Numerical investigation of parabolic trough collectors using hybrid nanofluids and modified receiver tube

Enhancing the thermal efficiency of parabolic trough collectors while reducing entropy generation remains a significant challenge in solar thermal energy systems, with limited exploration of advanced hybrid nanofluids combined with innovative receiver tube designs. This study aims to improve the thermal performance and operational stability of parabolic trough collectors through integration of hybrid nanofluids and a rotating concentric tube receiver equipped with porous fins. Computational fluid dynamics simulations are performed using ANSYS Fluent to evaluate the thermal behavior of an LS-2 model featuring an inner receiver tube rotating at angular velocities from 0 to 15 rad/s. Porous fins attached to the inner tube's surface increase the heat transfer surface area and promote fluid turbulence. Three hybrid nanofluid compositions with a fixed 1 % total volume fraction consisting of aluminium oxide and copper oxidenanoparticles in different ratios (25:75, 50:50, 75:25) dispersed in a 50:50 base fluid mixture of water and Syltherm 800 are analyzed to identify the optimal formulation. The system achieved 74.62 % thermal and 66.62 % exergy efficiency, 640 Nusselt number, and 39.76 % entropy reduction. The optimized nanofluid and rotating porous fins synergistically enhanced heat transfer offering new performance capabilities not previously reported in parabolic trough collector studies.This study presents novel and effective approach by integrating hybrid nanofluids with rotating porous-finned receiver tube design, which substantially improves thermal efficiency and decreases irreversibility in systems. This research fills a notable gap in the literature, as few studies examine this synergistic combination, thereby providing new insights for advancing solar thermal collector technology.