Mixing in unbaffled high throughput experimentation reactors

With the increasing implementation of high-throughput experimentation techniques within research laboratories throughout the chemicals industries, it is important that the flow regimes in such unbaffled vessels be fully characterized and the implications on mixing performance be understood. Particle image velocimetry (PIV) and planar laser-induced fluorescence (PLIF) techniques are used in this work to study the mixing and hydrodynamic behavior of low-viscosity fluids in small stirred vessels with diameters 60 and 88 mm. Baffled and unbaffled vessels are considered, and the difference in efficiency is quantified at a constant power input per unit volume. Positioning the impeller into an eccentric configuration is adopted as a means toward improving mixing efficiency in unbaffled vessels. Results show that the eccentric configuration provides equally efficient mixing as the traditional baffled vessel in terms of mixing time and turbulent kinetic energy distribution. PIV and PLIF measurements show that the distribution of turbulent kinetic energy is more evenly spread in smaller vessels, leading to the conclusion that such vessels are better mixers.