Turbulent Residence Time

Large-scale reactors are usually made from stationary parts, often involving baffles. They make use of the baffled- imposed turbulence to provide mixing within the reactor. Yet, such reactors need to be optimized as too much baffling can create unnecessary turbulence and pressure drops. Too few can lead to short-circuiting and dead zones.

An indication of residence time is a pointer toward the effectiveness of a reactor design often indicated by tracers.

This model studies the residence time in a turbulent reactor and compares a 2D approximation with a full 3D model of the reactor. It does so by first solving for a stationary turbulent flow in the reactor, using the k-epsilon model, and then solving for a mass balance on top of this flow field in the time-domain.

Mass transport is described through convection and diffusion, where the turbulent viscosity from the k-epsilon model is used to describe the species diffusion in the mass balance. A tracer species is introduced as a burst of concentration, and its journey through the reactor is studied.

Slice and streamline plot showing the velocity field in the reactor.

Animated Model