Characterization of thermal performance and optical properties of a material under concentrated radiation using a high flux solar simulator

In this work, characterization of thermal performance and optical properties of a material using a new developed indoor facility is undertaken. The indoor facility is capable of independently controlling the temperature of the material and the flux incident on it. Thereby, allowing investigation of independent effect of temperature and flux on a material’s thermal performance and optical properties variations. An unpolished 304/304L stainless steel is selected as a candidate material. The selected material is machined to obtain a sample having 20 mm diameter and 10 mm thickness. The sample is exposed to five levels of homogenized fluxes in the range of 579.3 kW m⁻² to 917.1 kW m⁻² for the duration of 1000s and 3000s. It is found that the thermal performance of the materials decreases with the increase in incident flux but this decrement depends on the temperature of the material. The 21% decrement in the thermal performance is obtained when temperature of the material is changed by 159 K while only 6.7% decrement in thermal performance is observed under same condition when the temperature of the material changes by 22 K. The variation of optical properties also depends on the temperature of the material. Under the same flux of 917.1 kW m⁻² and exposure duration of 1000s, the reflectance of the material changes by 26% and 7% when temperature of the material is maintained at 557 K and 368 K respectively.