Solar photo-thermal utilization system based on Fresnel point focusing lens

Abstract

The invention provides a solar photo-thermal utilization system based on a Fresnel point focusing lens, which comprises a heat collecting pipe, the heat collecting pipe is arranged in a cavity type heat collector, the Fresnel point focusing lens is arranged above the cavity type heat collector, the Fresnel point focusing lens and the cavity type heat collector are collinear in axis, and the Fresnel point focusing lens is arranged above the cavity type heat collector. Sunlight penetrates through the Fresnel point focusing lens to be converged in the cavity type heat collector and irradiates on the heat collecting pipe through the cavity type heat collector, and then a working medium in the heat collecting pipe absorbs energy to complete the temperature rising process. By means of the solar photo-thermal utilization system, the condensation ratio can be larger than 100, the working temperature of the heat collector is 250 DEG C or above, and the problem that the temperature of a traditional solar utilization mode is low can be effectively solved. Meanwhile, the Fresnel lens has the advantages of being high in optical efficiency, small in size, light in weight and compact in structure, miniaturization and distributed photo-thermal utilization can be achieved, and the problems that an existing photo-thermal power generation derivative system is high in cost, complex in system and large in economic scale are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar thermal utilization, and in particular relates to a solar thermal utilization system based on a Fresnel point-focusing lens. Background Art

[0002] As a renewable energy source with rich reserves, clean and pollution-free, solar energy has received more and more extensive attention. Since the solar radiation energy flux density reaching the ground is very low, in order to obtain a high-temperature medium, a concentrating solar power system must be used for solar thermal power generation. According to the different devices for collecting sunlight, solar thermal power generation is generally divided into trough type, tower type, linear Fresnel type, and dish-Stirling and other technical routes. Among them, the tower type and the dish type belong to point-focusing technologies, and the trough type and the linear Fresnel type belong to line-focusing technologies. At present, except for the dish-Stirling technology, power plants operating commercially with the other three solar thermal power generation technical routes exist both at home and abroad. The energy demand in the eastern region of China is huge, the pressure of carbon emission reduction is heavy, and the prospect of renewable energy substitution is broad. The application of solar thermal utilization technology in the industrial field has great potential for energy conservation and emission reduction. Most of the industrial heat uses temperatures between 80°C and 180°C. The temperature of traditional solar thermal utilization methods (such as domestic solar water heaters, heating, solar swimming pools) is relatively low. The existing solar thermal utilization methods derived from solar thermal power generation aim at high power generation efficiency and stability, and have problems such as complex systems, large heat dissipation, high investment, high operating costs, and the need for a large economic scale, and are not perfect in themselves. This makes the application adaptability of the existing solar thermal utilization methods in the eastern region poor. Summary of the Invention

[0003] In view of this, the present invention aims to overcome the defects in the prior art and proposes a solar thermal utilization system based on a Fresnel point-focusing lens to solve the problems of high cost, complex system, large economic scale required by the existing solar thermal power generation-derived system, and low temperature of traditional solar utilization methods, which are poorly adaptable in the eastern region.

[0004] To achieve the above object, the technical solution of the present invention is realized as follows:

[0005] A solar thermal utilization system based on a Fresnel point-focusing lens includes a heat collection tube installed in a cavity type collector. A Fresnel point-focusing lens is provided above the cavity type collector, and the axis of the Fresnel point-focusing lens is collinear with that of the cavity type collector. Sunlight passes through the Fresnel point-focusing lens and converges on the cavity type collector, and then irradiates the heat collection tube through the cavity type collector. Then, the working medium in the heat collection tube absorbs energy to complete the temperature rise.

[0006] Furthermore, the internal shape of the cavity collector is conical, compound parabolic or dish-shaped.

[0007] Furthermore, a transparent cover plate is provided on the upper side of the cavity collector.

[0008] Furthermore, the cavity type collector adopts a vacuum form.

[0009] Furthermore, the Fresnel point focusing lens is circular, oval, rectangular or square.

[0010] Furthermore, the heat collecting tube is made of metal.

[0011] Furthermore, a functional coating is covered on the surface of the metal tube wall of the heat collecting tube.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] Applying the solar energy photothermal utilization system provided by the present invention, with the help of the Fresnel point focusing lens and the cavity type collector, a concentration ratio greater than 100 and a collector working temperature above 250 °C can be achieved, effectively solving the problem of low temperature in traditional solar energy utilization methods. At the same time, the Fresnel lens has advantages such as high optical efficiency, small volume, light weight, compact structure, and low manufacturing cost, and can realize miniaturized and distributed photothermal utilization, solving the problems of high cost, complex system, and large economic scale required by existing solar thermal power generation derivative systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0015] Figure 1 is a schematic diagram of the system of the present invention;

[0016] Figure 2 is a schematic diagram of the heat collecting tube part in the embodiment of the present invention.

[0017] Wherein the reference numerals are:

[0018] 1 - Fresnel point focusing lens; 2 - cavity type collector; 3 - heat collecting tube; 4 - transparent cover plate; 5 - functional coating; 6 - metal tube wall; 7 - working medium. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0022] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0023] A solar thermal utilization system based on a Fresnel point-focusing lens, as Figure 1 and Figure 2 shown, includes a heat collection tube 3, which is installed in a cavity-type collector 2. A Fresnel point-focusing lens 1 is provided above the cavity-type collector. The axes of the Fresnel point-focusing lens and the cavity-type collector are collinear, and the relative position between the two is determined by the concentration ratio. For example, the designed focal length of the Fresnel point-focusing lens is f, the designed concentration ratio of the system is CR, and the relative distance h between the Fresnel point lens and the upper surface of the cavity collector is Sunlight passes through the Fresnel point-focusing lens and converges on the cavity-type collector, and then irradiates the heat collection tube through the cavity-type collector. Furthermore, the working medium 7 in the heat collection tube absorbs energy to complete the heating process.

[0024] A transparent cover plate 4 is provided on the upper side of the cavity collector. Sunlight passes through the Fresnel point-focusing lens and converges on the cavity collector, and then irradiates the heat collection tube through the transparent cover plate of the cavity collector. In addition, the internal shape of the cavity collector is conical, compound parabolic or dish-shaped. In addition, the cavity collector adopts a vacuum form. The Fresnel point-focusing lens is circular, oval, rectangular or square.

[0025] The heat collection tube is made of metal. In a further improved solution, a functional coating 5 is covered on the surface of the metal tube wall 6 of the heat collection tube. The working medium in the heat collection tube can be water, and steam can be directly produced by using water. As an example, the functional coating adopts a solar selective absorption coating, which can efficiently absorb and converge solar energy and reduce the loss of solar energy reflection.

[0026] Applying the solar thermal utilization system provided by the present invention, with the help of the Fresnel point-focusing lens and the cavity collector, a concentration ratio greater than 100 and a collector working temperature above 250 °C can be achieved, effectively solving the problem of low temperature in the traditional solar energy utilization method. At the same time, the Fresnel lens has the advantages of high optical efficiency, small volume, light weight, compact structure and low manufacturing cost, and can realize miniaturized and distributed solar thermal utilization, solving the problems of high cost, complex system and large economic scale required by the existing solar thermal power generation derivative system. In addition, it can solve the environmental constraints existing in the low concentration ratio of the existing trough type and linear Fresnel and tower type concentration, and enhance the adaptability of the solar thermal utilization technology in the eastern region.

[0027] In an optional embodiment, all components in the solar thermal utilization system of the present invention are installed on a bracket, and a light tracker is installed on the bracket. The bracket can rotate around two-dimensional axes (vertical axis, horizontal axis) to realize two rotational degrees of freedom. The light tracker judges the position of the sun according to the difference in light intensity in different regions of the sky and drives the motor to rotate the bracket for tracking. Therefore, the solar thermal utilization system provided by the present invention has the ability of two-axis light tracking, can efficiently track sunlight and improve the solar energy utilization efficiency.

[0028] Therefore, with the characteristics of simple structure, convenient arrangement and low cost of the present invention, sunlight passes through the Fresnel point-focusing lens and converges on the cavity collector, irradiates the heat collection tube through the transparent cover plate of the cavity collector, and the working medium in the heat collection tube absorbs energy to complete the heating process. This high-concentration ratio solar thermal utilization system can be applied to the field of solar thermal energy, and can effectively solve the problems of high cost, complex system, large economic scale required by the existing solar thermal power generation derivative system and low temperature in the traditional solar energy utilization method, which are poorly adaptable in the eastern region.

[0029] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A solar thermal utilization system based on Fresnel point focusing lens, characterized by: It includes a heat collecting tube, which is installed in a cavity collector. A Fresnel point focusing lens is arranged above the cavity collector. The Fresnel point focusing lens and the axis of the cavity collector are collinear. Sunlight passes through the Fresnel point focusing lens and converges on the cavity collector. It is then irradiated on the heat collecting tube through the cavity collector, and then the working fluid in the heat collecting tube absorbs energy to complete the heating.

2. According to claim 1, a solar thermal utilization system based on Fresnel point focusing lens is characterized in that: The internal shape of the cavity collector is conical, compound parabolic or dish-shaped.

3. The solar thermal utilization system based on Fresnel point focusing lens according to claim 1, characterized in that: A transparent cover plate is provided on the upper side of the cavity collector.

4. The solar thermal utilization system based on Fresnel point focusing lens according to claim 1, characterized in that: The cavity type heat collector adopts a vacuum form.

5. The solar thermal utilization system based on Fresnel point focusing lens according to claim 1, characterized in that: The Fresnel point focusing lens is circular, elliptical, rectangular or square.

6. The solar thermal utilization system based on Fresnel point focusing lens according to claim 1, characterized in that: The heat collecting tube is made of metal.

7. A solar thermal utilization system based on Fresnel point focusing lens according to any one of claims 1 to 6, characterized in that: The metal tube wall surface of the heat collecting tube is covered with a functional coating.

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