Dependence of Optical and Thermal Properties on Substrate of Solar Thermal Collectors

The optical and thermal properties of the black crome based Solar thermal collectors (STCs) deposited on three different substrates (aluminium, Al; galvanized iron, GI; and stainless steel, SS) were investigated. The devices were prepared by two different methods: electro-deposition and dip coating and were heat treated at 300 °C. Each STC's performance was evaluated by measuring optical and thermal properties: Optical properties were measured with UV-Vis, Raman and IR Spectroscopy. For later measurements, all the STC samples were kept inside an air tight glass box and are exposed to the solar radiation over all the sunshine hours in summer (from 7:30 am – 5 pm, August). Then, the instantaneous temperature was recorded, simultaneously, of all samples with IR-temperature sensor. Among all the samples, the STC with black chrome coated on Al substrate showed the highest temperature, reaching the maximum value of ca. 95 °C at about 1 pm. Moreover, the STC samples fabricated by dip coating found to possess as equal optical and thermal properties as samples prepared by electro-deposition. (paper)