Solar flat-panel collector industry has made progress in three major problems

 

Design: combined with market demand to enhance innovation

 

Solar flat-panel collector design is a very critical link. China's solar thermal industry alliance Secretary-General Jia Tieying recently pointed out in Jinan flat panel, flat-panel collector design is the industry's short board, the industry really flat plate collector production enterprises much innovation is not enough, most companies To imitate the main, resulting in the industry flat plate collector technology development process is slow, serious product homogeneity and so on. Therefore, in the future should continue to strengthen the enterprise's technological innovation capability.

 

In this case,

 

In the coating, the relevant experts believe that the coating should be combined with the needs of the market, whether the coating process or equipment companies need to be technology into products. For the flat-panel solar hot water system, should consider the absorption ratio and emission ratio and other issues, these two points is to improve the high-performance flat-panel collector of the key points. Such as the blue film of salt spray resistance is poor, but closed breathing plate to solve this problem, with the conditions can be used blue film, can get the best thermal performance, but also allow its thermal stability and lasting. Second, to avoid the damage caused by the high-temperature air drying on the collector, the air drying assessment is the working temperature of the supporting material can meet the requirements, if the product back use of polyester fiber insulation effect is poor, the working temperature of less than 120 ℃, Poor flat air drying will exceed this temperature; EPDM seals and manifold seals long-term working temperature of 150 ℃, according to strict requirements for the failure. Second, most of the flat plate collector can not be confined, but occasionally made of airtight glass, easy to break, this is the flat panel technology must be closed and controlled respiration of the truth. Third, the air drying a huge heat distortion, causing structural damage, pipeline leakage, backplane stripping and so on.

 

Water mist: the formation of natural breathing

 

In the developed countries, the flat solar collectors are the effective products of solar energy heat utilization. The thermal theory and methods of the products are perfect, and the materials of their products have great progress in resisting the influence of high temperature and high pressure and the structure of heat absorbing plate , The application share of up to 90%. But there is still inadequate anti-rainwater infiltration, and occasionally as the enclosure of the collector is also varying degrees of water seepage, moisture absorption and poor moisture and so on. If not removed in time, will lead to lower endothermic effect, long-term will lead to heat-absorbing body corrosion, and reduce the insulation effect.

 

Solar flat plate collector water mist

 

Experts believe that flat-panel solar collector will be the city's leading high-rise building products, but the emergence of mist, seriously affected the thermal performance and life of the plate. Therefore, it is necessary to decompose and analyze the components and materials of the flat plate collectors and analyze the influence of the potential failure modes. At last, the main factors of the water mist are as follows: moisture absorption of the insulation materials is too large; Poor results in three areas.

 

As long as the internal collector and the atmosphere connected to avoid the "water mist" phenomenon, to solve the water mist-related problems, we must do a good seal and the appropriate location in the collector to install a one-way outlet, the internal temperature rise after the water mist Naturally disappear.

 

Some experts believe that the most common form of flat-panel collector is the water mist, water evaporation, cold condensed into the water droplets and the formation of diffuse, mainly from the residual moisture, moisture infiltration, damp moisture. Some of these phenomena are caused by external factors, the need to work through the internal factors, the main internal cavity is not closed, resulting in the infiltration of external moisture and damp. The advantage is not closed the gap with the formation of respiratory function, the cavity of the internal moisture can be subject to heat evaporation after the exhaled into the water, but the gap size is unpredictable and control, when the gap can be discharged when the residual moisture. On the contrary, it is not enough to exclude moisture, there will be mist. This general practice at home and abroad with a simple installation of the ventilation tube, there can be the effect of residual water discharge, but it is also the man-made ventilation tube and the subsequent opening of the water seepage channel. It is reported that the invasion of environmental factors will directly or indirectly through the water caused by secondary hazards, non-sealed flat-plate collector can not escape the disaster, so the heat collection chamber must be closed in order to resist environmental hazards outside the collector cavity , For the collector of the collector to create a dry and good operating environment.

 

Should be used as far as possible "sparse" rather than "blocking" concept, the water sparse to the collector enclosure outside the boundary. So the flat-plate collector in order to seepage water must be sealed, sealed flat plate collector in order to balance the positive and negative pressure generated during the operation, but also need to breathe the channel, the breathing channel must be waterproof and breathable; with waterproof Ventilation channel, the need to be dust, moisture measures. The study shows that the ePTFE dustproof and waterproof breathable membrane and moisture absorption and quick drying bamboo fiber material can achieve the purpose of controlling the respiration of dust collecting, waterproofing, dehumidifying, moisture-proofing and self-balance internal and external pressure of the whole collector. Can be summarized as the future development of flat-panel collector cavity closed and controllable breathing is to improve the thermal stability, reliability, durability and longevity of the only way.

 

In many enterprises interviewed, the majority of enterprises believe that to solve the problem of water mist is the appropriate location in the collector to install a one-way outlet; the second is to ensure that the product sealing and exhaust structural water resistance; Third, the use of temperature Low and low moisture content of the insulation material enough to dry, can try to avoid the generation of water mist.

 

Sealing technology and the use of the performance of the flat plate collector is closely related to the design of the frame structure of the existence of various defects will lead to backplane is not tight and so on, backplane and the shell of the seal is insufficient, prone to seepage, water phenomenon. Leading to corrosion of heat absorbers, insulation layer of water failure, the water will lead to serious shell corrosion.

 

Common flat panel collector frame structure

 

Some experts pointed out that the current transparent cover at most do not have rubber seal, and the use of adhesive or double-sided sealing tape way, and then deducted based on the lever principle of pressure; lower set of crocodile mouth, backplane into which, and then by Backplane pressure machine to press the bite, the four corners of the connection fixed in two ways. Corner of the outer structure of the angle, the impact angle and the back plate is more common pressure, on this basis there will be a small difference, which is basically no external rivets, relative to the early four corners and rivets are also regarded as a back and Great progress. But the face of the requirements of the new plate closed, need to be further improved. The current plate structure is not due to extremely homogeneous denial, but within the angle code, the impact angle and back plate lamination way to solve the problem of flat sealing more difficult and cumbersome, because in the need to be sealed place will produce exposure and Flashing seam. The key point is the four corners of the 45 ° and crocodile mouth of the back bite, it is a bending process, the bite is difficult to do all the tight fit, especially the 45 ° seams is not easy to guarantee, for a large area of ​​the backplane , The overall formation will be a problem. Crocodile mouth and the back of the occlusion due to the need to take up more space here, the thickness can not be too thin, which had to increase supplies and costs. To this end, he proposed technical measures: First, the outer corner of the border code to form a closed geometry; Second, curing closed structure, the third is to strengthen the framework structure, through the backplane reinforcement and core support to achieve.

 

For the sealing problem, respondents are given the same answer, there is pressure to switch to the way companies, through the continuous border glue, rather than with the combined border, the sealing effect will be much better, there will not be dislocation, but the overall border Production equipment investment. Some companies are sealed through the silicone rubber, the advantage is to improve product reliability, has good weather resistance, temperature resistance, the temperature range of -55 ℃ ~ 210 ℃ with good flexibility and sealing effect.

 

Through the telephone interviews with the views and opinions of many people, the flat plate collector design, water mist and sealing problem theoretical analysis, I hope that through the several key points mentioned in the control, can improve product heat collection performance, the maximum degree To eliminate the use of hidden products and user concerns. The future, I believe that through industry common innovation, optimization, flat-panel solar collectors can continue to enhance competitiveness, and green, environmentally friendly, clean hot water available to users.