Tower type solar condensation heat absorption system based on novel cavity type absorber

Abstract

The invention discloses a tower type solar condensation and heat absorption system based on a novel cavity type absorber. The tower type solar condensation and heat absorption system is composed of a condensation mirror field and an absorption tower. The absorption tower comprises two cavity absorbers which are arranged up and down and have the same structure. According to the cavity type absorber, an internal heat absorption pipe set is arranged in a cylindrical heat preservation cavity, and the inner wall face of the heat preservation cavity is coated with a heat absorption coating. The two heat absorbers are provided with lighting openings in one side of the heat preservation cavity, the directions of the lighting openings of the two heat absorbers are opposite, the sides, provided with the lighting openings, of the two heat absorbers serve as the light facing sides of the two heat absorbers respectively, and sunlight converged by mirror fields of the light facing sides of the two heat absorbers is obtained respectively. The heat absorber is provided with an exposed heat-absorbing pipe group on the outer wall surface of the heat-insulating cavity on the light-facing side; the heat absorption medium firstly exchanges heat through the external heat absorption pipe set on the light facing side, and then further absorbs heat through the heat absorption pipe set in the heat preservation cavity. Sunlight is reflected and converged to the light facing sides of the corresponding absorbers through the mirror fields on the two sides of the absorption tower, so that the area of the mirror fields is enlarged, and the field is more fully utilized.

Description

Technical Field

[0001] The present invention relates to the field of optimization of tower solar thermal concentrator heat absorption systems, and in particular to a tower solar concentrator heat absorption system based on a novel cavity absorber. Background Art

[0002] With the promotion of clean energy utilization, solar energy as a clean and renewable energy has attracted much attention. Among them, tower solar concentrating thermal power generation has a high concentration ratio and can produce a higher operating temperature, thereby generating high-parameter steam to bring high power generation efficiency; at the same time, based on the development of energy storage technology, the second-generation tower solar thermal power generation system is equipped with an energy storage device, which can overcome the shortcoming that solar power generation cannot work at night. Therefore, tower solar concentrating thermal power generation technology has been vigorously promoted in recent years.

[0003] Solar radiation absorber is the core component of tower solar concentrating solar thermal system. The tower absorber currently in operation mainly includes multi-tube exposed absorber and chamber absorber. Multi-tube exposed absorber arranges parallel heat absorbing tubes in a circle. The exposed side of the absorber can receive sunlight reflected from the mirror field on all four sides. This allows the system to arrange a sufficiently large elliptical heliostat field, with a high land utilization rate. A larger area of ​​concentrating mirror field can also gather higher radiation energy flux density and produce a higher temperature heat absorbing medium to improve work capacity. However, the thermal radiation generated by the exposed absorber at high temperature will be directly dissipated into the surrounding environment, resulting in higher thermal radiation losses. The chamber absorber arranges the absorber inside the chamber and collects solar radiation through the opening of the chamber. This makes the thermal radiation emitted by the absorber restricted by the chamber and absorbed twice, reducing the dissipation of thermal radiation. However, the chamber absorber usually avoids collecting sunlight at multiple openings to ensure sufficient light capture capacity. Most of the chamber absorbers currently in operation have light inlets on one side, which greatly restricts the arrangement of the mirror field. The heliostat can only be arranged on the side facing the light inlet in a fan-shaped or elliptical shape, which restricts the concentration area and land use. Therefore, in view of the future development trend of tower solar thermal power generation towards larger scale and higher parameters, the arrangement of the tower solar concentrating heat absorption system still needs to consider equipping a larger area of ​​concentrating mirror field while effectively reducing thermal radiation, so as to improve the efficiency of solar thermal power generation, reduce the cost of power generation, and achieve wider technology promotion. Summary of the invention

[0004] In view of the above existing problems, the present invention designs a tower-type solar concentrating and collecting system based on a new cavity absorber, provides a new absorber structure and absorber layout, so as to effectively reduce the thermal radiation loss in the collection process, and meet the requirements of arranging a large-area, highly compact concentrating mirror field, thereby improving land utilization.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention first provides a tower-type solar energy concentrating heat absorption system based on a novel cavity absorber, which consists of an absorption tower and a concentrating mirror field around the absorption tower; the absorption tower includes two cavity absorbers arranged up and down and having the same structure; each cavity absorber includes a cylindrical insulation cavity, one side half of the cylindrical insulation cavity serves as the light-facing side, an opening for installing a light-collecting window is axially opened in the middle of the light-facing side, an exposed heat-absorbing pipe group is arranged on the outer wall surface of the light-facing side, a heat-absorbing coating is coated on the inner wall surface of the insulation cavity, and an internal heat-absorbing pipe group is arranged in the inner area of ​​the insulation cavity, the light-facing sides of the two cavity absorbers are opposite, and the light-collecting ports face opposite directions; the light-facing sides of the two cavity absorbers respectively obtain the sunlight reflected and gathered by the concentrating mirror field on the side they face.

[0007] According to a preferred embodiment of the present invention, the exposed tubular heat absorption tube group is only arranged in the half circle of the heat preservation cavity facing the light side to reduce the heat radiation loss caused by the exposure of the heat absorption tube; the heat absorption tubes of the internal heat absorption tube group and the exposed heat absorption tube group are arranged along the axial direction of the heat preservation cavity, and the exposed heat absorption group is connected with the internal heat absorption tube group through a working medium conveying pipeline, and the working medium flows to the internal heat absorption tube group after absorbing heat in the exposed heat absorption group.

[0008] According to a preferred embodiment of the present invention, the heat absorbing tubes of the internal heat absorbing tube group are evenly distributed in a circle around the central axis of the thermal insulation cavity; there is a certain interval between the internal heat absorbing tube group and the inner wall of the thermal insulation cavity; the heat absorbing coating coated on the inner wall of the thermal insulation cavity is used for secondary absorption of thermal radiation from the internal heat absorbing tube group, and at the same time performs radiation heat exchange with the internal heat absorbing tube group to heat the backlight part of the internal heat absorbing tube group.

[0009] The present invention also provides a solar energy utilization method based on the tower-type solar energy concentrating heat absorption system, which comprises the following steps:

[0010] The concentrating mirror field around the absorption tower is divided into a near-sun mirror field and a far-sun mirror field. The two mirror fields respectively reflect and converge sunlight to the light-facing side of the two cavity absorbers.

[0011] For any side of the mirror field, the heliostats whose central angle is equal to the daylighting opening angle will focus all the reflected sunlight on the daylighting window of the corresponding cavity absorber, and the sunlight reflected by the remaining heliostats on this side of the mirror field will be focused on the exposed heat absorption group of the corresponding cavity absorber and absorbed;

[0012] The sunlight entering the heat preservation cavity through the lighting window is absorbed by the internal heat absorption tube group and the heat absorption coating on the cavity wall. The heat radiation flow radiated by the internal heat absorption tube group is absorbed by the heat preservation cavity again, thereby effectively reducing the heat radiation dissipation of the heat absorber. At the same time, the radiation heat exchange between the inner wall of the heat preservation cavity and the heat absorption tube improves the uniformity of the heat flux distribution of the heat absorption tube.

[0013] After entering the absorption tower, the heat absorbing medium is split and then passes into a cavity absorber from bottom to top. In each cavity absorber, it absorbs heat by passing through an exposed tube heat absorbing tube group and an internal heat absorbing tube group in turn. After that, the two paths of heat absorbing medium are combined and output from the absorption tower.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) Compared with the traditional multi-tube exposed absorber, the novel cavity absorber adopted in the present invention arranges most of the absorber groups in the heat preservation cavity, and can utilize the cavity structure and the barrier between the absorber tubes to absorb thermal radiation for the second time, thereby effectively reducing the thermal radiation dissipation. The traditional heat absorption coating has a high emissivity to the outside, and the thermal radiation is serious at high temperature. The absorber structure can reduce the proportion of the emitted thermal radiation energy to less than 10%. At the same time, the inner surface of the circular cavity is also sprayed with the heat absorption coating. Through the radiation heat exchange between the coating and the absorber tube, the heat flux distribution on the surface of the absorber tube is more uniform, thereby reducing the loss of the absorber tube material.

[0016] (2) Compared with the traditional chamber absorber, the absorber of the present invention adopts a semi-circular retained partially exposed absorber group on one side of the lighting entrance to collect reflected sunlight that cannot enter the cavity due to the limited opening angle of the cavity, thereby expanding the mirror field area and improving the efficiency of solar energy utilization.

[0017] (3) Compared with the traditional absorption tower, the present invention arranges two absorbers in one absorption tower, and the light windows of the absorbers face the near-sun side and the far-sun side respectively. Combined with the semi-circular exposed heat absorber on the same side as the light window and the heat absorber group in the cavity, the absorption tower can collect reflected sunlight from all around. The concentrating mirror field can be arranged in a circular or elliptical shape around the absorption tower, making up for the defect that the single cavity absorber can only arrange the mirror field on one side of the absorption tower. Combined with the efficient energy capture of the absorber, the land area required for producing unit electricity can be reduced by nearly 52% (m 2 / GWh), significantly reducing the land cost of solar power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the top view of the structure of the novel cavity absorber of the present invention;

[0019] Figure 2 It is a top view schematic diagram of the novel cavity absorber of the present invention receiving solar radiation;

[0020] Figure 3 It is a schematic diagram of a light-collecting and heat-absorbing system with double absorbers of the present invention;

[0021] Figure 4 is a schematic top view of the structure of the concentrating heliostat field of the present invention;

[0022] Figure 5 It is a schematic diagram of the radiation heat transfer process inside the novel cavity absorber of the present invention;

[0023] Figure 6 It is a schematic diagram of a lighting window of a novel cavity absorber of the present invention;

[0024] Figure 7 It is a schematic diagram of the process of the heat absorbing medium passing through the novel cavity absorber of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described and illustrated below in conjunction with specific embodiments. The embodiments are merely exemplary of the present disclosure and do not define the scope of limitation. The technical features of each embodiment of the present invention may be combined accordingly without conflicting with each other.

[0026] like Figure 1 and Figure 3 As shown, a tower-type solar energy concentrating heat absorption system based on a novel cavity absorber of the present invention comprises an absorption tower and a concentrating mirror field around the absorption tower, wherein the absorption tower comprises two cavity absorbers I and II which are arranged up and down and have the same structure; the present invention divides the concentrating mirror field around the absorption tower into a near-sun side mirror field and a far-sun side mirror field, and the two mirror fields respectively reflect and converge sunlight to the light-facing sides of the two cavity absorbers; the light-facing sides of the two cavity absorbers are opposite.

[0027] like Figure 1 As shown, the main body of the novel cavity absorber of the present invention comprises a cylindrical heat-insulating cavity 4, one half of the cylindrical heat-insulating cavity 4 is used as the light-facing side, an opening for installing a light-collecting window 5 is axially provided in the middle of the light-facing side, and an exposed heat-absorbing pipe group 1 is arranged on the outer wall surface of the light-facing side, a heat-absorbing coating 3 is coated on the inner wall surface of the heat-insulating cavity, and an internal heat-absorbing pipe group 2 is arranged in the inner area of ​​the heat-insulating cavity,

[0028] In a specific embodiment of the present invention, for the convenience of arrangement, a plurality of heat absorbing tubes are arranged in parallel to form a heat absorbing tube row, wherein, in the exposed heat absorbing tube group 1, three heat absorbing tubes form a heat absorbing tube row, and the exposed heat absorbing tube group 1 is composed of 8 groups of heat absorbing tube rows. The opening on the heat preservation cavity 4 is a rectangular opening, and the opening width is the width of two groups of heat absorbing tube rows, and a lighting window 5 is arranged on the opening; the exposed heat absorbing tube group 1 is on the same side as the lighting window 5, and the exposed heat absorbing tube group 1 includes a total of 24 heat absorbing tubes, each of which has an outer diameter of 60 mm, and each heat absorbing tube is closely arranged; each heat absorbing tube row is arranged on the outer wall surface of the heat preservation cavity 4 except the lighting window, and is only arranged on the semi-circular wall surface on one side of the lighting window. In this embodiment, there are 4 groups of heat absorbing tube rows on each side of the lighting window. The internal heat absorption tube group 2 is arranged inside the insulation cavity 4, which consists of 18 groups of heat absorption tube rows, each group of heat absorption tube rows includes 2 heat absorption tubes, and the outer diameter of each heat absorption tube is 40mm; the heat absorption tube rows are arranged in a circular manner, with 10 groups of heat absorption tube rows arranged in each half circle, and 8 groups of heat absorption tube rows are arranged in the half circle on one side of the light window, that is, no heat absorption tubes are arranged at the position opposite to the opening of the insulation cavity, and an opening with the width of two groups of heat absorption tubes is reserved to ensure that the sunlight passing through the light window can be irradiated on most of the heat absorption tubes of the heat absorber group 2 more evenly; at the same time, the internal heat absorption tube group 2 is arranged in a circular manner in the cavity to limit the heat radiation dissipation and make the heat absorption tubes evenly heated, and each group of heat absorption tube rows are arranged at intervals with a spacing distance of 0.3m, and the same interval is also reserved between each heat absorption tube and the inner wall of the insulation cavity to promote radiation heat exchange between the heat absorption tubes and between the heat absorption tube and the heat absorption coating 3 on the inner surface of the insulation cavity, thereby reducing heat radiation dissipation.

[0029] The light-facing sides of the two cavity heat absorbers of this embodiment are opposite, and the light-collecting openings face in opposite directions; the light-facing sides of the two cavity heat absorbers respectively obtain the sunlight reflected and gathered by the concentrator field on the side they face. The exposed heat absorption pipe group is only arranged on the half-circle of the light-facing side of the heat preservation cavity to reduce the heat radiation loss caused by the exposure of the heat absorption pipe; the heat absorption pipes of the internal heat absorption pipe group and the exposed heat absorption group are arranged along the axial direction of the heat preservation cavity, and the exposed heat absorption group is connected to the internal heat absorption pipe group.

[0030] The surfaces of the heat absorbing tubes of the internal heat absorbing tube group 2 and the exposed heat absorbing tube group 1 are sprayed with heat absorbing paint; when working, the heat absorbing medium first enters the exposed heat absorbing group 1 on the light side from bottom to top for preheating, and the exposed heat absorbing group is arranged with large-diameter heat absorbing tubes; then the heat absorbing medium is further heated to a higher temperature through the internal heat absorbing tube group 2, and the internal heat absorbing tube group 2 is arranged with small-diameter heat absorbing tubes to keep the heat absorbing area consistent with that of the exposed heat absorbing group 1.

[0031] In a specific embodiment, the heat-absorbing coating applied on the inner wall of the insulation cavity 4 is consistent with the absorption coating on the surface of the heat-absorbing tube; its composition consists of high-temperature resistant resin, light-absorbing pigment, solvent, dispersant and filler, with a mass fraction ratio of 22%:5%:57%:6%:10%, wherein the high-temperature resistant resin is vinyl cage polysilsesquioxane; the light-absorbing pigment is a mixture of copper oxide, ferrosoferric oxide and manganese oxide nanoparticles, with a mass fraction of 1:1:1; the solvent is methyl acetone; the dispersant is a wetting dispersant DISPERSANT-2070; the filler is rare earth yttrium; the coating thickness is 30μm, with an absorptivity of more than 90% and an emissivity of less than 30%. The insulation cavity is composed of hard insulation materials on both sides (such as ceramic fiberboard or nano aerogel insulation board) and a filler layer in the middle (such as high-temperature rock wool and aluminum silicate refractory fiber wool), and a metal plate is installed outside the hard insulation material layer on the outside of the insulation cavity; the insulation cavity wraps the internal heat absorption pipe group without exposing it to reduce heat radiation dissipation.

[0032] Attached Figure 2 A top view of a new type of cavity absorber absorbing solar radiation is given; Figure 3 A schematic diagram of the concentrating heat absorption system consisting of an absorption tower with double absorbers and a mirror field is given; Figure 4 A top view of the heliostat structure in a circular concentrator field is given. Figure 2 , 3 As shown in Figure 4, a new cavity absorber is responsible for receiving the solar radiation reflected by the semicircular mirror field on one side of the circular mirror field. The opening angle of the outer expansion surface of the lighting window of the new cavity absorber is θ. Based on the internal heat absorption pipe group 2 with less heat radiation dissipation in the insulation cavity, the main heat absorption link is provided. The opening angle θ is selected to be 120°, so that most of the solar radiation reflected by the mirror field can be captured by the lighting window. The two semicircular mirror fields are respectively provided with the first fan-shaped mirror field 6 with the center angles of θ1 and θ2, and θ=θ1=θ2 is satisfied. The second fan-shaped mirror field 7 is the two mirror fields in the semicircular mirror field except the first fan-shaped mirror field 6, and the center angles thereof are (180°-θ) / 2=30°. The solar radiation reflected by the first fan-shaped mirror field 6 is received by the lighting windows of the two absorbers respectively, and irradiates the internal heat absorption pipe group 2 inside the cylindrical cavity. The two parts of the solar radiation reflected by the second fan-shaped mirror field 7 are respectively irradiated to the semicircular exposed heat absorption group 1 on both sides of the lighting window. Since the area of ​​the daylighting window in the novel cavity absorber is smaller than the receiving area of ​​the absorber, the first fan-shaped mirror field 6 uses small-sized heliostats to ensure that the daylighting window can capture as much sunlight reflected by the fan-shaped mirror field as possible. The second fan-shaped mirror field 7 uses large-sized heliostats corresponding to the receiving area of ​​the half-circle exposed heat absorption group 1.

[0033] The central absorption tower includes two identical new cavity absorbers I and II, which are coaxially arranged up and down. The two absorbers each have an exposed heat absorption group 1 and a lighting window on one side facing the near-sun side and the far-sun side, respectively, so that the two absorbers receive solar radiation reflected by the semicircular mirror fields on both sides. Compared with the traditional cavity absorber, the structure of the new cavity absorber and the arrangement of the double absorbers expand the layout range of the heliostat field.

[0034] Attached Figure 5 The schematic diagram of the radiation heat transfer process inside the new cavity absorber is given. Figure 5 As shown, the internal heat absorbing tube group 2 inside the heat preservation cavity 4 first receives the solar radiation through the lighting window 5, and performs light-heat conversion through the high-performance selective absorption coating sprayed on the surface; due to its own high temperature, the heat absorbing tube will emit a heat radiation flow to the outside. Due to the circular arrangement of the internal heat absorber group and the cylindrical chamber structure of the heat preservation cavity, the heat radiation emitted by the heat absorbing tube can be effectively reabsorbed by other heat absorbing tubes and the heat absorbing coating 3 on the inner wall of the heat preservation cavity, reducing the heat radiation loss of the heat absorber group. In addition, the heat absorbing coating 3 heats up after receiving the heat radiation of the heat absorbing tube, and also generates a certain amount of heat radiation flow to the outside. These heat radiations are absorbed by the heat absorbing tubes outside a certain interval, and then heat the backlight side of the heat absorbing tube, so that the heat flow distribution of each heat absorbing tube in the internal heat absorbing tube group 2 is more uniform, reducing the surface stress of the tube. The selective absorption coating has an absorptivity of more than 90% and an infrared emissivity of less than 35%, ensuring good light-heat conversion performance.

[0035] Attached Figure 6 The structural schematic diagram of the new cavity absorber lighting window is given. Figure 6 As shown, according to the opening size of the thermal insulation cavity, the lighting window is composed of a stepped outward-expanding reflective surface 5-1 and a rectangular reflective channel 5-2. The solar radiation reflected by the fan-shaped mirror field 6 can directly enter the lighting channel, or enter the cavity after secondary reflection by the reflective surfaces 5-1 and 5-2. The outward-expanding reflective surface 5-1 and the reflective channel 5-2 have high reflective performance, and are arranged with a composite high-reflective material composed of a glass substrate and a silver-plated or aluminum-plated emission layer, with a high reflectivity of 92% to 94%. The outward-expanding secondary reflective surface is connected to the light-facing side of the rectangular channel, and its opening angle is 110° to 120°; the length of the lighting opening is consistent with the overall height of the absorber, and the width is 1 / 15 to 1 / 10 of the circumference of the thermal insulation cavity.

[0036] Attached Figure 7 The schematic diagram of the process of the heat absorbing medium passing through the new cavity absorber is given. Figure 7As shown, when the heat absorption system is working, the heat absorbing medium such as high temperature molten salt first passes through the exposed heat absorption group 1 on the light side from bottom to top, receives solar radiation to initially increase the temperature, and then passes through each tube row of the internal heat absorption tube group 2 inside the cavity to further increase the heat absorption temperature, and then enters the heat storage system and the subsequent cycle to generate electricity. In terms of structural size, based on the above-mentioned arrangement of the diameter of the internal heat absorption tube group 1 and the internal heat absorption tube group 2, the number of heat absorption tube rows, and the number of single-row heat absorption tubes, it can ensure that the heat absorption area of ​​the two heat absorber groups is equivalent.

[0037] It should be noted that the specific embodiments described in this specification are examples of the inventive structure, and the names of the various structures therein may be different. The structure of the present invention is not limited to the above-mentioned implementation methods. Any equivalent or simple changes made based on the structure or principle of the patent of the present invention should fall within the scope of protection of this application.

Claims

1. A tower solar concentrating heat absorption system based on a novel cavity absorber, characterized in that: The system consists of an absorption tower and a condenser field around the absorption tower; the absorption tower includes two cavity absorbers arranged up and down and having the same structure; Each cavity heat absorber includes a cylindrical heat-insulating cavity, one half of the cylindrical heat-insulating cavity is used as the light-facing side, an opening for installing a light-collecting window is axially opened in the middle of the light-facing side, and an exposed heat-absorbing pipe group is arranged on the outer wall surface of the light-facing side, a heat-absorbing coating is coated on the inner wall surface of the heat-insulating cavity, and an internal heat-absorbing pipe group is arranged in the inner area of ​​the heat-insulating cavity. The light-facing sides of the two cavity heat absorbers are opposite to each other, and the light-collecting openings are in opposite directions; the light-facing sides of the two cavity heat absorbers respectively obtain the sunlight reflected and concentrated by the concentrating mirror field on the side they are facing.

2. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 1 is characterized in that: The exposed heat absorption tube group is only arranged in the half circle of the heat preservation cavity facing the light side to reduce the heat radiation loss caused by the exposure of the heat absorption tube; the heat absorption tubes of the internal heat absorption tube group and the exposed heat absorption tube group are arranged along the axial direction of the heat preservation cavity, and the exposed heat absorption tube group is connected with the internal heat absorption tube group through the working medium conveying pipeline, and the working medium flows to the internal heat absorption tube group after absorbing heat in the exposed heat absorption group.

3. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 1 is characterized in that: The heat absorbing tubes of the internal heat absorbing tube group are evenly distributed in a circle around the central axis of the insulation cavity; there is a certain interval between the internal heat absorbing tube group and the inner wall of the insulation cavity; the heat absorbing coating coated on the inner wall of the insulation cavity is used for secondary absorption of the thermal radiation of the internal heat absorbing tube group, and at the same time, radiation heat exchange is carried out with the internal heat absorbing tube group to heat the backlight part of the internal heat absorbing tube group.

4. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 2 is characterized in that: The surfaces of the heat absorption tubes of the internal heat absorption tube group and the exposed heat absorption tube group are sprayed with heat absorption paint; when working, the heat absorption medium first enters the exposed heat absorption group on the light side from bottom to top for preheating, and the exposed heat absorption group is arranged with large-diameter heat absorption tubes; then the heat absorption medium is further heated to a higher temperature through the internal heat absorption tube group, and the internal heat absorption tube group is arranged with small-diameter heat absorption tubes to keep the heat absorption area consistent with that of the exposed heat absorption group.

5. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 4 is characterized in that: The heat-absorbing coating applied on the inner wall of the insulation cavity is consistent with the absorption coating on the surface of the heat-absorbing tube; the insulation cavity is composed of hard insulation materials on both sides and a filler layer in the middle, and a metal plate is installed outside the hard insulation material layer outside the insulation cavity; the insulation cavity wraps the internal heat-absorbing tube group without exposing it to reduce heat radiation dissipation.

6. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 1 is characterized in that: The daylighting window consists of a rectangular channel and an outward-expanding secondary reflection surface. The outward-expanding secondary reflection surface is connected to the light-facing side of the rectangular channel, and its opening angle is 110° to 130°. The four sides of the rectangular channel and the outward-expanding secondary reflection surface are all coated with high-reflectivity materials to improve the ability to capture reflected light. The length of the daylighting window is consistent with the overall height of the absorber, and the width is 1 / 15 to 1 / 10 of the circumference of the insulation cavity.

7. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 5 is characterized in that: The heat absorbing material has an absorptivity of over 90% and an infrared emissivity of less than 35%.

8. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 6 is characterized in that: The high reflectivity material of the light-collecting opening adopts a composite reflector composed of a glass substrate and a silver-plated or aluminum-plated emission layer.

9. The tower solar concentrating heat absorption system based on the novel cavity absorber according to claim 1 is characterized in that: Two cavity absorbers are arranged up and down on the central axis of the absorption tower. The two cavity absorbers have a lighting window and one side of the exposed heat absorption group facing the near-sun side and the far-sun side of the concentrator field respectively, and receive the solar radiation reflected by the semicircular space concentrator fields on the near-sun side and the far-sun side respectively.

10. A method for utilizing solar energy based on the tower-type solar concentrating heat absorption system according to any one of claims 1 to 9, characterized in that: The steps include: The concentrating mirror field around the absorption tower is divided into a near-sun mirror field and a far-sun mirror field. The two mirror fields respectively reflect and converge sunlight to the light-facing side of the two cavity absorbers. For any side of the mirror field, the heliostats whose central angle is equal to the daylighting opening angle will focus all the reflected sunlight on the daylighting window of the corresponding cavity absorber, and the sunlight reflected by the remaining heliostats on this side of the mirror field will be focused on the exposed heat absorption group of the corresponding cavity absorber and absorbed; The sunlight entering the heat preservation cavity through the lighting window is absorbed by the internal heat absorption tube group and the heat absorption coating on the cavity wall, and the heat radiation flow radiated by the internal heat absorption tube group is absorbed by the heat preservation cavity for the second time, thereby effectively reducing the heat radiation dissipation of the absorber; At the same time, the radiation heat exchange between the inner wall of the heat preservation cavity and the heat absorption tube improves the uniformity of the heat flux distribution of the heat absorption tube; After entering the absorption tower, the heat absorbing medium is split and then passes into a cavity absorber from bottom to top. In each cavity absorber, it absorbs heat by passing through an exposed tube heat absorbing tube group and an internal heat absorbing tube group in turn. After that, the two paths of heat absorbing medium are combined and output from the absorption tower.

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