Solar heat utilization
Solar energy is a kind of radiant energy. With real-time, must immediately converted to other forms of energy can be used and stored. Converting solar energy into different forms of energy require different forms of energy conversion device. Collector through its absorption surface can convert solar energy into heat energy; Solar cells, solar energy into electricity by photovoltaic effect; Plant through photosynthesis converting solar energy into biomass energy. Theoretically, solar energy can be directly or indirectly into any form of energy, but the transformation, the more the less solar energy conversion efficiency of the final.
As a result of the solar radiation energy flow density is low, so the use of solar energy in order to get enough energy, or in order to raise the temperature, we must adopt the corresponding collector of solar energy collection. Collector according to whether the condenser, can be divided into concentrating collectors and non thermal machine two broad categories of glory. The glory collector, such as the flat collector and vacuum tube collector and able to take advantage of solar radiation in the direct radiation and scatter radiation, heating temperature is low; Concentrating collectors can heat-absorbing surface of sunlight gathered in the area is lesser, can obtain higher temperature, but can only use the direct radiation, and the need to track the sun.
Early in the history of the solar energy utilization device, mainly for the solar power plant, most of them adopt concentrating collectors, only a few USES flat collector. Collector on the plate was invented in the late 17th century, but it was not until 1960 years later, an in-depth research and large-scale application. In the field of solar energy used in low temperature, flat collector technical and economic performance is far better than concentrating collectors. In order to improve efficiency, reduce cost, or in order to meet specific application requirements, developed a variety of flat collector; Mechanic divided, there is air collector collectors, at present a lot of use liquid collector; Materials are classified according to the heat absorbing plate core, with steel pipe, copper, aluminum, copper and aluminum composite, stainless steel, plastic and the gold of the collector, etc.; According to its structure, has a tube plate, flat cartridge, pipe heat exchanger, the heat pipe fin, the coil type collector, etc.; According to the cover plate, with single layer or multi-layer glass, glass steel or lang polymer transparent material, transparent insulation material collector, etc. At home and abroad at present are common used copper collector and copper aluminum composite
Solar energy is a kind of radiant energy. With real-time, must immediately converted to other forms of energy can be used and stored. Converting solar energy into different forms of energy require different forms of energy conversion device. Collector through its absorption surface can convert solar energy into heat energy; Solar cells, solar energy into electricity by photovoltaic effect; Plant through photosynthesis converting solar energy into biomass energy. Theoretically, solar energy can be directly or indirectly into any form of energy, but the transformation, the more the less solar energy conversion efficiency of the final.
As a result of the solar radiation energy flow density is low, so the use of solar energy in order to get enough energy, or in order to raise the temperature, we must adopt the corresponding collector of solar energy collection. Collector according to whether the condenser, can be divided into concentrating collectors and non thermal machine two broad categories of glory. The glory collector, such as the flat collector and vacuum tube collector and able to take advantage of the direct radiation and scattering solar radiation radiation, heating temperature is low; Concentrating collectors can heat-absorbing surface of sunlight gathered in the area is lesser,
High temperature can be obtained, but can only use direct radiation, and the need to track the sun.
Early in the history of the solar energy utilization device, mainly for the solar power plant, most of them adopt concentrating collectors, only a few USES flat collector. Collector on the plate was invented in the late 17th century, but it was not until 1960 years later, an in-depth research and large-scale application. In the field of solar energy used in low temperature, flat collector technical and economic performance is far better than concentrating collectors. In order to improve efficiency, reduce cost, or in order to meet specific application requirements, developed a variety of flat collector; Mechanic divided, there is air collector and liquid collector, the extensive use of liquid collector; Materials are classified according to the heat absorbing plate core, with steel pipe, copper, aluminum, copper and aluminum composite, stainless steel, plastic and the gold of the collector, etc.; According to its structure, has a tube plate, flat cartridge, pipe heat exchanger, the heat pipe fin, the coil type collector, etc.; According to the cover plate, with single layer or multi-layer glass, glass steel or lang polymer transparent material, transparent insulation material collector, etc. At home and abroad at present are common used copper collector and copper aluminum composite
(1) panels. Its role is to absorb solar heat medium heating and its set. In order to improve the collection efficiency, panels, often by special processing or selective coating in order to improve the heating surface absorption of sunlight, and the thermal radiation rate of panels itself is very low, in order to reduce the heat collection hot threatening the environment.
(2) the transparent cover plate. Arrangement at the top of the collector, the effect is to reduce panels and the environment, the convection and radiation heat transfer between the and protect panels from rain, snow, dust. Transparent cover plate of sunlight transmission cell is high, and its absorptivity and reflectivity is small. In order to improve the thermal efficiency of collectors, can use two layers of cover plate.
(3) the thermal insulation layer. Decorate in the bottom of the panels and side, can prevent around the collector to heat dissipation.
(4) shell. The shell, as a skeleton of a collector, should have a certain mechanical strength and good water sealing performance and corrosion resistance.
To reduce the number of flat collector heat loss, improve the heating temperature, the successful development in the 1970 s vacuum tube-a, its heat sealed in high vacuum glass vacuum tube, greatly improving the thermal performance. Will put some vacuum tube-a together, that is, a vacuum tube collector. In order to increase the amount of sunlight collection, some in a vacuum tube-a back with a rigid. Vacuum tube-a generally can be divided into all-glass vacuum tube-a, a u-shaped tube vacuum tube-a, glass, straight through the metal tube glass vacuum heat-collecting tube vacuum tube-a and heat accumulation type vacuum tube-a. Our country has formed with independent intellectual property rights of all glass vacuum tube-a modernization of industry, the production product quality reached the world advanced level in the world first.
Concentrating collectors is mainly composed of condenser and absorber and tracking system of three most. According to the principle of concentrating, concentrating collectors can be divided into two categories, reflex condenser and refraction condenser. In order to meet the requirements of solar energy utilization, simplify the tracking mechanism, to improve the reliability and reduce the cost, the glory of the research and development in the 20th century is a wide variety of collector, the number of application but far less than the plate collector. Applied in the reflex concentrating collectors more glory is revolving paraboloidal mirror collector (point focusing) trough paraboloidal mirror concentrating collectors (focus). The former can obtain high temperature, but must carry on the two-dimensional tracking; The latter can gain medium temperature, with one dimensional tracking. These two kinds of concentrating collectors is applied in the early 20th century, many improvements were made for decades, such as increasing reflective surface machining accuracy, high reflective materials, developing high reliability tracking mechanism and so on, now the two parabolic mirror concentrating collectors can completely meet the requirements of all kinds of medium temperature, high temperature solar energy utilization, but due to their high cost, restricts their wide application.
Other types of reflective concentrator and conical reflector strip, spherical mirror, mirror, bucket trough reflects pound, etc. In addition, there is a kind of application in the solar power tower condenser (heliostats). Heliostat is composed of many surface mirror or a plane mirror, the mirror will reflect sunlight under computer control to the same absorber, absorber can achieve very high temperature, get a lot of energy.
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