Chemical Engineering Science, Vol.63, No.19, 4649-4655, 2008
Measurements of micro- and macromixing in liquid mixtures of reacting components using two-colour laser induced fluorescence
The progress in mixing of two liquids with two way solubility is visualised by means of two-colour laser induced fluorescence (LIF). The mixing process is divided into two steps. In the first step, the so-called macromixing, the fluid elements of a multicomponent system are dispersed and deformed due to viscous friction. During the second step, the micromixing, local concentration differences are reduced due to diffusion transport on molecular scale. Both transport phenomena can be simultaneously measured by injecting a mixture of an inert and a reacting dye. The performance of mixing is recalculated from the local measurements of the concentration fields and visualised by the local degree of deviation. The mass transport on the microscopic scale varies because of the locally diverse dissipation of energy. Particle image velocimetry (PIV) measurements are used for the calculation of the source terms of local energy dissipation. The experimental results correlate the progress of mixing to the local energy dissipation. (c) 2007 Elsevier Ltd. All rights reserved.