Hybrid PIV/PTV measurements of velocity and position distributions of gas-conveyed particles in small, narrow channels

Pneumatic conveying of particles is generally applied in large ducts. However, new applications are emerging which benefit from millimeter-sized ducts; for example, triboelectric separators where intensive wall-particle contact is desirable. An optical method is proposed to measure the distribution of the position and velocity of 100–1000 µm particles in such narrow ducts. Images of the system are captured using a digital camera on which a Hough transform is applied to detect the particles and their positions. The velocities are acquired by applying a hybrid particle tracking and particle image velocimetry approach. This made it is possible to overcome challenges caused by suboptimal lighting, nonsmooth background, and a large ratio between particle and duct diameter . It is shown that the algorithm is subpixel accurate when sufficient particles can be sampled. Finally, typical results are shown to illustrate the method's capabilities. © 2015 American Institute of Chemical Engineers AIChE J, 2015