Hydraulic-thermal-mechanical optimization of a bayonet tube for solar power tower receivers

This study presents a first-of-its-kind thermomechanical optimization of bayonet tubes for application in solar power tower (SPT) receivers, explicitly coupling three-dimensional CFD heat-transfer simulations with ASME-based analytical stress sizing under realistic, non-uniform solar flux. Bayonet tubes, composed of two tubes with one housed inside the other, are assessed for their ability to simultaneously reduce thermal gradients, mechanical stresses, and pumping losses without compromising thermal efficiency. A parametric analysis was conducted by varying the ratio of cross-sectional area ( R A ) and eccentricity ( ξ ), applying CFD simulations coupled with analytical thermal stress modeling. The results demonstrate that eccentricity enhances internal convection and reduces pressure drops, especially in configurations with RA close to unity. An optimal bayonet tube layout, defined by R A ≈ 0 . 95 and ξ ≈ 0 . 37 , was identified, achieving significant reductions in both peak temperature (832.5 K) and von Mises stress ( 556 . 7 MPa ). Multiple neighboring designs remain within 2.5% of these minima, offering design flexibility. A direct comparison with standard receiver tubes demonstrates superior thermal performance and comparable structural reliability, confirming that eccentric bayonet tubes constitute a validated, next-generation absorber concept for high-flux SPT receivers. • Parametric analysis reveals an optimal bayonet layout that minimizes peak temperature and stress. • Thermomechanical analysis of eccentric bayonet tubes for solar tower receivers. • Eccentric design reduces exterior wall temperature by more than 15%. • Optimal configuration at RA ≈ 0 . 95 and ξ ≈ 0 . 37 minimizes stress and peak temperature. • Pressure drop lowered by up to 32% with eccentric configurations.