Determination of local velocity, energy dissipation and phase fraction with LIF- and PIV-measurement in a Kühni miniplant extraction column

Laser based measurement techniques were used to investigate the local velocities, the energy dissipation and the phase fraction inside a Kühni miniplant extraction column. The velocity field was determined with particle image velocimetry (PIV). The energy dissipation was obtained based on these measurements. The velocity measurements show that at extreme low dispersed phase flow the flow pattern alters extremely. The local time averaged phase fraction was measured with a laser induced fluorescence (LIF) system. It is shown that the accumulation underneath the stirrer has a high impact on the concentration of the dispersed phase in a single compartment. A higher rotational speed leads to a better distribution of droplets inside the column, whereas at lower stirring speed the droplets by-pass the impeller. Due to the shear force, especially near the stirrer outflow region, drop deformation and breakage occurs.

► We measure local velocity field, energy dissipation and phase fraction.
► We examine an influence of throughput to the vortex structure.
► Energy dissipation can be calculated using an analytical method and a gradient method.
► Influence of the spatial resolution is observed.
► LIF measurements are used for local phase fraction measurements.