A comparative study for selecting more efficient black selective coating in solar water heating system

Document Type : Original Article

Authors

1 Chemical Engineering &Pilot Plant Dep., National Research Centre

2 National Research Centre

3 Solar Energy Dep., National Research Centre

4 chemical Engineering&pilot Dep.,National Research Centre

5 chemical Engineering &Pilot Plant Dep.,, National Research Centre

6 Professor chemical engineering

Abstract

Solar thermal collector represents a common system for efficient solar energy conversion. In the field of solar panels, there are numerous types of coatings, their absorptivity is almost more than 90%. The challenge now is to lower the heat loss through emissivity as it predicts the ultimate efficiency (i.e. performance). The solar selective coating is showing higher solar absorption efficiency compared to the commercial black paint, that are applied in most usual solar water heating systems. The present research is devoted to test two types of coatings: second anodized aluminum and traditional matte black paint. Two prototypes of solar water heating system were designed, one having aluminum solar panel coated by matte black paint and the other including solar panel of anodized aluminum electrolytically colored by tin metal ions after two steps of anodization. The second anodized was found to be superior. The calculated performance or efficiency was about 62%. The efficiency of matte black paint was less than the second anodized type. Moreover, the performance without collector glass cover is lowered drastically

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