Concentrating solar power (CSP) technologies have the potential of replacing global natural gas and liquid fuels consumptions by producing solar hydrogen. There are many factors that hinders the competitive low production price of this technology such as degradation of given properties of a solar absorber material over time due to temperature and solar radiation (Brunold
et al., 2004). In case of solar absorber materials, the most important factor for aging is degradation of reflectance/absorptance over time and its mechanical integrity (Boubault
et al., 2014a). Furthermore, sudden variation of temperature over a short period of time due to variation of solar radiation is another cause of aging (Boubault
et al., 2012). It is proposed (Boubault
et al., 2014a) that measurement of thermal performance of a material can serve as an ageing criterion (Boubault
et al., 2014b), which can be achieved by quantification of its absorption and heat transfer ability. In this work, we will investigate the thermal performance and the optical properties of stainless steel, as a reference material, using a high flux solar simulator and a low power light source. The testing facility consists of a high flux solar simulator which is capable of irradiating Gaussian distributed variable flux (Sarwar
et al., 2014). A light collimator was used to homogenize the incident flux. The flux characterization was carried out before and after homogenization using a water cooled Gardon-type circular foil radiometer. The material was exposed to the homogenized flux for given time periods, while we were monitoring continuously the temperature of the material and the heat flux at the back side of the material. The optical properties of the material such as absorption and reflectance were measured and compared before and after exposure to the high concentrated irradiance. Here we present the results of the characterization and the method validation against a total integrated reflectance/transmittance method employing a spectrometer with an integrating sphere.
Acknowledgements
This publication was made possible by a PDRA award [PDRA2-1105-14044] from the Qatar National Research Fund (a member of The Qatar Foundation). The statements made herein are solely the responsibility of the authors.
References
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