WO2014029259A1

WO2014029259A1 - Solar concentrating and collecting line-focus fresnel lens

Info

Publication number: WO2014029259A1
Application number: PCT/CN2013/080372
Authority: WO
Inventors: 陈鼎凌
Original assignee: Chen Dinglin
Priority date: 2012-08-22
Filing date: 2013-07-30
Publication date: 2014-02-27
Also published as: CN103630951B; CN103630951A

Abstract

A solar concentrating and collecting line-focus Fresnel lens. Distribution of microprism elements (2) in each microprism cluster of the lens follows the following principle: middle parts of the microprism elements have equal widths, and outer parts of the microprism elements have equal heights; in addition, the middle parts are relatively wide (the widths range from 3 to 5 mm), and the outer parts are relatively narrow (the widths range from 1 to 3 mm), so that the thickness of a substrate is more uniform, structural stability is significantly improved, and the total number of the microprism elements (2) and the total number of vertical shearing points are greatly reduced, thereby lowering the processing difficulty and improving convergence efficiency. The lens can concentrate sunlight into a focal line more efficiently, and can be used as a condenser of a high-temperature solar collector, so as to provide a green high-temperature heat source for domestic and industrial fields such as heating, air conditioning, textile, printing and dyeing, papermaking, rubber, sea water desalination, and sewage purification.

Description

Concentrating collector Fresnel line focal lens

The invention relates to a concentrating and collecting Fresnel line focus lens, belonging to the field of solar energy and high temperature application, and the lens can be more efficiently concentrated into line focus by the lens, and is used as a concentrator of the solar high temperature collector. High temperature is generated on the focal line and can be efficiently collected, exchanged and exported through existing solar vacuum collector tubes for life and industrial fields such as heating, air conditioning, textile, printing and dyeing, paper making, rubber, desalination, sewage purification, etc. Green and high temperature heat source. Background technique

Optical concentrating can be divided into two types: reflection concentrating and refracting concentrating. The former is a front focus type (the focus is between the light source and the mirror), and the latter is a back focus type (the focus is on the back side of the lens). Light. The research direction of refractive concentrating technology is mainly concentrated on the Fresnel lens. This was first discovered by the French scientist Augustin. Fresnel, who first used the lens in 1822 and applied it to the concentrating lens of the beacon beacon light, creating a flat spotlight. The first of its kind. From the early 1970s to the end of the 1990s, the solar industry and many universities and optical research institutes carried out in-depth and long-term research and practice on Fresnel lenses for solar installations, such as Huazhong University of Science and Technology and Shaoyang Glass Factory. Co-developed a wide range of glass-based Fresnel-line lens; National Solar Energy Research Institute and Shaanxi Normal University have also conducted in-depth theoretical and technological research; Tsinghua University has also tried many times on its production equipment, and Have done a variety of prototypes; this issue A number of research papers have been published in the solar energy publications and optical publications; some have used a molding method to process a large area of flexible transparent plastic Fresnel lens, and some have used a combined forming tool to process a point-focusing Fresnel lens with a diameter of 1.5 m. For various reasons, the above studies have only stayed at the experimental level and have never been applied in actual engineering.

Fresnel lens is a light and thin flat lens lens, which belongs to the field of microstructured optical film technology. According to the type of focal spot, it can be divided into two types: point focus and line focus, but they all belong to the "back focus" type concentrator. The advantage is that the focus or focal line is behind the light source and the lens, which gives the collector The implementation of the setup and insulation measures is very convenient.

Due to its light and thin advantages, its support structure and tracking system can be made simple, lightweight, easy to implement, and can be inexpensive. At the same time, it is also convenient to miniaturize and lighten the equipment, that is, it can be combined into a large-scale array for large-scale industrial use or centralized heating and power supply, and can be made into a smaller system, which is convenient for household or dispersed users to heat nearby. , power supply, is expected to be an ideal solar collector.

However, for a long time, it is also difficult to be shaped and installed due to its lightness and thinness, making it not widely used. Moreover, in the design of optical path, because people pay too much attention to the overall "optical resolution" force factor, the focus of optical path design is based on reducing the distortion of the image, rather than paying attention to its convergence efficiency, Fresnel line lens Each microprism element is designed to have a completely equal width microstructure with a width of lmm, and the number of microprism elements is too large, and the vertical shear point is too much, so that the convergence efficiency to sunlight is reduced (downward range > 30%). The self-loss is large, and the temperature rises in the application, resulting in large macroscopic dimensional changes (thermal expansion and contraction) and unstable convergence performance, which have not played their due role in solar energy applications. Summary of the invention

The purpose of the invention is: 1. Based on improving the convergence efficiency of the Fresnel condenser lens, reasonably adjusting the width of each microprism element, in order to minimize the total number of microprism elements, adjacent microprisms below a certain height The elements are merged, increasing their width, reducing the number, minimizing the total number of vertical shear points, minimizing their own losses, minimizing their own temperature rise, and maximizing convergence efficiency. 2. The light and thin giant collecting and collecting Fresnel lens is matched with the aluminum alloy groove by the convex edge around it, and is tensioned on the rigid bracket to make the geometric shape well fixed. , optical performance is guaranteed. The object of the invention is achieved by the following technical solutions:

The concentrating and collecting Fresnel line focal lens is a rectangular transparent sheet, and the sheet has one or more focal lines, wherein one or more sets of Fresnel line focal concentrating lens elements, two pairs of rims directly formed or bonded together are formed. The width of the microprism elements of each group of Fresnel line focal concentrating lenses is distributed according to the principle of equal width of the central width.

The two pairs of convex edges around the concentrating heat collecting Fresnel line focal lens can be interposed with the aluminum alloy profiles with hook grooves, and are tensioned evenly by the tensioning device in four directions. Advantages of the invention:

The concentrating and collecting Fresnel line focus lens of the present invention has the following excellent features:

1. High convergence efficiency to sunlight: Since the width of the microprism elements of each group of Fresnel focal concentrating lenses is distributed according to the principle of equal width and external height in the middle, and the middle is wider (can be selected between 3 and 5 mm) ), the outer part is narrow (l~3mm), making the total number of microprisms Greatly reduced, the structure is more reasonable, and the convergence efficiency is improved.

2. The thickness of the plate base is more uniform: In the Fresnel line focal concentrating lens, if the microprism elements are distributed according to the principle of equal width, the height of the central microprism element is very small, and the height of the outer microprism element is large (there are ten The difference of several times), the macroscopically, will make the thickness of the plate base "thick in the middle, thin on both sides", which will cause the "die" flow unevenness and pressure delay melting state of the plate extruder during the production process. The material produces cross-flow, the product is prone to wrinkles, and the scrap rate is high. After forming, the shrinkage rate of the cross-section is also inconsistent, which makes the optical performance unstable and the transmittance decrease, which directly leads to a decrease in convergence efficiency. The invention

When the method of "central width, outer contour, etc." is designed, the width of the central microprism element is increased, so that its height is correspondingly increased, and gradually approaches the outer height. On the cross section, the middle and the outer are obtained. A plate base of substantially uniform thickness.

3. Easy to install and shape: Through the organic cooperation of the Fresnel line focal lens flange and the aluminum alloy groove, the light and thin giant collecting and collecting Fresnel line lens is easy to shape and fixed.

4, can make appropriate amount of thermal expansion and contraction compensation: through the elastic pre-tensioning of the lower abdomen of the aluminum alloy groove, in the outdoor environment, can be a light and thin giant collecting and collecting Fresnel line focal lens The thermal expansion and contraction are compensated in an appropriate amount to ensure that the flatness is not affected. DRAWINGS

Figure 1 is a front view of a single focal line concentrating heat collecting Fresnel line focus lens;

Figure 2 is a plan view of Figure 1;

3 is a schematic diagram of a double focal line concentrating and collecting Fresnel line focus lens; 4 is a partial enlarged view of a theoretical curve of a concentrating heat collecting Fresnel line focal lens microprism element;

Figure 5 is an enlarged view of the actual processing effect of the concentrating heat collecting Fresnel line focal lens microprism element;

6 is a single focal line concentrating heat collecting Fresnel line focal lens microprism element partition map; FIG. 7 is a single focal line concentrating heat collecting Fresnel line focus lens concentrating schematic diagram;

Figure 8 is a schematic diagram of the concentrating of the bifocal concentrated concentrating Fresnel line focal lens;

Figure 9 is a partial elevational view of the assembly of the Fresnel line focus lens and tensioning device. Numbers in the figure: 1 convex edge, 2 microprism element, 3 plate base, vertical shear point of 4 microprism element, theoretical apex angle of 5 microprism element, theoretical bottom angle of 6 microprism element, 7 microprism element Actual apex angle, actual base angle of 8 microprism elements, 9 solar incident light, 10 single focal line concentrating heat collecting Fresnel line focal lens, 11 refracted sunlight (convergence light), 12 focal lines, 13 pairs Focus line concentrating heat collecting Fresnel line focal lens, 14 tension aluminum alloy profiles, 15 tension screws, 16 rigid frames. detailed description

Further description will be made below with reference to the accompanying drawings and specific embodiments.

The structural principle of the present invention is shown in FIG. The concentrating and collecting Fresnel line focal lens of the present invention is composed of three parts: a flange 1, a microprism element 2 and a plate base 3, wherein the microprism element 2 is distributed on the plate according to the principle of the outer width of the middle width. Above the base 3; in this embodiment, the microprism element is designed according to the principle of central c = 3 mm wide (Fig. 4) and external h = lmm height; As shown in Fig. 6, the a portion of the central portion is originally a small part of the height of the microprism element. Today, several microprism elements are combined into a wider prism element with a suitable height, so that the a portion is a The number of microprism elements is greatly reduced, and the height of each microprism element is increased to a suitable size (h), which is easy to form and improve its refractive efficiency.

4 and FIG. 5 are partial enlarged views of the present invention, wherein FIG. 4 is a theoretical curve of the microprism element, FIG. 5 is an actual curve of the microprism element; and in the Fresnel lens, a vertical shear point of the microprism element The less the 4, the sharper the apex angle 5 and the bottom corner 6, the less the total light loss and the higher the refractive efficiency. However, in the actual forming process, the apex angle 5 and the bottom angle 6 are always inevitable. The ground has a certain "R" degree, as shown by 7 and 8 in Fig. 5, so that within the range "δ" of the cover of the two "R" degrees, the light cannot be effectively refracted to the focal line 12 Only the light of the "ρ" segment can be effectively refracted to the focal line 12. Therefore, in order to improve the refractive efficiency of the concentrating collector Fresnel focal length lens, in addition to taking effective measures in the processing process to make "R" In addition to the angle as small as possible, the number of micro-mode mirror elements should be as small as possible in the design, that is, the width of each micro-mode mirror element should be as large as possible, but with the corresponding vertical side height h (Fig. 4) Not higher than the set height of the microprism element. In the microprism element cluster of the Fresnel lens, the inclination angle λ of each microprism element (Fig. 4) tends to gradually increase from the middle to the both sides, and the middle portion is smaller and gradually increases toward both sides. Therefore, the middle portion The vertical side height h of the micro-prism element of part a (Fig. 6) also tends to increase gradually along the middle, but always set the height (lmm in this embodiment); When the vertical side height h of the prism element 2 breaks through the set height of the portion b of the portion in FIG. 6 (lmm in this embodiment), the width of the microprism element of the prism element is appropriately reduced to satisfy the vertical side height thereof is not more than The condition of setting the height of the b-zone part (Fig. 6), starting from this microprism element, The microprism elements spread out on both sides should adopt a method of reducing the width one by one to satisfy the condition that the height h is equal to the set height (lmm in this embodiment), that is, in the microprism element cluster, the constant width portion The end of zone a begins, and the zone b of the contour begins.

In Fig. 6, the width c of each microprism element in the a region is equal (3 mm in this embodiment), but the height h is different, and the height h gradually increases along the middle to the both sides, but Hmax does not exceed the set height (lmm in this embodiment); the inclination angle λ tends to increase gradually.

In Fig. 6, the height h of each microprism element in the b zone is equal, but the width c is different, and the width c gradually decreases along the middle to the both sides, and the inclination angle λ gradually increases. , but the maximum is not greater than the total reflection angle of the material.

The concentrating and collecting Fresnel line lens produced by this design method, when the focal length f (see Fig. 7, Fig. 8) and the cell width n-time, the total number of microprism elements will be the least, therefore, The number of vertical shear points 4 (see Figure 4) that affect the refractive efficiency and the light-receiving area δ (see Figure 5) occupied by the process R angle will be the least, so the refractive efficiency is the most. Figure 7 is designed using this method. A sectional view of a single-focus line concentrating and collecting Fresnel line focal lens, extending along the front and rear of the section, forms a concentrating and collecting Fresnel line lens lens of a single-focus line of a certain width and an arbitrary length.

Figure 8 is a cross-sectional view of a bifocal concentrated concentrating Fresnel line lens designed by this method. The section is extended forward and backward to form a concentrating heat collector of a double-focus line of a certain width and an arbitrary length. Nerve line focal lens sheet; Similarly, in this way, a multi-focal concentrated concentrating collector Fresnel line lens lens can be designed. Figure 9 is a partial cross-sectional view showing the application of the flange of the Fresnel lens and the aluminum alloy groove assembly, which will make the light and thin giant collecting and collecting Fresnel lens lens easy to shape and fix. installation. Since the tensioned aluminum alloy profile 14 is fixed to the rigid frame 16 by the tensioning screw 15, the tensioned aluminum alloy four-slot lower web has a certain elastic pretensioning effect, and in an outdoor environment, it can be light and thin. The thermal expansion and contraction of the concentrating collector Fresnel line lens is compensated in an appropriate amount to ensure that the flatness is not affected.

By projecting the focus lines of the "stretched" and "straight" concentrating collector Fresnel line focal planes in parallel on the solar vacuum tube or the metal heat collecting tube, the area of the main body of the heat collecting tube can be larger than that. After the sunlight is "concentrated", it is projected on a relatively small solar vacuum tube or metal heat collecting tube to form a solar energy medium and high temperature collector. An array of a plurality of such solar high temperature collectors can be used to form a solar boiler or a desalination or sewage purifier or as a city heating device or as a heating device for other industrial equipment.

The concentrating and collecting Fresnel line lens of the present invention has a convergence efficiency of more than 30% than that of the conventional type, and is highly efficient, economical, and widely used, and can be collected by such a concentrating and collecting Fresnel line lens. A solar energy medium and high temperature heat collector for various purposes, and therefore, is not limited to the contents described in the embodiments.

Claims

claims

1. A light-concentrating and heat-collecting Fresnel line focus lens, as the concentrator of a high-temperature solar collector, is made of polymer transparent optical materials and consists of a substrate and microprism elements. It is characterized by: light-concentrating Thermal Fresnel line focus lens is a rectangular transparent sheet with one or more focal lines formed on the sheet, which contains one or more groups of Fresnel line focus condensing lens microprism clusters. Each cluster of Fresnel line focus condensing lens has one of the microprism elements. The width is distributed according to the principle of equal width in the middle and equal height on the outside.

2. The light-concentrating and heat-collecting Fresnel line focus lens according to claim 1, characterized in that: the light-concentrating and heat-collecting Fresnel line focus lens sheet is surrounded by two pairs of convex edges that are directly made or bonded to form.

3. The light-concentrating and heat-collecting Fresnel line focus lens according to claim 2, characterized in that: the two pairs of convex edges around the light-concentrating and heat-collecting Fresnel line focus lens can interact with the aluminum alloy profile with hook grooves. Set, and tightened by evenly pulling sideways in four directions through the tensioning device.

4. The light-concentrating and heat-collecting Fresnel line focus lens according to claim 1 or 2, characterized in that: the two pairs of convex edges around the light-concentrating and heat-collecting Fresnel line focus lens are continuous in the middle and four corners. Cut off and separate a section so that the aluminum alloy profile with the hook groove can penetrate from all four sides without creating a gap with geometric interference.

5. The light-concentrating and heat-collecting Fresnel line focus lens according to claim 1, characterized in that: the entire light-concentrating and heat-collecting Fresnel line focus lens is subjected to one-time surface hardening by inorganic silicone resin with super hydrophilic function. , obtaining high hardness and super-hydrophilicity of the surface at the same time.

6. The light-concentrating and heat-collecting Fresnel line focus lens according to claim 1 or 2, characterized in that: each focusing line in the light-concentrating and heat-collecting Fresnel line focus lens is projected parallel to the solar vacuum tube or metal On the collector tube, a solar medium and high temperature collector is formed.

7. The solar high-temperature collector according to claim 6, characterized in that: multiple such solar medium and high-temperature collectors are used to form an array to form a solar steam boiler or seawater desalination device or sewage purifier or as urban heating. equipment or as a heater for other industrial equipment.