EXPERIMENTAL AND NUMERICAL INVESTIGATION OF THERMAL -HYDRAULIC PERFORMANCE IN WAVY FIN-AND-FLAT TUBE HEAT EXCHANGERS

摘要

To more deeply understand the enhanced heat transfer mechanism and optimization design for wavy fin and flat tube heat exchangers, three-dimensional numerical simulations and experimental investigation of air flow and heat transfer characteristics are presented in this study. The numerical simulation results compared with the wind tunnel test data, the results show that the numerical simulation results are in good agreement with the test. The experimental results show that the flow transition from laminar to turbulent occurs at earlier Reynolds number around 1000. In the range of Re=1000-5500, the standard k-ε mode (SST) is more suitable to predict the air flow and heat transfer of wavy fin. The waviness amplitude has the distinct effect on the heat transfer and pressure drop of wavy fin, while the wavy fin profile (Triangular, Sinusoidal and Triangular round corner) has little effect on the heat transfer performance. In additional, the enhanced heat transfer mechanism of wavy fin is explained in view of field synergy principle. Reduction the synergy angle between velocity and temperature gradient will lead to increase the heat transfer coefficients of wavy fin.