Heat transfer intensification of a compact heat exchanger through- composed passive techniques with wavy-fin and longitudinal vortices generators

Resumo

Considering the current need for continuous research to develop heat exchangers with high efficiency
with low-pressure drop penalty, aiming to cost reduction in materials and manufacturing process, the present
work evaluates a compact heat exchanger with wavy-fin and longitudinal vortex generator. The numerical
approach considers a heat exchanger with circular and elliptical tubes and delta-winglet and rectangular-winglet
vortex generator with an aspect ratio of 2 and angle of attack angle of 45°, for low Reynolds number. The heat
transfer is evaluated by Colburn’s factor (j) and the pressure drop is analyzed by Friction factor (f). The flow is
considered tridimensional, steady-state and turbulent. In comparison to the reference heat exchanger, the results
showed a heat transfer improvement of 41% by using elliptical tubes associated with a rectangular-winglet
vortex generator. For the friction factor, the configuration with rectangular-winglet vortex generators presented a
higher pressure drop than the delta-winglet type and the arrangements of circular tubes showed a higher friction
factor than elliptical tubes. Overall, the results showed that the composed passive technique is effective to
enhance the heat exchange in compact heat exchangers.