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 solidwall surface to enhance the mass transfer near themembrane surface and suppress the concentration polarization. Thewinglet performancewas 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 mmfor 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 awinglet interval equal to the channel height. The optimal deltawingletswere comparedwith the optimal rectangular wingletswe found previously

and it is shown that the rectangular winglets yield a somewhat better performance than the delta winglets.