Research Of CuO Selective Absorbing Coating And Apply To Solar Collector With A Micro-channel

Solar is an inexhaustible and clean energy which has received much attention from scholars. Solar collector can transform Solar energy to heat, the performance of solar collector need to be analyzed in this paper. In order to improve the performance of solar collector, the main research work are selective absorbing coating and solar collector structure.There are many different selective absorbing coating and various preparation methods. Copper oxide selective absorbing coating has been widely used in flat-plate solar collector. The process of preparation by paint method is simple and low-cost, it’s suitable for commercial production. Copper oxide selective absorbing coating by sol-gel method is homogenous and its preparation is save-time. This two methods to prepare copper oxide selective absorbing coating are adopted in this paper. In addition, the effects of coating thickness, pigment composition and different binders on coating optical properties and heat resistance performance are mainly discussed in this paper. Experiments find that optical performances of those two coating are equal, but the heat resistance and frictional resistance performance of copper oxide selective absorbing coating made by the paint method is superior to the sol-gel method. What’s more, paint coating operation is simpler and more suitable for flat-plate solar collector. The best performance is achieved on the stainless steel when the thickness of the paint is about 10μm and organic silicon resin as the blinder. The solar absorbance and infrared emittance of the paint are 0.87 and 0.32.Flat-plate solar collector is popular all over the world owing to simple process, low cost and high pressure. At present, the size of channel of flat-plate solar collector is big. It’s hard to achieve high temperature in short time, the temperature difference of import and export water is small, it can cause lager heat loss and low efficiency. Solar collector with a micro-channel is designed in this paper to solve these problems. This paper introduces its structure. The best performance is achieved when the channel size is 0.7mm, the distance of cover board and endothermic board is 17 mm. Copper oxide selective absorbing coating is used by sprayer. The performance of the flat-plate solar collector with a micro-channel is researched by this paper.At first, energy distribution, thermal efficiency, heating rate of collector are analyzed by using the theories. The relationship between flow rate and thermal efficiency is researched by experiments. Instantaneous efficiency is proportional to flow rate and unit of length heating rate is inversely proportional to flow rate. Heat transfer coefficient of solar collectorwith a micro-channel is more than ten times ordinary solar collector. The average heat transfer temperature difference is only about 3% of the ordinary solar collector. unit of length heating rate is about 50 times ordinary solar collector. The performance of solar collector with a micro-channel is better than ordinary solar collector.