CN106766257A - A kind of trough type solar heat-collector - Google Patents

Abstract

In order to overcome the shortcomings of traditional trough system solar vacuum heat collectors, which are difficult to manufacture, short in service life, and high in manufacturing and maintenance costs, the invention discloses a trough solar collector, which includes a heat collecting tube, a condenser mirror and a bracket, wherein, The heat collecting tube includes a glass round tube, an absorption coating, an insulation layer and a heat-absorbing working medium; the absorption coating is arranged on the inner wall of the glass round tube, the insulation layer is arranged on the outer wall of the glass round tube, and the insulation layer is provided with an arc-shaped opening of the insulation layer to absorb heat. The coating is provided with an arc-shaped opening of the absorbing coating at a position corresponding to the arc-shaped opening of the insulation layer; the heat-absorbing working medium is filled in the glass circular tube. Further, a low-emissivity film is also provided between the glass circular tube and the insulation layer. The trough solar collector with this structure can not only make full use of the characteristics of the high absorption rate of the black body cavity, and greatly improve the heat collection efficiency; at the same time, it can also overcome the harsh requirements of the traditional vacuum tube for vacuum, and has the advantages of simple structure, convenient maintenance, and low manufacturing cost. low merit.

Description

A trough solar collector

technical field

The invention relates to a trough-type solar collector, which belongs to the technical field of solar thermal application.

Background technique

The characteristics of low density, intermittent, and changing spatial distribution of solar energy also put forward high requirements for the collection and utilization of solar thermal energy. According to different types of collectors, concentrated solar thermal power generation systems can be divided into trough systems, tower systems and dish systems. Among them, the trough solar thermal power generation system has a commercial scale and relatively low technical requirements, which is an ideal power generation technology.

The heat collector is an important part of the solar heat collection system. The heat collector used in the traditional trough solar heat collection system is generally a vacuum heat collection tube. The main structure of the heat collection tube is a metal tube with an absorbing coating on the surface and a The concentric glass tube, and evacuated in the interlayer of glass tube and metal tube. This structure has the following technical problems: the welding sealing between the metal and the glass, the internal stress caused by the different expansion of the metal pipe and the glass pipe, and the difficulty in ensuring the vacuum in the interlayer. These technical problems determine its high production cost and short service life. In view of the problems of the traditional vacuum tube mentioned above, it is necessary to develop a new type of trough solar collector.

The absorptance ratio of a black body is 1, which means that a black body can completely absorb solar radiation energy of various wavelengths. A cavity with uniform temperature with a small hole is a black body model. When the solar radiation enters the cavity through the small hole, it undergoes multiple absorption and reflection in the cavity, and every time it passes through an absorption, the radiant energy is absorbed according to the inner wall. The share of the rate is weakened once, and the energy that can finally leave the small hole is negligible, which can be considered to be completely absorbed inside the cavity. Therefore, in terms of radiation characteristics, the pinhole has the same properties as the surface of a black body.

Chinese patent CN102135331A discloses a trough solar collector, which includes an open ring tube, an absorbing coating, a thermal insulation material and an inlet glass cover. The inner surface is provided with an absorption coating, the outer surface is provided with a heat insulating material, and the opening is connected with an inlet glass cover. It has the advantages of simple structure, convenient maintenance, low cost, high heat collection efficiency and the like. However, the open annular tube has a hollow structure, and the inner glass is heated first, and then the heat is transferred to the outer glass by the heat-absorbing working fluid. Therefore, the internal stress of the inner and outer glass is likely to be deformed or even damaged due to the temperature difference; secondly, the set The radiator radiates more heat to the outside, resulting in more heat loss; thirdly, due to the special shape of the glass sleeve, there is no ready-made pipeline that can be directly connected to it to achieve the purpose of drawing out the heat-absorbing working fluid in the tube, which will bring Come to the connection problem of the end of the heat collecting tube.

Contents of the invention

In order to solve the above problems, the present invention proposes a trough solar heat collector, which makes the temperature of the inner and outer walls of the glass circular tube uniform, not easily deformed, and has a longer service life; moreover, the heat collection efficiency is higher and the structure is simpler.

The trough solar collector provided by the present invention comprises a heat collecting tube, a condenser mirror and a bracket; the condenser adopts a converging paraboloid structure, and the heat collecting tube is fixedly connected to the condenser through a bracket, and is characterized in that: the heat collecting tube includes a glass circular tube 1, an absorbing coating 2. The insulation layer 4 and the heat-absorbing working medium 6; the absorption coating 2 is arranged on the inner wall of the glass tube 1, and the insulation layer 4 is arranged on the outer wall of the glass tube 1; the insulation layer 4 is provided with an arc-shaped opening 5 of the insulation layer, and the absorption coating The layer 2 is provided with an absorption coating arc opening 7 at a position corresponding to the arc opening 5 of the insulation layer; the endothermic working medium 6 is filled in the glass circular tube 1 .

Preferably, a low-emissivity film 3 is also provided between the glass round tube 1 and the heat preservation layer 4 .

Preferably, the glass tube 1 is made of high borosilicate glass material

Preferably, the widths of the arc-shaped openings 5 of the insulation layer and the arc-shaped openings 7 of the absorbing coating are greater than or equal to the width of the linear light spot formed after the light is focused by the condenser lens.

Preferably, the heat-absorbing working medium 6 is heat-conducting oil or water.

Beneficial effect:

(1) Structural characteristics such as a slit formed by the arc-shaped opening of the trough solar collector, using the characteristics of the high absorption rate of the blackbody cavity, the focused sunlight is absorbed by the heat-absorbing working fluid and the inner wall of the glass tube through repeated cycles. Absorption, fully absorbs the focused light, high heat collection efficiency; and overcomes the harsh requirements of traditional vacuum tubes for vacuum, greatly simplifies the structure, and significantly reduces manufacturing and maintenance costs.

(2) The temperature of the inner and outer walls of the glass cavity is relatively uniform, and it is not easy to form local overheating, resulting in deformation of the heat collector, with stable thermal performance and longer service life.

(3) The low-emissivity film on the outer surface of the glass tube allows solar radiation to enter the glass tube directly through the arc-shaped opening of the insulation layer, and at the same time reduces the outward long-wave radiation of the glass tube; in addition, the use of the insulation layer can also reduce heat dissipation.

(4) Under the condition of the same outer diameter and the same tube length, the trough solar heat collector disclosed by the present invention can hold more heat-absorbing working fluid, which can further save the cost of heat collector materials and use space.

Description of drawings

Fig. 1 is the schematic diagram of the sectional structure of the heat collecting tube in the embodiment;

Fig. 2 is a schematic diagram of the working state of the trough solar collector in the embodiment;

In the figure: 1-glass tube; 2-absorbing coating; 3-low-emissivity film; 4-insulation layer; 5-curved opening of thermal insulation layer; 6-endothermic working fluid; - bracket; 9 - concentrating paraboloid.

detailed description

FIG. 1 is a schematic diagram of a sectional structure of a trough solar heat collector disclosed in the present invention. The heat collector includes a heat collecting tube, a concentrating paraboloid 9 and a bracket 7 . Wherein, the heat collecting tube includes a glass circular tube 1 , an absorbing coating 2 , a low-emissivity film 3 , an insulating layer 4 , an arc-shaped opening 5 of the insulating layer, and an arc-shaped opening 7 of the absorbing coating.

The glass tube 1 is made of high borosilicate glass with strong external impact resistance, and its linear thermal expansion coefficient is (3.3±0.1)×10-6/K, which is a low expansion rate, high temperature resistance, high strength and high hardness. , special glass material with high light transmittance and high chemical stability. The inner surface of the glass tube 1 is attached with an absorbing coating 2, and the absorbing coating with high absorption rate is preferred; the outer surface is wrapped with a low-emissivity film 3, such as Low-E film; Oil or water; in order to reduce energy loss, the outer wall of the glass tube is provided with an insulating layer 4 with an arc-shaped opening 5 on the insulating layer, and an absorbing coating arc-shaped opening 7 at the position corresponding to the arc-shaped opening of the insulating layer.

As shown in Fig. 2, the concentrating mirror adopts a concentrating paraboloid structure, and the concentrating paraboloid 9 is a line focusing device, which can track sunlight. After the light is collected by the converging paraboloid 9, a linear spot is formed at the focal line. The glass round tube 1 is fixedly connected to the concentrating paraboloid 9 through the bracket 8, so that the arc-shaped opening 5 of the insulation layer and the arc-shaped opening 7 of the absorbing coating face the linear light spot formed by the concentrating paraboloid 9. Place the arc-shaped opening 5 of the insulation layer and the arc-shaped opening 7 of the absorbing coating on the linear light spot, and the width of the arc-shaped opening 5 is slightly larger than the width of the linear light spot. The absorption coating 2 on the inner surface of the glass tube 1 is provided with an absorption coating arc opening 7 at a position corresponding to the arc opening of the insulation layer, so that solar light can enter the glass tube through the opening.

In actual work, after the light is gathered by the converging paraboloid 9, a line-shaped light spot band is formed at the focal line, and the arc-shaped opening 5 of the insulation layer and the arc-shaped opening 7 of the absorbing coating are facing the line-shaped light spot, and the focused light passes through The arc-shaped opening enters the glass round tube 1 to heat the heat-absorbing working medium 6 in the glass round tube 1 . The width of the arc-shaped opening 5 of the insulation layer and the arc-shaped opening 7 of the absorbing coating should be greater than the width of the linear light spot band, so as to ensure that the focused sunlight does not overflow the absorption range. After the light is reflected by the concentrating paraboloid 9 and enters the glass tube 1 through the arc-shaped opening, it undergoes multiple absorption and reflections by the heat-absorbing working medium 6 and the inner surface of the glass tube 1. Through the use of the absorbing coating 2, the energy is distributed according to the inner wall. The higher absorption rate is continuously absorbed by the heat-absorbing working medium 6 inside the glass tube 1, so that the energy that can finally leave the glass tube 1 through the arc-shaped opening 5 of the insulation layer is small, and the effect of high absorption rate is achieved.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. 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 (5)

1. a kind of trough type solar heat-collector, including thermal-collecting tube, condenser and support；Condenser uses optically focused paraboloid structure, Thermal-collecting tube is fixedly connected condenser by support, it is characterised in that：Thermal-collecting tube includes glass round tube (1), absorber coatings (2), protects Warm layer (4) and heat absorption working medium (6)；Absorber coatings (2) are arranged in glass round tube (1) inwall, and heat-insulation layer (4) is arranged in glass round tube (1) outer wall；Heat-insulation layer (4) is provided with heat-insulation layer arc opening (5), and absorber coatings (2) are corresponding with heat-insulation layer arc opening (5) Position at be provided with absorber coatings arc opening (7)；Heat absorption working medium (6) is filled in glass round tube (1).

2. a kind of trough type solar heat-collector according to claim 1, it is characterised in that：In the glass round tube (1) and Low-radiation film (3) is additionally provided between the heat-insulation layer (4).

3. a kind of trough type solar heat-collector according to claim 1, it is characterised in that：The glass round tube (1) uses High-boron-silicon glass material.

4. a kind of trough type solar heat-collector according to claim 1, it is characterised in that：The heat-insulation layer arc opening (5) and absorber coatings arc opening (7) width more than or equal to light through condenser focus on after formed linear beam spot width Degree.

5. a kind of trough type solar heat-collector according to claim 1, it is characterised in that：Heat absorption working medium (6) is to lead Deep fat or water.