Multilayer multifunctional advanced coatings for receivers of concentrated solar power plants
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Research Letter
Multilayer multifunctional advanced coatings for receivers of concentrated solar power plants L. Charpentier , PROMES-CNRS, 7 rue du Four Solaire, F-66120 Font-Romeu Odeillo, France D. Chen, SIMaP-Université Grenoble-Alpes/CNRS/Grenoble INP, 1130 rue de la piscine, Domaine Universitaire, BP75, F-38402 Saint-Martin d’Hères, France J. Colas, PROMES-CNRS, 7 rue du Four Solaire, F-66120 Font-Romeu Odeillo, France F. Mercier and M. Pons, SIMaP-Université Grenoble-Alpes/CNRS/Grenoble INP, 1130 rue de la piscine, Domaine Universitaire, BP75, F-38402 SaintMartin d’Hères, France D. Pique and G. Giusti, Sil’tronix Silicon Technologies, 382 rue Louis Rustin, Technopole d’Archamps, F-74160 Archamps, France J.L. Sans, and M. Balat-Pichelin, PROMES-CNRS, 7 rue du Four Solaire, F-66120 Font-Romeu Odeillo, France Address all correspondence to L. Charpentier at [email protected] (Received 17 June 2019; accepted 6 September 2019)
Abstract The extending market of concentrated solar power plants requires high-temperature materials for solar surface receivers that would ideally heat an air coolant beyond 1300 K. This work presents investigation on high-temperature alloys with ceramic coatings (AlN or SiC/AlN stacking) to combine the properties of the substrate (creep resistance, machinability) and coating (slow oxidation kinetics, high solar absorptivity). The first results showed that high-temperature oxidation resistance and optical properties of metallic alloys were improved by the different coatings. However, the fast thermal shocks led to high stress levels not compatible due to the differences in thermal expansion coefficients.
Introduction The market of the concentrated solar power plants is extending and several commercial plants are operating using steam-based Rankine cycles below 870 K. A major improvement can be achieved by using gas-based Brayton cycles that could ideally heat an air coolant beyond 1070 K, which requires the use of high-temperature materials for solar surface receivers.[1] Heat exiting from the Brayton cycle could be then sent to a steam generator following a secondary Ranking cycle. A recent paper has shown that the combination of gas-based Brayton, steam-based Rankine, and organic-based Rankine cycles could afford to reach an efficiency (defined as the ratio of the electric power produced to the incoming solar power) of 33%.[2] The efficiency of the solar receiver to convert the incoming solar flux into thermal energy mainly relies on two radiative properties: (i) the solar absorptivity α which determines the fraction of the incoming solar flux that could be absorbed and (ii) the total emissivity ε that determines the radiative thermal losses. An ideal receiver would present an absorptivity close to 1 and an emissivity close to 0. This is difficult to obtain because solar spectrum and blackbody emittance areas overlap when the temperature is increasing. Additionally, the formation of an oxide layer can seriously affect satisfactory native properties as already observed for TaC.[
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