|کد مقاله||کد نشریه||سال انتشار||مقاله انگلیسی||ترجمه فارسی||نسخه تمام متن|
|6456691||1420649||2018||8 صفحه PDF||سفارش دهید||دانلود کنید|
- The n and k spectra at high temperature were needed for actual efficiencies.
- High temperature efficient solar-thermal conversion by Î²-FeSi2 on a Ag base.
- High efficiency originates from a steep cut-off at the band-edge absorption.
- Low emissivity originates from thermally stabilized Ag base.
- Thermally stable Ag layer contained SiNx additives and W layers.
In-situ high-temperature measurements of optical constants (refractive indices n and extinction coefficients k) for each layer of solar selective absorbing multilayers were carried out to simulate solar-thermal conversion efficiency at high temperatures. Conventional Mo layers showed a significant rise in infrared emissivity and a degradation of selective absorbing behavior with the increasing temperature. In contrast, thermally stabilized Ag layers maintained low emissivity even at temperatures below 700Â Â°C. In these layers, agglomeration and vaporization were suppressed by SiNx nano-particles dispersed in the Ag matrix and interfacial W adhesive layers, respectively. The interband absorption of Î²-FeSi2 layers at higher temperatures revealed that larger n and k in the infrared region due to thermally excited electrons induced no rise in emissivity of the multilayers, and the narrower band gap based on Einstein's model shifted the absorptance cut-off wavelength closer to the ideal value and hence resulted in a higher solar absorptance. The solar-thermal conversion efficiencies of the multilayers consisting of low emissivity Ag layers with Î²-FeSi2 absorbers were found to be greater than 75.9%, as estimated from the temperature dependence of n and k spectra.
Journal: Solar Energy Materials and Solar Cells - Volume 174, January 2018, Pages 351-358