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This work presents a systematic experimental study aimed at improving the efficiency of volumetric solar receivers through the use of periodic porous ceramic absorbers with tailored morphologies and pore sizes. The primary objective is to assess how controlled geometric design parameters influence the thermo-fluid dynamic behavior of solar absorbers operating under forced convection and simulated solar irradiation.
A total of 21 porous absorbers were investigated, corresponding to seven different periodic morphologies. Each morphology was manufactured with three characteristic pore size levels (large, medium, and small), resulting in a structured experimental matrix that enables isolation of pore size and morphology effects. All samples were produced using additive manufacturing techniques from the same ceramic material, ensuring identical material composition and optical properties across the test campaign. This approach allows observed performance differences to be attributed primarily to geometric effects rather than material variability.
The absorbers exhibit comparable external dimensions, with diameters close to 59 mm and depths of approximately 80 mm, while spanning a wide range of experimentally measured porosities (approximately 77–88%) and specific surface areas (roughly 350–850 m²/m³). This broad parameter diversity is representative of structures useful for volumetric receiver applications and enables investigation of the interplay between porosity, internal surface area, and convective heat transfer potential.
All experiments were conducted in a laboratory-scale solar simulator under controlled operating conditions. The incident radiative power was maintained quasi-constant throughout the experimental campaign to ensure repeatability. Each absorber was tested under two strongly contrasted air mass flow rates, representative of low and high forced-convection regimes, in order to evaluate the sensitivity of thermal behavior to flow conditions. The experimental setup allows qualitative assessment of the thermo-fluid response as a function of absorber geometry and operating regime.
The experimental results obtained for the periodic absorbers are systematically compared against a reference configuration featuring a constant pore size and a Voronoi-type structure, commonly employed as a benchmark geometry in volumetric solar absorber studies. This comparison provides a consistent baseline for evaluating the potential benefits of periodic architectures relative to more conventional, stochastic porous designs.
Although the present study focuses on experimental characterization rather than full performance optimization, it constitutes, to the authors’ knowledge, the first systematic experimental comparison of multiple periodic porous morphologies and pore sizes for volumetric solar receiver applications under controlled irradiation and flow conditions. The results provide a structured experimental dataset that can support future performance assessment, numerical modeling, and geometry-driven optimization of advanced volumetric solar absorbers.
COOPERANT project is funded by the European Union under the Grant Agreement Nº 101172882. This work was supported by the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract Nº 2400402.
| Country | SPAIN |
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