基于多孔陶瓷的体吸收太阳能集热器性能分析

体吸收型太阳能集热器是3种主要的太阳能集热器之一，具有结构简单，效率高等优点，并且出口空气温度可达800℃以上，应用前景广阔。在体吸收太阳能集热器中，采用多孔材料而不是管路来加热工质，入射辐射可以从外到内逐步进行吸收。该文基于多孔泡沫陶瓷材料构建了一个一维体吸收太阳能集热器计算模型，在此基础上，计算分析了不同参数下的温度分布情况及热辐射吸收效率。研究结果表明，随着多孔陶瓷孔隙率的降低，出口空气温度及陶瓷内部气体与固体达到稳定的深度均逐渐降低，而接收器前表面温度逐渐提高；随着孔径的下降接收器尾部气体出口温度逐渐下降，内部气体和固体达到稳定的深度逐渐减小，但由于孔径的减小使得对流换热系数显著上升，因此其前表面的温度变化并不明显。太阳能吸收效率随着空气流速的降低和入口空气温度的增大而明显提高，但随着入射辐射强度的提高而降低。

Performance Analysis of Volumetric Solar Receiver Based on Porous Foam Ceramics

Volumetric solar receiver is one of three main categories of solar receivers. It has great application prospect due to the simple structure, high thermal efficiency, and the air exit temperature can reach above more than 800℃. The porous material is used instead of tube as absorber in volumetric solar receiver to heat the working medium, and the incident radiation can be absorbed gradually from outside to inside. In this study, an one-dimensional volumetric solar receiver calculating model based on porous foam ceramics is constructed. The temperature distributions and radiation absorption efficiencies at different conditions are analyzed. The results show that both the outlet air temperature and the depth for the temperature of air and ceramic solid reaching to stability decreases apparently with decrease of porosity of ceramic foam, but the temperature of front surface of the receiver increases gradually. With decrease of porous ceramic diameter, the air exit temperature decreases gradually, and the depth for the temperature of air and ceramic solid reaching to stability is decreasing, while, the diameter change has little effect on the temperature of front surface. The air exit temperature increases apparently with decrease of air flow rate and rise of inlet air temperature, and increases with increase of incident radiation intensity. The energy absorbing efficiency is decreasing with decrease of air flow rate and rise of inlet air temperature, and decreases with increase of incident radiation intensity.