Concentrating solar thermal power generation device assisted by composite PCM (Pulse Code Modulation) material

Abstract

The invention discloses a condensation type solar thermal power generation device assisted by a composite PCM material. The condensation type solar thermal power generation device comprises a condensation and heat collection subsystem, a heat energy guide and storage subsystem, a temperature difference power generation subsystem and a cooling subsystem. Through the coupling design of the heat energy guiding and storing subsystem, the thermoelectric power generation subsystem abandons the vertical lamination distribution form of a traditional STEG, and adopts a wrapping type device structure, so that the maximum output power of the STEG system under the unit light receiving area is remarkably improved. Meanwhile, the light condensation and heat collection subsystem adopts a light condenser and a spectrum selective absorption device, so that the light condensation rate and the heat absorption performance are improved; the cooling subsystem is provided with a heat conduction interface material-liquid cooling plate-heat conduction interface material sandwich structure, and the temperature difference between the cold end face and the hot end face of the thermoelectric power generation subsystem is increased, so that the power generation efficiency of the device is improved. According to the device, the problem of instability of existing solar power generation is solved, the energy utilization rate is improved through an innovative device structure, and the technical problem that the thermoelectric conversion efficiency of an STEG system is low is solved.

Description

Technical Field

[0001] The present invention relates to the technical fields of concentrated solar energy utilization, PCM energy storage and temperature difference power generation, and in particular to a concentrated solar thermal power generation device assisted by a composite PCM material. Background Art

[0002] Concentrated solar energy technology refers to the use of mirrors or lenses to concentrate and focus the energy in sunlight to directly use solar radiation to heat fluids. According to different concentration methods, the structure of concentrated solar energy is mainly divided into four categories: Fresnel type, tower type, dish type and trough type. However, no matter what form of application, its power generation will be affected by the inherent intensity fluctuations of solar energy. This requires an integrated thermal energy storage system to absorb and store solar energy as much as possible when solar energy is sufficient, and release it when needed to improve the efficiency, reliability, economy and dispatchability of the energy system.

[0003] In existing solar thermal power systems using PCM, the thermal conductivity of most PCMs generally does not exceed 1 Wm -1 K -1 , which seriously restricts the heat transfer effect of block PCMs. It causes problems such as low thermal energy storage efficiency, low light-to-heat conversion efficiency, energy waste, and may cause damage to the thermoelectric power generation device due to local overheating of the PCM. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present application proposes a concentrating solar thermal power generation device assisted by a composite PCM material, which can improve energy utilization and smooth the output power of the device, reduce fluctuations in solar power generation, and improve the power generation quality of the system.

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

[0006] A concentrating solar thermal power generation device assisted by composite PCM materials, comprising: a concentrating heat collection subsystem, a heat conduction and storage subsystem, a temperature difference generation subsystem and a cooling subsystem;

[0007] The light-collecting and heat-collecting subsystem comprises a Fresnel lens, a vacuum chamber and a spectrally selective absorber; the Fresnel lens is connected to the spectrally selective absorber through the vacuum chamber, and the Fresnel lens collects light to the spectrally selective absorber;

[0008] The thermal energy conducting and storing subsystem comprises a composite PCM material, a side-emitting optical fiber and a PCM container, wherein the composite PCM material is filled in the PCM container, and the spectrally selective absorber is coated on one end face of the composite PCM material; one end of the side-emitting optical fiber passes through the spectrally selective absorber and extends into the vacuum chamber, and the remaining part of the side-emitting optical fiber is embedded in the composite PCM material;

[0009] The thermoelectric power generation subsystem includes a TEG device, which is embedded on the outer surface of the PCM container to generate electricity by thermoelectric power;

[0010] The temperature difference generating subsystem is equipped with a cooling subsystem.

[0011] Furthermore, a plurality of the side-emitting optical fibers are arranged in parallel in the PCM container, and the side-emitting optical fibers are evenly distributed in the PCM container.

[0012] Furthermore, a temperature difference power generation subsystem is provided on at least one side surface of the PCM container.

[0013] Furthermore, the temperature difference generating subsystems are connected in series or in parallel.

[0014] Furthermore, the cooling subsystem includes a liquid cooling plate and a thermal interface material.

[0015] Furthermore, the thermal interface material is in contact with the outer wall of the TEG device, and the liquid cooling plate is embedded in the thermal interface material to form a sandwich structure of "thermal interface material-liquid cooling plate-thermal interface material".

[0016] Furthermore, the side walls of the PCM container are detachably connected to each other.

[0017] Furthermore, the side wall of the PCM container is made of 304 stainless steel.

[0018] Furthermore, fireproof fibers are provided at the bottom of the PCM container.

[0019] Furthermore, the outer surface of the Fresnel lens is a convex smooth curved profile, and the inner surface of the Fresnel lens is divided into an inner domain and an outer domain. The inner domain is designed using the refraction principle and the edge light principle, and the outer domain is designed using the total internal reflection principle to converge the light.

[0020] Beneficial effects of the present invention:

[0021] (1) Improving energy conversion efficiency: The design of the Fresnel lens can achieve efficient convergence and uniform distribution of light, thereby improving the focusing ratio; the vacuum chamber can reduce heat loss caused by air convection; the application of the spectrally selective absorber ensures that more bands of sunlight are effectively absorbed and converted into thermal energy, thereby reducing the loss of solar energy; the installation method of the TEG device improves the power generation capacity of the device per unit light receiving area; the cooling system maintains the low temperature of the cold source of the TEG device, thereby improving the power generation efficiency of the device.

[0022] (2) Optimizing thermal energy storage and utilization: Due to the high heat storage capacity of the composite PCM material, the present invention can store a large amount of thermal energy when the solar energy is sufficient and release it when needed, thereby improving the efficiency and reliability of the system. The side-emitting optical fiber adopts a strategy of mainly guiding light and supplementing heat transfer inside the composite PCM material, realizing three-dimensional heating of the composite PCM material in the spatial dimension, optimizing the overall thermal conductivity, significantly expanding the effective area of ​​light-to-heat conversion, and ensuring uniform distribution and efficient utilization of thermal energy.

[0023] (3) Enhanced system stability: Through the design of the thermal energy storage subsystem, the present invention can stabilize the operating temperature of the TEG device when the solar energy fluctuates, smooth the output power of the power generation system and improve the power generation quality, reduce the decrease in power generation efficiency caused by temperature fluctuations, and further detect the temperature of the PCM material and the liquid cooling plate, predict the power generation change of the device, thereby achieving precise control of energy output. In addition, the independent disassembly design of the PCM container makes maintenance and replacement more convenient, and improves the long-term stability of the system.

[0024] (4) Enhanced system safety: The fireproof fiber bottom design of the PCM container effectively prevents heat from escaping from the bottom, reducing the risk of fire. At the same time, the sandwich structure design of the cooling subsystem ensures that the coolant will not leak into the TEG module and circuit connection parts, improving the safety of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the main structure of the device;

[0026] Figure 2 This is a schematic diagram of the improved Fresnel lens focusing light path;

[0027] Figure 3 This is a schematic diagram of the improved Fresnel lens structure model;

[0028] Figure 4 It is a schematic diagram of the downstream system model;

[0029] Figure 5 It is a schematic diagram of the PCM container model;

[0030] Figure 6 This is a schematic diagram of the "sandwich" structure of the cooling system;

[0031] Figure 7 The diagram is a schematic diagram of the system workflow.

[0032] Description of the drawings: 1. Fresnel lens, 2. Vacuum chamber, 3. Spectrally selective absorber, 4. Composite PCM material, 5. Side-emitting optical fiber, 6. PCM container, 7. Fireproof fiber, 8. TEG equipment, 9. Thermal interface material, 10. Liquid cooling plate. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0034] In conjunction with Figure 6, the present invention provides a concentrating solar thermal power generation device assisted by a composite PCM material. According to the function, the device can be divided into a concentrating heat collection subsystem, a heat conduction and storage subsystem, a temperature difference generation subsystem, and a cooling subsystem. The structure is shown in the attached figure. Figure 1 To facilitate the description and understanding of the device structure proposed by the present invention, the device as a whole can also be divided into an upstream system and a downstream system according to the layout.

[0035] The upstream system is composed of the light-collecting and heat-collecting subsystem. The light-collecting and heat-collecting subsystem is composed of a Fresnel lens 1, a vacuum chamber 2 and a spectrally selective absorber 3. The Fresnel lens 1 and the spectrally selective absorber 3 are connected through the vacuum chamber 2. The Fresnel lens 1 refracts light to the spectrally selective absorber 3 using a single groove, and each groove has its own focus, which evenly collects the direct light at the receiving end, as shown in the attached figure. Figure 2 shown.

[0036] In this embodiment, the structure design of the Fresnel lens 1 includes an outer surface and an inner surface. Figure 3 As shown, the outer surface is a convex smooth curved surface profile. The outer surface not only absorbs direct light, but also enhances the absorption of diffuse light; in addition, the outer surface profile of the Fresnel lens 1 can also reduce surface dust and protect the surface structure.

[0037] The inner surface of the Fresnel lens 1 is used to converge light and evenly distribute the light on the receiving end face of the spectrally selective absorber 3. The inner surface of the Fresnel lens 1 is divided into an inner domain and an outer domain. The inner domain is designed using the refraction principle and the edge light principle, and the outer domain is designed using the total internal reflection principle to reduce optical loss. The theoretical geometric focusing ratio of the Fresnel lens 1 structure can reach more than 900 times, which can make the converged light more evenly distributed on the receiving end face.

[0038] The vacuum chamber 2 is used to connect the Fresnel lens 1 and the spectrally selective absorber 3, and the interior is evacuated. The vacuum environment formed by the closed chamber can reduce the heat loss caused by air convection.

[0039] The spectrally selective absorber 3 is sprayed on the upper surface of the composite PCM material 4 to play the role of spectrally selective absorption and efficient light-to-heat conversion. The light concentrated by the Fresnel lens 1 is converted into heat energy here, thereby improving the light-to-heat conversion efficiency.

[0040] The upstream and downstream systems are divided by the spectrally selective absorber 3, and the downstream system is composed of a heat conduction and storage subsystem, a temperature difference generation subsystem and a cooling subsystem.

[0041] The thermal energy conducting and storing subsystem is composed of a composite PCM material 4, a side-emitting optical fiber 5 and a PCM container 6. The PCM container 6 is filled with the composite PCM material 4, and the side-emitting optical fiber 5 is embedded in the composite PCM material 4. The upper end of the side-emitting optical fiber 5 penetrates the spectrally selective absorber 3 and extends into the vacuum chamber 2.

[0042] like Figure 4 As shown, the upper end of the side-emitting optical fiber 5 can guide part of the incident light in the vacuum chamber 2 into the interior of the composite PCM material 4 for light-to-heat conversion, and at the same time, by utilizing the property that the thermal conductivity is greater than that of the composite PCM material 4, the thermal conductivity rate of the composite PCM material 4 is increased to avoid uneven temperature of the bulk PCM material. The side-emitting optical fiber 5 realizes three-dimensional heating of the composite PCM material 4 in the spatial dimension, optimizes the overall thermal conductivity, and significantly expands the effective area of ​​light-to-heat conversion.

[0043] PCM container 6 Figure 5 As shown, the composite PCM material 4 is contained inside, the side wall of the PCM container 6 is made of 304 stainless steel, which has good thermal conductivity and corrosion resistance, and the bottom is made of fireproof fiber 7, thereby preventing heat from escaping from the bottom. The PCM container 6 can be disassembled independently, which is convenient for replacing the phase change material, prolonging the service life of the system, saving energy and protecting the environment, and reducing the carbon footprint of the device.

[0044] The thermoelectric power generation subsystem includes a TEG device 8. One side of the TEG device 8 is in direct contact with the outer surface of the PCM container 6, and the contact end is the hot end surface; the other side of the TEG device 8 is the cold end surface, thereby realizing thermoelectric power generation. The PCM container 6 has four side surfaces, and four TEG devices 8 can be independently installed on each side. The four TEG devices 8 are connected in series or in parallel.

[0045] The cooling subsystem includes a liquid cooling plate 10 and a thermal interface material 9, wherein the liquid cooling plate 10 is embedded in the thermal interface material 9 to form a sandwich structure of "thermal interface material 9-liquid cooling plate 10-thermal interface material 9"; and the thermal interface material 9 on one side contacts the cold end surface of the TEG device 8. Figure 6 As shown, the coolant can be prevented from leaking and contacting the TEG module 8 and the circuit connection parts.

[0046] like Figure 7The working principle of the present invention is shown as follows: solar radiation energy is the energy input of the system. The light is collected by the Fresnel lens 1 and evenly distributed on the spectrum selective absorber 3, where the most important light-to-heat conversion of the device is performed. The spectrum selective absorber 3 conducts heat downward to the composite PCM material 4. At the same time, the side-emitting optical fiber 5 itself has a higher thermal conductivity, which performs three-dimensional heating on the composite PCM material 4, and conducts part of the light to the inside of the composite PCM material 4 for light-to-heat conversion, so that its temperature is evenly increased. The composite PCM material 4 is the core of the device for conducting and storing thermal energy. As the hot end face of the TEG device 8 power generation system, the phase change latent heat is used to maintain the TEG device 8 at a suitable operating temperature. The TEG device 8 is the core component of the device, where thermal energy is converted into electrical energy. The cooling system cools the cold end face of the TEG device 8 to improve the power generation efficiency.

[0047] The above embodiments are only used to illustrate the design ideas and features of the present invention, and their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The protection scope of the present invention is not limited to the above embodiments. Therefore, any equivalent changes or modifications made based on the principles and design ideas disclosed by the present invention are within the protection scope of the present invention.

Claims

1. A concentrating solar thermal power generation device assisted by a composite PCM material, characterized in that: Including: light-collecting and heat-collecting subsystem, heat-conducting and storing subsystem, temperature-difference generating subsystem and cooling subsystem; The light-collecting and heat-collecting subsystem comprises a Fresnel lens (1), a vacuum chamber (2) and a spectrally selective absorber (3); the Fresnel lens (1) is connected to the spectrally selective absorber (3) via the vacuum chamber (2), and the Fresnel lens (1) collects light onto the spectrally selective absorber (3); The thermal energy conduction and storage subsystem comprises a composite PCM material (4), a side-emitting optical fiber (5) and a PCM container (6); the composite PCM material (4) is filled in the PCM container (6); the spectrally selective absorber (3) is coated on one end face of the composite PCM material (4); one end of the side-emitting optical fiber (5) passes through the spectrally selective absorber (3) and extends into the vacuum chamber (2); the remaining part of the side-emitting optical fiber (5) is embedded in the composite PCM material (4); The temperature difference power generation subsystem comprises a TEG device (8), and the TEG device (8) is embedded on the outer surface of the PCM container (6), thereby generating electricity by temperature difference; The temperature difference generating subsystem is equipped with a cooling subsystem.

2. A concentrating solar thermal power generation device assisted by composite PCM materials according to claim 1, characterized in that: A plurality of the side-emitting optical fibers (5) are arranged in parallel in the PCM container (6); the side-emitting optical fibers (5) are evenly distributed in the PCM container (6).

3. A concentrating solar thermal power generation device assisted by composite PCM materials according to claim 2, characterized in that: A temperature difference power generation subsystem is arranged on at least one side surface of the PCM container (6).

4. A concentrating solar thermal power generation device assisted by composite PCM materials according to claim 3, characterized in that: The temperature difference generating subsystems are connected in series or in parallel.

5. The concentrating solar thermal power generation device assisted by composite PCM material according to claim 1, characterized in that: The cooling subsystem comprises a liquid cooling plate (10) and a thermally conductive interface material (9).

6. A concentrating solar thermal power generation device assisted by composite PCM materials according to claim 5, characterized in that: The thermal interface material (9) is in contact with the outer wall of the TEG device (8), and the liquid cooling plate (10) is embedded in the thermal interface material (9), forming a sandwich structure of "thermal interface material (9) - liquid cooling plate (10) - thermal interface material (9)".

7. The concentrating solar thermal power generation device assisted by composite PCM materials according to claim 1, characterized in that: The side walls of the PCM container (6) are detachably connected to each other.

8. The concentrating solar thermal power generation device assisted by composite PCM materials according to claim 1, characterized in that: The side wall of the PCM container (6) is made of 304 type stainless steel.

9. The concentrated solar thermal power generation device assisted by composite PCM materials according to claim 1, characterized in that: The bottom of the PCM container (6) is provided with fireproof fibers (7).

10. A concentrating solar thermal power generation device assisted by a composite PCM material according to any one of claims 1 to 9, characterized in that: The outer surface of the Fresnel lens (1) is a convex smooth curved surface profile, and the inner surface of the Fresnel lens (1) is divided into an inner domain and an outer domain, the inner domain is designed using the refraction principle and the edge light principle, and the outer domain is designed using the total internal reflection principle to converge light.

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