Submillimeter solid particles have been considered as thermal storage media for concentrated solar power applications. Knowledge of the scattering and absorption properties of individual particles is crucial for modeling the radiative heat transfer of the particle bed. In this work, a laser scatterometer is used to measure the single-particle scattering properties at a wavelength of 635 nm by using two configurations: (1) a falling particle curtain and (2) a taped particle layer. Because a one-particle nominal thickness is formed with area fractions of 5−55% depending on the configuration, multiple scattering is minimized and hence the single scattering phase function, averaged over all illuminated particles, is directly measured. Bauxite-based ceramic particles that are strongly absorbing in the solar spectrum and silica particles that are nonabsorbing in the visible and near-infrared are investigated. The directional-hemispherical reflectance and transmittance of the taped particles are also measured to deduce the forward and backward scattering efficiency factors and the absorption efficiency factors. Only weak wavelength dependence is observed in the measured region from 380 nm to 1020 nm. The scattering phase functions of all bauxite-based particles with varying sizes and compositions are very similar and can be fitted to a Henyey−Greenstein phase function with an asymmetry factor g = −0.20. For the silica particles, forward scattering dominates and g = 0.45 yields the best fit. A Monte Carlo method is developed to model the particle scattering characteristics, and reasonable agreements between the modeling and experimental results are observed by introducing a specularity parameter.

亚毫米固体颗粒已被认为是聚光太阳能应用的蓄热介质。了解单个粒子的散射和吸收特性对于模拟粒子床的辐射传热至关重要。在这项工作中，激光散射仪用于测量波长为 635 nm 的单粒子散射特性，使用两种配置：(1) 下落粒子幕和 (2) 胶带粒子层。由于单粒子标称厚度形成的面积分数为 5-55%，具体取决于配置，因此多重散射被最小化，因此直接测量对所有照射粒子求平均值的单个散射相位函数。研究了在太阳光谱中强烈吸收的铝土矿基陶瓷颗粒和在可见光和近红外光中不吸收的二氧化硅颗粒。还测量了胶带粒子的定向半球反射率和透射率，以推导出前向和后向散射效率因子和吸收效率因子。在 380 nm 至 1020 nm 的测量区域中仅观察到弱波长依赖性。所有具有不同尺寸和成分的铝土矿颗粒的散射相函数非常相似，可以拟合到具有不对称因子的 Henyey-Greenstein 相函数 还测量了胶带粒子的定向半球反射率和透射率，以推导出前向和后向散射效率因子和吸收效率因子。在 380 nm 至 1020 nm 的测量区域中仅观察到弱波长依赖性。所有具有不同尺寸和成分的铝土矿颗粒的散射相函数非常相似，可以拟合到具有不对称因子的 Henyey-Greenstein 相函数 还测量了胶带粒子的定向半球反射率和透射率，以推导出前向和后向散射效率因子和吸收效率因子。在 380 nm 至 1020 nm 的测量区域中仅观察到弱波长依赖性。所有具有不同尺寸和成分的铝土矿颗粒的散射相函数非常相似，可以拟合到具有不对称因子的 Henyey-Greenstein 相函数g  = -0.20。对于二氧化硅颗粒，前向散射占主导地位，g  = 0.45 产生最佳拟合。开发了一种蒙特卡罗方法来模拟粒子散射特性，并通过引入镜面反射参数观察到建模和实验结果之间的合理一致性。