Flat-panel solar collectors have always been the mainstream products of global solar thermal utilization. When China’s solar thermal utilization industry started in the 1970s, it also took the same road of developing flat-panel collectors. Due to the poor living conditions of Chinese urban and rural residents at that time, the vast majority of urban workers and residents lived in “cone towers” with no separate bathrooms and kitchens for their families, but only an inner walkway.
Therefore, the domestic solar water heater is still in the status of a “new concept” experimental demonstration product. Since the natural circulation compact domestic solar water heater of “circular water tank and flat plate”, since the late 1970s from Yunnan to the whole country, after large-scale promotion and application in different regions, it has proved the reliability and reliability of its original innovative structure design. Reasonable; only as the “standard model” of China’s domestic solar water heaters, it has been widely promoted and applied nationwide for decades. On the other hand, this phenomenon also shows that in order to make any substantial improvement to the system structure, there are still some technical limitations so far.
But after decades of practical application, especially the rise of China’s real estate industry, with the emergence of various new modern buildings, especially the construction of new high-rise and super-high-rise buildings, people have further discovered that “round bed” The “water tank plus flat plate” type system and its “thin metal groove plus benzene plate” as the typical structure of the “flat plate solar collector” are not all perfect, and the system does have some areas that need to be further improved and perfected. .
First, from the perspective of the structure of this system, the high-level circular horizontal thermal insulation circulating water tank is placed at the top of the system, which leads to a high center of gravity of the system, which reduces the stability, safety and wind resistance of the system; The structure of the piping system is too complicated, which not only causes the heat dissipation area of the circulating piping to be too large, but also restricts the coordinated installation of the natural and organic combination of the hot water system and the building structure. Simply erecting it on a flat roof or a sloping roof will not only destroy the architectural landscape, but also cause visual pollution and safety hazards to the building’s shape.
Second, the installation angle of the collector cannot be adjusted as needed. The installation angle must be installed for a lifetime when it leaves the factory. Not only can it not be adjusted according to the sunshine conditions of the installation site and the sunshine height in different seasons of use, it can be adjusted as needed to improve the efficiency of collecting sunlight; According to the architectural style structure of the surface, the system can be combined and adjusted accordingly; it also does not have the flexibility and reliability of integrated and coordinated installation with the buildings it carries.
Third, the water temperature of the system cannot be regulated, and the capacity configuration of the circulating water tank is generally low; the system cannot make any necessary separation of storage and storage according to local conditions, so that the collector and the facade of the building can be matched with each other, so that the light-to-heat conversion efficiency is better. Working state; the thermal insulation circulating water tank can enter the home and be installed at a low position.
Fourth, the system does not have technical measures for windproof, shockproof, high-temperature scaling and low-temperature antifreeze, or related basic functions.
Fifth, when the hot and cold water is mixed in a heat preservation water tank, and the “top water method” is used to obtain hot water, the hot and cold water is seriously mixed; as a result, the hot water produced by the system on that day cannot be all up to the standard, and even most of it is used. Effective extraction and utilization.
Sixth, the pipeline cannot be automatically emptied after a delay. Because the hot water output pipeline is too long, every time the hot water is taken (especially the floor users), it will cause a large number of pipelines to dissipate heat and clean the waste water; With remote control sewage self-cleaning function.
In actual use, we also found that the existing metal frame of flat-panel collectors (including the so-called “aluminum profile frame and polyester insulation strip” that appeared recently) caused the metal frame of the hot-box type flat-panel collector to be “around the four corners”. As well as the transparent cover and bottom plate, the upper and lower “both sides” leak water, air and heat, and the root cause of the poor sealing is.
In recent years, some Chinese manufacturers have “returned to the basics” and returned to the “old method” used in the design and manufacture of the first batch of quantitatively produced “round horizontal water tank and flat plate” and “TGB-150” water heater products in Yunnan. The cold-rolled sheet is first punched into a “thin metal shallow pool” type shell, and then a thermal insulation layer (perlite or mineral wool) is established in the “shallow pool” shell, and then the heat collector core is installed by the embedded method to strengthen the shell. The sealing and thermal insulation performance of the bottom and surrounding areas of the body. However, this process has not been able to simultaneously solve the internal thermal insulation and leak-proof sealing of the glass cover and the surrounding shallow pool box, and the old problems of anchoring and installation around the external collector frame.
In order to solve the sealing problem of the glass cover, some products use high-performance colloid to bond the glass cover and the metal frame together. One of the consequences of this method is that the flat-panel collector completely loses its minimum maintainability. . Today, China’s flat-panel solar collectors still exist: high transmittance, tempered white glass assembly; metal frame collector’s “four corners, four sides, two sides” all-round thermal insulation and sealing technology breakthrough; high absorption rate , Low emissivity, good weather resistance and economical vacuum magnetron sputtering metal coating (blue film; or black chrome type) new heat collector plate popularization and application; flat plate anti-freezing, sewage, anti-scaling and other new technologies development ; The supporting development of the simple anchoring installation tripod of the collector: the solution of new technologies, new materials and related production line production problems.
In the design of the natural circulation system of the flat plate: the high center of gravity of the natural circulation system, the separation of collection and storage, the heat loss of the system circulation pipeline, the passive automatic time delay emptying, the development of new technologies for the special pipe valve control system: the water tank enters the home, the split A series of technical problems such as wall-mounted, building integration coordination and concealed installation: effective extraction of hot water that meets the standard produced on that day; passive secondary circulation heating of the residual water for heat dissipation in the water tank, etc., require in-depth research and solutions one by one. As far as the current demand is concerned, if my flat panel wants to return to the mainstream position of the market, it is now facing a period of opportunity to solve the development of integrated solar heating technology for high-rise and super high-rise buildings; Design and production technology is at an inflection point that needs to be updated. The solution of the above-mentioned related problems will surely usher in a great recovery of tablet technology.
Rise and fall, success or failure, in one fell swoop. It can be asserted that the new generation of tablet is not just tinkering on traditional products, but must be integrated from the aspects of system structure, material selection, performance improvement, function improvement, production process development, research and development of special machinery and equipment, and manufacturing. It is necessary to introduce innovative design concepts, innovative technical means, modern special equipment, mold-based tooling processes; and new production technical standards, overall consideration, and collaborative research. Only then can a complex system project be completed.
China’s natural circulation flat-panel solar collectors have been stagnant in technology for more than 30 years, coupled with market interference by unscrupulous merchants cutting corners and excessive price competition, resulting in China’s flat-panel solar energy series products, which are far behind foreign countries in terms of technical performance and product quality Passive situation of similar products. It’s time for the Chinese tablet to sound the alarm. China’s flat-panel solar panels will no longer keep pace with the times and are determined to overcome the long-standing shortcomings and problems in system structure and technology, and push the technical quality and thermal performance of products to a new level. China’s flat-panel solar energy is not only difficult to enter the world, but will inevitably face Dangerous situation to be eliminated.
At the critical moment when China’s flat-panel collectors were marginalized, Kunming Nankai Energy Research Institute made a list of various problems existing in traditional flat-panel, and organized forces to explore the way to revive China’s flat-panel. They first started with the secondary development of the basic components of the flat-panel collector. In order to improve the sealing performance of the flat-panel “hot box”, they screened out the thermal conductivity of less than 1/1250 of aluminum, which is resistant to ultraviolet radiation, heat-resistant aging, and easy to process and form. Thermoplastic non-metal engineering plastic materials, instead of traditional metal materials such as aluminum profiles or thin stainless steel plates, are used to manufacture new multi-functional flat plate collector frames, so that the collector frames have good weather resistance, heat preservation and sealing in essence. , Insulation performance.
In addition, while strengthening the sealing and anti-leakage function of the frame of the collector, a full range of locking slides and matching special buckles are added around the frame to facilitate the collector to be able to operate in any state. It realizes the anchoring installation at any point around the frame; at the same time, it also strengthens the steel structure of the flat plate to prevent deformation. In order to prevent rainwater that may leak into the rubber sealing strip around the transparent (glass) cover and leak into the inside of the hot box to cause heat loss; the rear eaves of the special rubber strips on the transparent cover and the lower side are also specially set. Under the premise of ensuring that the sealing of the heat box is not damaged, the water collecting ditch and the drainage groove can automatically collect and drain the rainwater that may be immersed into the heat collector box.
The plastic-steel frame also has plate core positioning; transparent cover and bottom plate are easy to seal and lock and install; four corners, two sides, and four all-round insulation and sealing: convenient for large-scale assembly line production and assembly. Because it is a multi-functional frame special profile manufactured by optimizing the structural design and special mold assembly line according to the special performance requirements of the flat-panel collector, this not only completely solves the functional and performance defects that the traditional metal frame has not overcome for a long time, It has innovated the production process of traditional flat plates and improved the quality standards of related production technologies.
Moreover, it creates conditions for the realization of building-integrated installation of flat-panel collectors, especially the simple anchoring installation on tiled sloping roofs, balcony guardrails, and window sills. The mass production cost of this patented new product is comparable to the price of aluminum profiles or thin stainless steel plates of the same size, and its service life is more than ten years. The sealing performance, weather resistance, craftsmanship, safety and reliability, appearance and internal quality of the collector, the cost performance of the product, and the environmental protection function and recyclability of the material are all greatly improved compared with traditional products. The successful development of plastic-steel frame profiles for multi-functional flat-panel collectors has explored a new path for reference and choice for China’s flat-panel upgrade.
Subsequently, Kunming Nankai Energy Research Institute successfully developed a “venting water stop valve” matching the plastic-steel frame and a tube-sheet high-performance core integrated with a natural circulation system, thus developing a new generation of “tube-sheet natural circulation system”. Integrated Flat Plate Collector”. This type of patented new technology product realizes a flat plate, which is a set of “natural circulation hot water system” with ultra-thin and ultra-light structure. The new technology product enables the natural circulation system to remove the high-level thermal insulation water tank, and realizes the complete separation of collection and storage; so that the collector can steplessly adjust the installation angle between 10°-50°: it is easy to realize the constant temperature water discharge or replenishment of the natural circulation. control.
The new technology products can also be arbitrarily assembled into a large-scale solar water heating engineering system with high efficiency through various combinations such as parallel and series; and can meet the requirements of higher standards for building-integrated coordinated installation. The new generation of “tube-sheet natural circulation system integrated flat-panel collector”, as a replacement product of traditional flat-panel, has comprehensively improved the technical performance of China’s flat-panel hot water system, and has developed a high-performance natural circulation with independent intellectual property rights and Chinese characteristics. The road to innovation in solar thermal systems. The beneficial exploration made by Kunming Nankai Energy Research Institute on the integration of flat panel natural circulation system has important reference value and typical demonstration significance for the innovative development of flat panel technology in China (province).
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