Biomimetic design for In-tube heat transfer enhancement: experimental evaluation and thermodynamic optimization

This study addresses the trade-off between heat transfer enhancement and pressure penalty by investigating three novel bio-inspired turbulators (Wavy-Cell, Fish-Scale, Dragon-Egg). Comprehensive experiments were conducted under fully turbulent conditions (Re = 10,500- 15,000), integrated with Second-Law thermodynamic analysis and multi-objective optimization. The primary innovation lies in combining biomimetic geometries with entropy generation minimization. Results indicate that the 3-piece Wavy-Cell configuration achieved the highest thermal performance (TPF = 1.11) and a 15.4% reduction in total entropy generation compared to a plain pipe. Response Surface Methodology (RSM) yielded high-accuracy predictive models (R2 > 98%). Furthermore, a multi-criteria decision-making framework using Pareto-TOPSIS was employed to simultaneously optimize conflicting objectives: maximizing Nusselt number while minimizing friction factor and entropy generation. This analysis identified the 2-piece Fish-Scale configuration at Re = 15,000 as the optimal solution, offering the best thermodynamic balance despite having a slightly lower TPF than the Wavy-Cell. These findings validate the efficacy of bio-inspired designs for next-generation energy-efficient thermal systems.