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- Ensayos de envejecimiento acelerado de reflectores solares sometidos a radiación UV y corrosiónPublication . Buendía-Martínez, F.; Fernández-García, A.; Sutter, F.; Wette, Johannes; Valenzuela, L.RESUMEN: La energía termosolar de concentración desempeña un rol fundamental en la transición energética prevista para los próximos años. La generación energética de esta tecnología depende enormemente del comportamiento óptico de los reflectores; si éste se ve mermado, el rendimiento de toda la planta solar se verá afectado. En consecuencia, utilizar un reflector adecuado puede suponer la diferencia entre el éxito o el fracaso de un proyecto. Para ciertas aplicaciones de esta energía, es necesario situar la planta solar en zonas cercanas a la costa donde la corrosividad y la dosis de radiación UV son muy elevadas. Por lo tanto, es necesario evaluar la durabilidad de los reflectores en dichos ambientes. Para ello, se han expuesto varias muestras de reflectores en Almería (España) para identificar los principales mecanismos de degradación que tienen lugar en los materiales. Además, se han realizado con éxito varios ensayos de envejecimiento acelerado que reproducen adecuadamente los principales mecanismos de degradación observados en intemperie, pero en un tiempo mucho menor. En particular, se ensayaron en condiciones aceleradas tres tipos de reflectores para evaluar su durabilidad frente a la corrosión y degradación UV.
- The importance of developing accelerated tests on the reliability of solar absorber and solar reflector coatingsPublication . Cunha Diamantino, Teresa; Gonçalves, Rita; Páscoa, Soraia; Alves, Isabel N.; Carvalho, Maria João; Fernández-García, Aránzazu; Wette, Johannes; Sutter, FlorianABSTRACT: Selective absorber coatings for solar thermal collectors and reflector coatings for Concentrating Solar Power (CSP) plants are the key components of these technologies and their durability is one of their most important characteristics. They should be low cost and withstand 20-30 years under different kinds of environments without significant loss of optical performance. Commercially, there are different physical vapour deposition (PVD) coatings for aluminium absorbers and reflectors. Results obtained with two commercial PVD solar absorber coatings (SA) and two solar reflector coatings (SR), under different accelerated aging tests (AAT), are presented and correlated with outdoor exposure. An Outdoor Exposure Testing (OET) site with maritime and industrial influence was used for an exposure campaign of the absorbers and reflectors for two years. Alternative artificial aging tests are proposed for absorbers and reflectors that better reproduce the corrosion mechanism obtained in natural conditions with maritime and industrial influence. The characterization of the coatings and degradation mechanisms of different aluminium absorbers and reflectors were evaluated optically, morphologically and chemically. The results obtained in an atmosphere with high corrosivity as in marine and/or industrial areas are a reliable way to verify the corrosion resistance of new materials in a short time and are a valuable tool to validate the different methodologies of accelerated aging tests.
- Detection of corrosion on silvered glass reflectors via image processingPublication . Wiesinger, Florian; Baghouil, Sarah; Le Baron, Estelle; Collignon, Romain; Santos, Filipa; Cunha Diamantino, Teresa; Catarino, Isabel; Facão, Jorge; Ferreira, Cristina; Páscoa, Soraia; Sutter, Florian; Fernández-García, Aránzazu; Wette, JohannesABSTRACT: A novel characterization technique based on image analysis is presented, intended to complement state-of-the-art reflectometer measurements. The technique is developed by experts from different laboratories (OPAC, AGC, CEA and LNEG), which subsequently conduct two Round Robin experiments on corroded solar reflectors for validation. Regarding the inter-comparability, it is found that parameters like the corrosion spot density or the penetration maximum on coated edges exhibit an average coefficient of variation of 62.6 % and 54.9 %. Better agreement is found for parameters like the total corroded area and the maximum edge corrosion penetration, with coefficients of variation of 14.3 % and 13.4 %, respectively. The developed methodology is further applied during a 68-month lasting outdoor exposure campaign of two types of solar reflectors at two representative sites, one exhibiting corrosivity class C2 and the other C3. On the commercial coating RL1, a total corroded area of 59 mm2 and 426 mm2 is measured after the outdoor exposure on the C2 and the C3 site, respectively, while on the novel low-lead coated reflector RL3 corresponding values are 280 mm2 and 1308 mm2. This shows the superior quality of the coating RL1 in terms of corrosion resistance. Furthermore, the analysis highlights the importance of proper edge sealing for corrosion protection, since corrosion penetration is increased by a factor between 1.3 and 4.0 if the edges are unprotected. The reflectance decrease after the outdoor exposure is regarded as negligible (0.000 - 0.005), thus not permitting any of the conclusions that are made from the novel image analysis technique.