Novel groove type concentrating solar heat collection system

Abstract

The utility model discloses a novel groove-type concentrating solar heat collection system, which is characterized in that a primary reflector is a line focusing reflector, a secondary reflector is a cylindrical reflector, the secondary reflector is arranged between the vertex and the focus of the primary reflector, the concentrating direction of the secondary reflector is vertical to the concentrating direction of the primary reflector, and the concentrating direction of the secondary reflector is vertical to the concentrating direction of the secondary reflector. The main reflector is installed on the single-axis tracking device, the receiver is installed on a focus of the concentrating solar heat collection system, and the receiver can move front and back to track focus position movement under different incident angles. The working temperature of the system is 550 DEG C, and the photo-thermal efficiency of the system can reach 63.3% and is close to the efficiency of a tower type system, so that the performance of the system is quite excellent. According to the system, the receiver needs to be moved to receive focused solar rays under different incident angles, a second tracking device does not need to be provided for the main reflecting mirror, the large-scale and low-cost single-shaft horizontally-installed groove type system is kept, and the reliability of the system is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of solar heat collection systems, in particular to a novel trough-type concentrating solar heat collection system. Background Art

[0002] Line-focus solar concentrators are usually designed as parabolic trough concentrators or linear Fresnel concentrators. These concentrators only need to rotate around one axis to track the sun, and their linear geometry matches well with the receiver tubes placed on the focal line. The receiver tubes convert light energy into heat energy and transport the energy through a liquid medium. Line-focus concentrators are one of the most widely used solar concentrators. However, the disadvantage of these linear-focus concentrators is their limited concentration ratio. Since they can only concentrate sunlight in one direction, the maximum concentration ratio does not exceed the result calculated by the following formula:

[0003]

[0004] Here, θ is the acceptance half-angle of the concentrator. For a common line-focus parabolic trough concentrator with a tubular receiver, the theoretical maximum concentration ratio is:

[0005]

[0006] Ideally, the interception half-angle is equal to the half-angle of the solar photosphere, that is, 4.65 mrad. For a parabolic trough system with a tubular receiver, the theoretical concentration ratio is 68.45. If considering atmospheric scattering, the installation of the concentrator, tracking errors, and optical errors of the mirrors, etc., the interception half-angle needs to be much larger. The geometric concentration ratio of trough concentrators on the European market is only 26 1 , and the product design is based on the average Gaussian distribution error of the system being about 8 mrad, and the interception half-angle is about 20 mrad 2 , and the interception rate is only 90%. Plus the loss of the cosine factor, the system efficiency is low.

[0007] Since the radiative and convective heat losses of the concentrator are proportional to the light-transmitting area of the receiver, increasing the concentration ratio of the line-focus concentrator, that is, reducing the light-transmitting area of the receiver, is beneficial to improving the system efficiency. Increasing the concentration ratio is one of the main measures to improve the system efficiency, and many methods have been proposed. Using a cavity or flat-plate receiver instead of a tubular receiver, the theoretical concentration ratio can be increased to 107.53; adding a compound parabolic concentrator or V-groove concentrator in front of the receiver can reduce the radius of the tubular receiver 3 ; and using a similar two-stage concentrator designed by the multi-surface method at the same time 4 etc.

[0008] In the field of astronomical optics, telescopes are often composed of two reflectors, which can also achieve the function of light collection, simultaneously eliminate spherical aberration and coma, and form an aplanatic optical system. At this time, the radius of the image spot decreases and the imaging quality is improved. This technical solution is also widely applied to solar concentrators. 5 It has been applied to, including being applied to online focusing concentrators. The latest technical solution has increased the concentration ratio of the line-focusing trough system to 55. 6 However, these methods are all restricted by the concentration ratio brought about by the fact that the line-focusing system can only focus in one direction. Although there is an improvement in the geometric concentration ratio, adding reflectors not only increases the reflection loss but also increases the divergence of the reflected light, and the overall efficiency does not necessarily increase, so it is less used in actual products.

[0009] Compared with point-focusing reflectors such as a rotating paraboloid, which can focus sunlight in two directions, its theoretical concentration ratio is the square of that of a linear concentrator, reaching 46,248 times theoretically. The main measure to exceed the theoretical limit of the linear concentrator and at the same time maintain the advantage of only using a single tracking device in the line-focusing system is to introduce a concentrator in the other direction, thereby increasing the concentration ratio. As far as we know, the earliest solution 7 is to use a cylindrical lens to continue focusing light after a parabolic cylinder concentrator. Experiments show that the geometric concentration ratio is as high as 1100X, and the interception rate is about 50%. However, this method requires dual-axis external tracking of the sun and requires a relatively large number of reflections and refractions. Each reflection and refraction will reduce the efficiency.

[0010] The latest improvement measure is to use a second concentrator to focus in the other direction, which is equivalent to using two line-focusing concentrators to achieve the point-focusing function. Using a two-way V-groove or two-way compound parabolic concentrator does not require adding tracking equipment, is the easiest to achieve focusing in the other direction, and improves the original direction focusing, thereby greatly increasing the concentration ratio. The V-groove concentrator uses a flat reflector, with a simple structure and low cost. However, its disadvantage is that it requires multiple reflections inside the concentrator. Since each reflection will result in energy loss, even if it has a high geometric concentration ratio, the collection efficiency is reduced and the energy concentration ratio is much lower, so it has no practical application value in the field of medium- and high-temperature concentrating solar energy. Even considering 4 reflections, the geometric concentration ratio is only 5.7 times. If ordinary reflectors are used, even if the reflectivity is as high as 94%, 22% of the energy will be lost due to multiple reflections; moreover, the reflector area is large and a lot of materials are consumed.

[0011] Compound parabolic concentrators use two parabolic mirrors instead of the two flat mirrors in the V-groove concentrator. For line-focus compound parabolic concentrators, the theoretical concentration ratio is also 1 / sinθ. As a solar concentrator, in an ideal situation, the theoretical value is 215.1, which is the same as that of the V-groove concentrator. Due to the use of parabolic mirrors, the manufacturing difficulty increases, and its practical application value in medium-temperature concentrating solar thermal utilization systems is even smaller. The latest design is to use multiple flat mirrors spliced together to form a quasi-parabolic mirror. 8 。

[0012] Using refractive compound parabolic or V-groove concentrators means manufacturing the V-groove or compound parabola with transparent materials. 9 In this case, the reflection occurring on the side is total reflection without reflection loss. However, the path of light in the internal refractive material is longer, and the absorption effect is relatively large, which also brings energy loss. But at this time, the concentration ratio will increase by the square of the refractive index n compared to the reflective compound parabolic concentrator. Under north-south axis tracking, using a two-way compound parabolic concentrator, even if it is fixedly installed without adding a second tracking device, the incident angle can be within the range of plus or minus 23.5 degrees, and the concentration multiple can reach 7.6 times. The overall concentration multiple of the system can reach 300 times. 10 。

[0013] When this secondary concentrator is fixedly used on the common north-south or east-west horizontal axis, the incident angle will become very large. In many operating conditions, not only is there no concentration effect, but it even blocks the incident light from reaching the receiver. At this time, a rotating device needs to be added to track the incident angle of sunlight, thereby significantly increasing the concentration multiple. For a parabolic trough concentrator using a refractive compound parabolic secondary concentrator, the estimated theoretical concentration multiple can reach 6000 times, and the maximum concentration ratio for a design working at a latitude of 20 degrees reaches 1482 times. 11 However, when this secondary refractive concentrator works at such a high energy flux density, the temperature will increase significantly, bringing problems such as the expansion of the refractive material, resulting in an increase in optical errors and a reduction in the actual concentration multiple. Moreover, the secondary concentrator used consumes a lot of materials and has a high cost, which also hinders its practical application.

[0014] The latest technical measure is to use a second curved mirror. 12, By concentrating light in another direction, the disadvantages of using the above compound parabolic concentrator are avoided. This technical solution uses specially designed curved mirrors of various types, and it is necessary to move and track sunlight at different incident angles. When the interception radius is 9 mrad and the interception rate reaches 80%, the concentration ratio reaches 335. Its disadvantage is that the system is very complex, and a special secondary concentrator needs to be designed for the mirrors with different edge angles in the linear parabolic concentrator. Although the concentration ratio can be increased to 1563, the types of specially designed and manufactured secondary reflective concentrators also increase sharply, and whether it has practical application value remains to be tested. Summary of the Utility Model

[0015] The purpose of the present utility model is to make up for the deficiencies of the existing technology and provide a new type of trough-type concentrating solar collector system.

[0016] The present utility model is realized through the following technical solutions:

[0017] A new type of trough-type concentrating solar collector system includes a main reflector, a secondary reflector, a receiver, and a single-axis tracking device. The main reflector is a line-focusing reflector, the secondary reflector is a cylindrical mirror, the secondary reflector is installed between the vertex and the focus of the main reflector, and the concentrating direction of the secondary reflector is perpendicular to the concentrating direction of the main reflector. The main reflector is installed on the single-axis tracking device, and the receiver is installed at the focus of the concentrating solar collector system. The receiver can move back and forth to track the movement of the focus position at different incident angles.

[0018] The main reflector is a line-focusing parabolic reflector or composed of multiple strip-shaped cylindrical mirrors spliced together. The centers of the multiple strip-shaped cylindrical mirrors form a parabola, and the normal vector of the center of each strip-shaped cylindrical mirror is consistent with the normal vector of the parabola at its installation position.

[0019] The receiver is a cavity receiver or a flat receiver.

[0020] The edge angle of the main reflector is between 30 and 60 degrees.

[0021] The position of the secondary reflector and the width of the main reflector in the focusing direction are determined by the shading ratio α of the secondary reflector. α is between 0.03 and 0.15. The width of the secondary reflector in the focusing direction of the main reflector = the width of the main reflector * shading ratio α. The distance from the vertex of the secondary reflector to the vertex of the main reflector = the focal length of the main reflector * (1 - α) + half of the height h of the secondary reflector; the upper half-width w of the secondary reflector in the focusing direction y is then determined by the spherical aberration θ generated by it in the focusing direction of the main reflector x and is calculated according to the following formula:

[0022]

[0023] is the edge angle of the primary mirror, and W is the half clear aperture width of the primary mirror. Among them, the spherical aberration θ x The smaller it is, the smaller the impact on the system performance.

[0024] The tracking axis of the concentrating solar collector system is installed in the north-south direction.

[0025] The working location of the concentrating solar collector system is within the Tropic of Cancer and the Tropic of Capricorn and is installed horizontally; while in high-latitude regions outside the Tropic of Cancer and the Tropic of Capricorn, the tracking axis is parallel to the earth's axis.

[0026] A design method for a new type of trough-type concentrating solar collector system specifically includes the following steps:

[0027] The first step is to complete the preliminary design, including:

[0028] 1) Preliminary design of the primary mirror. Determine the half clear aperture width W of the primary mirror according to requirements; the edge angle of the primary mirror Select 45 degrees for the preliminary design; the vertex curvature radius of the primary mirror is calculated by the following formula:

[0029]

[0030] Select the primary mirror as a paraboloid for the preliminary design, e = 1, then r1,

[0031]

[0032] Then the focal length f1 = r1 / 2; y1 is the half width of the primary mirror, and r1 is the curvature radius of the primary mirror;

[0033] 2) Preliminary design of the secondary mirror. Initially select the light-shielding ratio of the secondary mirror as α, then the half width of the secondary mirror in the x direction, that is, the focusing direction of the primary mirror, is:

[0034] w x = W * α

[0035] The half width of the secondary mirror in the other focusing direction is calculated by the following formula:

[0036]

[0037] θ x is the spherical aberration θ generated by the secondary mirror in the focusing direction of the primary mirror x , select 0.5 mrad for the preliminary design, and the focal length of the secondary mirror is calculated by the following formula:

[0038] f2 = f1 * α + h / 2

[0039] h is the height of the secondary mirror and is calculated by the following formula

[0040]

[0041]

[0042] r2 is the radius of curvature of the vertex of the secondary mirror, f1 is the focal length of the primary mirror, and f1 = r1 / 2;

[0043] Installation position of the secondary mirror, distance between the vertex and the vertex of the primary mirror:

[0044] d = (1 - α) * f1 - h / 2

[0045] 3) Preliminary design of the receiver, the calculation formulas for the half-widths in the x and y directions are:

[0046]

[0047]

[0048] k x and k y are the interception ratios of the receiver in the x and y directions respectively, and σ t is the total error of the Gaussian distribution of the reflected light intensity,

[0049] Both are taken as 3 in the preliminary design; the distance between the receiver and the vertex of the secondary mirror = the focal length of the secondary mirror = r2 / 2;

[0050] Second step, establish a system performance simulation calculation program for the ray tracing method;

[0051] Third step, with the net energy efficiency as the goal and the annual average incident angle of the trough system as the incident angle in the y direction, optimize the design parameters under different working locations.

[0052] The advantages of the present utility model are as follows: The working temperature of the system of the present utility model is 550 degrees, and the optical-thermal efficiency of the system can reach 63.3%, approaching the efficiency of the tower system, indicating that the system of the present utility model has excellent performance even when working at high temperatures. The system of the present utility model does not require installing a second tracking device for the primary mirror, thus simplifying the system design and improving the system reliability. The system needs to move the receiver to receive the focused solar rays at different incident angles. Compared with the dish system, the main advantage is that it does not require a second tracking device for the primary mirror, maintaining the characteristics of large-scale and low cost of the single-axis horizontal installation trough system. The present utility model can achieve a 400-fold point focusing effect for the line-focusing trough system at low cost only by using common industrial products, cylindrical mirrors. Description of the Drawings

[0053] Figure 1Stereogram of the installation of the primary mirror and secondary mirror of the present utility model;

[0054] Figure 2 Side view of the installation of the primary mirror and secondary mirror of the present utility model;

[0055] Figure 3 Another side view of the installation of the primary mirror and secondary mirror of the present utility model;

[0056] Figure 4 Schematic diagram of spherical aberration generated by a two-way focusing parabolic trough system composed of two mirrors of the present utility model;

[0057] Figure 5 Diagram of the influence of the incident angle on the system performance. Detailed implementation mode

[0058] As Figures 1 - 3 shown, a novel trough-type concentrating solar collector system includes a primary mirror 1, a secondary mirror 2, a receiver, and a single-axis tracking device. The primary mirror 1 is a line-focusing mirror, and the secondary mirror 2 is a cylindrical mirror. The secondary mirror 2 is installed between the vertex and the focus of the primary mirror 1, and the focusing direction of the secondary mirror 2 is perpendicular to the focusing direction of the primary mirror 1. The primary mirror 1 is installed on the single-axis tracking device, and the receiver is installed at the focus of the concentrating solar collector system. The receiver can move back and forth to track the movement of the focus position at different incident angles.

[0059] The primary mirror 1 is a line-focusing parabolic mirror or composed of a plurality of strip-shaped cylindrical mirrors spliced together. The centers of the plurality of strip-shaped cylindrical mirrors form a parabola, and the normal vector of the center of each strip-shaped cylindrical mirror is consistent with the normal vector of the parabola at its installation position.

[0060] The receiver is a cavity receiver or a flat receiver.

[0061] The edge angle of the primary mirror 1 is between 30 and 60 degrees.

[0062] The position of the secondary mirror 2 and the width of the focusing direction of the primary mirror 1 are determined by the light-shielding ratio α of the secondary mirror 2. α is between 0.03 and 0.15. The width of the secondary mirror 2 in the focusing direction of the primary mirror 1 = the width of the primary mirror 1 * light-shielding ratio α. The distance from the vertex of the secondary mirror 2 to the vertex of the primary mirror 1 = the focal length of the primary mirror 1 * (1 - α) + the height h of the secondary mirror 2 / 2; The upper half-width w y of the secondary mirror 2 in the focusing direction x is then determined by the spherical aberration θ

[0063]

[0064] is the edge angle of the main reflector 1, and W is the half clear aperture width of the main reflector 1. Among them, the spherical aberration θ x The smaller it is, the smaller the impact on the system performance.

[0065] The tracking axis of the concentrating solar collector system is installed in the north-south direction.

[0066] The working location of the concentrating solar collector system is within the Tropic of Cancer and the Tropic of Capricorn and is installed horizontally; while in high-latitude regions outside the Tropic of Cancer and the Tropic of Capricorn, the tracking axis is parallel to the earth's axis.

[0067] The present utility model only uses a commonly used industrial product, a cylindrical mirror, to achieve a 400-fold point focusing effect for a line-focusing trough system at low cost. Another line-focusing mirror is used as a secondary concentrator to concentrate the light rays in another direction, thereby achieving the point focusing effect. In the field of astronomical optics, two mirrors are often used to simultaneously eliminate spherical aberration and coma, forming an aplanatic optical system. At this time, the radius of the image spot is reduced and the imaging quality is improved. This technical solution can also be applied to the line-focusing system 13 , and the main reflector can also use a linear Fresnel system 14 , which only focuses in one direction. Although the geometric concentration ratio is improved, adding a mirror not only increases the reflection loss but also increases the divergence of the reflected light, and the overall efficiency does not necessarily increase, so it is less used. The added secondary concentrating mirror is mainly used to concentrate the light rays in another direction, which can greatly increase the concentration multiple. Its disadvantage is that a tracking device must be added so that the secondary line-focusing concentrator can concentrate the light. However, the light rays in the focusing direction of the main reflector are simultaneously reflected by the secondary reflector, which may cause divergence due to the curved surface of the secondary reflector. Therefore, the curved surface of the secondary reflector must consider the negative impact on the focusing direction of the main reflector. The simplest design is a plane in the direction of the main reflector, that is, the secondary mirror is a cylindrical mirror, and the simplest cylindrical mirror is a cylindrical surface. This article introduces a reduced design scheme accordingly. The main reflector is a parabolic trough mirror, and the tracking axis is installed in the north-south direction. With the trough half-width W being 4 meters and the edge angle being 30 degrees, the focal length f = 0.5W / tan(φ). According to the design of the secondary mirror concentrating system, the secondary mirror is selected as a plane mirror. When α = 0.1, the distance between the secondary mirror and the vertex of the main reflector is (1 - α)f, and the distance between the receiving surface and the vertex of the main reflector is (1 - 2α)f. If the secondary mirror is a circular surface in another direction, that is, actually a cylindrical surface, and its half-width in the vertical (y direction) is w y , and the radius is r, then its height is This causes the light reflected by the secondary mirror to change in the focusing direction of the primary mirror, increasing the image spot width. To reduce the image spot size, a smaller w should be selected; at the same time, the vertex should be (1-α)f + 0.5*h away from the vertex of the primary mirror to minimize the influence caused by the curvature of the cylindrical surface. At this time, the focus of the cylindrical secondary mirror is on the receiving surface of the primary mirror, as Figure 4 shown, so there is:

[0068] F2 = αf1 + 0.5*h = 0.5*r

[0069] From this, we get:

[0070]

[0071] The half-width w of the cylindrical surface in the x direction x , can be calculated by the following formula:

[0072]

[0073] At this time, the spherical aberration generated by the marginal rays focused by the primary mirror:

[0074]

[0075] Converted to an angle:

[0076]

[0077] If the longitudinal width of the secondary mirror is selected to be 0.2 meters, the spherical aberration is 1.2 mrad, and the average spherical aberration can be obtained by integral solution as one-third of it, that is, 0.4 mrad. If the marginal angle of the primary mirror is increased to 45 degrees, the maximum spherical aberration is 2.07 mrad, and the average spherical aberration is 0.69 mrad. From this, the following formula can be obtained to calculate the width of the secondary mirror in the focusing direction (perpendicular to the focusing direction of the primary mirror):

[0078]

[0079] Calculated with a parabolic surface slope error of 2.5 mrad, a cylindrical surface slope error of 1 mrad, a Gaussian radius of the solar image spot of 3.0 mrad, and other optical errors of 1 mrad, the total error is 6.285 mrad. Then the half-width of the receiver in the x direction can be approximately calculated as the image spot width generated by 3 times the total error. The half-width of the receiver in the y direction can use the image spot width generated by 5 times the total error.

[0080] Ray tracing calculations show that with one-way tracking, the system performance varies with the incident angle in the other direction and drops rapidly. The best case is to install a tracking device on the receiver and use the earth axis tracking. When the incident angle is at the intermediate value, the optimized design of the optical-thermal efficiency can reach 57.6%. However, when the incident angles are 0 and the maximum of 23.5 degrees, the efficiency drops to 52.7% and 47.3% respectively. The system should use two-axis tracking or use the earth axis tracking, but the earth axis inclination needs to be adjusted daily. When the receiver is installed on the tracking device, the performance can always be maintained at the best state, reaching 66.9%. The secondary reflector uses a cylindrical mirror, and its performance is significantly better than that of a parabolic cylinder mirror. This is because the parabolic mirror has a large error. However, even if the errors of the two are the same, their performances are similar.

[0081] Aiming at the net energy efficiency, the receiver is installed on the tracking device. The reflectivities of the primary reflector and the secondary reflector are 0.93 and 0.96 respectively; the slope error of the spherical mirror is 1 mrad, the slope error of the parabolic mirror is 2.5 mrad, other errors are 1 mrad, and the average error deviation of the Gaussian distribution of the sunlight intensity is 3 mrad. A cavity receiver is used, with an operating temperature of 550 °C, a heat loss coefficient of 35, an absorptivity of 0.98, and another 5% other losses are considered. The width of the primary reflector is 8 meters. For the spherical aberration added by the secondary reflector, aiming at 1 mrad, the following are the optimized design parameters:

[0082]

[0083] As Figure 5 shown, it is the influence of the system incident angle on the system interception rate and optical-thermal efficiency when both the receiver and the secondary reflector are fixedly installed. When the incident angle is only from 0.1 to 0.2 degrees, the system performance remains almost unchanged. However, when it increases to 1 degree, the interception rate drops to 70%, and the optical-thermal efficiency drops to 47.0%, both far lower than the vertical incidence. When using the earth axis tracking system, the inclination angle of the tracking axis changes by 47 degrees in a year, with an average daily change of 0.129 degrees. That is to say, the earth axis tracking system can be used, and only need to adjust the inclination angle once a day to maintain the system performance.

[0084] The operating temperature of the above-designed system is 550 degrees, belonging to the scope of high-temperature power generation applications. With the secondary reflector plus the tracking system, the optical-thermal efficiency of the system can reach 66.9%, and the system efficiency exceeds that of the tower type. The system should use two-axis tracking, but the earth axis tracking can also be used. By adjusting the earth axis inclination angle daily, there is no need to install a second tracking device on the primary reflector, thus simplifying the system design and improving the system reliability. Compared with the dish system, the main advantage is that there is no need to provide a second tracking device for the primary reflector, maintaining the low cost characteristic of the single-axis installed trough system.

[0085] The following are the references cited in this utility model:

[0086] 1. M. Geyer, E. Lüpfert, R. Osuna, A. Esteban, W. Schiel, A. Schweitzer, E. Zarza, P. Nava, J. Langenkamp, and E. Mandelberg, “EUROTROUGH - Parabolic Trough Collector Developed for Cost Efficient Solar Power Generation,” Proceedings of the 11th International Symposium on Concentrating Solar Power and Chemical Energy Technologies p. 7 (2002).

[0087] 2. Bendt P, Rabl A, Gaul H W, et al. Optical analysis and optimization of line focus solar collectors. Report of Solar Energy Research Institute, 1979, 29(9): 568. https: / / doi.org / 10.2172 / 5746400

[0088] 3. M. Collares - Pereira, J. M. Gordon, A. Rabl, and R. Winston, “High concentration two - stage optics for parabolic trough solar collectors with tubular absorber and large rim angle,” Sol. Energy 47(6), 457–466 (1991)

[0089] 4. P. Benítez, R. García, and J. C. Mi nano, “Contactless efficient two - stage solar concentrator for tubular absorber,” Appl. Opt. 36(28), 7119–7124 (1997)

[0090] 5. Jeffrey M. Gordon, Aplanatic optics for solar concentration, Opt. Express 18(S1) A41 - A52 (2010)

[0091] 6. Leonardo F. L. de Souza, Naum Fraidenraich, and Jeffrey M. Gordon, Aplanatic solar concentrators for tubular absorbers, Optics Letters Vol. 49, Issue 6, pp. 1441 - 1444 (2024)

[0092] 7. N. Davidson, L. Khaykovich, and E. Hasman, “Anamorphic concentration of solar radiation beyond the one - dimensional thermodynamic limit,” Appl. Opt. 39(22), 3963–3967 (2000)

[0093] 8. Chen Fei. Principles and Applications of Non - imaging Solar Concentration [M]. Beijing: Science Press, December 2021. pp148

[0094] 9. Winston, & Roland. (2005). Nonimaging optics. Elsevier Academic Press, pp69

[0095] 10. Brunotte, M., Goetzberger, A., & Blieske, U.. (1996). Two - stage concentrator permitting concentration factors up to 300x with one - axis tracking. Solar Energy, 56(3), pp285 - 300.

[0096] 11. Cooper, T., Ambrosetti, G., Pedretti, A., & Steinfeld, A.. (2013). Theory and design of line-to-point focus solar concentrators with tracking secondary optics. Appl Opt, 52(35), pp8586-8616

[0097] 12. J.D. Johnsen, et al. Line-focus solar concentration 10 times higher than the 2D thermodynamic limit,Opt. Express 30(14) pp24362-24374(2022)

[0098] 13. M. Collares-Pereira, J.M. Gordon, A. Rabl, and R. Winston, “High concentration two-stage optics for parabolic trough solar collectors with tubular absorber and large rim angle,” Sol. Energy 47, 457–466(1991). L.F.L. de Souza, N. Fraidenraich, and J.M. Gordon, Aplanatic solar concentrators for tubular absorbers,Optics Letters Vol.49(6), pp.1441-1444(2024) https: / / doi.org / 10.1364 / OL.517874

[0099] 14. L.F.L. de Souza, N. Fraidenraich, C. Tiba, et al., Analytic optical evaluation of linear aplanatic solar Fresnel reflectors,Sol. Energy 249(2023), 107-121。

Claims

1. A new type of trough-type concentrating solar collector system, characterized in that: It includes a primary reflector, a secondary reflector, a receiver, and a single-axis tracking device. The primary reflector is a line-focusing reflector, and the secondary reflector is a cylindrical reflector. The secondary reflector is installed between the vertex and the focus of the primary reflector, and the light-condensing direction of the secondary reflector is perpendicular to that of the primary reflector. The primary reflector is installed on the single-axis tracking device, and the receiver is installed at the focus of the concentrating solar collector system. The receiver can move back and forth to track the movement of the focus position at different incident angles.

2. The novel trough-type concentrating solar heat collection system according to claim 1, characterized in that: The primary reflector is a line-focusing parabolic reflector or is composed of a plurality of strip-shaped cylindrical reflectors spliced together. The centers of the plurality of strip-shaped cylindrical reflectors form a parabola, and the normal vector of the center of each strip-shaped cylindrical reflector is consistent with the normal vector of the parabola at its installation position.

3. A novel trough-type concentrating solar heat collection system according to claim 1, characterized in that: The receiver is a cavity receiver or a flat-plate receiver.

4. A novel trough-type concentrating solar heat collection system according to claim 1, characterized in that: The edge angle of the main reflector is between 30 and 60 degrees.

5. A novel trough-type concentrating solar heat collection system according to claim 1, characterized in that: The tracking axis of the concentrating solar collector system is installed in the north-south direction.

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