Study on the flow next to the membrane wall in air gap membrane distillation hot-cavity by PIV

The paper provides the experimental data and an application reference for designing high-performance air-gap membrane distillation system. Using the Particle Image Velocimetry (PIV) technology, this paper is to study the flow mechanism of rotary tangential inflow through capturing different parameters of inlet nozzle´s installation angles and gaps between the membrane and the nozzle like duck-mouth. The paper indicates that the positive correlation between the inlet nozzle scouring velocity and the fluid of the membrane flow on the hot side: the higher velocity on the membrane wall, the faster the fluid. When there is more fluid going through the membrane wall and, at the same time, the membrane wall has more heat and water molecules to destroy temperaturepolarization and concentration-polarization, the membrane flux increases accordingly. The inlet nozzle scouring area and the area of high membrane flux in membrane wall have the positive correlation, too. The experiment results show when hot-cavity parameters is δ=5mm, β=40°, it achieves the maximum scouring velocity and scouring area.