CN201032297Y - Pressurized Flat Panel Solar Collector - Google Patents

Abstract

The pressure-bearing flat-plate solar thermal collector is an improvement of a conventional flat-plate solar thermal collector so that it can be used in a conventional solar water heater mode with water as the working medium, and can also be used as a direct expansion solar heat pump evaporator with a refrigerant as the working medium. The upper part of the solar thermal collector is a glass cover plate (1), the lower part of the glass cover plate (1) is a polycarbonate transparent cover plate (2), the lower surface of the polycarbonate transparent cover plate (2) is connected with a small fin (3), the lower part of the polycarbonate transparent cover plate (2) is a heat-absorbing core plate (4), the upper surface of the heat-absorbing core plate (4) is provided with a honeycomb structure material (7), the lower part of the heat-absorbing core plate (4) is a bottom insulation layer (5), and a pressure-bearing pipe (6) is provided in the bottom insulation layer (5). The flat-plate structure of the solar thermal collector can be well combined with a building without a water storage tank, thereby realizing building integration.

Description

Pressurized Flat Panel Solar Collector

technical field

The utility model is an improved traditional flat solar heat collector, so that it can be used not only in the traditional solar water heater with water as the working medium, but also in the direct expansion solar heat pump evaporator with refrigerant as the working medium, belonging to Technical field of solar water heater and solar heat pump.

Background technique

The development of solar heat collection technology today has the conditions for large-scale promotion and use in terms of technical heat collection efficiency and commercial cost performance, but there are still many problems in terms of installation form, safety, life, and coordination with buildings. Needs further improvement. The heat collector must be a part of the building, the two are organically combined in aesthetic effect, and the heat collector must have the same life as the building. Flat plate collectors have advantages over other collectors in this respect:

1) The flat plate collector has no vacuum requirement and has a long service life, especially the high-quality self-fluxing all-copper collector, whose service life is even longer than that of the building itself.

2) In the flat plate collector, the working medium flows in the metal pipe, without contact with the glass, the system will not be paralyzed due to large leakage of water or working fluid caused by cold frying or hot frying.

3) In the flat plate heat collector, the heat collecting element and the water-flowing part are welded or all-metal sealed, and the rubber ring that is bound to age with time is not used, and the long-term operation reliability is better.

4) While achieving seamless installation and production of hot water, the flat plate collector also has all the functions of traditional roofs such as heat preservation, heat insulation, shading, and wind and rain, thereby partially or completely replacing roof materials and reducing construction costs.

5) The shape and structure of the flat plate heat collector are flexible, and it is easy to achieve an organic combination of the heat collector and the building body.

It is precisely because of the above-mentioned many advantages of flat-plate collectors that the production and sales of flat-plate collectors in economically developed regions such as Europe, the United States, and Australia account for more than 80% of the total production and sales of solar collectors.

However, since the working medium of traditional flat-panel solar collectors is generally water, the water is directly heated by solar energy to meet domestic hot water supply. Although this method is simple, it may freeze and even crack the collector itself in the cold winter. However, the current antifreeze technology is still in the research and development stage, which is unsatisfactory, which limits the use of traditional flat-plate collectors in high-latitude cold regions. And when the solar radiation is insufficient, only using solar energy to heat water cannot meet the temperature requirements of domestic hot water. The defects of flat plate collectors in terms of heat loss are also obvious, and certain measures need to be taken to improve the heat collection efficiency.

Contents of the invention

Technical problem: The purpose of this utility model is to provide a pressurized flat panel solar collector that can use different working media, can use different refrigerants according to different needs, and can work normally under different evaporation pressures.

Technical solution: The pressure-bearing flat solar collector of the utility model, glass cover plate, polycarbonate transparent cover plate, small ribs, heat-absorbing core plate, bottom insulation layer, pressure-bearing pipe, honeycomb structure material; the solar energy The upper part of the heat collector is a glass cover, the lower part of the glass cover is a polycarbonate transparent cover, the lower surface of the polycarbonate transparent cover is connected with small ribs, and the lower part of the polycarbonate transparent cover is The heat-absorbing core board is provided with a honeycomb structure material on the upper surface of the heat-absorbing core board, and the lower part of the heat-absorbing core board is a bottom insulation layer, and a pressure-bearing pipe is arranged in the bottom insulation layer. An electronic expansion valve is installed on the pressure pipeline

The medium pipe welded under the heat-absorbing core plate is improved. In order to adapt to the operation of the solar heat pump, the thickness of the pipe wall is appropriately increased to improve its pressure-bearing performance. At the same time, due to the poor water solubility of some refrigerants, a drier is installed at an appropriate position of the heat collector to avoid the "ice plug" phenomenon. In order to make full use of solar energy and reduce heat loss, a polycarbonate transparent cover with ribs is used, and a honeycomb structure material is placed on the heat-absorbing core plate to reduce convection and radiation losses, and greatly increase heat collection efficiency. Install an electronic expansion valve on the medium pipeline to adjust the refrigerant flow to match the load.

Beneficial effects: the beneficial effects of the utility model are: adopting the pressure-bearing pipe flow channel, the working medium can be changed to refrigerant, and the heat collector can be used as a solar heat pump evaporator, so that when domestic hot water cannot be obtained directly, the Works in the form of a solar heat pump. At the same time, due to the use of pressure-bearing structural pipelines, different refrigerants can be used according to different needs, and they can work normally under different evaporation pressures.

1. The flat plate collector can use different working media, and it can be used flexibly;

2. Double heat loss prevention measures greatly improve the heat collection efficiency of the heat collector.

Description of drawings

Figure 1 is a schematic diagram of the flat plate collector.

Among them are: glass cover plate 1, polycarbonate transparent cover plate 2, small ribs 3, heat-absorbing core plate 4, bottom insulation layer 5, pressure-bearing pipe 6, and honeycomb structure material 7.

FIG. 2 is a schematic cross-sectional structure diagram of FIG. 1 .

Figure 3 Schematic diagram of the structure of the honeycomb material.

Detailed ways

Figure 1 is a schematic diagram of the flat plate collector. The glass cover plate 1 plays the role of reducing heat dissipation and producing the greenhouse effect; the polycarbonate transparent cover plate 2 and the small ribs 3 are integrated to form a polycarbonate transparent cover plate with small ribs, and these small ribs are placed on the heat-absorbing core Many small spaces are formed above the board to suppress the natural convection of air; the heat-absorbing core board 4 is a coated heat-absorbing aluminum plate, and the coating adopts selective anodized coating; the pressure-bearing pipe 6 adopts copper with good thermal conductivity tube material, appropriately increase the thickness of the tube wall, improve its pressure bearing capacity, so that the working medium can be various refrigerants, and the heat collector can be used as a solar heat pump evaporator; the honeycomb structure material 7 is that this material is directly placed on the On the surface of the board, it can not only reduce the natural convection of the surface air, but also greatly reduce the radiation heat dissipation. The honeycomb structure and the ribbed polycarbonate cover play a double role in inhibiting the heat loss of the collector. The bottom is insulated with glass wool, which further reduces heat loss and improves heat collection efficiency. During processing, the pressure-bearing tube and the heat-absorbing plate are connected by welding, and the welding strength should be sufficient to avoid air gaps and minimize contact thermal resistance.

The top of this solar heat collector is a glass cover plate 1, and the bottom of the glass cover plate 1 is a polycarbonate transparent cover plate 2, and the lower surface of the polycarbonate transparent cover plate 2 is connected with a small rib 3, and the polycarbonate transparent cover plate 2 is connected with a small rib 3. The lower part of the ester transparent cover plate 2 is a heat-absorbing core plate 4, and a honeycomb structure material 7 is arranged on the upper surface of the heat-absorbing core plate 4. A pressure pipeline 6 is provided. An electronic expansion valve is provided on the pressure-bearing pipeline 6 . Since the evaporation pressure of the refrigerant is much higher than the pressure of normal domestic hot water when the heat pump is running, the pressure bearing performance of the traditional medium channel cannot meet the evaporation pressure requirements, so it is necessary to use a pipeline with a higher pressure bearing capacity. The medium channel is specially processed to withstand a certain pressure, so as to meet the requirements of refrigerant evaporation in the pipeline.

The heat loss of flat-plate collectors is mainly concentrated in the convective heat dissipation between the collector plate and the surrounding air. For a collector with a cover, the convection loss is further divided into the internal convection loss from the heat absorbing plate to the cover plate, and the external convection loss from the cover plate to the surrounding air. In calm conditions, external convective losses are caused by natural convection. Air convection also dominates at low wind speeds. Although we should also try to reduce the external convective loss, the most effective way is to reduce the internal convective loss to reduce the temperature of the cover plate. To reduce the internal convection loss, the common method is to reduce the air gap and fill the heat insulating material between the heat absorbing plate and the cover plate. In this design, a polycarbonate transparent cover is placed above the heat absorbing plate, and the small ribs under the cover divide the air flow channel into many small channels, which is equivalent to reducing the air gap; at the same time, the honeycomb placed on the heat absorbing plate The material itself also reduces the space for air flow. Therefore, the internal convection loss can be effectively reduced.

During the working process of the collector, when the plate temperature is higher than the ambient temperature, the collector will inevitably radiate heat to the surrounding environment, and this part of the radiation heat loss is also an important part of the heat loss of the flat panel collector. In this design, by arranging a honeycomb structure material on the heat absorbing plate, the heat loss of the radiation part is effectively reduced. The honeycomb structure is shown in Figure 3. The principle of reducing radiation loss is: each cell of the honeycomb is a regular hexagonal hollow cylinder, and the light transmittance of the cell can reach more than 97% for parallel light. With parallel light, the honeycomb wall can attach a panel to one side of the non-perpendicular honeycomb, so the honeycomb has good light absorption performance. Because the honeycomb wall can block most of the sunlight, the multiple reflections of light are carried out on the honeycomb wall, so the light is almost completely absorbed by the honeycomb structure. If the honeycomb is black, the light absorption performance of the honeycomb will be close to an absolute black body. By this measure, radiation losses are considerably reduced. At the same time, placing the honeycomb structure material on the heat absorbing plate itself also reduces the air flow space and effectively reduces the internal convection loss.

The quality of the heat-absorbing coating attached to the heat-absorbing plate core of the collector directly affects the performance of the solar water heater. Heat-absorbing coatings can be generally divided into two categories: non-selective coatings and selective coatings. The important index to distinguish their heat-absorbing properties is the ratio α/ε of their absorption ratio α to emission ratio ε. α/ε=1 for non-selective heat-absorbing coatings; α/ε>1 for selective heat-absorbing coatings, and both are selective heat-absorbing coatings. Generally, the larger the ratio, the better the performance. Another important indicator of the heat-absorbing coating is its weather resistance, which is related to the service life of the coating and even the water heater. Selective anodized coating is currently an ideal coating widely used on flat-plate solar collectors, its α/ε>3, and its service life is about ten years. Considering its heat absorption performance and service life, this design adopts selective anodized coating.

The ribbed polycarbonate transparent cover and the honeycomb structure material greatly reduce the air convection on the surface of the heat-absorbing core plate, and significantly reduce the radiation loss, so that the heat collection efficiency is significantly increased. The selective anodized coating improves the overall performance of the collector.

The electronic expansion valve on the medium pipeline can adjust the refrigerant flow according to different load requirements, and at the same time throttle and reduce the pressure, so that the evaporation can meet the load matching.

Since the medium pipeline can flow different refrigerants, it is possible to use different refrigerants for experiments to find out a refrigerant with relatively high efficiency and meet environmental protection requirements as the working medium of the collector. The double heat loss prevention measures of polycarbonate and honeycomb structure improve the heat collection efficiency of the heat collector, so that the system can still be used more efficiently in occasions where the solar radiation is not good.

Claims (2)

1. A pressurized flat panel solar heat collector is characterized in that the top of the solar heat collector is a glass cover (1), and the bottom of the glass cover (1) is a polycarbonate transparent cover (2) , the lower surface of the polycarbonate transparent cover (2) is connected with small ribs (3), the bottom of the polycarbonate transparent cover (2) is a heat-absorbing core plate (4), and the heat-absorbing core plate ( 4) is provided with a honeycomb structure material (7) on the upper surface, and a bottom insulation layer (5) is provided at the bottom of the heat-absorbing core board (4), and a pressure-bearing pipe (6) is arranged in the bottom insulation layer (5). 2. The pressurized flat panel solar heat collector according to claim 1, characterized in that polycarbonate fin cover plate and honeycomb structure are used to prevent heat loss, while the pressurized pipeline (6) is provided with electronic Expansion valve.

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