CN104849844A - Dish type Fresnel reflection concentration method and apparatus thereof - Google Patents

Abstract

The invention relates to a dish-type Fresnel reflection concentrating method and its device, comprising a series of strip-shaped annular reflection surfaces with different radii and receivers. The incident light is reflected by the corresponding bar-shaped annular reflective surface and converged to the receiver on the other side of the light source. The bar-shaped ring-shaped reflective surfaces at different positions reflect and converge the light incident on it to the receiver, which improves the energy density on the receiver and achieves the purpose of light concentration. According to the actual application, different parameter strip ring reflectors can be designed to achieve the required light-gathering multiple. The receiver and the light source are located on both sides of the concentrator, which improves the flexibility of the receiver arrangement, and there are more gaps in the middle of the strip-shaped annular reflective surface, which improves the wind resistance of the device.

Description

Dish-type Fresnel reflection concentrating method and device

technical field

The invention relates to the technical field of solar energy utilization, and is a dish-type Fresnel reflective concentrating device, which can generate a suitable focused energy flow according to the requirements of a receiver.

Background technique

Solar energy is a green energy with a large amount of cleanness. The total global radiation is about 1.7×10 ¹⁷ W, of which China accounts for about 1% (1.8×10 ¹⁵ W, equivalent to 1.9 trillion tons of standard coal per year). 680 times the current annual energy consumption. Solar energy will occupy an important position in future energy.

Solar power generation technology is mainly divided into photovoltaic power generation and photothermal power generation. Photovoltaic power generation mainly uses the photovoltaic effect of photovoltaic cells to generate electricity. Due to the low flux density of solar energy, the area of photovoltaic panels required for unit power generation capacity is large, and the manufacturing process of photovoltaic panels consumes a lot of energy and causes serious pollution. Therefore, the consumption of the battery can be reduced by using the concentrating device to gather the sunlight with low energy flux density and then projecting it onto the photovoltaic cell. It is equivalent to replacing photovoltaic cell materials with relatively cheap light-gathering materials. Photothermal power generation is mainly to gather sunlight by using concentrating mirrors, convert it into thermal energy of working fluid through light and heat, and then generate electricity through a heat engine. Similarly, in order to achieve higher temperatures, solar thermal power generation requires concentrating devices.

Traditional concentrators include Fresnel lenses, trough, dish and tower reflective concentrators. The Fresnel lens adopts transmissive materials and concentrates light through the principle of light refraction. Generally, it can be made of optical plastic, but the limitation of the refractive index of optical plastic affects the improvement of light concentration ratio. Using glass would make the system too heavy. In addition, the optical performance of the material will have a large attenuation with time. Reflective concentrators require precise continuous reflective surfaces. When the reflective surface increases, it will bring great troubles to manufacture and installation. Moreover, its receiver is generally located above the concentrator, that is, at a high altitude, which causes partial shading and brings great difficulties to the installation of the receiver. In addition, both photovoltaic and photothermal utilization require as uniform energy flux density distribution on the receiver as possible, while traditional concentrators do not have this characteristic.

Contents of the invention

In order to overcome the disadvantages of the traditional concentrator, the invention provides a dish Fresnel reflection concentrating method and a device thereof.

A dish-type Fresnel reflection concentrating method. The device used in the method includes a reflector array and a receiver. The reflector array is composed of several strip-shaped ring-shaped reflective surfaces arranged according to the size of the diameter. The described The strip-shaped annular reflective surface reflects and converges the light incident on it to the receiver, and the receiver and the incident light are respectively on both sides of the reflector array.

The inside of the strip-shaped annular reflective surface has a smooth reflective surface, which can effectively reflect light incident on its surface.

The profile line cut by the plane passing through the axis of the strip-shaped annular reflective surface is one or more of straight line, parabola, circular arc, ellipse, hyperbola, and high degree curve.

The receiver is a photovoltaic power generation device or a heat collection device.

A secondary concentrator is installed at the entrance of the receiver to increase the energy density reaching the receiver.

The strip-shaped annular reflector and the receiver are installed on a dual-axis tracking system so that the axis of the concentrator faces the sun.

The strip-shaped annular reflective surface is composed of smaller secondary strip-shaped annular reflective surfaces, and the secondary strip-shaped annular reflective surfaces are arranged along the direction of the optical axis. There are several secondary annular strip reflective surfaces arranged along the optical axis direction inside the strip-shaped annular reflective surface.

A Fresnel lens is added to the middle area of the reflector array formed by the strip-shaped annular reflector. The Fresnel lens is perpendicular to the optical axis, and a part of the incident light is focused to the receiver through the reflection of the strip-shaped reflector. , another part of the incident light is refracted by the Fresnel lens and focused onto the receiver.

The dish-type Fresnel reflective concentrating device of the method is characterized in that it comprises a reflector array, a receiver and a Fresnel lens, and the described reflector array is composed of several strip-shaped annular reflectors arranged according to the size of the diameter Composition, the Fresnel lens is located in the middle of the reflector array composed of strip-shaped annular reflective surfaces, the receiver and the incident light are respectively located on both sides of the reflector array, and a part of the incident light passes through the bar-shaped The reflection of the reflective surface is focused on the receiver, and another part of the incident light is focused on the receiver through the refraction of the Fresnel lens.

The device consists of a series of strip-shaped annular reflectors and receivers. The sunlight incident on the strip-shaped annular reflectors is reflected and converged on the set receivers. Different strip-shaped ring-shaped reflective surfaces reflect the received sunlight to the receiver to form a focused spot, which improves the energy flow density on the receiver. Different strip-shaped ring-shaped reflective surfaces are arranged at appropriate positions to avoid blocking of incident light or reflected light by one reflective ring facing another reflective ring. The shape of the reflective surface can be selected from parabola, ellipse, circle and high-order curve, etc. When the light-gathering effect can be guaranteed, a straight line can be selected instead of a curved surface. In addition, a single concentrator can be composed of the same type of curved torus, and can also be composed of different types of curves.

The present invention provides an improved down concentrating device that produces the concentrating light required by the receiver. This device combines the local concentrating similar to Fresnel mirror and the idea of local design optimization to optimize the concentrating effect. The use of a narrow annulus provides greater convenience for manufacturing and installation, and lighter reflective materials can be used, which reduces the weight of the device and reduces the cost.

The focused sunlight can be efficiently used in various ways, the common receivers are thermal receivers and photovoltaic cells, which generate heat or electricity. The device requires a corresponding bracket and a tracking system, so that the device can be aligned with the sunlight for efficient concentration. In addition, the device can be further coupled with a secondary light concentrating device to further improve the light concentrating ability and the uniformity of energy flux density distribution.

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

1. The present invention uses a plurality of strip-shaped annular reflective ring surfaces to reflect and concentrate light, and can design the light-condensing performance according to the characteristics of the receiver to meet the light-gathering multiples required by different receivers and improve the uniformity of energy flow at the focus point , flexible design.

2. The present invention adopts many reflective rings to concentrate light, and the receiver is under the light collector, which facilitates the design of the bracket and the installation and arrangement of the receiver, and reduces the incident light blocking caused by the traditional installation above the light-condensing reflective surface.

3. The monolithic ring-shaped concentrating part is more convenient to manufacture and install, which reduces the cost of the whole device.

Description of drawings

Fig. 1 is a schematic diagram of the down converging disc type Fresnel reflection concentrating device;

Figure 2 is a schematic diagram of a single strip annular reflector;

Figure 3 is a schematic diagram of the light gathering of multiple strip-shaped annular reflectors passing through the optical axis section;

Fig. 4 is a schematic cross-sectional view of a Fresnel lens converging device set in the center through the optical axis;

Fig. 5 is a schematic diagram of the secondary annular strip reflective surface of the present invention.

The names of the serial numbers in the figure are: 1, axis, 2, incident light, 3 reflective surfaces inside the strip-shaped annular reflective surface, 4, strip-shaped annular reflective surface, 5, reflected light, 6, receiver, 7, phenanthrene Neel lens, 8, secondary strip annular reflective surface.

Detailed ways

Now in conjunction with accompanying drawing, the present invention will be further described.

As shown in Fig. 1-4, a kind of dish type Fresnel reflection concentrating method, the device that it uses comprises reflector array and receiver 6, and described reflector array is made up of several bar rings arranged according to the size of diameter Shaped reflective surface 4, the strip-shaped annular reflective surface 4 reflects the light 2 incident on it and converges it to the receiver 6, and the receiver 6 and the incident light 2 are respectively in the on both sides of the mirror array.

The inner side 3 of the strip-shaped annular reflective surface has a smooth reflective surface, which can effectively reflect light incident on its surface.

The profile line cut by the plane passing through the axis 1 of the strip-shaped annular reflective surface 4 is one or more of straight lines, parabolas, arcs, ellipses, hyperbolas, and high-degree curves.

The receiver 6 is a photovoltaic power generation device or a heat collection device.

A secondary concentrator is installed at the entrance of the receiver to increase the energy density reaching the receiver.

The strip-shaped annular reflector 4 and the receiver 6 are installed on a dual-axis tracking system so that the axis of the concentrator faces the sun. As shown in FIG. 5 , there are several secondary annular strip-shaped reflective surfaces 8 arranged along the optical axis on the inner side of the strip-shaped annular reflective surface 4 .

Fresnel lens 7 is added in the middle area of the reflector array formed by described strip-shaped annular reflector 4, and described Fresnel lens 7 is perpendicular to optical axis, and a part of incident light 2 passes through the strip reflector 4. The reflection is focused on the receiver 6 , and another part of the incident light 2 is refracted by the Fresnel lens 7 and focused on the receiver 6 .

As shown in FIG. 1 , the incident light 2 along the optical axis 1 is reflected by the reflective surface 3 inside the strip-shaped annular reflective surface 4 , and the reflected light 5 changes direction and reaches the receiver 6 . Figure 2 shows a single strip-shaped annular reflective surface, the axis has a certain width, and the inner surface has reflective properties. The profile of the reflective surface can be a straight line, an arc, a parabola, an ellipse, a hyperbola, and a high degree curve. Each bar-shaped ring-shaped reflective surface 4 in different positions is designed according to its own position, its surface specific profile and the width and diameter along the axis direction, so that the light can be reflected on the receiver 6 of a certain area, and the adjacent The strip-shaped ring-shaped reflective surface reduces occlusion as much as possible and improves optical efficiency. What Fig. 3 shows is a sectional view of a concentrator formed by a plurality of strip-shaped annular reflective surfaces 4, and the light falling on each strip-shaped annular reflective surface is all reflected on the receiver 6, so that the receiver accepts The energy flow density is greatly improved to meet the requirements of practical applications.

Improvement plan 1: When the diameter of the strip-shaped annular reflective surface 4 is getting smaller and smaller, the slope of the tangent line of the reflective surface is larger, which makes the area of the strip-shaped annular reflective surface larger. In order to save materials, as shown in the middle of the concentrator The Fresnel lens 7 is set so that its focus just falls on the receiver 6, so as to improve the utilization rate of light energy and also increase the energy flux density on the receiver.

Improvement Solution 2: The strip-shaped annular reflective surface 4 is composed of smaller secondary strip-shaped annular reflective surfaces 8, and the secondary strip-shaped annular reflective surfaces 8 are arranged along the optical axis direction. As shown in Figure 5, the strip-shaped annular reflective surface is divided into smaller secondary strip-shaped annular reflective surfaces 8, each of which reflects light incident on it to the receiver 6 Therefore, the shape of the reflective surface of the secondary strip-shaped annular reflective surface 8 can be replaced by a straight line to obtain a better light-gathering effect, and the entire strip-shaped annular reflective surface is in the shape of a flat plate, which is convenient for manufacture and installation.

Claims (9)

1. A dish-type Fresnel reflection concentrating method is characterized in that it includes a reflector array and a receiver (6), and the reflector array is composed of several strip-shaped annular reflectors (4 ), the strip-shaped annular reflective surface (4) reflects and converges the light (2) incident on it to the receiver (6), and the receiver (6) and the incident light (2) Respectively on both sides of the mirror array. 2. The dish-type Fresnel reflection concentrating method according to claim 1, characterized in that the inner side (3) of the strip-shaped annular reflective surface has a smooth reflective surface, which can effectively reflect the light incident on its surface. 3. The dish-type Fresnel reflection concentrating method according to claim 2, characterized in that the profile line cut by the plane of the strip-shaped annular reflective surface (4) passing through the axis (1) is a straight line, a parabola, One or more of arcs, ellipses, hyperbolas, and high-degree curves. 4. The dish-type Fresnel reflection concentrating method according to claim 1, characterized in that the receiver (6) is a photovoltaic power generation device or a heat collection device. 5. The dish-type Fresnel reflection concentrating method according to claim 4, characterized in that a secondary concentrator is installed at the entrance of the receiver to increase the energy density reaching the receiver. 6. The dish-type Fresnel reflection concentrating method according to claim 1, characterized in that the strip-shaped annular reflective surface (4) and the receiver (6) are installed on a two-axis tracking system, so that the concentrator The optics axis is facing the sun. 7. The dish-type Fresnel reflection concentrating method according to claim 1, characterized in that there are several secondary annular strip reflectors arranged along the optical axis on the inner side of the strip-shaped annular reflective surface (4) Surface (8). 8. The dish-type Fresnel reflection concentrating method according to claim 1, characterized in that a Fresnel lens (7 ), the Fresnel lens (7) is perpendicular to the optical axis, a part of the incident light (2) is focused on the receiver (6) through the reflection of the strip reflective surface (4), and the other part of the incident light (2) passes through The refraction of the Fresnel lens (7) is focused onto the receiver (6). 9. A dish-type Fresnel reflection concentrating device according to the method of claim 8, characterized in that it includes a mirror array, a receiver (6) and a Fresnel lens (7), and the mirror array Composed of several strip-shaped annular reflective surfaces (4) arranged according to their diameters, the Fresnel lens (7) is located in the middle of the mirror array composed of strip-shaped annular reflective surfaces (4) , the receiver (6) and the incident light (2) are respectively located on both sides of the mirror array, a part of the incident light (2) is focused on the receiver (6) through the reflection of the strip-shaped reflective surface (4), and the other part The incident light (2) is refracted by the Fresnel lens (7) and focused onto the receiver (6).