Unsteady-State Lumped Systems

The systems to be studied in some detail here involve various aspects of a continuous-flow, well-agitated vessel, with interacting variables such as flow, pressure, mixing, and chemical reaction. The study of stirred tanks is important for two reasons. First, stirred tank vessels are an important and frequent piece of process equipment, and engineers must be capable of modeling this kind of system. Second, the stirred tank concept is an important idealized lumped unit which can be used effectively by an experienced engineer to simulate the behavior of more complicated process equipment. 

This chapter deals only with initial-value problems, for which numerical methods are well developed. 

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Batch reactors can be considered unsteady-state lumped systems with no input and no output, or it can be considered a distributed system in time (not in space) with the initial conditions as the feed conditions and the final conditions as the exit conditions. 

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