Enhancement of the Solar-Thermal Response of Flat-plate Collector Coated with a Heat-resistant Paint

Abstract: A commercially available heat-resistant paint (HRP) is used as the primary component of a composite coating for low-temperature flat collector system. The same is mixed with small amounts of carbon black powder (CBP), lithium metal oxide (LMO) powder or both in an attempt to enhance the coating solar-thermal conversion characteristics. The optical characteristics of these coatings are investigated by means of optical microscopy, optical spectrophotometry and measurement of reflectance. The solar-thermal conversion characteristics are investigated by measuring the maximum collector temperature due to exposure to solar radiation. Results show that the solar-thermal conversion (maximum temperature) of the collector plate can be improved with the addition of CBP and LMO particles at low concentrations. The solar-thermal characteristics of the coatings are reported and compared with those of different coatings. The coatings prepared in the present work can easily be applied on the collector surface, which makes them suitable for flat-plate collector systems. Keywords: Flat plat collector, Selective coating, Optical properties, Solar irradiance.