Comparative Experimental Study of New Absorbent Surface Coatings for Flat Plate Solar Collectors

AbstractUse of solar energy has a huge an enormous importance around the world especially in processes for the generation of electric power and heating applications; these processes such as thermal heating of pools, have been a very important factor to obtain a benefits in terms of technology and economy as regards of the usage of other conventional energy sources. In this work, the pool heating process was realized using a glass covered flat plate solar collector heating system with a copper absorber tube and aluminum fins operating in forced flow; they were installed in an elementary school. The objective was to make a comparative study of the adhesion, hardness, reflectivity, absorptivity and durability of two different commercial coatings on an absorbent surface of copper and aluminum, compared to the original coating of the absorber. The adhesion force was established in accordance with ASTM D3330-09 where the original coating is classified in a scale 5B showing no damages by desquamation. While the epoxy test was classified in a scale 4B and 5B; it indicates that it has a very good adhesion force, and few damages by scaling was observed. The reflectivity was measured based on ASTM D3330-09 standards. Another result was that the absortivity of the epoxy coating had values between 0,93 and 0,95; better results than the original coating that had values between 0,88 and 0,94. The durability assessment of the epoxy coating, which is exposed since December 2011 in the pool solar heating field, confirms that at first sight appreciable alteration was not observed on its surface, neither detachment. These studies are essential to establish which of these coatings are the most adequate technically and economically for a preventive and corrective maintenance of flat plate solar collectors