Heat transfer performance comparison of wavy finned tube heat exchanger with delta winglets under different arrays

3D numerical simulations were performed to investigate the flow and heat transfer characteristics of the wavy finned-tube heat exchanger with delta-wing vortex generators. Three rows of round tubes with in-lined or staggered arrangements are studied. Results show that the longitudinal vortex generated by the delta winglet includes a main vortex and a corner vertex. For in-lined array, the longitudinal vortices not only improve the heat transfer of the wake region, but also greatly enhance the heat transfer of the downstream tube wall of the delta winglet. While for staggered array, longitudinal vortices are inhibited immediately by the downstream wave trough, so the enhancement of heat transfer only exists in the wake region. When Re_DC is 3000, compared with the wavy fin without delta winglet, the j and f factors of the wavy fin with delta winglets in in-lined and staggered arrays are increased by 15.4%, 10.5% and 13.1%, 7.0%, respectively. The longitudinal vortices generated by delta winglet improve the heat transfer performance of wavy finned tube heat exchanger for both in-lined and staggered arrays.