Recent extensions of the residence time distribution concept: Unsteady state conditions and hydrodynamic model developments.

Two recent extensions of the residence time distribution concept are develo ped. The first one concerns the use of this method under transient conditio ns, a concept theoretically treated but rarely confirm by relevant experime nts. In the present work, two experimental set-ups have been used to verify some limits of the concept. The second extension is devoted to the develop ment of hydrodynamic models. Up to now, the hydrodynamics of the process ar e either determined by simple models (mixing cells in series, plug flow rea ctor with axial dispersion) or by the complex calculation of the velocity p rofile obtained via the Navier Stokes equations. An alternative is to devel op a hydrodynamic model by use of a complex network of interconnected eleme ntary reactors. Such models should be simple enough to be derived easily an d sufficiently complex to give a good representation of the behavior of the process.