Several Key Technologies Research Of Flat-plate Solar Collector

The flat-plate solar collector has high thermal efficiency, simple structure, good ability of under pressure, and a high degree of integration with buildings. It has become the hot topic in the study of solar energy utilization today. However, the flat-plate solar collectors which are existing in the market have low design efficiency and high manufacturing costs. In order to improve the thermal performance of flat plate solar collectors and reduce the manufacturing costs, this paper use computational fluid dynamics technology to study form two angles that external structural factors and internal working conditions of flat plate collectors. The geometry factor for collector plate thickness and material, the internal fluid tube space and air layer thickness are optimized and analyzed by using numerical simulation technology; The flow and heat transfer mechanism of different concentrations of grapheme oxide nano-fluid heat working fluid that in fluid tube are analyzed, a new working heat transfer fluid is used to flat plate collectors; The influent of the different fluid tube diameter, wall heat flux and fluid inlet velocity on collector performance are discussed and analyzed.The results indicate that:When collector plate thickness is beyond 0.6mm, continuously increasing the thickness of collector plate has little impact on efficiency of flat plate collector. If the collector plate is made of aluminum, the efficiency of collector is only about 2.36% lower than that the collector plate is made of cooper. When the collector fluid tube space is smaller and the collector plate is thicker, the efficiency factor is larger. When the air layer is thicker and the temperature difference is smaller between collector plate and cover, the convective loss is smaller in air layer. Considering the stability of the collector and economy, the air layer thickness should be about 30-40mm. Graphene oxide nano-fluids as working fluid can significantly improve the heat transfer performance, but small difference is between different concentrations of nano-fluids. When the fluid tube diameter, the heat flux and fluid inlet velocity are larger, fluid flow reaches turbulent condition, and then the wall heat transfer with fluid is more fully.