The thermal-hydraulic performance evaluation of a triangular groove duct with L-shaped baffles: Multi-objective optimization and numerical analysis

Abstract

Enhancing heat transfer efficiency is crucial for improving performance and reducing the energy consumption of thermal equipment in various industrial sectors. The emergence of passive enhancement methods, such as corrugated grooves, has improved convective heat transfer cost-efficiently. To this end, this study addresses the thermal and hydraulic performance of the baffle duct with numerical analysis and multi-objective optimization methods. The study is innovative in that it places movable L-shaped baffles inside the duct, which have their own internal connections and a connection to the grooved channel. L-shaped baffles have the ability to move at alpha angles (α = 30°, 60°, 90°) with the upper wall of the duct and at beta angles (β = 60°, 90°, 120°, 150°) with their internal connection points, which affect the thermal and hydraulic performance of the duct. Air, water, mono (GO/water), and tetra hybrid (Al₂O₃-Au-Ag-TiO₂/water) nanofluids are used as coolant fluids in the range of Re = 2500 to 3100. The coolant air and a baffle-less triangular grooved duct are used for comparison to evaluate the thermal and hydrodynamic performance in other cases. The results show that at Re = 2500, the baffled duct achieves a 65% higher Nu than the one without baffles. As α = 90° decreases to 30°, Nu increases by 12.85% and 12.11%, respectively. As β = 60° to 120° increases, Nu increases by 21.67%, while f increases by 59% from β = 90° to 120°. The highest performance evaluation criteria (PEC) is achieved at β = 90° and the lowest at β = 150°. The tetra hybrid nanofluid exhibits the highest Nu and f values across all Re ranges, demonstrating the most efficient cooling performance with a PEC value approximately 8% higher than that of water. Multi-objective optimization reveals that the combination of α = 30°, β = 35°, Re = 2500, and water is the most suitable design. Generally, thermal and hydraulic performance can be significantly improved by carefully selecting channel geometry and fluid properties.