ABSTRACT
Residence time distribution (RTD) describes the distribution
of times required for fluid elements to pass through a
continuous-flow system. RTD function and associated flow
models have been widely used to characterize hydrodynamic
behavior of a variety of systems encountered in agricultural,
food, and biological engineering. RTD alone tells us how
long the various fluid elements have been in the system, and
it yields distinctive clues to the type of macromixing (dis-
tribution of matters by bulk circulation currents) occurring
within the system, but it does not tell us anything about the
degree of intermixing between fluid elements of different
ages (i.e., micromixing).[1] In addition to the RTD, an ade-
quate model of the flow pattern and knowledge of the extent
of micromixing or degree of segregation[2] are required to
fully characterize the hydraulic characteristics of a system.[1]
In the entry Fermentation: Residence Time Distribution, pp.
489-494, the basic concept, measurement techniques, and
associated mathematical models of RTD have been dis-
cussed. The scope of this entry is to review recent literature
on bioprocess applications of the RTD analysis. Additional
applications of the RTD analysis in the biomedical, food
process, and environmental fields are reviewed in the entry,
Residence Time: Distribution, pp. 1460-1468.
