(393b) Mean Age Distribution in General Time Dependent Flows of Multiphases

Residence time and age analysis has been a standard tool in chemical engineering for many types of flow systems. In this talk, governing equations for mean age and higher moments for general fluid flows of time dependent, multispecies, multiphase, with arbitrary number of inlets and outlets will be discussed. Tracer species can be released at any inlets or selected locations in the interior of the flow. It will be shown that mean residence time of a species or phase at an outlet is the mass flow averaged mean age at the outlet. Residence time frequency function can be defined at an outlet with the age frequency function that defines mean age in the interior of a flow. This residence time frequency function extends current residence time theory to fully time dependent for multiple species and multiple inlets and outlets. For a steady flow, the sum of the mass flow weighted mean residence times of a species at all outlets is equal to the total mass of the species in the flow. For an unsteady flow, mean residence time also depends on the rate of change of mass averaged age concentration. With these equations mean age and residence time analysis can be extended to flows and mixing in all types of flow systems, not limiting to steady flows of single phase only anymore.