超临界二氧化碳太阳能腔式吸热器光热特性研究

Investigation of Optic-thermal Characteristics of Supercritical Carbon Dioxide Solar Cavity Heat Receiver

针对太阳能碟式聚光器,设计了一种工质为超临界二氧化碳(sCO_(2))的圆台形腔式吸热器,建立了吸热器的光热模型。采用蒙特卡洛光线追踪法分析了腔式吸热器的光学特性,并基于腔式吸热器的相关理论将热边界条件导入Ansys Fluent软件中,对吸热器的流动传热特性进行了计算流体力学(CFD)仿真模拟。研究了工质进口温度为150℃、太阳光辐射强度为800 W/m^(2)时,吸热器不同采光口直径、倾斜角和辐射发射率对其光热特性影响的规律。研究结果表明:吸热器采光口直径对其光热效率的影响较大,采光口直径增加会降低吸热器光学效率,采光口直径过大或过小都会降低吸热器的热效率;随着吸热器倾斜角的增大,采光口内部热空气和外部冷空气之间的自然对流传热明显增加;辐射发射率对吸热器热效率的影响较小。

For the solar energy disk concentrator,a type of supercritical carbon dioxide(sCO_(2))truncated cone cavity heat receiver was designed and developed,and the optic-thermal model of the heat receiver was established.The Monte Carlo ray tracing method was used to analyze the optical characteristics of the cavity heat receiver.Based on the related theory of the cavity heat receiver,the thermal boundary conditions were introduced into the Ansys Fluent software,and the flow and heat transfer characteristics of the cavity heat receiver were simulated by computational fluid dynamics(CFD).When the inlet temperature of the working fluid was 150℃ and the solar radiation intensity was 800 W/m^(2),the effects of different diameters of the aperture,tilt angles and radiation emissivity on its optic-thermal characteristics were studied.The results show that the diameter of the aperture has a great influence on the thermal efficiency of the receiver.The increase of the diameter of the aperture will reduce the optical efficiency of the receiver.If the diameter of the aperture is too large or too small,the thermal efficiency of the receiver will be reduced;with the increase of the tilt angle of the receiver,the natural convection heat transfer between the hot air in the aperture and the external cold air increases obviously;the radiation emissivity has little effect on the thermal efficiency of the receiver.