Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver
Infrared-Reflective Coating on Fused Silica for a Solar High-Temperature Receiver
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DOI：
10.1115/1.3097270
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发表时间：
2007
影响因子：
2.3
通讯作者：
Marc Röger;C. Rickers;R. Uhlig;Frank Neumann;C. Polenzky
中科院分区：
文献类型：
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作者：
Marc Röger;C. Rickers;R. Uhlig;Frank Neumann;C. Polenzky
在集中太阳能发电中，高温太阳能接收器可以为电力或化学生产的高效循环提供热量。熔融石英窗口的过度加热和由此产生的重结晶是使用窗口的高温接收器的主要问题。通过在玻璃窗内部涂上红外反射太阳能透明涂层，可以避免玻璃窗温度过高。玻璃温度和接收器损耗都可以降低。理想的涂层将热吸收体（1100°C）的部分热光谱（λ>2.5 µm）反射回其上，而不会降低太阳光透射率。进行了广泛的辐射模拟以筛选不同的滤波器类型。所研究的透明导电氧化物（TCO）涉及高太阳能吸收率，抑制其在高聚光太阳能系统中的使用。虽然传统的介电干涉滤光片具有低的太阳能吸收，但来自各个方向的太阳辐射的反射太高。结果发现，只有rugate过滤器满足高通量的太阳辐射与不同的入射角下的操作要求。一个热力学资格模拟的褶皱涂层的平板接收器的窗口上显示出减少了近175 K的平均窗口温度和11%的接收器的损失相比，未涂覆的窗口。对于加压接收器（REFOS型）的配置，温度可以降低65 K，接收器损耗略有降低。最后，制造了第一个25 μm厚的rugate过滤器并进行了光学表征。测量的光谱拟合近似的设计光谱，除了两个吸收峰，可以避免在未来的沉积通过改变沉积几何形状和使用原位监测。本文的议题是分享在过滤器类型的选择、过滤器设计、热力学评估和沉积实验方面所做的工作。
In concentrating solar power, high-temperature solar receivers can provide heat to highly efficient cycles for electricity or chemical production. Excessive heating of the fused-silica window and the resulting recrystallization are major problems of high-temperature receivers using windows. Excessive window temperatures can be avoided by applying an infrared-reflective solar-transparent coating on the fused-silica window inside. Both glass temperatures and receiver losses can be reduced. An ideal coating reflects part of the thermal spectrum (lambda>2.5 µm) of the hot absorber (1100°C) back onto it without reducing solar transmittance. Extensive radiation simulations were done to screen different filter types. The examined transparent conductive oxides (TCO) involve a high solar absorptance, inhibiting their use in high-concentration solar systems. Although conventional dielectric interference filters have a low solar absorption, the reflection of solar radiation which comes from various directions is too high. It was found that only rugate filters fulfill the requirements for operation under high-flux solar radiation with different incident angles. A thermodynamic qualification simulation of the rugate coating on a window of a flat-plate receiver showed a reduction of almost 175 K in mean window temperature and 11% in receiver losses compared to an uncoated window. For the configuration of a pressurized receiver (REFOS type), the temperature could be reduced by 65 K with slightly reduced receiver losses. Finally, a first 25-µm thick rugate filter was manufactured and optically characterized. The measured spectra fitted approximately the design spectra, except for two absorption peaks which can be avoided in future depositions by changing the deposition geometry and using in-situ monitoring. The issue of this paper is to share the work done on the choice of filter type, filter design, thermodynamic evaluation, and deposition experiments.