Impact of swallow-shaped bionic ribs on the thermal–hydraulic performance of parabolic trough solar collector

• Swallow-shaped bionic ribs are proposed for heat transfer enhancement . • Longitudinal vortices enhance the synergy between velocity and temperature gradients . • Smaller rib included angles intensify fluid scouring in high-heat-flux regions. • Reduced rib pitch sustains vortices for broader heat transfer enhancement . Parabolic trough solar collectors play an important role in the utilization of renewable energy. However, their thermal efficiency is limited by the insufficient heat transfer in the absorber tube, leading to significant energy losses. This study investigated the efficacy of two novel swallow-shaped bionic ribs in enhancing the heat transfer while reducing entropy generation and mitigating thermal gradients. Numerical simulation methods were employed to analyze the flow dynamics, temperature distribution, entropy production, and influence of rib geometry parameters (included angle and pitch) on the performance of absorber tubes. The longitudinal vortices induced by the swallow-shaped bionic ribs enhanced the synergy between the velocity and temperature gradients , reduced the peak temperature, rendered the temperature gradient more uniform, reduced the maximum heat loss by 13.02 %, and reduced the total entropy production by 26.6 %. The Nusselt number ( Nu ) increased by 29–40 %, accompanied by an increase in the friction factor ( f ) (54.5–92.1 %), achieving a peak performance evaluation criterion (PEC) of 1.21. Smaller swallow-shaped bionic ribs included angles intensified fluid scouring in high-heat-flux regions, whereas a reduced rib pitch prolonged vortex persistence, expanding the heat transfer enhancement zones. This work demonstrated that swallow-shaped bionic ribs significantly improve the energy utilization efficiency of parabolic trough solar collectors, providing a reference for the design of next-generation high-efficiency solar heat collector systems.