12.6.3 Energy Balance for Multiple Reactions in a CSTR

Recall that for the steady-state mole balance in a CSTR with a single reaction [–F_A0X = r_AV,] and that , so that for T₀ = T_i0 Equation (11-27) may be rewritten as

11-27A

Again, we must account for the “heat generated” by all the reactions in the reactor. For q multiple reactions and m species, the CSTR energy balance becomes

12-39

Substituting Equation (12-20) for , neglecting the work term, and assuming constant heat capacities, Equation (12-39) becomes

12-40

For the two parallel reactions described in Example 12-5, the CSTR energy balance is

12-41

One of the major goals of this text is to have the reader solve problems involving multiple reactions with heat effects (cf. Problems P12-23_C, P12-24_C, P12-25_C, and P12-26_B). That’s exactly what we are doing in the next two examples!