇形管14；蛇形管14的外径为21mm，壁厚为2.7mm，相邻两个蛇形管14之间的最小间距为1mm、最大间距为3.11mm；蛇形管14的两个端面之间的距离为6200mm。蛇形管中心线21的表达式为

x∈[0,6200]，单位：mm。Each flow circuit includes 12 heat-absorbingpipe rows 1 and 11 connectingpipes 2; each heat-absorbing pipe row 1 contains 32serpentine pipes 14; the outer diameter of theserpentine pipes 14 is 21mm, and the wall thickness is 2.7mm , the minimum distance between twoadjacent serpentine tubes 14 is 1 mm, and the maximum distance is 3.11 mm; the distance between the two end surfaces of theserpentine tubes 14 is 6200 mm. The expression of thecenterline 21 of the serpentine tube is

x∈[0,6200], unit: mm.

集箱、汇管和歧管的形状以及尺寸不重要，可自由改变。The shape and size of headers, headers and manifolds are not critical and can be freely changed.

实施例2Example 2

在管径、壁厚、材质、长度及运行工况等其他条件相同的情况下，对比研究了单根直圆管和单根蛇形管的流动换热特性。边界条件为：入口质量流量为0.2kg、入口温度为773.15K、操作压力为20MPa、两端面以及一半外表面均为绝热边界、另外一侧外表面外部热流密度分别为200kW、300kW、400kW、500kW的条件。传热工质采用超临界CO₂。In the case of the same pipe diameter, wall thickness, material, length and operating conditions, the flow and heat transfer characteristics of a single straight circular tube and a single serpentine tube were compared and studied. The boundary conditions are: the inlet mass flow rate is 0.2kg, the inlet temperature is 773.15K, the operating pressure is 20MPa, both ends and half of the outer surface are adiabatic boundaries, and the external heat flux on the other side of the outer surface is 200kW, 300kW, 400kW, 500kW respectively conditions of. The heat transfer working fluid adopts supercritical CO₂ .

具体是：蛇形管14的外径为35mm，壁厚为7.5mm。蛇形管14的两个端面之间的距离为1000mm。蛇形管14的材料为Inconel 625合金。蛇形管中心线21的表达式为

x∈[0,1000]，单位：mm。Specifically: the outer diameter of theserpentine tube 14 is 35mm, and the wall thickness is 7.5mm. The distance between the two end faces of theserpentine tube 14 is 1000mm. The material of theserpentine tube 14 is Inconel 625 alloy. The expression of thecenterline 21 of the serpentine tube is

x∈[0,1000], unit: mm.

直管的外径为35mm，壁厚为7.5mm，直管两个端面之间的距离为1000mm。直管材料为Inconel 625合金。The outer diameter of the straight pipe is 35mm, the wall thickness is 7.5mm, and the distance between the two end faces of the straight pipe is 1000mm. Straight tube material is Inconel 625 alloy.

由图6可以看出，在相同的边界条件下，蛇形管的出口截面平均温度高于直管出口截面平均温度，且随着外部热流密度的增加，蛇形管的出口温度增长速率也高于直管。It can be seen from Figure 6 that under the same boundary conditions, the average temperature of the outlet section of the serpentine tube is higher than that of the straight tube outlet section, and with the increase of the external heat flux, the growth rate of the outlet temperature of the serpentine tube is also high Yu Zhiguan.

从图7可以看出，蛇形管的出口最高温度低于直管出口最高温度，且蛇形管出口最低温度高于直管出口最低温度，这说明蛇形管在增加流体出口温度的同时，还减小了管道中流体温差。It can be seen from Figure 7 that the highest temperature at the outlet of the serpentine tube is lower than the highest temperature at the outlet of the straight tube, and the lowest temperature at the outlet of the serpentine tube is higher than the lowest temperature at the outlet of the straight tube, which shows that the serpentine tube increases the outlet temperature of the fluid while It also reduces the fluid temperature difference in the pipeline.

从图8可以看出，出口截面温差(即最高温度和最低温度之差)的减小有助于降低管道热应力，减少吸热器失效风险。It can be seen from Fig. 8 that the reduction of the outlet cross-section temperature difference (that is, the difference between the highest temperature and the lowest temperature) helps to reduce the thermal stress of the pipeline and reduce the failure risk of the heat sink.

由图6-8可以看出，相同参数的蛇形管和直管，在相同边界条件下蛇形管的换热效果优于直管。It can be seen from Figure 6-8 that the heat transfer effect of the serpentine tube and the straight tube with the same parameters is better than that of the straight tube under the same boundary conditions.

本发明未述及之处适用于现有技术。What is not mentioned in the present invention is applicable to the prior art.

Claims

1. A solar heat absorber with a circumferential array type radial bending coiled pipe is characterized in that the heat absorber is composed of a plurality of flow loops in a parallel connection mode; the single flow loop is arc-shaped, and a plurality of flow loops are spliced into a cylindrical heat absorber along the circumferential direction;

each flow loop comprises N heat absorption tube rows and N-1 connecting tubes; the heat absorption tube rows are sequentially connected end to end through connecting pipelines to form a serial connection type communication structure; the initial end of the first heat absorption tube row of each flow loop is a flow loop inlet, and the tail end of the last heat absorption tube row is a flow loop outlet;

each heat absorption tube row comprises an upper header, a manifold, a lower header, a coiled tube, an upper header and a lower header;

one end of the upper header is provided with an upper header, and the other end of the upper header is connected with one end of the K serpentine pipes through the K manifold pipes; the other ends of the K serpentine pipes are connected with one end of the lower header through K manifolds; the other end of the lower header is provided with a lower header; the upper end collecting pipe and the lower end collecting pipe are communicated with the connecting pipeline; the coiled pipe is uniformly distributed between the upper end header and the lower end header along the circumferential direction of the heat absorber to form an arc-shaped structure; the peaks and valleys of each serpentine tube are directed toward the axis of rotation of the heat sink.

2. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein the number N of rows of heat absorbing tubes is determined based on design requirements for the heat transfer fluid outlet temperature, the temperature at the flow circuit outlet being 400-800 ℃.

3. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein adjacent manifolds are staggered on either side of the upper header or the lower header to facilitate a reduction in spacing between adjacent manifolds and to facilitate a more compact arrangement of manifolds on the upper header and the lower header.

4. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein each heat absorber tube row is symmetrically designed along a respective horizontal and vertical midplane.

5. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein between two flow circuits, two flow circuit inlets are adjacent and two flow circuit outlets are adjacent.

6. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein the serpentine centerline curve function is sinusoidal with a sinusoidal period of T; the linear distance between the two ends of each serpentine tube is an even multiple of the sinusoidal period T.

7. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein the sections taken tangentially to any point on the centerline of the serpentine tube each provide an identical ring having an inner radius R and an outer radius R.

8. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein a thermal insulation layer is added to the inside of the heat absorber.

9. The circumferentially arrayed radially curved serpentine solar heat absorber of claim 1, wherein during operation, a spacing is maintained between the serpentine tubes and is filled with a heat conductive material that is resistant to high temperatures in order to avoid contact between the serpentine tubes after endothermic expansion.