Computational Scheme for Variable-Density CSTRs

Example 4.3 represents the simplest possible example of a variable-density CSTR. The reaction is isothermal, first order, and irreversible and the density is a linear function of reactant concentration. This simplest system is about the most complicated one for which an analytical solution is possible. Realistic variable-density problems, whether in liquid or gas systems, require numerical solutions. These numerical solutions use the method of false transients and involve sets of first-order ODEs with various auxiliary functions. The solution methodology is similar to but simpler than that used for PERs in Chapter 3. Temperature is known and constant in this chapter. An equation for temperature will be added in Chapter 5 and is conceptually incorporated in the methodology that follows. 

The method of false transients begins with the inlet stream set to its steady-state values 

Pick the initial values ao, bo, Use the equation of state to calculate an initial 

Set flout, bout, , Tout, gout to the initial values determined in Step 0. 

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