Solar energy concentration and heat collection system

Abstract

This invention provides a solar concentrating and collecting system, comprising: multiple rows of first reflectors configured to receive and reflect sunlight; a second reflector optically configured to receive and reflect sunlight reflected by the multiple rows of first reflectors; and a heat collection tube comprising an outer tube and an inner tube nested within the outer tube, the heat collection tube being optically configured to receive and convert sunlight reflected twice by the second reflector into heat energy, wherein the multiple rows of first reflectors comprise 14-30 rows, and the outer diameter of the inner tube of the heat collection tube is between 60mm and 120mm.

Description

Technical Field

[0001] This invention relates to solar concentrating collectors, and more particularly to a linear Fresnel solar concentrating collector. Background Technology

[0002] Solar energy, as a clean and environmentally friendly energy source, has long been a focus of attention. In recent years, environmental protection and energy security issues have become increasingly prominent, and many countries are accelerating the research and development of solar energy utilization technologies. How to utilize solar energy more efficiently and economically has become the main direction for the development of solar energy application technologies.

[0003] Concentrated solar power (CSP) is a high-quality renewable energy source that can serve as both a base power and base heat source. Due to its photothermal conversion process, CSP can provide large-scale green heat output, functioning as a base heat source. Simultaneously, it can achieve power generation even during periods without sunlight and provide smooth power output through large-scale heat storage, delivering high-quality electricity suitable for base power. CSP uses solar energy as its primary energy source and represents a medium-to-high temperature thermal utilization technology for solar energy, capable of providing heat and electricity with parameters comparable to existing coal-fired boilers.

[0004] The overall technical approach to concentrated solar power (CSP) is to first concentrate sunlight and then utilize it. The main concentrating methods include four types: parabolic trough, tower, linear Fresnel, and dish. Linear Fresnel CSP is one of these, belonging to the same line-focusing concentrating solar collector technology as parabolic trough technology. In a linear Fresnel concentrating system, a primary mirror focuses sunlight onto a secondary composite parabolic mirror (CPC). A tubular absorber is installed along the focal line of the CPC to absorb the focused solar radiation. Linear Fresnel CSP technology offers advantages such as low construction cost, small footprint, excellent wind resistance, and convenient maintenance.

[0005] The development trend of concentrated solar power (CSP) technology is towards higher collector temperatures to ensure that the generated high-parameter steam can drive more efficient generator sets, thereby improving the overall efficiency of CSP power generation. Tower and dish CSP technologies, because they concentrate light at a single point, can more easily achieve collector temperatures of 500°C or higher, while linear focusing technologies such as trough and linear Fresnel collectors face relatively greater challenges. Currently, most operating linear Fresnel solar concentrators use water as the heat transfer medium and employ large-diameter second reflectors and multiple collector tubes. Due to insufficient concentration precision and concentration multiple, the highest temperature range of the heat energy generated after concentration by currently used linear Fresnel collectors is below 400°C.

[0006] The contents of the background technology section are merely the technologies known to the inventors and do not necessarily represent the existing technologies in this field. Summary of the Invention

[0007] In view of one or more of the problems existing in the prior art, the present invention is mainly intended to solve the following problems: improve the heat generation capacity of the concentrator by increasing the efficiency and concentration factor of the concentrator; enable the collector to generate and transmit heat at a temperature higher than 500°C by using high-temperature media such as molten salt or CO2, high thermal conductivity oil or solid particles for heat transfer; and improve land utilization while maintaining heat collection efficiency through a flexible reflector arrangement scheme.

[0008] To address the aforementioned problems, this invention provides a solar thermal collector system, comprising multiple rows of first reflectors, a row of second reflectors, and a collector tube assembled within the second reflectors. The collector tube includes an outer tube and an inner tube nested within the outer tube. The key feature is that the outer diameter of the inner tube of the collector tube is between 60mm and 120mm, and the multiple rows of first reflectors correspond to 14 to 30 rows.

[0009] In a further embodiment, the first reflecting mirror is a micro-arc mirror with an arc focal length ranging from 10 meters to 30 meters, and the columns of first reflecting mirrors are arranged in parallel.

[0010] Preferably, the arc shape of the micro-arc mirrors used in each column of the first reflector is not completely consistent, and at least two different arc shapes of micro-arc mirrors are used in the first reflector of a condenser.

[0011] In a further embodiment, the spacing between the multiple rows of first reflectors can be uniform or non-uniform, and the spacing between the rows of first reflectors is between 0.2 meters and 1.0 meters.

[0012] In a further embodiment, the vertical distance between the second reflector and the multiple rows of first reflectors is between 8 meters and 20 meters, and the first reflectors and the second reflectors are arranged in parallel.

[0013] Preferably, the vertical distance between the second reflector and the multiple rows of first reflectors increases with the increase of the light concentration ratio.

[0014] In a further embodiment, the collector uses molten salt or a heat transfer medium at a higher temperature, so that the heat output temperature can be higher than 500°C.

[0015] Preferably, the concentration factor of the concentrator is designed to be increased to more than 100 times, so as to achieve higher heat output parameters and greater heat density.

[0016] In a further embodiment, the sunlight reflected by the first reflector should be concentrated entirely within the arc-shaped opening of the second reflector, and the sunlight is concentrated onto the heat collection tube by the reflection of the second reflector.

[0017] In a further embodiment, multiple collectors can be connected to form a heat collection loop, which can be arranged off-center (not due north-south or due east-west) to flexibly adapt to site conditions and expand land utilization without reducing the heat collection efficiency of the heat collection system.

[0018] This invention further optimizes the design of the concentrator, including the overall optical performance, the reflective and heat transfer components, and increases the concentration factor and efficiency, enabling the concentrator to generate higher temperatures. It can also use high-temperature working fluids such as molten salt, CO2, high thermal conductivity oil, or solid particles for heat transfer, thereby further improving the concentrator's heat generation capacity. Attached Figure Description

[0019] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of the overall structure of the solar concentrator of the present invention;

[0021] Figure 2 This is a schematic diagram of sunlight incident according to the present invention;

[0022] Figure 3 This is a schematic diagram of light incident through the second reflecting mirror of the present invention;

[0023] Figure 4 This is a schematic diagram of the micro-arc surface of the first reflecting mirror of the present invention. Detailed Implementation

[0024] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0027] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0028] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0029] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] Figure 1 This is a schematic diagram of the solar concentrating collector system 100 of the present invention. Figure 1 As shown, the solar concentrating collector system 100 of the present invention includes a horizontal support 105 and a vertical support 103. The horizontal support 105 and the vertical support 103 are fixedly installed on a foundation or ground, for example, via support legs 106, which support other components of the solar concentrating collector system 100. Those skilled in the art will understand that the present invention is not limited to the specific supports 103 and 105, and other methods and devices can be conceived to support other components of the solar concentrating collector system 100.

[0031] The horizontal support 105 has multiple rows of first reflectors (primary reflectors) 104 distributed along the horizontal direction, for example. The reflecting surfaces of the first reflectors 104 face upwards to reflect incident sunlight. The first reflectors are preferably arranged symmetrically with respect to the vertical support 103, and the number of rows is, for example, between 14 and 30, such as 14, 16, 18, 20, 22, 24, 26, 28, or 30 rows.

[0032] The solar concentrating solar collector system 100 also includes a second reflector (secondary reflector) 101 and a collector tube 102, both located above the first reflector 104. The second reflector 101 is positioned above the multiple rows of first reflectors 104, at a vertical distance of approximately 8 to 20 meters, preferably approximately 12 meters. This vertical distance refers, for example, the distance from the plane of the first reflector 104 to the center point of the lower edge of the second reflector 101. The multiple rows of first reflectors 104 are configured to receive sunlight and reflect it to the second reflector 101. The second reflector 101 is optically configured to receive the sunlight reflected by the multiple rows of first reflectors and perform secondary reflection, reflecting it to the collector tube 102. The collector tube 102 typically includes an outer tube and an inner tube nested within the outer tube, and is optically configured to receive sunlight reflected secondaryly by the second reflector 101 and convert it into heat energy. According to a preferred embodiment of the present invention, the outer diameter of the inner tube of the heat collection tube 102 is between 60mm and 120mm, for example, 70mm, 80mm, 90mm, 100mm, 110mm, or any value between them. According to one embodiment of the present invention, the number of rows of the first reflectors and the outer diameter of the inner tube can be flexibly combined according to design requirements to achieve optimal optical and heat collection performance of the heat collector, particularly to achieve high parameter output of the heat transfer medium to meet the need for higher thermoelectric conversion efficiency. According to another embodiment of the present invention, the number of rows of the first reflectors has a certain proportional relationship with the outer diameter of the inner tube of the heat collection tube. To achieve high-concentration light and high-temperature output, generally, the fewer the number of mirror arrays, the smaller the outer diameter of the inner tube of the heat collector. For example, 14 mirror arrays correspond to an outer diameter of 60mm. The larger the number of mirror arrays, the larger the outer diameter of the inner tube of the heat collector can be. However, heat collectors with smaller outer diameters can also be selected to further increase the concentration factor. Therefore, 16 mirror arrays may correspond to heat collectors with an outer diameter of 70mm, and 22 mirror arrays may also correspond to heat collectors with an outer diameter of 70mm. However, to achieve high-temperature output, heat collectors with larger outer diameters are only selected when the number of mirror arrays is large. These are all within the scope of protection of this invention.

[0033] The following is for reference. Figure 2 and Figure 3 A light path diagram describing the solar concentrating thermal collector system 100 of the present invention.

[0034] Figure 2 In the diagram, downward arrows represent sunlight incident on the first reflector 104, and upward arrows represent light reflected by the first reflector 104. The first reflector 104 has a reflective surface oriented generally upwards, thus reflecting the incident sunlight toward the second reflector 101. It can be seen that when sunlight is incident in a parallel manner, after reflection by the first reflector 104, all the light rays converge within the width of the opening of the second reflector 101. Figure 3As shown, after receiving the light reflected by the first reflector 104, the second reflector 101 reflects the light towards the heat collection tube 102. It can be seen that the second reflector is, for example, a double parabolic reflector formed by two parabolic surfaces connected together. The array of first reflectors is symmetrically arranged relative to the central main support bracket of the concentrator. Therefore, the second reflector works by having two parabolic surfaces jointly reflect and converge the light. After entering the interior of the second reflector, the light undergoes a second reflection and is evenly irradiated onto the heat collection tube arranged inside the second reflector.

[0035] According to a preferred embodiment of the invention, the first reflector 104 is pivotally mounted on the horizontal support 105, so that the angular orientation of each first reflector 104 can be adjusted individually.

[0036] According to a preferred embodiment of the present invention, the spacing between each row of the first reflector 104 is optimized. The spacing between multiple rows of the first reflector 104 can be uniform or non-uniform, but they are arranged in a centrally symmetrical manner with respect to the second reflector. The spacing between the rows of the first reflector is preferably between 0.2 meters and 1.0 meters. Figure 2 This is a schematic diagram illustrating an implementation example where the first reflector array is arranged in a non-uniform manner. For example... Figure 2 As shown, the closer to the vertical support 103, the smaller the spacing between the first reflectors 104; the farther away from the vertical support 103, the larger the spacing between the first reflectors 104. When the first reflector array is arranged non-uniformly as shown in the figure, with the mirror field width and mirror width remaining unchanged, the average shading and blocking effect between the first reflector arrays is reduced. By non-uniformly designing the spacing between each array, the light reflected to the second reflector can be more concentrated, thereby improving the heat collection efficiency and concentration factor of the concentrating solar collector. At the same time, the non-uniform arrangement can reduce the distance between some arrays, improving the land utilization rate when arranging the solar collector.

[0037] According to a preferred embodiment of the present invention, in order to ensure that the light reflected by the first reflector 104 can accurately enter the second reflector 101 for secondary reflection, the first reflector 104 can be a micro-arc reflector with curvature to better focus sunlight. Figure 4 This is a schematic diagram of sunlight reflected by a single first reflecting mirror micro-arc surface. The focal length range of the curve of the micro-arc mirror is, for example, between 10 meters and 30 meters, preferably between 20 meters and 30 meters.

[0038] According to a preferred embodiment of the present invention, the multiple rows of first reflecting mirrors 104 may be partially micro-arc reflecting mirrors and partially plane mirrors.

[0039] In existing linear Fresnel concentrators, a concentrator design with a low focusing ratio is often used, and water or thermal oil is commonly used as the heat collection medium, resulting in heat energy temperatures below 400°C. In this invention, the number of rows of the first reflector 104 is increased, correspondingly increasing the reflective area of ​​each concentrator. By optimizing the optical positional relationship between the first reflector row and the second reflector system shown in Figure 101, and by optimizing the design of the first and second reflectors respectively, the concentrator can still accurately focus sunlight onto the heat collection tube even when the distance between the first and second reflectors is increased, achieving a focusing ratio higher than 100 times, with a maximum focusing ratio exceeding 200 times. This further improves the efficiency and heat collection capacity of the heat collector, enabling it to heat the working medium to above 500°C.

[0040] When increasing the focusing power, the design of a linear Fresnel concentrator requires corresponding adjustments to the height and width of the collector, and also necessitates redesigning and adjusting the first and second reflectors. To further increase the focusing power, the second reflector of this invention can be used with a single row of collector tubes, and vacuum collector tubes can be employed to reduce heat loss. The second reflector should ensure uniform reflection of the light onto the surface of the collector tubes. Simultaneously, the first reflector can be a single, integrated micro-arc mirror, rather than a multi-piece composite mirror.

[0041] This invention designs the first reflector array with 14 to 30 columns. Currently, internationally, reflector arrays of this size typically use multiple heat-collecting tubes arranged within the second reflector, each with a diameter less than 70mm. These tubes are arranged in parallel, resulting in a high concentration factor for the concentrator despite the large number of first reflector columns, leading to low heat generation temperatures. This invention uses a first reflector array with 14-30 columns, while the corresponding second reflector contains a single column of vacuum heat-collecting tubes. The inner and outer diameters of these tubes are 70mm-120mm, enabling the concentrator to achieve a concentration factor exceeding 100, thus generating high-temperature heat. The single column of heat-collecting tubes can be a single tube or a series of single tubes connected together. These are all within the scope of this invention.

[0042] When a concentrator is designed to generate heat exceeding 500°C, the current heat transfer medium capable of transmitting this temperature is molten salt. The solidification temperature of commercially available molten salts is far above room temperature, some reaching over 200°C. Therefore, the heat transfer medium must maintain good flowability within the concentrator to prevent pipe freezing. This invention uses a single-row collector tube as the heat absorber, and the collector tube diameter is relatively large. As the collector tube diameter increases, the flow resistance of the medium within the pipe decreases accordingly, reducing the risk of pipe freezing. Simultaneously, the heat output of the collector at the same flow rate is significantly increased, and the system power consumption at the same flow rate is reduced, thereby improving the overall heat generation and heat efficiency of the collector. According to a preferred embodiment, CO2, high thermal conductivity oil, or solid particles can be used as the heat transfer medium.

[0043] According to another embodiment of the present invention, a method for manufacturing a solar thermal collector system is also provided, comprising:

[0044] Install multiple rows of first reflectors, and configure the multiple rows of first reflectors to receive and reflect sunlight;

[0045] Install a second reflector, optically configured to receive sunlight reflected by the multiple rows of first reflectors and perform secondary reflection; and

[0046] A solar collector tube is installed, comprising an outer tube and an inner tube nested within the outer tube. The solar collector tubes are connected and optically configured to receive sunlight reflected twice by a second reflector and convert it into heat energy.

[0047] The multi-row first reflector comprises 14-30 rows, and the outer diameter of the inner tube of the heat collection tube is between 60mm and 120mm.

[0048] The first reflecting mirror is preferably a micro-arc mirror, and the arc focal length of the micro-arc mirror is between 10 meters and 30 meters.

[0049] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A linear Fresnel solar concentrating collector system, comprising: The heat collection tube consists of multiple rows of first and second reflectors, among which... The multiple rows of first reflectors are configured to receive sunlight and reflect it to the second reflectors; The second reflector is a double parabolic reflector formed by connecting two parabolic surfaces together. The second reflector is optically configured to receive sunlight reflected by the multiple rows of first reflectors and perform secondary reflection to uniformly reflect the sunlight onto the heat collection tube. The heat collection tube is mounted on a vertical support and includes an outer tube and an inner tube nested within the outer tube. The heat collection tube is optically configured to receive sunlight reflected twice by the second reflector and convert it into heat energy. The first reflector array comprises 14-30 arrays, and the outer diameter of the inner tube of the heat collection tube is between 70mm and 120mm. The fewer the number of arrays of the first reflector arrays, the smaller the outer diameter of the inner tube of the heat collection tube. The multiple rows of first reflectors are arranged symmetrically with respect to the second reflectors, and the spacing between the rows of first reflectors is between 0.2 meters and 1 meter. The closer to the vertical support, the smaller the spacing between the first reflectors; the farther away from the vertical support, the larger the spacing between the first reflectors. The linear Fresnel solar concentrating collector system has a concentration factor of more than 100 times, the collector tube is a single-row collector tube, and molten salt, CO2, high thermal conductivity oil or solid particles can be used as heat transfer medium in the collector tube so that the collector can generate and transfer heat at a temperature higher than 500°C.

2. The linear Fresnel solar concentrator system according to claim 1, characterized in that: The first reflecting mirror is a micro-arc mirror, and the arc focal length of the micro-arc mirror is between 10 meters and 30 meters.

3. The linear Fresnel solar concentrator system according to any one of claims 1-2, characterized in that: The multiple rows of first reflectors may have the same or different linear designs.

4. The linear Fresnel solar concentrator system according to any one of claims 1-2, characterized in that: The second reflector is positioned above the multiple rows of first reflectors at a vertical distance of 8 to 20 meters.

5. The linear Fresnel solar concentrator system according to any one of claims 1-2, characterized in that: The second reflector is positioned above the plurality of first reflectors, and the vertical distance between the second reflector and the plurality of first reflectors increases with the increase of the light concentration ratio.

6. The linear Fresnel solar concentrating collector system according to any one of claims 1-2, characterized in that: The first and second reflectors are configured such that light incident on the second reflector is concentrated in a range smaller than the width of the opening of the second reflector.

7. The linear Fresnel solar concentrator system according to claim 2, characterized in that: The micro-arc mirror is an integral micro-arc mirror.

8. The linear Fresnel solar concentrator system according to claim 4, characterized in that: The vertical distance is 12 meters.

9. A method for constructing a linear Fresnel solar concentrating collector system, comprising: Install multiple rows of first reflectors, and configure the multiple rows of first reflectors to receive and reflect sunlight; A second reflector is installed, optically configured to receive and reflect sunlight reflected by the multiple rows of first reflectors, wherein the second reflector is a double-parabolic reflector consisting of two parabolic surfaces joined together; and A solar collector tube is installed on a vertical support. The solar collector tube includes an outer tube and an inner tube nested inside the outer tube. The solar collector tubes are connected and optically configured to receive sunlight reflected twice by the second reflector and convert it into heat energy. The multi-row first reflector comprises 14-30 rows, and the outer diameter of the inner tube of the heat collection tube is between 70mm and 120mm. The fewer the number of rows of the first reflector, the smaller the outer diameter of the inner tube of the heat collection tube, and the higher the concentration factor of the solar concentrating heat collection system is than 100 times. The multiple rows of first reflectors are arranged symmetrically with respect to the second reflectors, and the spacing between the rows of first reflectors is between 0.2 meters and 1 meter. The closer to the vertical support, the smaller the spacing between the first reflectors; the farther away from the vertical support, the larger the spacing between the first reflectors. The heat collection tube is a single-row heat collection tube, and molten salt, CO2, high thermal conductivity oil, or solid particles can be used as the heat transfer medium inside the heat collection tube so that the heat collector can generate and transfer heat at a temperature higher than 500°C.

10. The manufacturing method according to claim 9, characterized in that: The first reflecting mirror is a micro-arc mirror, and the arc focal length of the micro-arc mirror is between 10 meters and 30 meters.

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