Abstract:
The Performances of direct absorption solar collectors (DASC) are limited by the stability of the nanofluid’s optical properties. This study investigates the performance and long-term stability of a graphene-based nanofluid under real on-sun operating conditions using an experimental parabolic trough pilot. The on-sun experiments were complemented with a detailed off-sun experimental evaluation of the nanofluid stability with temperature. Experimental results show that while the nanofluid optical properties remained stable over long periods (over two and a half months) and across varying temperatures (up to 80 °C) in a controlled environment, exposure to actual operational conditions in a parabolic trough collector working in closed loop caused significant degradation of optical properties, particularly due to pH changes due to corrosion in the collector hydraulic circuit. Despite this, overall photo-thermal conversion efficiencies of 62.3 ± 0.6 % and 74.3 ± 0.8 % were achieved with graphene concentrations of 0.2 and 0.3 g/L respectively, a substantial improvement over the 24.5 ± 0.5 % achieved using demineralized water. These findings highlight the critical role of material compatibility in hydraulic systems with graphene/water nanofluids to minimize corrosion, maintain particle stability and preserve collector performance in practical applications.
Miguel Sainz-Manas, Alexis Vossier, Roger Garcia, Cyril Caliot, Françoise Bataille, Gilles Flamant,On-sun performance and stability of graphene nanofluids in concentrating direct absorption solar collectors,Sustainable Energy Technologies and Assessments,Volume 83,2025,104605,ISSN 2213-1388, https://doi.org/10.1016/j.seta.2025.104605
