Soot-based coatings for solar cookers

Different kinds of soot were evaluated as selective coverings for use in solar cookers. The coatings were analyzed by measuring their thermal parameters and reflectance in the range of 280-2400 nm. Analyses include a comparison of black paints with coatings made from different kinds of soot. Coatings were prepared with different particle sizes and applied to a solar cooker to determine standard cooking power, thermal performance and exergetic efficiency. The thermal parameters obtained for the solar cooker after applying the coatings made with different kinds of soot showed no significant differences in relation to particle size or the kind of soot. Findings show that measurements of thermal parameters of the soot-based coatings were 20% higher than the values obtained for commercial black paints. Also, the solar reflectance values of the soot-based coatings averaged 2.5%, while the figure for the commercial black paints was 4.5%. Finally, a semiempirical model using the measured reflectance was employed to estimate the standardized cooking power, with favorable results in accordance with the experimental data.