Views:0 Author:Site Editor Publish Time: 2019-09-06 Origin:Site
In recent years, with the continuous high-rise construction, flat-panel solar collector systems are characterized by their high pressure resistance, long life, easy to form a secondary loop system, easy to combine with buildings, and large effective lighting area, not only in large areas abroad. Promote the application and quickly occupy the market in China and become an important member of the solar thermal market. According to statistics, in 2017, the domestic flat-type collector system sold 5.77 million square meters, an increase of 8.9% year-on-year, accounting for 15.50% of the total sales of solar thermal utilization heat collection systems in China. However, compared with foreign countries, especially Europe accounts for more than 90% of the total market, the gap is still very large. Correspondingly, there is also a large gap in the core of the flat absorbing body and the overall level. The specific comparison is shown in the table below.
Advanced level abroad
National standard requirements
The types of foreign film layers are mainly magnetron sputtering blue film cores, accounting for more than 90%.
The domestic film types are anodized, black chrome, sprayed, and blue film. The anodizing and black chrome plating technology has been dominated by the domestic market due to its good weather resistance and low cost. In 2014, the market accounted for 44% of anodizing, 22% of blue film, 18% of black chromium, and 16% of spraying. From the development point of view, the anodizing and black chrome process technology is not as environmentally friendly as physical vapor deposition such as magnetron sputtering and spraying.
Blue film absorption ratio is between 0.93 and 0.97;
The emission ratio is between 0.03 and 0.07.
The absorption ratio of the domestic film layer is between 0.92 and 0.96;The emission ratio of the blue film is 0.05 to 0.1;The other film layer is 0.1 to 0.2 or more.In recent years, the main performance indicators of domestic blue film have reached the international advanced level. In addition to adapting to the improvement of weather resistance in China, if it can further digest and absorb, improve the process level, and solve the problems of performance fluctuation, color difference and unit energy consumption in mass production, it is expected to occupy the domestic mainstream market.
The endothermic coating absorption ratio is ≥ 0.92.The heat absorbing coating emits ≤0.10 than vacuum plating and plating;Other processes ≤0.20.
Materials, processes, heat transfer performance, reliability
The process technology is mature, the equipment is advanced, and the performance is relatively stable. Process research is more in-depth.
In the film substrate and runner material, core heat transfer performance, manufacturing process, coating optical properties and weather resistance, anti-aging properties, adhesion, high temperature durability, welding strength and core life evaluation index, film material Insufficient research on the composition and environmental requirements of the preparation process. Affects life and reliability.
Table 1 Comparison of flat cores at home and abroad
From this table, it can be seen that the plate heat absorbing core should continue to evolve toward the international high level in the future, which is embodied in the core thermal properties; coating adhesion; after the high temperature endurance test, the optical properties of the surface of the heat absorbing body Attenuation coefficient; after the aging test of the coating, the solar absorption ratio of the coating and the normal emission ratio; the film substrate; the flow path of the heat absorber and the service life of the heat absorbing material weld are further refined and standardized.
Advanced level abroad
Domestic product data
Instantaneous efficiency intercept η
Total heat loss coefficient W/(·K)
Mainly automated or semi-automatic production lines.
It has about 25 automated production lines and about 16 semi-automatic production lines. The rest are handmade production lines.
Most can be designed based on engineering needs.
Mostly regular sizes.
Internal structure design
The layout is reasonable and the research is fine.
More reference to imitation.
The process level is high, and the product has strong resistance to freezing, high temperature and waterproof fog.
The overall level of the process is not high, and it is resistant to freezing and high temperature. After use, water mist and absorption surface fogging and white spots are more serious.
After the test, the collector should be free from water seepage and damage.
Commitment for 20 years or more.
Generally less than 10 years.
No corresponding projects and methods
Table 2 Comparison of flat panel collectors at home and abroad
It can be seen from the table that the domestic flat panel collector has a large room for improvement in instantaneous efficiency intercept η, total heat loss coefficient, assembly, external dimensions, internal structural design, internal process, and service life.
Throughout the development of the industry in the past two years, flat panel collectors have been improved in many aspects. In terms of equipment, Shandong Linuoruite New Energy Co., Ltd. was selected as the CCTV national brand plan, and the flat-panel solar collector production line integrating automation, flexibility, informationization and intelligence was completed and put into production, creating a high-level intelligent interconnected production mode. . Dezhou Jinheng New Energy Co., Ltd. focuses on the R&D and production of flat solar collectors, and is determined to use the industry 4.0 concept to build a global professional flat collector production base. The 4th generation production line put into production in 2017, only 13 workers on the whole line, the production line cycle time is 55 seconds. The fifth-generation automated production line, which will be put into production, requires only one final inspection personnel, and the production line cycle time is 40 seconds.
In terms of internal structure design and technology, Tianpu and Wuxing have launched large-scale high-efficiency flat panel collectors for use in alpine regions, extending the use of flat-panel solar energy from hot water to heating; Hebei Light Source “interference membrane heat pipe without junction box solar heating system” "After the evaluation of scientific and technological achievements in Hebei Province, a number of innovations have been implemented on the core components and structures; Shandong Hawker has introduced a vertical mosaic flat solar collector that uses the heat-absorbing rainbow instead of the traditional core; the grating type introduced by Hebei Juri Flat-panel solar energy, Tianshang also launched a flat collector that will breathe. In addition, many companies, such as Zhuhai Xingye, can also develop photovoltaic photothermal comprehensive utilization products, such as photovoltaic water heaters, based on flat panel collectors, using laser welding and integral lamination processes. These measures have improved and improved the production process of flat plate collectors, not only accelerated the replacement iteration of flat plate collectors, but also broadened the application fields of flat plate collectors, which greatly promoted the development process of flat plate collectors in China.
For the instantaneous efficiency intercept η, some professionals have suggested that it should start from four o'clock. First, research and development of selective coatings for flat-plate solar collectors, and coatings should have high absorption, low infrared emissivity, excellent heat and humidity resistance, and suitable processing costs; Low-iron high-transmittance cover glass is widely used. At present, a number of glass manufacturers have begun to produce low-iron glass suitable for solar collectors, and the gap between glass quality at home and abroad is getting smaller and smaller. Third, attention is paid to the optimal design of collectors, improving manufacturing processes and ensuring structural rigor. , to reduce the heat loss of the collector; Fourth, the use of tempered glass as a collector cover, improve the quality of the collector components, using optimized structural design to ensure that the collector can withstand hail, rain, air, Performance tests such as pressure resistance and thermal shock improve the life of the collector and reduce system maintenance costs.
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