Solar selective adsorption coating is a key technology in the solar thermal utilization and it is essential to improve the efficiency of the collector. Selective heat-absorbing coatings can be prepared by a variety of methods, such as spray coating, electrochemical, vacuum evaporation, and magnetron sputtering. However, these methods all have certain deficiencies, such as environmental pollution, harsh process conditions, high production costs, poor weatherability, and high emissivity. Spinel-type transition metal oxides (spinel-type pigments) are an important class of solar selective heat-absorbing materials with appropriate energy gaps Eg, absorption of energy in the visible and near-infrared range, and at the same time Through low energy infrared radiation.
Researchers at the R&D Center for Environmental Materials and Eco-Chemistry of the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences prepared spinel-type transition metal oxides by sol-gel self-propagating combustion, and calcined the burned powders at a certain temperature to obtain black spinel. The pigment is used as a light absorbing agent to prepare a solar selective heat absorbing coating with high selective heat absorption ability by a simple coating method. This technology was recently granted a national invention patent (a method for preparing solar selective heat absorbing paint using spinel pigments as a light absorber, patent number: ZL201110260189.4).
Researchers dispersed the nano-scale spinel pigments with resins, solvents, and additives using a ball-milling method, and added curing agents to obtain solar selective heat-absorbing coatings. The coating is uniformly coated on the metal substrate by a simple coating method, and a solar selective heat absorbing coating is obtained after curing at room temperature. Experiments show that the coating has high solar absorptivity (about 0.95) and lower emissivity (about 0.10), which can effectively improve the solar heat collector's light-to-heat conversion efficiency, and the coating has good mechanical properties. With strong weather resistance, the service life is more than 45 years.
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