Convective mass transfer enhancement in a membrane channel by delta winglets and their comparison with rectangular winglets

Numerical calculations were conducted to simulate the flow and mass transfer in narrow membrane channels equipped with delta winglets, which are often used as longitudinal vortex generators to enhance heat transfer in heat exchanger applications. The channel consists of an impermeable solid wall and a membrane. The delta winglets are attached to the solid wall surface to enhance the mass transfer near the membrane surface and suppress the concentration polarization. The winglet performance was evaluated in terms of concentration polarization factor versus consumed pumping power. Calculations were implemented for NaCl solution flow in a membrane channel having a height of 2.0 mm for Reynolds numbers ranging from 400 to 1000. The delta winglets were optimized under equal pumping power condition, and the results of optimization suggest winglet height of 5/6 of the channel height, aspect ratio of 2.0, attack angle of 30°, and a winglet interval equal to the channel height. The optimal delta winglets were compared with the optimal rectangular winglets we found previously, and it is shown that the rectangular winglets yield a somewhat better performance than the delta winglets.

Flow and mass transfer in membrane channels equipped with delta winglets were numerically simulated. The channel consists of an impermeable solid wall and a membrane with a spacing of 2.0 mm. The winglets were optimized in geometry under equal pumping power condition, with the winglet performance being evaluated in terms of concentration polarization factor versus consumed pumping power with Reynolds numbers ranging from 400 to 1000. The optimized delta winglets were compared with the rectangular winglets we optimized previously, and the results show that the rectangular winglets have a slightly better performance than the delta winglets.Membrane channel with delta wingletsFigure optionsDownload as PowerPoint slide