ايجاد پوشش هاي جاذب خورشيدي به روش آندايزينگ رنگي آلومينيوم و ارزيابي خواص تابشي آن

چكيده انگليسي :

Formation of Solar absorber coatings by color anodizing of aluminium and Evaluation of its optical properties Alireza Heydari a heydari@me iut ac ir October 28 2009 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSuperviser Dr Ali Akbar Alemrajabi rajabi@cc iut ac irAbstractNowadays the use of solar selective absorbers is prevalent in solar applications There is different methodsfor production of solar selective absorbers with desirable optical properties one of these methods isaluminium anodizing Anodizing was as a safe method to form coatings with excellent adhesion onaluminium substrate known so production of solar absorber coatings with this method uses from twovantage of enough good durability and low cost optical properties of produced surface with this method depends on several factors in the production process anodizing process is performed in an electrolytic cellincluding anod Al plate cathode Al electrod and appropriate electrolyte sulfuric acid by applyingelectric current and then the oxide layer during the process including mass loculate hexagonal cells on thesurface will be formed accurate and quantitative control of production process parameters as voltage temperature time and electrolytes density is very important on optical properties and stability of thecoatings thus it was always for attention of researchers in the past black anodized coatings was in solarapplication used But instability of optical properties of these films researchers encouraged to produce newcoatings In this research optical and microstructural properties of electrocolored anodized aluminiumbased coatings for the sake of arriving of the selective solar absorber was investigated anodizing timeeffect on anodic film thickness and saturating pigments contents on optical and microstructural of films wasexperimentally evaluated in this way oxidic anodic film was grown on commercial pure aluminium1100 which has excellent conductivity in a sulfuric acid electrolyte with 160 g lit 1 density and thenelectrocoloring treatment with copper tin and nickel inorganic pigments in a general procedure was down topography of surface of coatings has been investigated using Scanning Electron Microscopy theseinvestigations reveal that alumina film surface is embowed with average size ranged from approximately 1 10 m coating type layers thickness and morphology of surface are effective on solar absorptance Increasing of solar absorptance parameter of the selective absorbers used in domestic solar collectors playsan important effect on the performance of the collectors and caused their operational efficiency isincreased in this study a correlation between microstructural features and the optical properties of thesecoatings has been established and it is shown that the embowed morphology caused that the solarabsorptance is increased finally the observation of effects of anodic alumina thickness and depositiondensity of the inorganic pigments on spectral reflectivity was studied and efficiency of solar absorbercoatings for usage in solar thermal collectors has been evaluated and so it is found that colored coppercoatings in comparison with colored tin and nickel coatings have better optical properties and higher solarabsorptance Key WordsSolar absorber coatings optical properties color anodizing aluminium

حيدري، عليرضا

ايجاد پوشش هاي جاذب خورشيدي به روش آندايزينگ رنگي آلومينيوم و ارزيابي خواص تابشي آن

سطوح جاذب خورشيدي , سيتم هاي كلكتور حرارتي