Optical characterisation of alumina–mullite materials for solar particle receiver applications
Optical characterisation of alumina–mullite materials for solar particle receiver applications
复制标题
用于太阳能粒子接收器应用的氧化铝-莫来石材料的光学表征
DOI：
10.1016/j.solmat.2021.111170
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发表时间：
2021
影响因子：
6.9
通讯作者：
Wojciech Lipiński
中科院分区：
文献类型：
--
作者：
Jingjing Chen;Vincent M. Wheeler;Boqing Liu;Apurva Kumar;J. Coventry;Wojciech Lipiński
氧化铝-莫来石颗粒用于高温太阳能热应用，例如太阳能颗粒接收器。本研究在0.193-1.69 μ m光谱范围内测定了不同氧化铝和莫来石含量的氧化铝-莫来石材料的光学性质。利用变角椭圆偏振光谱仪对磁控溅射法制备的氧化铝-莫来石薄膜进行了测量。薄膜的特征在于通过扫描电子显微镜，原子力显微镜，和能量色散光谱法。采用B样条模型生成椭偏参数，拟合测量数据，获得光学特性。所研究的氧化铝和莫来石含量可变的材料在所考虑的光谱范围内具有相似的折射率。氧化铝-莫来石材料在0.193-0.4 μ m光谱范围内的吸收系数高于0.4-1.69 μ m光谱范围内的吸收系数。在0.193-0.4 μ m光谱范围内，随着氧化铝含量的增加，吸收系数减小。在0.4-1.1 μ m光谱范围内，由相似比例的氧化铝和莫来石组成的材料具有最高的吸收指数。确定的氧化铝-莫来石材料的光学性质被施加到获得球形均匀颗粒的辐射特性。Mie理论被用来计算吸收和散射效率因子，以及散射相函数。此外，散射相函数得到使用Henyey-Greenstein近似和输运近似。采用蒙特卡罗射线追踪方法研究了高通量太阳辐射下一维粒子幕模型中的辐射传输。研究发现，颗粒的总反射率、吸收率和透射率仅微弱地依赖于所研究的材料的光学性质。
Alumina–mullite particles are used in high-temperature solar thermal applications such as solar particle receivers. In this study, optical properties of alumina–mullite materials with variable content of alumina and mullite are determined in the spectral range of 0.193–1.69 μ m. Variable angle spectroscopic ellipsometry is performed for alumina–mullite thin films, which are fabricated by magnetron sputtering. The thin films are characterised by scanning electron microscopy, atomic force microscopy, and energy dispersive spectroscopy methods. The B-spline model is employed to generate ellipsometric parameters to fit the measured data and to obtain the optical properties. The investigated materials of variable content of alumina and mullite have a similar refractive index in the considered spectral range. The absorptive index of the alumina–mullite materials in the spectral range of 0.193–0.4 μ m is higher than in the range 0.4–1.69 μ m. The absorptive index decreases with increasing content of alumina in the spectral range of 0.193–0.4 μ m. The material composed of similar proportions of alumina and mullite yields the highest absorptive index in the spectral range of 0.4–1.1 μ m. The optical properties determined for the alumina–mullite materials are applied to obtain the radiative properties of spherical homogeneous particles. Mie theory is used to calculate absorption and scattering efficiency factors, as well as the scattering phase function. In addition, the scattering phase functions are obtained using the Henyey–Greenstein approximation and the transport approximation. The Monte Carlo ray-tracing method is employed to study the radiative transfer in a model one-dimensional particle curtain containing polydisperse particles exposed to high-flux solar irradiation. It is found that the overall reflectance, absorptance and transmittance of the particles only weakly depend on the optical properties of the materials investigated.